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Title: A Dictionary of Arts, Manufactures and Mines
       containing a clear exposition of their principles and practice

Author: Andrew Ure

Release Date: January 1, 2014 [EBook #44562]

Language: English

Character set encoding: ISO-8859-1


Produced by Malcolm Farmer, Harry Lamé and the Online
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Please see the Transcriber’s Notes at the end of this text.

An alphabetical list of articles may be found here.





Second Edition.



Printed by A. Spottiswoode,



It is the business of operative industry to produce, transform, and distribute all such material objects as are suited to satisfy the wants of mankind. The primary production of these objects is assigned to the husbandman, the fisherman, and the miner; their transformation to the manufacturer and artisan; and their distribution to the engineer, shipwright, and sailor.[1] The unworked or raw materials are derived,—1. from the organic processes of vegetables and animals, conducted either without or with the fostering care of man; 2. from the boundless stores of mineral and metallic wealth, arranged upon or within the surface of the earth by the benignant Parent of our being, in the fittest condition to exercise our physical and intellectual powers in turning them to the uses of life.

[1] For correct and copious information upon agricultural production, I have great pleasure in referring my readers to Mr. Loudon’s elaborate Encyclopedias of Agriculture, Gardening, and Plants; and for mercantile production and distribution, to Mr. M’Culloch’s excellent Dictionary of Commerce and Commercial Navigation.

The task which I have undertaken in the present work, is to describe and explain the transformations of these primary materials, by mechanical and chemical agencies, into general objects of exchangeable value; leaving, on the one hand, to the mechanical engineer, that of investigating the motive powers of transformation and transport; and, on the other hand, to the handicraftsman, that of tracing their modifications into objects of special or local demand. Contemplated in this view, an art or manufacture may be defined to be that species of industry which effects a certain change in a substance, to suit it for the general market, by combining its parts in a new order and form, through mechanical or chemical means. Iron will serve the purpose of illustrating the nature of the distinctions here laid down, between mechanical engineering; arts and manufactures; and handicraft trades. The engineer perforates the ground with a shaft, or a drift, to the level of the ore, erects the pumps for drainage, the ventilating, and hoisting apparatus, along with the requisite[iv] steam or water power; he constructs the roads, the bridges, canals, railways, harbours, docks, cranes, &c., subservient to the transport of the ore and metal; he mounts the steam or water power, and bellows for working the blast-furnaces, the forges, and the cupolas; his principal end and aim on all occasions being to overcome the forces of inertia, gravity, and cohesion. The ores extracted and sorted by the miner, and transported by the engineer to the smelting station, are there skilfully blended by the iron-master (manufacturer), who treats them in a furnace appropriately constructed, along with their due proportions of flux and fuel, whereby he reduces them to cast iron of certain quality, which he runs off at the right periods into rough pigs or regular moulds; he then transforms this crude metal, by mechanical and chemical agencies, into bar and plate iron of various sizes and shapes, fit for the general market; he finally converts the best of the bars into steel, by the cementation furnace, the forge, and the tilt-hammer; or the best of the plates into tin-plate. When farther worked by definite and nearly uniform processes into objects of very general demand in all civilized countries, these iron and steel bars still belong to the domain of manufactures; as, for example, when made into anchors, chain-cables, files, nails, needles, wire, &c.; but when the iron is fashioned, into ever varying and capricious forms, they belong either to the general business of the founder and cutler, or to the particular calling of some handicraft, as the locksmith, gratesmith, coachsmith, gunsmith, tinman, &c.

Such are the principles which have served to guide me in selecting articles for the present volume. By them, as a clue, I have endeavoured to hold a steady course through the vast and otherwise perplexing labyrinth of arts, manufactures, and mines; avoiding alike engineering and mechanical arts, which cause no change in the texture or constitution of matter,—and handicraft operations, which are multiform, capricious, and hardly susceptible of scientific investigation. In fact, had such topics been introduced into the volume, it would have presented a miscellaneous farrago of incongruous articles, too numerous to allow of their being expounded in a manner either interesting or instructive to the manufacturer and the metallurgist. I readily acknowledge, however, that I have not been able to adhere always so rigorously as I could have wished to the above rule of selection; having been constrained by intelligent and influential friends to introduce a few articles which I would gladly have left to the mechanical engineer. Of these Printing is one, which, having had no provision made for it in my original plan, was too hastily compiled to admit of my describing, with suitable figures, the flat-printing automatic machine of Mr. Spottiswoode, wherewith the pages of this volume were worked off; a mechanism which I regard as the most elegant, precise, and productive, hitherto employed to execute the best style of letter press.

I have embodied in this work the results of my long experience as a Professor of Practical Science. Since the year 1805, when I entered at an early age upon the arduous task of conducting the schools of chemistry[v] and manufactures in the Andersonian Institution, up to the present day, I have been assiduously engaged in the study and improvement of most of the chemical and many of the mechanical arts. Consulted professionally by proprietors of factories, workshops, and mines, of various descriptions, both in this country and abroad, concerning derangements in their operations, or defects in their products, I have enjoyed peculiar opportunities of becoming familiar with their minutest details, and have frequently had the good fortune to rectify what was amiss, or to supply what was wanting. Of the stores of information thus acquired, I have availed myself on the present occasion; careful, meanwhile, to neglect no means of knowledge which my extensive intercourse with foreign nations affords.

I therefore humbly hope that this work will prove a valuable contribution to the literature of science, serving—

In the first place, to instruct the Manufacturer, Metallurgist, and Tradesman, in the principles of their respective processes, so as to render them in reality the masters of their business, and to emancipate them from a state of bondage to operatives, too commonly the slaves of blind prejudice and vicious routine.

Secondly, to afford to Merchants, Brokers, Drysalters, Druggists, and Officers of the Revenue, characteristic descriptions of the commodities which pass through their hands.

Thirdly, by exhibiting some of the finest developments of chemistry and physics, to lay open an excellent practical school to students of these kindred sciences.

Fourthly, to teach Capitalists, who may be desirous of placing their funds in some productive bank of industry, to select judiciously among plausible claimants.

Fifthly, to enable Gentlemen of the Law to become well acquainted with the nature of those patent schemes which are so apt to give rise to litigation.

Sixthly, to present to our Legislators such a clear exposition of our staple manufactures, as may dissuade them from enacting laws which obstruct industry, or cherish one branch of it to the injury of many others: and,

Lastly, to give the General Reader, intent chiefly on intellectual cultivation, a view of many of the noblest achievements of science, in effecting those grand transformations of matter to which Great Britain owes her paramount wealth, rank, and power among the kingdoms.

The latest statistics of every important object of manufacture is given, from the best, and, usually, from official authority, at the end of each article.[2]

[2] The statistics of agriculture, trade, and manufactures is ably and fully discussed in Mr. M’Culloch’s Dictionary already referred to.

The following summary of our manufactures is extracted from Mr. Macqueen’s General Statistics of the British Empire, published in 1836. It shows the amount of capital embarked in the various[vi] departments of manufacturing industry, and of the returns of that capital:—

  Capital. Produce.
  £ £
Cotton manufactures 40,973,872 52,513,586
Woollen ditto 36,000,000 44,250,000
Silk ditto 8,000,000 10,000,000
Linen ditto 12,000,000 15,421,186
Leather ditto 13,000,000 16,000,000
Iron ditto, to making pig iron 10,000,000 7,098,000
Ditto, hardware, cutlery, &c. 25,000,000 31,072,600
Copper and brass 3,600,000 4,673,186
China, glass, &c. 8,600,000 10,892,794
Paper, furniture, books, &c. 10,000,000 14,000,000
Spirits (British), ales, soap, &c. 37,600,000 47,163,847
Sundries additional   9,000,000
Totals 204,773,872 262,085,199

In consequence of an arrangement with Mr. William Newton, patent agent, and proprietor of the London Journal of Arts, Sciences, and Manufactures, I have been permitted to enrich this Dictionary with many interesting descriptions and illustrative figures of modern patent inventions and improvements, which I could not otherwise have presented to my readers. Mr. Newton has lately enhanced the value of his Journal by annexing to it a catalogue raisonnée, entitled “An Analytical Index to the Subjects contained in the 23 Volumes,” which constitute the first and second series. The subsequent 13 volumes, of his Conjoined Series, are of still superior interest; and the whole form a vast storehouse of Mechanical and Chemical Invention.

Although I am conscious of having used much diligence for many years in collecting information for this work, from every quarter within my reach, the utmost pains in preparing it for publication, and incessant vigilance during its passage through the press, yet I am fully aware that it must contain several errors and defects. These I shall study to rectify, should the Public deem this volume worthy of a supplement. In this hope, I earnestly solicit the suggestions of my readers; trusting that ere long our Post Office system will cease to be such an obstacle as it has long been to the collection and diffusion of useful knowledge, and a tax upon science which the remuneration of its literature cannot by any means bear.

Since this book is not a Methodical Treatise, but a Dictionary, one extensive subject may be necessarily dispersed through many articles. Thus, for example, information upon the manufacture of Colours will be found under azure; black pigment; bone-black; bronze; brown dye; calico-printing; carmine; carthamus; chromium; cochineal; crayons; dyeing; enamels; gold; gilding; gamboge; gray dye; green dye; green paints; indigo; kermes; lac dye; lakes; madder; massicot; mercury, periodide of; Naples yellow; orange dye; orpiment; paints, grinding of; ochres; paper-hangings; pastes; pearl white; Persian berries; pottery pigments; Prussian blue; purple of Cassius; red lead;[vii] rouge; Scheele’s green; Schweinfurth green; stained glass; terra di Sienna; ultramarine; umber; verditer; vermilion; vitrifiable colours, weld, white lead; woad; yellow, king’s.

A casual consulter of the Dictionary, who did not advert to this distribution, might surmise it to be most deficient, where it is in reality most copious.

The elaborate and costly Encyclopedias, and Dictionaries of Arts, which have appeared from time to time in this country, and abroad, have, for the most part, treated of the mechanical manufactures, more fully and correctly than of the chemical. The operations of the former are, in fact, tolerably obvious and accessible to the inspection of the curious; nor are they difficult to transfer into a book, with the aid of a draughtsman, even by a person but moderately versed in their principles. But those of the latter are not unfrequently involved in complicated manipulations, and depend, for their success, upon a delicate play of affinities, not to be understood without an operative familiarity with the processes themselves. Having enjoyed the best opportunities of studying the chemical arts upon the greatest scale in this kingdom and on the Continent, I may venture, without the imputation of arrogance, to claim for my work, in this respect, more precision and copiousness than its predecessors possess. I have gone as far in describing several curious processes, hitherto veiled in mystery, as I felt warranted, without breach of confidence, to go; regarding it as a sacred duty never to publish any secret whatever, without the consent of its proprietor. During my numerous tours through the factory districts of Great Britain, France, &c., many suggestions, however, have been presented to my mind, which I am quite at liberty to communicate in private, or carry into execution, in other districts too remote to excite injurious competition against the original inventors. I am also possessed of many plans of constructing manufactories, of which the limits of this volume did not permit me to avail myself, but which I am ready to furnish, upon moderate terms, to proper applicants. I conclude by pointing attention to the very insecure tenure by which patents for chemical or chemico-mechanical inventions are held; of which there is hardly one on record which may not be readily evaded by a person skilled in the resources of practical chemistry, or which could stand the ordeal of a court of law directed by an experienced chemist. The specifications of such patents stand in need of a thorough reform; being for the most part not only discreditable and delusive to the patentees, but calculated to involve them in one of the greatest of evils—a chancery suit.

13. Charlotte Street, Bedford Square,
March 1. 1839.

Dr. URE is preparing for publication, in one large volume, 8vo., Chemistry in Theory and Practice; embodying a New System of Research, of such facility and precision, as will enable chemical manufacturers of every class, medical practitioners, metallurgists, farmers, merchants, brokers, druggists, drysalters, officers of the revenue, as well as general students, to analyze their respective objects in much less time than is usually required at present by professional chemists. A descriptive Index will be annexed for converting this systematic work into a Dictionary of Chemical Science.




ABB-WOOL. Among clothiers, this term signifies the woof or weft.

ACETATE. (Acétate, Fr.; Essigsäure, Germ.) Any saline compound of which the acetic is the acid constituent; as acetate of soda, of iron, of copper, &c.

ACETATE OF ALUMINA, see Red Liquor and Mordant; of Copper, see Copper; of Iron, see Iron; of Lead, see Lead; of Lime, see Pyrolignous Acid.

ACETIC ACID (Acide Acétique, Fr.; Essigsäure, Germ.) is the name of the sour principle which exists in vinegar. It occurs, ready formed, in several products of the vegetable kingdom, and is generated during the spontaneous fermentation of many vegetable and animal juices. The sambucus nigra, or black elder, the phœnix dactilifera, and the rhus typhinus are plants which afford a notable quantity of vinegar. It is found, likewise, in the sweat, urine, milk, and stomach of animals. All infusions of animal or vegetable matters in water, when exposed for some time to the air, at a moderate temperature, ferment into vinegar; and most vegetables, when subjected to decomposition by fire, give off condensable vapours of acetic acid. All liquids containing alcohol are susceptible of passing into the state of vinegar; but the pre-existence of alcohol is not necessary to this change, as we learn from the acetification of vegetable soups, infusion of cabbage, starch—paste, &c.

Vinegar may be distinguished into four varieties, according to the mode of its production, though all of them are capable of being converted, by chemical means, into one identical acetic acid. 1. Wine vinegar. 2. Malt vinegar. 3. Sugar vinegar. 4. Wood vinegar, or pyrolignous acid. Fermentation is the source of the acid in the first three varieties. Here alcohol is first generated, and is next converted into vinegar by the influence of the air at a genial temperature; a change which will be investigated under Fermentation. But the conversion of spirit of wine into acetic acid may be demonstrated by direct experiment. When the vapour of alcohol is brought into contact in the atmosphere with the black powder obtained by mixing muriate of platina, potash, and alcohol, vinegar is rapidly formed at the expense of the alcohol. In Germany, where crude alcohol bears a low price, the manufacture of vinegar has been arranged upon that principle, which, as throwing some light on the process of acetification, I shall briefly describe. See Platinum for the mode of preparing the above powder.

Under a large case, which for experimental purposes may be made of glass, several saucer-shaped dishes of pottery or wood are to be placed in rows, upon shelves over each other, a few inches apart. A portion of the black platina powder moistened being suspended over each dish, let as much vinous spirits be put into them as the oxygen of the included air shall be adequate to acidify. This quantity may be inferred from the fact, that 1000 cubic inches of air can oxygenate 110 grains of absolute alcohol, converting them into 122 grains of absolute acetic acid, and 6412 grains of water.

The above simple apparatus is to be set in a light place (in sunshine, if convenient), at a temperature of from 68° to 86° Fahr., and the evaporation of the alcohol is to be promoted by hanging several leaves of porous paper in the case, with their bottom edges dipped in the spirit. In the course of a few minutes, a most interesting phenomenon will be perceived. The mutual action of the platina and the alcohol will be displayed by an increase of temperature, and a generation of acid vapours, which, condensing on the sides of the glass-case, trickle in streams to the bottom. This striking transformation continues till all the oxygen of the air be consumed. If we wish, then, to renew the process, we must open the case for a little, and replenish it with air. With a box of 12 cubic feet in capacity, and with a provision of 7 or 8 ounces of the platina powder[2] we can, in the course of a day, convert one pound of alcohol into pure acetic acid, fit for every purpose, culinary or chemical. With from 20 to 30 pounds of the platina powder (which does not waste), we may transform, daily, nearly 300 pounds of bad spirits into the finest vinegar. Though our revenue laws preclude the adoption of this elegant process upon the manufacturing scale in this country, it may be regarded as one of the greatest triumphs of chemistry, where art has rivalled nature in one of her most mysterious operations.

To readers acquainted with chemical symbols, the following numerical representation of the conversion of alcohol into acetic acid may be acceptable:—

580·64 parts by weight  of alcohol = H12 C4 O2  consist of
74·88   of hydrogen = H12
305·76   of carbon = C4
200·00   of oxygen = O2

If we combine with this mixture, 400 parts of oxygen = O4, we have,—

of water  =  337·44  =  H6 O3
acetic acid  =  643·20  =  H6 C4 O3

Hence, in this formation of vinegar, 100 parts by weight of alcohol take 68·89 parts of oxygen; and there are produced 58·11 parts of water, and 110·78 of acetic acid.

These beautiful experiments prove, that when in a mere mixture of alcohol and water, under the influence of the atmospheric air and heat, some vinegar comes to be formed after a considerable time, the same formation of vinegar takes place in a similar, but more effective, manner, when a ferment is present, which acts here in a somewhat analogous way to the platina powder in the preceding case. Several azotized substances serve as re-agents towards the acetous fermentation,—such as vinegar ready-made, vinegar-yeast, or lees, barley bread, leaven, beer barm, and similar vegetable matters, which contain gluten. The best and purest ferment is, however, vinegar itself. With this ferment we must conjoin, as an essential condition of acetification, the free access of atmospheric air.

It is a well-known fact, that spirituous liquors, as weak brandy, wine, and beer, &c., may be preserved for years in close vessels, without undergoing the acetous fermentation, even when they repose upon a layer of lees. It is equally well known, that these very liquors, if they stand for some time in open vessels, become readily sour, especially if exposed, also, to a somewhat high temperature. If we fill a flask with common brandy, and subject it, without a stopper, to the influence of air and warmth, the contained liquor may, at the end of many weeks, discover no sensible acidity: if we add to the same brandy a ferment, and stop the flask air-tight, everything will still remain unchanged; but if we leave a portion of air in the flask, or leave it uncorked, vinegar will soon make its appearance in the brandy.

If we investigate the nature of the air which remains over brandy in the act of acetification, we shall find that it consists entirely of carbonic acid and azote, the oxygen being absorbed and combined in the acetic acid and water formed.

Since this absorption of oxygen from the air can take place only at the surface of the fermenting liquors, we thus see the necessity and the practical importance of amplifying that surface, in order to accelerate and complete the acetification, by multiplying the points of contact between the alcohol and the oxygen. The essence of the new German method of rapid acetification depends upon this principle.

Temperature has also a remarkable influence on the formation of vinegar. The acid fermentation proceeds very feebly in the cold, but takes an accelerated pace as the heat is raised. It would even appear that spirituous vapours brought by themselves in contact with atmospheric air, without the aid of any ferment, are capable of being converted into acetic acid, since it has happened in the rectification of brandy, in a still furnished with a large capital and adopter pipe into which air was allowed to enter, that vinegar made its appearance. Hence, warmth does not seem to act as a promoter of the combination of alcohol with oxygen in a merely chemical point of view, but it acts, so to speak, physically. Over the warm liquor a stratum of spirit vapour appears to float, which, coming there into conflict with the atmospherical oxygen, probably causes the generation of some acetic acid, and thus accelerates the operation, much more than by the mere contact of the oxygen with the liquid surface.

When we expose any spirituous liquors, as wine, beer, &c., with the requisite ferment, to the external air, at a temperature of from 64° to 68° Fahr., the fluid, however clear before, becomes soon turbid; filamentous slimy particles begin to appear moving in the middle and on the sides of the vessel, and then form a scum on the top of the liquor. When this scum has acquired a certain thickness and consistence, it falls in a sediment to the bottom. The Germans call it the vinegar mother, as it serves to excite acetification in fresh liquors. Meanwhile, the liquor has become warmer than the surrounding[3] air, and the vinegar process betrays itself by diffusing a peculiar aroma in the apartment. Whenever all the alcohol present has been converted into acetic acid, the liquor comes into a state of repose; its temperature sinks to the pitch of the atmosphere; it becomes bright, and is the article well known by its taste and smell under the name of vinegar.

Genuine wine or raisin vinegar differs from that formed either from apples, or sugar, beer, &c., in containing wine-stone or tartar; by which peculiarity it may be distinguished, except in those cases where crude tartar has been artificially added to the other vinegars, as a disguise. Barley-malt vinegar contains some phosphoric acid, in the state of phosphate of lime or magnesia, derived from the grain.

After these general observations upon acetification, we shall now proceed to describe the processes for manufacturing vinegar on the commercial scale.

1. Wine vinegar.—The first consideration with a vinegar maker is a good fermenting room, in which the wines may be exposed to a steady temperature, with an adequate supply of atmospherical air. As this air is soon deprived of its oxygenous constituent, facilities ought to be provided for a renewal of it by moderate ventilation. The air holes for this purpose ought to be so contrived that they may be shut up when the temperature begins to fall too low, or in windy weather. The best mode of communicating the proper warmth to a chamber of this kind is by means of fire-flues or hot water pipes, running along its floor at the sides and ends, as in a hothouse; the fireplace being on the outside, so that no dust may be created by it within. The flue is best made of bricks, and may have a cross section of 10 or 12 inches by 15 deep. The soot deposited, even when coals are burned, will find ample space in the bottom of the flue, without interfering essentially with the draught, for a very long period, if it be made of the above dimensions. Low-roofed apartments are preferable to high ones; and those built with thick walls, of imperfectly conducting materials, such as bricks, lined with lath and plaster work. Should the chamber, however, have a high ceiling, the fermenting tuns must be raised to a suitable height on scaffolding, so as to benefit by the warmest air. Sometimes the vinegar vessels are placed at different levels; in which case the upper ones acetify their contents much sooner than the under, unless they are emptied and filled alternately, which is a good plan.

Orleans is the place most famous for vinegars. The building there destined to their manufacture is called a vinaigrerie, and is placed, indifferently, either on the ground floor or the floor above it; but it has always a southern exposure, to receive the influence of the sunbeams. The vessels employed for carrying on the fermentation are casks, called mothers. Formerly they were of a large capacity, containing about 460 litres (115 gallons, Eng.); but at the present day they are barrels of half that capacity, or somewhat less than an old English hogshead. It is now known that the wine passes sooner into vinegar the smaller the mass operated upon, the more extensive its contact with the air, and the more genial its warmth. These casks were formerly arranged in three ranks by means of massive scaffolding; they are now set in four ranks, but they rest on much smaller rafters, sustained by uprights, and can be packed closer together. The casks, which are laid horizontally, are pierced at the upper surface of their front end with two holes: one, to which the name of eye is given, is two inches in diameter; it serves for putting in the charge, and drawing off the vinegar when it is made; the other hole is much smaller, and is placed immediately alongside; it is merely an air hole, and is necessary to allow the air to escape, because the funnel completely fills the other hole in the act of filling the cask.

When new vessels are mounted in a vinegar work, they must be one third filled with the best vinegar that can be procured, which becomes the true mother of the vinegar to be made; because it is upon this portion that the wine to be acidified is successively added. At the ordinary rate of work, they put at first upon the mother, which occupies one third of the vessel, a broc of 10 litres of red or white wine; eight days afterwards they add a second broc; then a third, and a fourth, always observing the same interval of time, 8 days. After this last charge, they draw off about 40 litres of vinegar, and then recommence the successive additions.

It is necessary that the vessel be always one third empty if we wish the acetification to go on steadily; but as a portion of the tartar and the lees forms and accumulates in the lower part of the cask, so as eventually to counteract the fermentation, the time arrives when it is requisite to interrupt it, in order to remove this residuum, by clearing out all the contents. The whole materials must be renovated every 10 years; but the casks, if well made and repaired, will serve for 25 years.

We have mentioned a definite period at which the vinegar may be drawn off; but that was on the supposition that the process had all the success we could wish: there are circumstances, difficult to appreciate, which modify its progress, as we shall presently show. We ought, therefore, before discharging the vinegar, to test and see if the fermentation[4] has been complete. We proceed as follows: we plunge into the liquor a white stick or rod, bent at one end, and then draw it out in a horizontal direction: if it be covered with a white thick froth, to which is given the name of work (travail), we judge that the operation is terminated; but if the work, instead of being white and pearly, be red, the manufacturers regard the fermentation to be unfinished, and they endeavour to make it advance, by adding fresh wine, or by increasing the heat of the apartment.

It is not always easy to explain why the fermentation does not go on as rapidly in one case as in another. There are even certain things which seem at present to be entirely inexplicable. It happens sometimes, for example, that although all the vessels have been equally charged, and with the same wine, yet the fermentation does not form in the same manner in the whole; it will move rapidly in some, be languid, or altogether inert, in others. This is a very puzzling anomaly; which has been ascribed to electrical and other obscure causes, because it is not owing to want of heat, the casks in the warmest positions being frequently in fault; nor to the timber of the cask. It, however, paralyses the process so completely that the most expert vinegar makers have nothing else for it, when this accident happens, than to empty entirely what they call the lazy cask, and to fill it with their best vinegar. The fermentation now begins, and proceeds as well in it as in the others. See Fermentation.

We must here make an important remark, relatively to the temperature which should prevail in the fermentation room. In many chemical works we find it stated, that the heat should not exceed 18° R., or 65° Fahr., for fear of obtaining bad products. But the vinegar makers constantly keep up the heat at from 24° to 25° R., 75° to 77° F.; when the acetification advances much more rapidly, and the vinegar is equally strong. The best proof of this heat not being too high is, that under it, the vessels in the upper part of the room, work best and quickest. In Orleans, cast-iron stoves and wood fuel are used for communicating the requisite warmth.

Before pouring the wine into the mothers, it is clarified in the following manner. There are tuns which can contain from 12 to 15 pieces of wine. Their upper end has at its centre an opening of four or five inches diameter, which may be closed afterwards with a wooden cover; this opening is for the purpose of receiving a large funnel. The inside of the tun is filled with chips of beechwood, well pressed down. The wine is poured upon these chips, allowed to remain for some time, and then gently drawn off by a pipe in the lower part of the vessel. The lees are deposited upon the chips, and the wine runs off quite clear. However, it happens sometimes, notwithstanding this precaution, that the vinegar, after it is made, requires to be clarified, more particularly if the wine employed had been weak. The vinegar must be filtered in the same way; and it derives an advantage from it, as the products of different casks get thereby mixed and made uniform.

By this Orleans method several weeks elapse before the acetification is finished; but a plan has been lately devised in Germany to quicken greatly the acid fermentation by peculiar constructions. This system is called, the quick vinegar work, because it will complete the process in the course of 2 or 3 days, or even in a shorter time. It depends, chiefly, upon the peculiar construction of the fermenting vessels, whereby the vinous liquor is exposed on a vastly expanded surface to the action of the atmospheric air.

An oaken tub, somewhat narrower at the bottom than the top, from 6 to 7 feet high and 3 feet in diameter, is furnished with a well-fitted grooved, but loose, cover. About half a foot from its mouth, the tub has a strong oak or beech hoop fitted to its inside surface, sufficiently firm to support a second cover, also well fitted, but moveable. The space under this second cover is destined to contain the vinous liquor, and in order to bring it very amply into contact with the atmosphere, the following contrivances have been resorted to: This cover is perforated, like a sieve, with small holes, of from 1 to 2 lines in diameter, and about 112 inch apart. Through each of these holes a wick of pack-thread or cotton is drawn, about 6 inches long, which is prevented from falling through by a knot on its upper end, while its under part hangs free in the lower space. The wicks must be just so thick as to allow of the liquor poured above the cover passing through the holes in drops. The edges of the lid must be packed with tow or hemp to prevent the liquor running down through the interval.

The whole lower compartment is now to be filled with chips of beechwood up to nearly the perforated cover. The liquor, as it trickles through the holes, diffuses itself over the chips, and, sinking slowly, collects at the bottom of the tub. The chips should be prepared for this purpose by being repeatedly scalded in boiling water, then dried, and imbued with hot vinegar. The same measures may also be adopted for the tub. To provide for the renewal of the air, the tub is perforated at about a foot from its bottom with eight holes, set equally apart round the circumference, two thirds of an inch wide, and sloping down, through which the air may enter into this lower compartment, without the trickling liquor being allowed to flow out. In order that the foul air which has[5] become useless may escape, four large holes are pierced in the sieve cover, at equal distances asunder and from the centre, whose united areas are rather smaller than the total areas of the holes in the side of the tub. Into these four holes open glass tubes must be inserted, so as to stand some inches above the cover, and to prevent any of the liquor from running through them. The proper circulation of the air takes place through these draught holes. This air may afterwards pass off through a hole of 212 inches diameter in the uppermost cover, in which a funnel is placed for the supply of liquor as it is wanted to keep up the percolation.

The temperature of the fermenting compartment is ascertained by means of a thermometer, whose bulb is inserted in a hole through its side, and fastened by a perforated cork. The liquor collected in the under vessel runs off by a syphon inserted near its bottom, the leg of which turns up to nearly the level of the ventilating air pipes before it is bent outwards and downwards. Thus the liquor will begin to flow out of the under compartment only when it stands in it a little below the sieve cover, and then it will run slowly off at the inclined mouth of the syphon, at a level of about 3 inches below the lower end of the glass tubes. There is a vessel placed below, upon the ground, to receive it. The tub itself is supported upon a wooden frame, or a pier of brickwork, a foot or 18 inches high.

A tub constructed like the above is called a GRADUATION VESSEL, which see. It is worked in the following way:—The vinegar room must be, in the first place, heated to from 100° to 110° F., or till the thermometer in the graduation vessel indicates at least 77°. The heat may then be modified. We now pour through the uppermost cover of the tub a mixture, warmed to 144° F., of 8 parts proof spirits, 25 parts soft water, 15 parts of good vinegar, and as much clear wine or beer. The water should be first heated, and then the vinegar, spirits, and wine may be added to it. Of this mixture, so much should be poured in as is necessary to cover over the second lid, 2 or 3 inches deep, with the liquor; after which, the rest may be poured slowly in, as it is wanted.

When the liquor has run for the first time through the graduation vessel, it is not yet sufficiently acidified; but the weak vinegar collected in the exterior receiving cistern must be a second time, and, if need be, a third time, passed through the graduation tub, in order to convert all the alcohol into acetic acid. In general, we may remark, that the stronger the vinous liquor the more difficult and tedious is its conversion into vinegar, but it is so much the stronger. To lessen this difficulty somewhat, it would be well not to put all the spirits at first into the wash, or mixed liquors, but to add a little more of it at the second and the third running, especially when we desire to have very strong vinegar.

After the graduation vessel has been some days at work, it is no longer necessary to add vinegar to the mixture of spirits and water, since the sides of the graduation tub, the beech chips, and the packthreads, are all impregnated with the ferment, and supply its place. The mixture must, however, be always maintained at the temperature of 100°.

Instead of the above mixture of brandy, water, and wine, we may employ, according to Dingler, a clear fermented wort of malt, mixed with a little spirits. The perfect vinegar, which collects in the receiving cistern, may be immediately racked off into the store casks for sale.

It has been objected to this process, that, in consequence of the mixture of saccharine and glutinous materials, which are contained in beer or worts, along with the acetous fermentation, there is also, partially, a vinous fermentation, and much carbonic acid, thereby disengaged, so as to obstruct the acetification. This obstruction may be remedied by a freer circulation of air, or by the exposure of quicklime in the chamber. It is a more substantial objection, that, from the addition of beer, &c., more lees, or dregs, are deposited in the graduation tub, whereby a more frequent cleansing of it, and of the beech chips, with a loss of time and vinegar, becomes necessary. The only mode of obviating this difficulty is, to take well-clarified fermented wash.

Another evil attendant on the quick process is, the evaporation of the spirituous liquors. Since, in the graduation tub, there is a temperature of 110°, it is impossible to avoid a loss of spirit from the circulation and efflux of the air. The air, indeed, that issues from the top hole in the uppermost cover, might be conducted over an extensive surface of fresh water, where its spirit would be condensed in a great measure. But, after all, this fear of great loss is, I believe, groundless; because the spirit is rapidly acidified by the oxygen of the air, and thereby rapidly loses its volatility.

The supply of the warm wash should be drawn from a cistern placed near the ceiling, where the temperature of the apartment is hottest; and it may be replenished from the partly acetified liquor in the cistern on the floor. With this view, two cisterns should be placed above, so that one of them may always contain liquor sufficiently hot, and thus the process will suffer no interruption.

When malt wash is used for this quick process, the resulting vinegar must be clarified[6] in a tun with beech chips, as above described. In two or three days the impurities will be deposited, and the fine vinegar may be racked off.

The following prescription, for preparing what he calls malt wine, is given by Dr. Kastner. Eighty pounds of pale barley malt, and 40 pounds of pale wheat malt, are to be crushed together. These 120 pounds are to be infused with 150 quarts of water, at the temperature of 122° Fahr., afterwards with 300 quarts of boiling water, and the whole body is to be mashed thoroughly, till all the lumps disappear. It is then to be left at rest in a large covered tub, for two or three hours, to allow the grains to settle down, from which the wort is to be drawn off. When it has fallen to the temperature of 64° Fahr., 15 pounds of good yeast are to be stirred in, and it must now be left for two or three days to ferment, in a loosely covered tun. When the vinous fermentation has taken place, the clear liquor must be drawn off by a tap hole, a little above the bottom, so as to leave the lees and scum in the tun. This malt wine, he adds, may be kept for a long time in close vessels, and is always ready for making quick vinegar.

2. Malt Vinegar.—The greater part of British vinegar is made from malt, by the following process:—1 boll of good barley malt, properly crushed, is to be mashed with water at 160° Fahr. The first water should have that temperature; the second must be hotter than 160°, and the third water, for the extraction of all the soluble matter, may be boiling hot. Upon the whole, not more than 100 gallons of wort should be extracted. After the liquor has cooled to 75° Fahr., 3 or 4 gallons of beer yeast are poured in, and well mixed with a proper stirrer. In 36 or 40 hours, according to the temperature of the air, and the fermenting quality of the wash, it is racked off into casks, which are laid upon their sides in the fermenting apartment of the vinegar work, which should be kept at a temperature of 70° at least; in summer partly by the heat of the sun, but in general by the agency of proper stoves, as above described. The bung-holes should be left open, and the casks should not be full, in order that the air may act over an extensive surface of the liquor. It would be proper to secure a freer circulation to the air, by boring a hole in each end of the cask, near its upper edge. As the liquor, by evaporation, would be generally a few degrees colder than the air of the apartment, a circulation of air would be established in at the bung-hole, and out by the end holes. By the ordinary methods, three months are required to make this vinegar marketable, or fit for the manufacture of sugar of lead.

In making vinegar for domestic purposes, the casks are usually set on their ends; and they have, sometimes, a false bottom, pierced with holes, placed about a foot above the true one. On this bottom, a quantity of rape, or the refuse raisins, &c. from the making of British wines, is laid. The malt liquor has a proper quantity of yeast added to it. In about 24 hours it becomes warm, and is then racked off into another similar cask. After some time, this racking process is discontinued, and the vinegar is allowed to complete its fermentation quietly. The proper temperature must always be kept up, by placing the cask in a warm situation. A little wine-stone (argal) added to the malt wash, would make the vinegar liker that made from wine. Sometimes a little isinglass is employed to clarify vinegar. A portion of sulphuric acid is often added to it.

3. Sugar vinegar.—By pursuing the following plan, an excellent sugar vinegar may be made. In 158 quarts of boiling water dissolve 10 pounds of sugar, and 6 pounds of wine-stone; put the solution into a fermenting cask, and when it is cooled to the temperature of from 75° to 80°, add 4 quarts of beer yeast to it. Stir the mixture well, then cover the vessel loosely, and expose it for 6 or 8 days to the vinous fermentation, at a temperature of from 70° to 75° Fahr. When it has become clear, draw off the vinous liquor, and either acetify it in the graduation tub above described, or by the common vinegar process. Before it is finished, we should add to it 12 quarts of strong spirits (brandy), and 15 quarts of good vinegar, to complete the acetous fermentation. With a graduation tub which has been used, this addition of vinegar is unnecessary.

The following simpler prescription for making sugar vinegar deserves attention. For every gallon of hot water take 18 ounces of sugar; and when the syrup has cooled to 75°, add 4 per cent., by measure, of yeast. When the vinous fermentation is pretty well advanced, in the course of 2 or 3 days, rack off the clear wash from the lees into a proper cask, and add 1 ounce of wine-stone, and 1 of crushed raisins, for every gallon of water. Expose it in a proper manner, and for a proper time, to the acetifying process; and then rack off the vinegar, and fine it upon beech chips. It should be afterwards put into bottles, which are to be well corked.

Vinegar obtained by the preceding methods has always a yellowish or brownish colour. It may be rendered colourless by distillation. For nicer chemical purposes, this is done in a glass retort; but on a large scale, it is usually performed in a clean copper still, furnished with a capital and worm-refrigeratory, either of silver or block tin. It is volatile at the boiling temperature of water; and if the process be carried on briskly, it will not sensibly corrode the copper. But we can never obtain, in this way, a strong article; for, as soon as the vinegar gets concentrated to a certain degree, we[7] cannot force off the remainder by heat, for fear of giving it an empyreumatic odour; because the gluten, colouring matter, &c. begin to adhere to the bottom of the still. We are, therefore, obliged to suspend the operation at the very time when the acid is acquiring strength. It has been also proposed to concentrate vinegar by the process of congelation; but much of it remains entangled among the frozen water; and common distilled vinegar is so weak, that it congeals in one mass.

Vinegar still

Fig. 1.

Before the process for pyrolignous acid, or wood vinegar, was known, there was only one method of obtaining strong vinegar practised by chemists; and it is still followed by some operators, to prepare what is called radical or aromatic vinegar. This consists in decomposing, by heat alone, the crystallised binacetate of copper, commonly, but improperly, called distilled verdigris. With this view, we take a stoneware retort, (fig. 1.) of a size suited to the quantity we wish to operate upon; and coat it with a mixture of fire clay and horsedung, to make it stand the heat better. When this coating is dry, we introduce into the retort the crystallised acetate slightly bruised, but very dry; we fill it as far as it will hold without spilling when the beak is considerably inclined. We then set it in a proper furnace. We attach to its neck an adopter pipe, and two or three globes with opposite tubulures, and a last globe with a vertical tubulure. The apparatus is terminated by a Welter’s tube, with a double branch; the shorter issues from the last globe, and the other dips into a flask filled with distilled vinegar. Every thing being thus arranged, we lute the joinings with a putty made of pipeclay and linseed oil, and cover them with glue paper. Each globe is placed in a separate basin of cold water, or the whole may be put into an oblong trough, through which a constant stream of cold water is made to flow. The tubes must be allowed a day to dry. Next day we proceed to the distillation, tempering the heat very nicely at the beginning, and increasing it by very slow degrees till we see the drops follow each other pretty rapidly from the neck of the retort, or the end of the adopter tube. The vapours which pass over are very hot, whence a series of globes are necessary to condense them. We should renew, from time to time, the water of the basins, and keep moist pieces of cloth upon the globes; but this demands great care, especially if the fire be a little too brisk, for the vessels become, in that case, so hot, that they would infallibly be broken, if touched suddenly with cold water. It is always easy for us to regulate this operation, according to the emission of gas from the extremity of the apparatus. When the air bubbles succeed each other with great rapidity, we must damp the fire.

The liquor which passes in the first half hour is weakest; it proceeds, in some measure, from a little water sometimes left in the crystals, which when well made, however, ought to be anhydrous. A period arrives towards the middle of the process when we see the extremity of the beak of the retort, and of the adopter, covered with crystals of a lamellar or needle shape, and of a pale green tint. By degrees these crystals are carried into the condensed liquid by the acid vapours, and give a colour to the product. These crystals are merely some of the cupreous salt forced over by the heat. As the process approaches its conclusion, we find more difficulty in raising the vapours; and we must then augment the intensity of the heat, in order to continue their disengagement. Finally, we judge that the process is altogether finished, when the globes become cold, notwithstanding the furnace is at the hottest, and when no more vapours are evolved. The fire may then be allowed to go out, and the retort to cool.

As the acid thus obtained is slightly tinged with copper, it must be rectified before bringing it into the market. For this purpose we may make use of the same apparatus, only substituting for the stoneware retort a glass one, placed in a sand bath. All the globes ought to be perfectly clean and dry. The distillation is to be conducted in the usual way. If we divide the product into thirds, the first yields the feeblest acid, and the third the strongest. We should not push the process quite to dryness, because there remains in the last portions certain impurities, which would injure the flavour of the acid.

The total acid thus obtained forms nearly one half of the weight of the acetate employed, and the residuum forms three tenths; so that about two tenths of the acid have been decomposed by the heat, and are lost. As the oxide of copper is readily reduced to the metallic state, its oxygen goes to the elements of one part of the acid, and forms water, which mingles with the products of carbonic acid, carburetted hydrogen, and[8] carbonic oxide gases which are disengaged; and there remains in the retort some charcoal mixed with metallic copper. These two combustibles are in such a state of division, that the residuum is pyrophoric. Hence it often takes fire the moment of its being removed from the cold retort. The very considerable loss experienced in this operation has induced chemists to try different methods to obtain all the acid contained in the acetate. Thus, for example, a certain addition of sulphuric acid has been prescribed; but, besides that the radical vinegar obtained in this way always contains sulphurous acid, from which it is difficult to free it, it is thereby deprived of that spirit called the pyro-acetic, which tempers the sharpness of its smell, and gives it an agreeable aroma. It is to be presumed, therefore, that the preceding process will continue to be preferred for making aromatic vinegar. Its odour is often further modified by essential oils, such as those of rosemary, lavender, &c.

4. Pyrolignous Acid, or Wood Vinegar.—The process for making this acid is founded upon the general property of heat, to separate the elements of vegetable substances, and to unite them anew in another order, with the production of compounds which did not exist in the bodies subjected to its action. The respective proportion of these products varies, not only in the different substances, but also in the same substance, according as the degree of heat has been greater or less, or conducted with more or less skill. When we distil a vegetable body in a close vessel, we obtain at first the included water, or that of vegetation; there is next formed another portion of water, at the expense of the oxygen and hydrogen of the body; a proportional quantity of charcoal is set free, and, with the successive increase of the heat, a small portion of charcoal combines with the oxygen and hydrogen to form acetic acid. This was considered, for some time, as a peculiar acid, and was accordingly called pyrolignous acid. As the proportion of carbon becomes preponderant, it combines with the other principles, and then some empyreumatic oil is volatilised, of little colour, but which becomes thicker, and of a darker tint, always getting more loaded with carbon.

Several elastic fluids accompany these different products. Carbonic acid comes over, but in small quantity, much carburetted hydrogen, and, towards the end, a considerable proportion of carbonic oxide. The remainder of the charcoal, which could not be carried off in these several combinations, is found in the retort, and preserves, usually, the form of the vegetable body which furnished it. Since mankind have begun to reason on the different operations of the arts, and to raise them to a level with scientific researches they have introduced into several branches of manufacture a multitude of improvements, of which, formerly, they would hardly have deemed them susceptible. Thus, in particular, the process for carbonising wood has been singularly meliorated, and in reference to the preceding observations, advantage has been derived from several products that formerly were not even collected.

Fig. 2.

Wood vinegar cylinder

The apparatus employed for obtaining crude vinegar from wood, by the agency of heat, are large iron cylinders. In this country they are made of cast iron, and are laid horizontally in the furnace; in France, they are made of sheet iron riveted together, and they are set upright in the fire. Fig. 2. will give an accurate idea of the British plan, which is much the same as that adopted for decomposing pit coal in gas works, only that the cylinders for the pyrolignous acid manufacture are generally larger, being frequently 4 feet in diameter, and 6 or 8 feet long, and built horizontally in brickwork, so that the flame of one furnace may play around two of them. It would, probably, answer better, if their size were brought nearer the dimensions of the gas-light retorts, and if the whole system of working them were assimilated to that of coal gas.

The following arrangement is adopted in an excellent establishment in Glasgow, where the above large cylinders are 6 feet long, and both ends of them project a very little beyond the brickwork. One end has a disc or round plate of cast iron, well fitted, and firmly bolted to it, from the centre of which disc an iron tube, about 6 inches diameter, proceeds and enters, at a right angle, the main tube of refrigeration. The diameter of this tube may be from 9 to 14 inches, according to the number of cylinders. The other end of the cylinder is called the mouth of the retort; this is closed by a disc of iron, smeared round its edge by clay lute, and secured in its place by fir wedges. The charge of wood for such a cylinder is about 8 cwt. The hard woods—oak, ash, birch, and beech—are alone used; fir does not answer. The heat is kept up during the day-time, and the furnace is allowed to cool during the night. Next morning, the door is opened, the charcoal removed, and a new charge of wood is introduced. The average product of crude vinegar called pyrolignous acid, is 35 gallons. It is much contaminated with tar, is of a deep brown colour,[9] and has a sp. gr. of 1·025. Its total weight is therefore about 300 lbs., but the residuary charcoal is found to weigh no more than one fifth of the wood employed; hence nearly one half of the ponderable matter of the wood is dissipated in incondensable gases. Count Rumford states, that the charcoal is equal in weight to more than four tenths of the wood from which it is made. The count’s error seems to have arisen from the slight heat of an oven to which his wood was exposed in a glass cylinder. The result now given, is the experience of an eminent manufacturing chemist.

The crude pyrolignous acid is rectified by a second distillation in a copper still, in the body of which about 20 gallons of viscid tarry matter are left from every 100. It has now become a transparent brown vinegar, having a considerably empyreumatic smell, and a sp. gr. of 1·013. Its acid powers are superior to those of the best household vinegar, in the proportion of three to two. By redistillation, saturation with quicklime, evaporation of the liquid acetate to dryness, and conversion into acetate of soda by sulphate of soda, the empyreumatic matter is so completely dissipated, that on decomposing the pure acetate of soda by sulphuric acid, a perfectly colourless and grateful vinegar rises in distillation. Its strength will be proportionable to the concentration of the decomposing acid.

The acetic acid of the chemist may be prepared also in the following modes:—1. Two parts of fused acetate of potash, with one of the strongest oil of vitriol, yield, by slow distillation from a glass retort into a refrigerated receiver, concentrated acetic acid. A small portion of sulphurous acid, which contaminates it, may be removed by redistillation from a little acetate of lead. 2. Or four parts of good sugar of lead, with one part of sulphuric acid, treated in the same way, afford a slightly weaker acetic acid. 3. Gently calcined sulphate of iron, or green vitriol, mixed with sugar of lead, in the proportion of 1 of the former to 212 of the latter, or with acetate of copper, and carefully distilled from a porcelain retort into a cool receiver, may be also considered an economical process. But that with binacetate of copper above described, is preferable to any of these.

Fig. 3.

French vessel and crane

The manufacture of pyrolignous acid is conducted in the following way in France. Into large cylindrical vessels (fig. 3.) made of rivetted sheet iron, and having at their top and side a small sheet iron cylinder, the wood intended for making charcoal is introduced. To the upper part of this vessel a cover of sheet iron, B, is adapted, which is fixed with bolts. This vessel, thus closed, represents, as we see, a vast retort. When it is prepared, as we have said, it is lifted by means of a swing crane, C, and placed in a furnace, D, (fig. 4.) of a form relative to that of the vessel, and the opening of the furnace is covered with a dome, E, made of masonry or brickwork. The whole being thus arranged, heat is applied in the furnace at the bottom. The moisture of the wood is first dissipated, but by degrees the liquor ceases to be transparent, and becomes sooty. An adopter tube, A, is then fitted to the lateral cylinder. This adopter enters into another tube at the same degree of inclination which commences the condensing apparatus. The means of condensation vary according to the localities. In certain works they cool by means of air, by making the vapour pass through a long series of cylinders, or sometimes, even, through a series of casks connected together; but most usually water is used for condensing, when it can be easily procured in abundance. The most simple apparatus employed for this purpose consists of two cylinders, F, F, (fig. 4.) the one within the other, and which leave between them a sufficient space to allow a considerable body of water to circulate along and cool the vapours. This double cylinder is adapted to the distilling vessel, and placed at a certain inclination. To the first double tube, F, F, a second, and[10] sometimes a third, entirely similar, are connected, which, to save space, return upon themselves in a zigzag fashion. The water is set in circulation by an ingenious means now adopted in many different manufactories. From the lower extremity, G, of the system of condensers, a perpendicular tube rises, whose length should be a little more than the most elevated point of the system. The water, furnished by a reservoir, L, enters by means of the perpendicular tube through the lower part of the system, and fills the whole space between the double cylinders. When the apparatus is in action, the vapours, as they condense, raise the temperature of the water, which, by the column in L G, is pressed to the upper part of the cylinders, and runs over by the spout K. To this point a very short tube is attached, which is bent towards the ground, and serves as an overflow.

Fig. 4.

Vinegar still

The condensing apparatus is terminated by a conduit in bricks covered and sunk in the ground. At the extremity of this species of gutter is a bent tube, E, which discharges the liquid product into the first cistern. When it is full, it empties itself, by means of an overflow pipe, into a great reservoir; the tube which terminates the gutter plunges into the liquid, and thus intercepts communication with the inside of the apparatus. The disengaged gas is brought back by means of pipes M L, from one of the sides of the conduit to the under part of the ash pit of the furnace. These pipes are furnished with stopcocks M, at some distance in front of the furnace, for the purpose of regulating the jet of the gas, and interrupting, at pleasure, communication with the inside of the apparatus. The part of the pipes which terminates in the furnace rises perpendicularly several inches above the ground, and is expanded like the rose of a watering can, N. The gas, by means of this disposition, can distribute itself uniformly under the vessel, without suffering the pipe which conducts it to be obstructed by the fuel or the ashes.

The temperature necessary to effect the carbonisation is not considerable: however, at the last it is raised so high as to make the vessels red hot; and the duration of the process is necessarily proportional to the quantity of wood carbonised. For a vessel which shall contain about 5 meters cube (nearly 6 cubic yds.), 8 hours of fire is sufficient. It is known that the carbonisation is complete by the colour of the flame of the gas: it is first of a yellowish red; it becomes afterwards blue, when more carbonic oxide than carbonic hydrogen is evolved; and towards the end it becomes entirely white,—a circumstance owing, probably, to the furnace being more heated at this period, and the combustion being more complete. There is still another means of knowing the state of the process, to which recourse is more frequently had; that is the cooling of the first tubes, which are not surrounded with water: a few drops of this fluid are thrown upon their surface, and if they evaporate quietly, it is judged that the calcination is sufficient. The adopter tube is then unluted, and is slid into its junction pipe; the orifices are immediately stopped with plates of iron and plaster loam. The brick cover, E, of the furnace is first removed by means of the swing crane, then the cylinder itself is lifted out and replaced immediately by another one previously charged. When the cylinder which has been taken out of the furnace is entirely cooled, its cover is removed, and the charcoal is emptied. Five cubic meters of wood furnish about 7 chaldrons (voies) and a half of charcoal. (For modifications of the wood-vinegar apparatus, see Charcoal and Pyrolignous Acid.)

The different qualities of wood employed in this operation give nearly similar product in reference to the acid; but this is not the case with the charcoal, for it is better the harder the wood; and it has been remarked, that wood long exposed to the air furnishes a charcoal of a worse quality than wood carbonised soon after it is cut.

Having described the kind of apparatus employed to obtain pyrolignous acid, I shall now detail the best mode of purifying it. This acid has a reddish brown colour; it holds in solution a portion of empyreumatic oil and of the tar which were formed at the same time; another portion of these products is in the state of a simple mixture; the latter may be separated by repose alone. It is stated, above, that the distilling apparatus terminates in a subterranean reservoir, where the products of all the vessels are mixed. A common pump communicates with the reservoir, and sinks to its very bottom, in order that it may draw off only the stratum of tar, which, according to its greater density, occupies the lower part. From time to time the pump is worked to remove the tar as it is deposited. The reservoir has at its top an overflow pipe, which discharges the clearest acid into a cistern, from which it is taken by means of a second pump.

The pyrolignous acid thus separated from the undissolved tar is transferred from this cistern into large sheet iron boilers, where its saturation is effected either by quicklime or by chalk; the latter of which is preferable, as the lime is apt to take some of the tar into combination. The acid parts by saturation with a new portion of the tar, which is removed by skimmers. The neutral solution is then allowed to rest for a sufficient time to let its clear parts be drawn off by decantation.

The acetate of lime thus obtained indicates by the hydrometer, before being mixed with the waters of edulcoration, a degree corresponding to the acidimetric degree of the acid[11] employed. This solution must be evaporated till it reaches a specific gravity of 1·114 (15° Baumé), after which there is added to it a saturated solution of sulphate of soda. The acids exchange bases; sulphate of lime precipitates, and acetate of soda remains in solution. In some manufactures, instead of pursuing the above plan, the sulphate of soda is dissolved in the hot pyrolignous acid, which is afterwards saturated with chalk or lime. By this means no water need be employed to dissolve the sulphate, and accordingly the liquor is obtained in a concentrated form without evaporation. In both modes the sulphate of lime is allowed to settle, and the solution of acetate of soda is decanted. The residuum is set aside to be edulcorated, and the last waters are employed for washing fresh portions.

The acetate of soda which results from this double decomposition is afterwards evaporated till it attains to the density of 1·225 or 1·23, according to the season. This solution is poured into large crystallising vessels, from which, at the end of 3 or 4 days, according to their capacity, the mother waters are decanted, and a first crystallisation is obtained of rhomboidal prisms, which are highly coloured and very bulky. Their facettes are finely polished, and their edges very sharp. The mother waters are submitted to successive evaporations and crystallisations till they refuse to crystallise, and they are then burnt to convert them into carbonate of soda.

To avoid guesswork proportions, which are always injurious, by the loss of time which they occasion, and by the bad results to which they often lead, we should determine experimentally, beforehand, the quantities absolutely necessary for the reciprocal decomposition, especially when we change the acid or the sulphate. But it may be remarked that, notwithstanding all the precautions we can take, there is always a notable quantity of sulphate of soda and acetic acid, which disappear totally in this decomposition. This arises from the circumstance that sulphate of soda and acetate of lime do not completely decompose each other, as I have ascertained by experiments on a very considerable scale; and thus a portion of each of them is always lost with the mother waters. It might be supposed that by calcining the acetate of lime we could completely destroy its empyreumatic oil; but, though I have made many experiments, with this view I never could obtain an acetate capable of affording a tolerable acid. Some manufacturers prefer to make the acetate of soda by direct saturation of the acid with the alkali, and think that the higher price of this substance is compensated by the economy of time and fuel which it produces.

The acetate of soda is easily purified by crystallisations and torrefaction; the latter process, when well conducted, freeing it completely from every particle of tar. This torrefaction, to which the name of fusion may be given, requires great care and dexterity. It is usually done in shallow cast iron boilers of a hemispherical shape. During all the time that the heat of about 500° Fahr. is applied, the fused mass must be diligently worked with rakes; an operation which continues about 24 hours for half a ton of materials. We must carefully avoid raising the temperature so high as to decompose the acetate, and be sure that the heat is equally distributed; for if any point of the mass enters into decomposition, it is propagated with such rapidity, as to be excessively difficult to stop its progress in destroying the whole. The heat should never be so great as to disengage any smoke, even when the whole acetate is liquefied. When there is no more frothing up, and the mass flows like oil, the operation is finished. It is now allowed to cool in a body, or it may be ladled out into moulds, which is preferable.

When the acetate is dissolved in water, the charcoaly matter proceeding from the decomposition of the tar must be separated by filtration, or by boiling up the liquor to the specific gravity 1·114, when the carbonaceous matter falls to the bottom. On evaporating the clear liquor, we obtain an acetate perfectly fine, which yields beautiful crystals on cooling. In this state of purity it is decomposed by sulphuric acid, in order to separate its acetic acid.

This last operation, however simple it appears, requires no little care and skill. The acetate of soda crystallised and ground is put into a copper, and the necessary quantity of sulphuric acid of 1·842 (about 35 per cent. of the salt) to decompose almost, but not all, the acetate, is poured on. The materials are left to act on each other; by degrees the acetic acid quits its combination, and swims upon the surface; the greater part of the resulting sulphate of soda falls in a pulverulent form, or in small granular crystals, to the bottom. Another portion remains dissolved in the liquid, which has a specific gravity of 1·08. By distillation we separate this remainder of the sulphate, and finally obtain acetic acid, having a specific gravity of 1·05, an agreeable taste and smell, though towards the end it becomes a little empyreumatic, and coloured; for which reason, the last portions must be kept apart. The acid destined for table use ought to be distilled in an alembic whose capital and condensing worm are of silver; and to make it very fine, it may be afterwards infused over a little washed bone-black. It is usually obtained in a pretty concentrated state; but when we wish to give it the highest degree of concentration, we mix with it a quantity of dry muriate of lime, and distil anew. This acid may[12] be afterwards exposed to congelation, when the strongest will crystallise. It is decanted, and the crystals are melted by exposing them to a temperature of from 60° to 70° Fahr.; this process is repeated till the acid congeals without remainder, at the temperature of 55° Fahr. It has then attained its maximum strength, and has a specific gravity of 1·063.

We shall add an observation on the above mode of decomposing the acetate of soda by sulphuric acid. Many difficulties are experienced in this process, if the sulphuric acid be poured on in small quantities at a time; for then such acrid fumes of acetic acid are disengaged, that the workmen are obliged to retire. This inconvenience may be saved by adding all the sulphuric acid at once; it occupies the lower part of the vessel, and decomposes only the portion of the acetate in contact with it; the heat evolved in consequence of this reaction is diffused through a great mass, and produces no sensible effect. When the sulphuric acid forms an opening, or a species of little crater, the workman, by means of a rake, depresses the acetate into it by degrees, and then the decomposition proceeds as slowly as he desires.

The acetic acid, like the nitric, chloric, and some others, has not hitherto been obtained free from water, and the greatest degree of concentration which we have been able to give it is that in which it contains only the quantity of water equivalent to the atomic weight of another oxidized body; a quantity which amounts to 14·89 per cent. The processes prescribed for preparing concentrated acetic acid sometimes tend to deprive it of that water without which it could not exist: hence, in all such cases, there is a part of the acid itself decomposed to furnish the water necessary to the constitution of the remainder. The constituent principles of the decomposed portion then form a peculiar, intoxicating, highly inflammatory liquid, called the PYRO-ACETIC SPIRIT.

The most highly concentrated acid of 1·063 becomes denser by the addition of a certain quantity of water up to a certain point. According to Berzelius, the prime equivalent of this acid is 643·189, oxygen being reckoned 100. Now, the above strongest acid consists of one prime of acid, and one of water = 1124·79. When it contains three atoms of water, that is, 337·437 parts to 643·189, or 34·41 to 65·59 in 100, it then has taken its maximum density of 1·075; after which the further addition of water diminishes its specific gravity, as the following table of Mollerat shows. His supposed anhydrous or dry acid contains, at 1·0630, 0·114 parts of water.

Table of Acetic Acid.

Water in
100 parts.
0·00 1 ·0630
8·37 1 ·0742
17·00 1 ·0770
23·00 1 ·0791
28·10 1 ·0763
33·83 1 ·0742
37·60 1 ·0728
47·00 1 ·0658
50·00 1 ·0637
51·80 1 ·063

Acetic acid readily takes fire when it is heated in open vessels to the boiling point, and it burns with a blue flame, nearly like alcohol. It must be kept in close vessels, otherwise it loses its strength, by attracting humidity from the air. When concentrated, it is used only as a scent, or pungent exciter of the olfactory organs, in sickness and fainting fits. Its anti-epidemic qualities are apocryphal. What is met with in the shops under the name of salts of vinegar is nothing but sulphate of potash, put up in small phials, and impregnated with acetic acid, sometimes rendered aromatic with oil of rosemary or lavender.

Acetic acid, in its dry state, as it exists in fused acetate of potash or soda, is composed of

47·536 carbon
5·822 hydrogen
46·642 oxygen

And its symbol by Berzelius is H6 C4 O3 = A. We must bear in mind that his atomic weight for hydrogen is only one half of the number usually assigned to it by British chemists, in consequence of his making water a compound of two atoms of hydrogen and one of oxygen.

When the vapour of acetic acid is made to traverse a red-hot tube of iron, it is converted into water, carbonic acid, carburetted hydrogen, but chiefly pyro-acetic spirit.[13] Acetic acid is a solvent of several organic products; such as camphor, gluten, gum-resins, resins, the fibrine of blood, the white of egg, &c.

It is an important problem to ascertain the purity and strength of vinegar. Spurious acidity is too often given to it by cheaper acids, such as the sulphuric and the nitric. The former, may most surely be detected by the nitrate of baryta, or even by acetate of lead, which occasion a white precipitate in such adulterated vinegar. For the case of nitric, which is more insidious, the proper test is, a bit of gold leaf, wetted with a few drops of muriatic acid. If the leaf dissolves, on heating the mixture in a watch glass, we may be sure that nitric acid is present.

Specific gravity, if determined by a sensible hydrometer, is a good test of the strength of the genuine vinegar; and the following table of Messrs. Taylor is nearly correct, or sufficiently so for commercial transactions.

Revenue proof vinegar, called by the English manufacturer No. 24., has a specific gravity of

1·0085 and contains of real acid in 100— 5
1·0170   10
1·0257   15
1·0320   20
1·0470   30
1·0580   40

An excise duty of 2d. is levied on every gallon of the above proof vinegar. Its strength is not, however, estimated directly by its specific gravity, but by the specific gravity which it assumes when saturated with quicklime. The decimal fraction of the specific gravity of the calcareous acetate is very nearly the double of that of the pure vinegar; or, 1·009 in vinegar becomes 1·018 in acetate of lime. The vinegar of malt contains so much mucilage or gluten, that when it has only the same acid strength as the above, it has a density of 1·0014, but it becomes only 1·023 when converted into acetate of lime: indeed, 0·005 of its density is due to mucilaginous matter. This fact shows the fallacy of trusting to the hydrometer for determining the strength of vinegars, which may be more or less loaded with vegetable gluten. The proper test of this, as of all other acids, is, the quantity of alkaline matter which a given weight or measure of it will saturate. For this purpose the bicarbonate of potash, commonly called, in the London shops, carbonate, may be employed very conveniently. As it is a very uniform substance, and its atomic weight, by the hydrogen radix, is 100·584, while the atomic weight of acetic acid, by the same radix, is 51·563, if we estimate 2 grains of the bicarbonate as equivalent to 1 of the real acid, we shall commit no appreciable error. Hence, a solution of the carbonate containing 200 grains in 100 measures, will form an acetimeter of the most perfect and convenient kind; for the measures of test liquid expended in saturating any measure,—for instance, an ounce or 1000 grains of acid,—will indicate the number of grains of real acetic acid in that quantity. Thus, 1000 grains of the above proof, would require 50 measures of the acetimetrical alkaline solution, showing that it contains 50 grains of real acetic acid in 1000, or 5 per cent.

It is common to add to purified wood vinegar, a little acetic ether, or caramelised (burnt) sugar to colour it, also, in France, even wine, to flavour it. Its blanching effect upon red cabbage, which it has been employed to pickle, is owing to a little sulphurous acid. This may be removed by redistillation with peroxide of manganese. Indeed, Stoltze professes to purify the pyrolignous acid solely by distilling it with peroxide of manganese, and then digesting it with bruised wood charcoal; or by distilling it with a mixture of sulphuric acid and manganese. But much acid is lost in this case by the formation of acetate of that metal.

Birch and beech afford most Pyrolignous acid, and pine the least. It is exclusively employed in the arts, for most purposes of which it need not be very highly purified. It is much used in calico printing, for preparing acetate of iron called Iron Liquor, and acetate of alumina, called Red Liquor; which see. It serves also to make sugar of lead; yet when it contains its usual quantity, after rectification, of tarry matter, the acetate of lead will hardly crystallise, but forms cauliflower concretions. This evil may be remedied, I believe, by boiling the saline solution with a very little nitric acid, which causes the precipitation of a brown granular substance, and gives the liquor a reddish tinge. The solution being afterwards treated with bruised charcoal, becomes colourless, and furnishes regular crystals of acetate or sugar of lead.

Pyrolignous acid possesses, in a very eminent degree, anti-putrescent properties. Flesh steeped in it for a few hours may be afterwards dried in the air without corrupting; but it becomes hard, and somewhat leather-like: so that this mode of preservation does not answer well for butcher’s meat. Fish are sometimes cured with it. See Pyro-acetic Spirit; Pyroxilic Ether; Pyroxolic Spirit; Pyrolignous Acid and Vinegar.


ACETIMETER. An apparatus for determining the strength of vinegar. See the conclusion of the preceding article for a description of my simple method of acetimetry.

ACETONE. The new chemical name of pyro-acetic spirit.

ACID OF ARSENIC. (Acide Arsenique, Fr.; Arseniksäure, Germ.)

ACIDS. A class of chemical substances characterised by the property of combining with and neutralising the alkaline and other bases, and of thereby forming a peculiar class of bodies called salts. The acids which constitute objects of special manufacture for commercial purposes are the following:—acetic, arsenious, carbonic, chromic, citric, malic, muriatic, nitric, oxalic, phosphoric, sulphuric, tartaric, which see.

ACROSPIRE. (Plumule, Fr.; Blattkeim, Germ.) That part of a germinating seed which botanists call the plumula, or plumes. See Beer and Malt.

ADDITIONS. Such articles as are added to the fermenting wash of the distiller are distinguished by this trivial name.

ADIPOCIRE. Fr. (Fettwachs, Germ.) The fatty matter generated in dead bodies buried under peculiar circumstances. In 1786 and 1787, when the churchyard of the Innocents, at Paris, was cleaned out, and the bones transported to the catacombs, it was discovered that not a few of the cadavres were converted into a saponaceous white substance, more especially many of those which had been interred for fifteen years in one pit, to the amount of 1500, in coffins closely packed together. These bodies were flattened, in consequence of their mutual pressure; and, though they generally retained their shape, there was deposited round the bones of several a grayish white, somewhat soft, flexible substance. Fourcroy presented to the Academy of Sciences, in 1789, a comprehensive memoir upon this phenomenon, which appeared to prove that the fatty body was an ammoniacal soap, containing phosphate of lime; that the fat was similar to spermaceti, as it assumed on slow cooling a foliated crystalline structure; as also to wax, as, when rapidly cooled, it became granular: hence he called it Adipocire. Its melting point was 52·5° C. (126·5° Fahr.). He likewise compared this soap to the fat of gall-stones, and supposed it to be a natural product of the slow decomposition of all animal matter, except bones, nails, and hairs.

This substance was again examined by Chevreul in 1812, and was found by him to contain margaric acid, oleic acid, combined with a yellow colouring, odorous matter, besides ammonia, a little lime, potash, oxide of iron, salts of lactic acid, an azotized substance; and was therefore considered as a combination of margaric and oleic acids, in variable proportions (whence arose its variable fusibility), but that it was not analogous with either spermaceti or cholesterine (gallstones). These fat acids are obviously generated by the reaction of the ammonia upon the margarine and oleine, though they eventually lose the greater part of that volatile alkali.

According to the views of both Gay Lussac and Chevreul, this adipocire proceeds solely from the pre-existing fat of the dead body, and not from the flesh, tendons, or cartilages, as had been previously imagined; which had led to some expensive and abortive attempts, upon the great scale of manufacture, to convert the dead bodies of cattle into adipocire, for the purposes of the candle-maker or soap-boiler, by exposing them for some time to the action of moisture.

Von Hartkol made experiments during 25 years upon this subject, from which he inferred, that there is no formation of adipocire in bodies buried in dry ground; that in moist earth the fat of the dead body does not increase, but changes into a fetid saponaceous substance, incapable of being worked into either soap or candles; that the dead bodies of mammalia immersed in running water, leave behind after 3 years a pure fat, which is more abundant from young than from old animals; that the intestines afford more fat than the muscles; that from this fat, without any purification, candles may be made, as void of smell, as hard, and as white, as from bleached wax; that from cadavers immersed for 3 years in stagnant water, more fat is procured than from those in running water, but that it needs to be purified before it can be made into soap or candles.

The cause of the difference between Hartkol’s and Chevreul’s results cannot be assigned, as the latter has not published his promised remarks upon the subject. At any rate, dead animal matter can be worked up more profitably than in making artificial adipocire.

ADIT. The horizontal entrance of a mine. It is sometimes called the drift. See Mining and Metallurgy.

ADULTERATION. The debasing any product of manufacture, especially chemical, by the introduction of cheap materials. The art of ascertaining the genuineness of the several products will be taught under the specific objects of manufacture.

ÆTHER. See Ether.

AFFINITY. The chemical term denoting the peculiar attractive force which produces the combination of dissimilar substances; such as of an alkali with an acid, or of sulphur with a metal.


AGARIC. A species of boletus or fungus, which grows in dunghills; with the salts of iron it affords a black dye. It is said to be convertible into a kind of china ink.

AGATE. A siliceous mineral which is cut into seals and other forms for the coarser kinds of jewellery. See Gem.

AIR. See Ventilation.

ALABASTER, is a stone usually white, and soft enough to be scratched by iron. There are two kinds of it: the gypseous, which is merely a natural semi-crystalline sulphate of lime; and the calcareous alabaster, which is a carbonate of lime. The oriental alabaster is always of the latter kind, and is most esteemed, because it is agreeably variegated with lively colours, and especially with zones of honey-yellow, yellow-brown, red, &c.; it is, moreover, susceptible of taking a marble polish.

The fineness of the grain of alabaster, the uniformity of its texture, the beauty of its polished surface, and its semi-transparency, are the qualities which render it valuable to the sculptor and to the manufacturer of ornamental toys.

The limestone alabaster is frequently found as a yellowish-white deposit in certain fountains. The most celebrated spring of this kind is that of the baths of San Filippo, in Tuscany. The water, almost boiling hot, runs over an enormous mass of stalactites, which it has formed, and holds the carbonate of lime in solution by means of sulphuretted hydrogen (according to M. Alexandre Brongniart), which escapes by contact of the atmosphere. Advantage has been taken of this property to make basso relievos of considerable hardness, by placing moulds of sulphur very obliquely, or almost upright, in wooden tubs open at the bottom. These tubs are surmounted at the top with a large wooden cross. The water of the spring, after having deposited in an external conduit or cistern the coarser sediment, is made to flow upon this wooden cross, where it is scattered into little streamlets, and thence lets fall, upon the sulphur casts, a precipitate so much the finer the more nearly vertical the mould. From one to four months are required for this operation, according to the thickness of the deposited crust. By analogous processes, the artists have succeeded in moulding vases, figures of animals, and other objects, in relief, of every different form, which require only to be trimmed a little, and afterwards polished.

The common alabaster is composed of sulphuric acid and lime, though some kinds of it effervesce with acids, and therefore contain some carbonate of lime. This alabaster occurs in many different colours, and of very different degrees of hardness, but it is always softer than marble. It forms, usually, the lowest beds of the gypsum quarries. The sculptors prefer the hardest, the whitest, and those of a granular texture, like Carrara marble, and so like that they can only be distinguished by the hardness.

The alabaster is worked with the same tools as marble; and as it is many degrees softer, it is so much the more easily cut; but it is more difficult to polish, from its little solidity. After it has been fashioned into the desired form, and smoothed down with pumice stone, it is polished with a pap-like mixture of chalk, soap, and milk; and, last of all, finished by friction with flannel. It is apt to acquire a yellowish tinge.

Besides the harder kinds, employed for the sculpture of large figures, there is a softer alabaster, pure white and semi-transparent, from which small ornamental objects are made, such as boxes, vases, lamps, stands of time-pieces, &c. This branch of business is much prosecuted in Florence, Leghorn, Milan, &c., and employs a great many turning lathes. Of all the alabasters the Florentine merits the preference, on account of its beauty and uniformity, so that it may be fashioned into figures of considerable size; for which purpose there are large work-shops where it is cut with steel saws into blocks and masses of various shapes. Other sorts of gypsum, such as that of Salzburg and Austria, contain sand veins, and hard nodules, and require to be quarried by cleaving and blasting operations, which are apt to crack it, and unfit it for all delicate objects of sculpture. It is, besides, of a gray shade, and often stained with darker colours.

The alabaster best adapted for the fine arts is pretty white when newly broken, and becomes whiter on the surface by drying. It may be easily cut with the knife or chisel, and formed into many pleasing shapes by suitable steel tools. It is worked either by the hand alone, or with the aid of a turning lathe. The turning tools should not be too thin or sharp-edged; but such as are employed for ivory and brass are most suitable for alabaster, and are chiefly used to shave and to scratch the surface. The objects which cannot be turned may be fashioned by the rasping tools, or with minute files, such as variegated foliage. Fine chisels and graving tools are also used for the better pieces of statuary.

For polishing such works, a peculiar process is required: pumice stone, in fine powder, serves to smooth down the surfaces very well, but it soils the whiteness of the alabaster. To take away the unevennesses and roughnesses dried shave-grass (equisetum) answers best. Frictions with this plant and water polish down the asperities left by the chisel: the fine streaks left by the grass may be removed by rubbing the pieces with slaked lime, finely pulverised and sifted, made into a paste, or putty, with water. The[16] polish and satin-lustre of the surface are communicated by friction, first with soap-water and lime, and finally with powdered and elutriated talc or French chalk.

Such articles as consist of several pieces are joined by a cement composed of quicklime and white of egg, or of well-calcined and well-sifted Paris plaster, mixed with the least possible quantity of water.

Alabaster objects are liable to become yellow by keeping, and are especially injured by smoke, dust, &c. They may be in some measure restored by washing with soap and water, then with clear water, and again polished with shave-grass. Grease spots may be removed either by rubbing with talc powder, or with oil of turpentine.

The surface of alabaster may be etched by covering over the parts that are not to be touched with a solution of wax in oil of turpentine, thickened with white lead, and immersing the articles in pure water after the varnish has set. The action of the water is continued from 20 to 50 hours, more or less, according to the depth to which the etching is to be cut. After removing the varnish with oil of turpentine, the etched places, which are necessarily deprived of their polish, should be rubbed with a brush dipped in finely-powdered gypsum, which gives a kind of opacity, contrasting well with the rest of the surface.

Alabaster may be stained either with metallic solutions, with spirituous tinctures of dyeing plants, or with coloured oils, in the same way as marbles.

This substance has been hardened, it is said, by exposing it to the heat of a baker’s oven for 10 or 20 hours, after taking it out of the quarry, and giving it the figure, roughly, which it is intended to have. After this exposure, it must be dipped for two minutes in running water; when it is cold, it must be dipped a second time for the same period. On being exposed to the air for a few days, alabaster so treated acquires a marble-like hardness. I doubt the truth of this statement.

ALBUM GRÆCUM. The white dung of dogs, sometimes used to soften leather in the process of dressing it after the depilatory action of lime.

ALCARAZZAS. A species of porous earthenware, made in Spain, for cooling liquors. See Pottery.

ALCOHOL. The well-known intoxicating liquor procured by distillation from various vegetable juices, and infusions of a saccharine nature, which have undergone the vinous fermentation. Common alcohol, or proof spirit, as it is called, contains about one half its weight of water. It may be concentrated till its specific gravity becomes so low as 0·825, by simple redistillation at a steam or water-bath heat; but to make it stronger, we must mix with it, in the still or retort, dry carbonate of potash, muriate of lime, or some other substances strongly attractive of water, and then it may be obtained of a specific gravity so low as 0·791 at 16° Reaumur (68° Fahr.), water being 1·000. At 0·825, it contains, still, 11 per cent. of water; and in this state it is as volatile as absolute alcohol, on account of the inferior density of the aqueous vapour, compared to the alcoholic. Indeed, according to Yelin and Fuchs, the boiling point of anhydrous alcohol is higher than of that which contains 2 or 3 per cent. of water; hence, in the distillation of alcohol of 94 per cent., the first portions that come over are more aqueous than the following. Absolute alcohol has its boiling point at 16812° Fahr.: but when it holds more than 6 per cent. of water, the first portions that come over are richest in alcohol, and the temperature of the boiling point, or of the spirituous vapour, is always higher the longer the distillation continues. According to Gröning’s researches, the following temperatures of the alcoholic vapours correspond to the accompanying contents of alcohol in per centage of volume, which are disengaged in the boiling of the spirituous liquid.

Temperature. Alcoholic
content of
content of
the boiling
Fahr. 170 ·0 93   92
  171 ·8 92   90
  172   91   85
  172 ·8 90 12 80
  174   90   70
  174 ·6 89   70
  176   87   65
  178 ·3 85   50
  180 ·8 82   40
  183   80   35
  185   78   30
  187 ·4 76   25
  189 ·8 71   20
  192 ·0 68   18
  164   66   15
  196 ·4 61   12
  198 ·6 55   10
  201   50   7
  203   42   5
  205 ·4 36   3
  207 ·7 28   2
  210   13   1
  212   0   0


Gröning undertook this investigation in order to employ the thermometer as an alcoholmeter in the distillation of spirits; for which purpose he thrust the bulb of the thermometer through a cork, inserted into a tube fixed in the capital of the still. The state of the barometer ought also to be considered in making comparative experiments of this kind. Since, by this method, the alcoholic content may be compared with the temperature of the vapour that passes over at any time, so, also, the contents of the whole distillation may be found approximately; and the method serves as a convenient means of making continual observations on the progress of the distillation.

The temperature, corresponding to a certain per centage of alcohol in vapour, suggests the employment of a convenient method for obtaining, at one process, a spirit as free from water as it can be made by mere distillation. We place over the top of the capital a water-bath, and lead up through it a spiral pipe from the still, which there passes obliquely downwards, and proceeds to the refrigeratory. If this bath be maintained, by a constant influx of cold water, at a certain temperature, only the alcoholic vapour corresponding to that temperature will pass over, and the rest will be recondensed and returned into the still. If we keep the temperature of the water at 174°, for example, the spirituous vapour which passes over will contain 90 per cent. of absolute alcohol, according to the preceding table. The skilful use of this principle constitutes the main improvement in modern distilleries. See Distillation and Still.

Another method for concentrating alcohol is that discovered by Sömmering, founded upon the property of ox bladders to allow water to pass through and evaporate out of them, but not to permit alcohol to transpire, or only in a slight degree. Hence, if an ox’s bladder is filled with spirit of wine, well tied at the mouth, and suspended in a warm place, the water will continually exhale, and the alcohol will become nearly anhydrous; for in this way alcohol of 97 or 98 per cent. may be obtained.

According to Sömmering, we should take for this purpose the bladder of an ox or a calf, soak it for some time in water, then inflate it and free it from the fat and the attached vessels; which is to be also done to the other surface, by turning it inside out. After it is again inflated and dried, we must smear over the outer side twice, and the inner side four times, with a solution of isinglass, by which its texture is made closer, and the concentration of the alcohol goes on better. A bladder so prepared may serve more than a hundred times. It must be charged with the spirits to be concentrated, leaving a small space vacant, it is then to be tightly bound at the mouth, and suspended in a warm situation, at a temperature of 122° Fahr., over a sand-bath, or in the neighbourhood of an oven. The surface of the bladder remains moist with the water, as long as the sp. gr. of the contained spirit is greater than 0·952. Weak spirit loses its water quicker than strong; but in from 6 to 12 hours the alcohol may be concentrated, when a suitable heat is employed. This economical method is particularly applicable in obtaining alcohol for the preparation of varnishes. When the alcohol is to serve for other purposes, it must be freed, by distillation, from certain matters dissolved out of the bladder. Alcohol may likewise be strengthened, as Sömmering has ascertained when the vessel that contains the spirit is bound over with a bladder which does not come into contact with the liquid. Thus, too, all other liquors containing alcohol and water, as wine, cider, &c., may be made more spirituous.

To procure absolute alcohol, we must take chloride of calcium recently fused, reduce it to coarse powder, and mix it with its own weight of spirit of wine, of sp. gr. 0·833, in a bottle, which is to be well stoppered, and to be agitated till the salt is dissolved. The clear solution is to be poured into a retort, and half of the volume of the alcohol employed, or so much as has the sp. gr. 0·791 at 68° Fahr., is to be distilled off at a gentle heat. Quicklime has also been employed for the same purpose, but it is less powerful and convenient. Alcohol, nearly free from water, may be obtained without distillation, by adding dry carbonate of potash to a spirit of wine, of sp. gr. 0·825. The water combines with the potash, and falls to the bottom in a dense liquid, while the pure spirit floats on the surface. This contains however a little alkali, which can only be separated by distillation.

Anhydrous alcohol is composed by weight of 52·66 carbon, 12·90 hydrogen, and 34·44 of oxygen. It has a very powerful attraction for water, and absorbs it from the atmosphere; therefore it must be kept in well-closed vessels. It also robs vegetable and animal bodies of their moisture; and hence common alcohol is employed for preserving anatomical preparations. Alcohol is a solvent for many substances: resins, essential oils, camphor, are abundantly dissolved by it, forming varnishes, perfumed spirits, &c. The solution of a resin or essential oil in alcohol becomes milky on the addition of water, which, by its attraction for alcohol, separates these substances. Several salts, especially the deliquescent, are dissolved by it, and some of them give a colour to its flame; thus, the solutions of the salts of strontia in alcohol burn with a crimson flame, those of copper and borax green, lime reddish, and baryta yellow.

When water is mixed with alcohol, heat and a condensation of volume are the result;[18] these effects being greatest with 54 per cent. of alcohol and 46 of water, and thence decreasing with a greater proportion of water. For alcohol which contains 90 per cent. of water, this condensation amounts to 1·94 per cent. of the volume; for 80 per cent., 2·87; for 70 per cent., 3·44; for 60 per cent., 3·73; for 40 per cent., 3·44; for 30 per cent., 2·72; for 20 per cent., 1·72; for 10 per cent., 0·72. Hence, to estimate the quantity of alcohol in any spirit it is necessary that the specific gravity be ascertained for each determinate proportion of alcohol and water that are mixed together. When this is done, we may, by means of an areometer constructed for liquids lighter than water, determine the strength of the spirit, either by a scale of specific gravities or by an arbitrary graduation corresponding to certain commercial objects, and thus we may determine the per centage of alcohol in whisky or brandy of any strength or purity. An areometer intended for this use has been called an alcoholmeter, in particular when the scale of it is so graduated that, instead of the specific gravity, it indicates immediately the per centage of anhydrous alcohol in a given weight or volume of the liquid. The scale graduated according to the per centage of pure alcohol by weight, constitutes the alcoholmeter of Richter; and that by the per centage in volume, the alcoholmeter of Tralles and Gay Lussac.

As liquors are sold in general by the measure, not by the weight, it is convenient, therefore, to know the alcoholic content of the mixtures in the per centage by volume. Tralles has constructed new tables upon the principles of those of Gilpin, in which the proportion is given by volume, and anhydrous alcohol is assumed for the basis; which, at 60° Fahr., has a specific gravity of 0·7939 compared with water at its maximum density, or a specific gravity 0·7946 compared with water of the temperature of 60° Fahr. Gilpin’s alcohol of 0·825 contains 92·6 per cent. by volume of anhydrous alcohol.

The following table exhibits the per centage of anhydrous alcohol by volume, at a temperature of 60° Fahr., in correspondence with the specific gravities of the spirits, water being considered at 60° Fahr. to have a specific gravity of 0·9991.

Alcoholmetrical Table of Tralles.

in 100
of spirit.
at 60° Fahr.
of the sp. gr.
0 9991  
1 9976 15
2 9961 15
3 9947 14
4 9933 14
5 9919 14
6 9906 13
7 9893 13
8 9881 12
9 9869 12
10 9857 12
11 9845 12
12 9834 11
13 9823 11
14 9812 11
15 9802 10
16 9791 11
17 9781 10
18 9771 10
19 9761 10
20 9751 10
21 9741 10
22 9731 10
23 9720 11
24 9710 10
25 9700 10
26 9689 11
27 9679 10
28 9668 11
29 9657 11
30 9646 11
31 9634 12
32 9622 12
33 9609 13[19]
34 9596 13
35 9583 13
36 9570 13
37 9556 14
38 9541 15
39 9526 15
40 9510 16
41 9494 16
42 9478 16
43 9461 17
44 9444 17
45 9427 17
46 9409 18
47 9391 18
48 9373 18
49 9354 19
50 9335 19
51 9315 20
52 9295 20
53 9275 20
54 9254 21
55 9234 20
56 9213 21
57 9192 21
58 9170 22
59 9148 22
60 9126 22
61 9104 22
62 9082 22
63 9059 23
64 9036 23
65 9013 23
66 8989 24
67 8965 24
68 8941 24
69 8917 24
70 8892 25
71 8867 25
72 8842 25
73 8817 25
74 8791 26
75 8765 26
76 8739 26
77 8712 27
78 8685 27
79 8658 27
80 8631 27
81 8603 28
82 8575 28
83 8547 28
84 8518 29
85 8488 30
86 8458 30
87 8428 30
88 8397 31
89 8365 32
90 8332 33
91 8299 33
92 8265 34
93 8230 35
94 8194 36
95 8157 37
96 8118 39
97 8077 41
98 8034 43
99 7988 46
100 7939 49

Remarks on the preceding Table of Alcohol.

The third column of this table exhibits the differences of the specific gravities, which give the denominator of the fraction for such densities as are not found sufficiently near in the table; and the difference of their numerators is the next greatest to the density found in the table. For example: if the specific gravity of the liquor found for 60° Fahr. = 9605 (the per centage will be between 33 and 34), the difference from 9609 (which is the next greatest number in the table) = 4, and the fraction is 413; therefore the true per centage is 33413. From the construction of this table the per centage of alcohol by weight may also be found. For instance: we multiply the number representing the volumes of alcohol (given in the table for any determinate specific gravity of the mixture) by the specific gravity of the pure alcohol, that is, by 7939, and the product is the number of pounds of alcohol in so many pounds as the specific gravity multiplied by 100 gives. Thus, in the mixture of 9510 specific gravity, there are 40 measures of alcohol; hence there are also in 95,100 pounds of this spirit 7939 + 40 = 31·756 pounds of alcohol; and in 100 pounds of the spirits of 0·9510 specific gravity, 33·39 pounds of alcohol are contained.

As the preceding table gives the true alcoholic content when the portion of spirit under trial has the normal temperature of 60° Fahr., the following table gives the per centage of alcohol for the specific gravities corresponding to the accompanying temperatures.

For example: if we have a spirituous liquor at 80° Fahr., whose specific gravity is 0·9342, the alcohol present is 45 per cent. of the volume, or that specific gravity at that temperature is equal to the specific gravity 0·9427 at the normal temperature of 60° Fahr. This table may also be employed for every degree of the thermometer and every per centage, so as to save computation for the intervals. It is evident from inspection that a difference of 5° Fahr. in the temperature changes the specific gravity of the liquor by a difference nearly equal to 1 volume per cent. of alcohol; thus at 35° and 85° Fahr. the very same specific gravity of the liquor shows nearly 10 volumes per cent. of alcohol more or less; the same, for example, at 60 and 40 per cent.

Temperature. Alco-
30° F. 35° F. 40° F. 45° F. 50° F. 55° F. 60° F. 65° F. 70° F. 75° F. 80° F. 85° F.
0 9994 9997 9997 9998 9997 9994 0 9991 9987 9991 9976 9970 9962
5 9924 9926 9926 9926 9925 9922 5 9919 9915 9909 9903 9897 9889
10 9868 9869 9868 9867 9865 9861 10 9857 9852 9845 9839 9831 9823
15 9823 9822 9820 9817 9813 9807 15 9802 9796 9788 9779 9771 9761
20 9786 9782 9777 9772 9766 9759 20 9751 9743 9733 9722 9711 9700
25 9753 9746 9738 9729 9720 9709 25 9700 9690 9678 9665 9652 9638
30 9717 9707 9695 9684 9672 9659 30 9646 9632 9618 9603 9588 9572
35 9671 9658 9644 9629 9614 9599 35 9583 9566 9549 9532 9514 9495
40 9615 9598 9581 9563 9546 9528 40 9510 9491 9472 9452 9433 9412
45 9544 9525 9506 9486 9467 9447 45 9427 9406 9385 9364 9342 9320
50 9460 9440 9420 9399 9378 9356 50 9335 9313 9290 9267 9244 9221
55 9368 9347 9325 9302 9279 9256 55 9234 9211 9187 9163 9139 9114
60 9267 9245 9222 9198 9174 9150 60 9126 9102 9076 9051 9026 9000
65 9162 9138 9113 9088 9063 9038 65 9013 8988 8962 8936 8909 8882
70 9046 9021 8996 8970 8944 8917 70 8892 8866 8839 8812 8784 8756
75 8925 8899 8873 8847 8820 8792 75 8765 8738 8710 8681 8652 8622
80 8798 8771 8744 8716 8688 8659 80 8631 8602 8573 8544 8514 8483
85 8663 8635 8606 8577 8547 8517 85 8488 8458 8427 8396 8365 8333
90 8517 8486 8455 8425 8395 8363 90 8322 8300 8268 8236 8204 8171
30° F. 35° F. 40° F. 45° F. 50° F. 55° F. 60° F. 65° F. 70° F. 75° F. 80° F. 85° F.
0 9994 9997 9997 9998 9997 9994 9991 9987 9991 9976 9970 9962
5 9924 9926 9926 9926 9925 9922 9919 9915 9909 9903 9897 9889
10 9868 9869 9868 9867 9865 9861 9857 9852 9845 9839 9831 9823
15 9823 9822 9820 9817 9813 9807 9802 9796 9788 9779 9771 9761
20 9786 9782 9777 9772 9766 9759 9751 9743 9733 9722 9711 9700
25 9753 9746 9738 9729 9720 9709 9700 9690 9678 9665 9652 9638
30 9717 9707 9695 9684 9672 9659 9646 9632 9618 9603 9588 9572
35 9671 9658 9644 9629 9614 9599 9583 9566 9549 9532 9514 9495
40 9615 9598 9581 9563 9546 9528 9510 9491 9472 9452 9433 9412
45 9544 9525 9506 9486 9467 9447 9427 9406 9385 9364 9342 9320
50 9460 9440 9420 9399 9378 9356 9335 9313 9290 9267 9244 9221
55 9368 9347 9325 9302 9279 9256 9234 9211 9187 9163 9139 9114
60 9267 9245 9222 9198 9174 9150 9126 9102 9076 9051 9026 9000
65 9162 9138 9113 9088 9063 9038 9013 8988 8962 8936 8909 8882
70 9046 9021 8996 8970 8944 8917 8892 8866 8839 8812 8784 8756
75 8925 8899 8873 8847 8820 8792 8765 8738 8710 8681 8652 8622
80 8798 8771 8744 8716 8688 8659 8631 8602 8573 8544 8514 8483
85 8663 8635 8606 8577 8547 8517 8488 8458 8427 8396 8365 8333
90 8517 8486 8455 8425 8395 8363 8322 8300 8268 8236 8204 8171


The importance of extreme accuracy in determining the density of alcoholic mixtures in the United Kingdom, on account of the great revenue derived from them to the State, and their consequent high price in commerce, induced the Lords of the Treasury a few years ago to request the Royal Society to examine the construction and mode of applying the instrument now in use for ascertaining and charging the duty on spirits. This instrument, which is known and described in the law as Sikes’s hydrometer, possesses, in many respects, decided advantages over those formerly in use. The committee of the Royal Society state, that a definite mixture of alcohol and water is as invariable in its value as absolute alcohol can be; and can be more readily, and with equal accuracy, identified by that only quality or condition to which recourse can be had in practice, namely, specific gravity. The committee further proposed, that the standard spirit be that which, consisting of alcohol and water alone, shall have a specific gravity of 0·92 at the temperature of 62° Fahr., water being unity at the same temperature; or, in other words, that it shall at 62° weigh 92100 or 2325 of an equal bulk of water at the same temperature.

This standard is rather weaker than the old proof, which was 1213, or 0·923; or in the proportion of nearly 1·1 gallon of the present proof spirit per cent. The proposed standard will contain nearly one half by weight of absolute alcohol. The hydrometer ought to be so graduated as to give the indication of strength; not upon an arbitrary scale, but in terms of specific gravity at the temperature of 62°.

The committee recommend the construction of an equation table, which shall indicate the same strength of spirit at every temperature. Thus in standard spirit at 62° the hydrometer would indicate 920, which in this table would give proof spirit. If that same spirit were cooled to 40°, the hydrometer would indicate some higher number; but which, being combined in the table with the temperature as indicated by the thermometer, should still give proof or standard spirit as the result.

It is considered advisable, in this and the other tables, not to express the quality of the spirit by any number over or under proof, but to indicate at once the number of gallons of standard spirit contained in, or equivalent to, 100 gallons of the spirit under examination. Thus, instead of saying 23 over proof, it is proposed to insert 123; and in place of 35·4 under proof, to insert its difference to 100, or 64·6.

It has been considered expedient to recommend a second table to be constructed, so as to show the bulk of spirit of any strength at any temperature, relative to a standard bulk of 100 gallons at 62°. In this table a spirit which had diminished in volume, at any given temperature, 0·7 per cent., for example, would be expressed by 99·3; and a spirit which had increased at any given temperature 0·7 per cent., by 100·7.

When a sample of spirit, therefore, has been examined by the hydrometer and thermometer, these tables will give first the proportion of standard spirit at the observed temperature, and next the change of bulk of such spirit from what it would be at the standard temperature. Thus, at the temperature of 51°, and with an indication (sp. gr.) of 8240, 100 gallons of the spirit under examination would be shown by the first table to be equal to 164·8 gallons of standard spirit of that temperature; and by the second table it would appear that 99·3 gallons of the same spirit would become 100 at 62°, or in reality contain the 164·8 gallons of spirit in that state only in which it is to be taxed.

But as it is considered that neither of these tables can alone be used for charging the duty (for neither can express the actual quantity of spirit of a specific gravity of 0·92 at 62° in 100 gallons of stronger or weaker spirit at temperatures above or below 62°), it is considered essential to have a third table, combining the two former, and expressing this relation directly, so that upon mere inspection it shall indicate the proportion of standard spirit in 100 gallons of that under examination in its then present state. In this table the quantities should be set down in the actual number of gallons of standard spirit at 62°, equivalent to 100 of the spirit under examination; and the column of quantities may be expressed by the term value, as it in reality expresses the proportion of the only valuable substance present. As this will be the only table absolutely necessary to be used with the instrument for the purposes of the excise, it may, perhaps, be thought unnecessary to print the former two.


The following specimen table has been given by the committee:—

Temperature 45°. Temperature 75°.
Strength. Value. Indica-
Strength. Value.
9074 114·5   8941 114·5  
7 114·3   4 114·3  
9 114·2   5 114·2  
81 114·0   8 114·0  
3 113·9   9 113·9  
5 113·7   52 113·7  
6 113·6   3 113·6  
9 113·4   6 113·4  
90 113·3   7 113·3  
3 113·1   9 113·1  

[3] By specific gravity.

The mixture of alcohol and water, taken as spirit in Mr. Gilpin’s tables, is that of which the specific gravity is 0·825 at 60° Fahr., water being unity at the same temperature. The specific gravity of water at 60° being 1000, at 62° it is 99,981. Hence, in order to compare the specific gravities given by Mr. Gilpin with those which would result when the specific gravity of water at 62° is taken at unity, all the former numbers must be divided by 99,981.

Table of the Specific Gravities of different Mixtures, by Weight, of Alcohol and Water, at different Temperatures; constructed by Mr. Gilpin, for the use of the British Revenue on Spirits.

30 0 ·83896 0 ·84995 0 ·85957 0 ·86825 0 ·87585 0 ·88282 0 ·88921 0 ·89511 0 ·90054 0 ·90558 0 ·91023 0 ·91449 0 ·91847 0 ·92217 0 ·92563 0 ·92889 0 ·93191 0 ·93474 0 ·93741 0 ·93991 0 ·94222
35   ·83672   ·84769   ·85729   ·86587   ·87357   ·88059   ·88701   ·89294   ·89839   ·90345   ·90811   ·91241   ·91640   ·92009   ·92355   ·92680   ·92986   ·93274   ·93541   ·93790   ·94025
40   ·83445   ·84539   ·85507   ·86361   ·87184   ·87838   ·88481   ·89073   ·89617   ·90127   ·90596   ·91026   ·91428   ·91799   ·92151   ·92476   ·92783   ·93072   ·93341   ·93592   ·93827
45   ·83214   ·84310   ·85277   ·86131   ·86905   ·87613   ·88255   ·88849   ·89396   ·89909   ·90380   ·90812   ·91211   ·91584   ·91937   ·92264   ·92570   ·92859   ·93131   ·93382   ·93621
50   ·82977   ·84076   ·85042   ·85902   ·86676   ·87384   ·88030   ·88626   ·89174   ·89684   ·90160   ·90596   ·90997   ·91370   ·91723   ·92051   ·92358   ·92647   ·92919   ·93177   ·93419
55   ·82736   ·83834   ·84802   ·85664   ·86441   ·87150   ·87796   ·88393   ·88945   ·89458   ·89933   ·90367   ·90768   ·91144   ·91502   ·91837   ·92145   ·92436   ·92707   ·92963   ·93208
60   ·82500   ·83599   ·84568   ·85430   ·86208   ·86918   ·87569   ·88169   ·88720   ·89232   ·89707   ·90144   ·90549   ·90927   ·91287   ·91622   ·91933   ·92225   ·92499   ·92758   ·93002
65   ·82262   ·83362   ·84334   ·85193   ·85976   ·86686   ·87337   ·87938   ·88490   ·89006   ·89479   ·89920   ·90328   ·90707   ·91066   ·91400   ·91715   ·92010   ·92283   ·92546   ·92794
70   ·82023   ·83124   ·84092   ·84951   ·85736   ·86451   ·87105   ·87705   ·88254   ·88773   ·89252   ·89695   ·90104   ·90484   ·90847   ·91181   ·91493   ·91793   ·92069   ·92333   ·92580
75   ·81780   ·82878   ·83851   ·84710   ·85496   ·86212   ·86864   ·87466   ·88018   ·88538   ·89018   ·89464   ·89872   ·90252   ·90617   ·90952   ·91270   ·91569   ·91849   ·92111   ·92364
80   ·81530   ·82631   ·83603   ·84467   ·85248   ·85966   ·86622   ·87228   ·87776   ·88301   ·88781   ·89225   ·89639   ·90021   ·90385   ·90723   ·91046   ·91340   ·91622   ·91891   ·92142
85   ·81291   ·82396   ·83371   ·84243   ·85036   ·85757   ·86411   ·87021   ·87590   ·88120   ·88609   ·89043   ·89460   ·89843   ·90209   ·90558   ·90882   ·91186   ·91465   ·91729   ·91969
90   ·81044   ·82150   ·83126   ·84001   ·84797   ·85518   ·86172   ·86787   ·87360   ·87889   ·88376   ·88817   ·89230   ·89617   ·89988   ·90342   ·90688   ·90967   ·91248   ·91511   ·91751
95   ·80794   ·81900   ·82877   ·83753   ·84550   ·85272   ·85928   ·86542   ·87114   ·87654   ·88146   ·88588   ·89003   ·89390   ·89763   ·90119   ·90443   ·90747   ·91029   ·91290   ·91531
100   ·80548   ·81657   ·82630   ·83513   ·84038   ·85031   ·85688   ·86302   ·86879   ·87421   ·87915   ·883671   ·88769   ·89158   ·89536   ·89889   ·90215   ·90522   ·90805   ·91066   ·91310
30 0 ·83896 0 ·84995 0 ·85957 0 ·86825 0 ·87585 0 ·88282 0 ·88921 0 ·89511 0 ·90054 0 ·90558 0 ·91023
35   ·83672   ·84769   ·85729   ·86587   ·87357   ·88059   ·88701   ·89294   ·89839   ·90345   ·90811
40   ·83445   ·84539   ·85507   ·86361   ·87184   ·87838   ·88481   ·89073   ·89617   ·90127   ·90596
45   ·83214   ·84310   ·85277   ·86131   ·86905   ·87613   ·88255   ·88849   ·89396   ·89909   ·90380
50   ·82977   ·84076   ·85042   ·85902   ·86676   ·87384   ·88030   ·88626   ·89174   ·89684   ·90160
55   ·82736   ·83834   ·84802   ·85664   ·86441   ·87150   ·87796   ·88393   ·88945   ·89458   ·89933
60   ·82500   ·83599   ·84568   ·85430   ·86208   ·86918   ·87569   ·88169   ·88720   ·89232   ·89707
65   ·82262   ·83362   ·84334   ·85193   ·85976   ·86686   ·87337   ·87938   ·88490   ·89006   ·89479
70   ·82023   ·83124   ·84092   ·84951   ·85736   ·86451   ·87105   ·87705   ·88254   ·88773   ·89252
75   ·81780   ·82878   ·83851   ·84710   ·85496   ·86212   ·86864   ·87466   ·88018   ·88538   ·89018
80   ·81530   ·82631   ·83603   ·84467   ·85248   ·85966   ·86622   ·87228   ·87776   ·88301   ·88781
85   ·81291   ·82396   ·83371   ·84243   ·85036   ·85757   ·86411   ·87021   ·87590   ·88120   ·88609
90   ·81044   ·82150   ·83126   ·84001   ·84797   ·85518   ·86172   ·86787   ·87360   ·87889   ·88376
95   ·80794   ·81900   ·82877   ·83753   ·84550   ·85272   ·85928   ·86542   ·87114   ·87654   ·88146
100   ·80548   ·81657   ·82630   ·83513   ·84038   ·85031   ·85688   ·86302   ·86879   ·87421   ·87915
30 0 ·91449 0 ·91847 0 ·92217 0 ·92563 0 ·92889 0 ·93191 0 ·93474 0 ·93741 0 ·93991 0 ·94222
35   ·91241   ·91640   ·92009   ·92355   ·92680   ·92986   ·93274   ·93541   ·93790   ·94025
40   ·91026   ·91428   ·91799   ·92151   ·92476   ·92783   ·93072   ·93341   ·93592   ·93827
45   ·90812   ·91211   ·91584   ·91937   ·92264   ·92570   ·92859   ·93131   ·93382   ·93621
50   ·90596   ·90997   ·91370   ·91723   ·92051   ·92358   ·92647   ·92919   ·93177   ·93419
55   ·90367   ·90768   ·91144   ·91502   ·91837   ·92145   ·92436   ·92707   ·92963   ·93208
60   ·90144   ·90549   ·90927   ·91287   ·91622   ·91933   ·92225   ·92499   ·92758   ·93002
65   ·89920   ·90328   ·90707   ·91066   ·91400   ·91715   ·92010   ·92283   ·92546   ·92794
70   ·89695   ·90104   ·90484   ·90847   ·91181   ·91493   ·91793   ·92069   ·92333   ·92580
75   ·89464   ·89872   ·90252   ·90617   ·90952   ·91270   ·91569   ·91849   ·92111   ·92364
80   ·89225   ·89639   ·90021   ·90385   ·90723   ·91046   ·91340   ·91622   ·91891   ·92142
85   ·89043   ·89460   ·89843   ·90209   ·90558   ·90882   ·91186   ·91465   ·91729   ·91969
90   ·88817   ·89230   ·89617   ·89988   ·90342   ·90688   ·90967   ·91248   ·91511   ·91751
95   ·88588   ·89003   ·89390   ·89763   ·90119   ·90443   ·90747   ·91029   ·91290   ·91531
100   ·883671   ·88769   ·89158   ·89536   ·89889   ·90215   ·90522   ·90805   ·91066   ·91310
30 0 ·94447 0 ·94675 0 ·94920 0 ·95173 0 ·95429 0 ·95681 0 ·95944 0 ·96209 0 ·96470 0 ·96719 0 ·96967 0 ·97200 0 ·97418 0 ·97635 0 ·97860 0 ·98108 0 ·98412 0 ·98804 0 ·99334
35   ·94249   ·94484   ·94734   ·94988   ·95246   ·95502   ·95772   ·96048   ·96315   ·96579   ·96840   ·97086   ·97319   ·97556   ·97801   ·98076   ·98397   ·98804   ·99344
40   ·94058   ·94295   ·94547   ·94802   ·95060   ·95328   ·95602   ·95879   ·96159   ·96434   ·96706   ·96967   ·97220   ·97472   ·97737   ·98033   ·98373   ·98795   ·99345
45   ·93860   ·94096   ·94348   ·94605   ·94871   ·95143   ·95423   ·95703   ·95993   ·96280   ·96563   ·96840   ·97110   ·97384   ·97666   ·97980   ·98338   ·98774   ·99338
50   ·93658   ·93897   ·94149   ·94414   ·94683   ·94958   ·95243   ·95534   ·95831   ·96126   ·96420   ·96708   ·96995   ·97284   ·97589   ·97920   ·98293   ·98745   ·99316
55   ·93452   ·93696   ·93948   ·94213   ·94486   ·94767   ·95057   ·95357   ·95662   ·95966   ·96272   ·96575   ·96877   ·97181   ·97500   ·97847   ·98239   ·98702   ·99284
60   ·93247   ·93493   ·93749   ·94018   ·94296   ·94579   ·94876   ·95181   ·95493   ·95804   ·96122   ·96437   ·96752   ·97074   ·97410   ·97771   ·98176   ·98654   ·99244
65   ·93040   ·93285   ·93546   ·93822   ·94099   ·94388   ·94689   ·95000   ·95318   ·95635   ·95962   ·96288   ·96620   ·96959   ·97309   ·97688   ·98106   ·98594   ·99194
70   ·92828   ·93076   ·93337   ·93616   ·93898   ·94193   ·94500   ·94813   ·95139   ·95469   ·95802   ·96143   ·96484   ·96836   ·97203   ·97596   ·98028   ·98527   ·99134
75   ·92613   ·92865   ·93132   ·93413   ·93695   ·93989   ·94301   ·94623   ·94957   ·95292   ·95638   ·95987   ·96344   ·96708   ·97086   ·97495   ·97943   ·98454   ·99066
80   ·92393   ·92646   ·92917   ·93201   ·93488   ·93785   ·94102   ·94431   ·94768   ·95111   ·95467   ·95826   ·96192   ·96568   ·96963   ·97385   ·97845   ·98367   ·98991
30 0 ·94447 0 ·94675 0 ·94920 0 ·95173 0 ·95429 0 ·95681 0 ·95944 0 ·96209 0 ·96470 0 ·96719
35   ·94249   ·94484   ·94734   ·94988   ·95246   ·95502   ·95772   ·96048   ·96315   ·96579
40   ·94058   ·94295   ·94547   ·94802   ·95060   ·95328   ·95602   ·95879   ·96159   ·96434
45   ·93860   ·94096   ·94348   ·94605   ·94871   ·95143   ·95423   ·95703   ·95993   ·96280
50   ·93658   ·93897   ·94149   ·94414   ·94683   ·94958   ·95243   ·95534   ·95831   ·96126
55   ·93452   ·93696   ·93948   ·94213   ·94486   ·94767   ·95057   ·95357   ·95662   ·95966
60   ·93247   ·93493   ·93749   ·94018   ·94296   ·94579   ·94876   ·95181   ·95493   ·95804
65   ·93040   ·93285   ·93546   ·93822   ·94099   ·94388   ·94689   ·95000   ·95318   ·95635
70   ·92828   ·93076   ·93337   ·93616   ·93898   ·94193   ·94500   ·94813   ·95139   ·95469
75   ·92613   ·92865   ·93132   ·93413   ·93695   ·93989   ·94301   ·94623   ·94957   ·95292
80   ·92393   ·92646   ·92917   ·93201   ·93488   ·93785   ·94102   ·94431   ·94768   ·95111
30 0 ·96967 0 ·97200 0 ·97418 0 ·97635 0 ·97860 0 ·98108 0 ·98412 0 ·98804 0 ·99334
35   ·96840   ·97086   ·97319   ·97556   ·97801   ·98076   ·98397   ·98804   ·99344
40   ·96706   ·96967   ·97220   ·97472   ·97737   ·98033   ·98373   ·98795   ·99345
45   ·96563   ·96840   ·97110   ·97384   ·97666   ·97980   ·98338   ·98774   ·99338
50   ·96420   ·96708   ·96995   ·97284   ·97589   ·97920   ·98293   ·98745   ·99316
55   ·96272   ·96575   ·96877   ·97181   ·97500   ·97847   ·98239   ·98702   ·99284
60   ·96122   ·96437   ·96752   ·97074   ·97410   ·97771   ·98176   ·98654   ·99244
65   ·95962   ·96288   ·96620   ·96959   ·97309   ·97688   ·98106   ·98594   ·99194
70   ·95802   ·96143   ·96484   ·96836   ·97203   ·97596   ·98028   ·98527   ·99134
75   ·95638   ·95987   ·96344   ·96708   ·97086   ·97495   ·97943   ·98454   ·99066
80   ·95467   ·95826   ·96192   ·96568   ·96963   ·97385   ·97845   ·98367   ·98991

Experiments were made, by direction of the committee, to verify Gilpin’s tables, which showed that the error introduced in ascertaining the strength of spirits by tables founded on Gilpin’s numbers must be quite insensible in the practice of the revenue. The discrepancies thus detected, on a mixture of a given strength, did not amount in any one instance to unity in the fourth place of decimals. From a careful inspection of such documents the committee are of opinion, that Gilpin’s tables possess a degree of accuracy far surpassing what could be expected, and sufficiently perfect for all practical or scientific purposes.

The following table is given by Mr. Lubbock, for converting the apparent specific gravity, or indication, into true specific gravity:—

-Temperature+ Indi-
30° 32° 37° 42° 47° 52° 57° 62° 67° 72° 77° 80°
·82 ·00083 ·00078 ·00065 ·00052 ·00039 ·00025 ·00012   ·00011 ·00024 ·00035 ·00042 ·82
·83 ·00084 ·00079 ·00066 ·00052 ·00039 ·00026 ·00012   ·00012 ·00024 ·00036 ·00042 ·83
·84 ·00085 ·00080 ·00066 ·00053 ·00039 ·00026 ·00013   ·00012 ·00024 ·00036 ·00043 ·84
·85 ·00086 ·00081 ·00067 ·00054 ·00040 ·00026 ·00013   ·00012 ·00025 ·00037 ·00043 ·85
·86 ·00087 ·00082 ·00068 ·00054 ·00040 ·00027 ·00013   ·00012 ·00025 ·00037 ·00044 ·86
·87 ·00088 ·00083 ·00069 ·00055 ·00041 ·00027 ·00013   ·00012 ·00025 ·00037 ·00044 ·87
·88 ·00089 ·00084 ·00070 ·00055 ·00041 ·00027 ·00013   ·00012 ·00026 ·00038 ·00045 ·88
·89 ·00090 ·00085 ·00070 ·00055 ·00042 ·00028 ·00013   ·00012 ·00026 ·00038 ·00045 ·89
·90 ·00091 ·00085 ·00071 ·00056 ·00042 ·00028 ·00014   ·00013 ·00026 ·00039 ·00046 ·90
·91 ·00092 ·00086 ·00072 ·00057 ·00043 ·00028 ·00014   ·00013 ·00026 ·00039 ·00046 ·91
·92 ·00093 ·00087 ·00073 ·00058 ·00043 ·00029 ·00014   ·00013 ·00027 ·00040 ·00047 ·92
·93 ·00094 ·00088 ·00073 ·00059 ·00044 ·00029 ·00014   ·00013 ·00027 ·00040 ·00047 ·93
·94 ·00095 ·00089 ·00074 ·00059 ·00044 ·00029 ·00014   ·00013 ·00027 ·00040 ·00048 ·94
·95 ·00096 ·00090 ·00075 ·00060 ·00045 ·00029 ·00014   ·00013 ·00028 ·00041 ·00048 ·95
·96 ·00097 ·00091 ·00076 ·00060 ·00045 ·00030 ·00014   ·00013 ·00028 ·00041 ·00049 ·96
·97 ·00098 ·00092 ·00077 ·00061 ·00046 ·00030 ·00015   ·00014 ·00028 ·00042 ·00049 ·97
·98 ·00099 ·00093 ·00077 ·00062 ·00046 ·00030 ·00015   ·00014 ·00028 ·00042 ·00050 ·98
·99 ·00100 ·00094 ·00078 ·00062 ·00047 ·00031 ·00015   ·00014 ·00029 ·00043 ·00050 ·99
1·00 ·00101 ·00095 ·00079 ·00063 ·00047 ·00031 ·00015           1·00


Fig. 5.


The hydrometer constructed, under the directions of the Commissioners of Excise, by Mr. Bate, has a scale of 4 inches in length divided into 100 parts, and 9 weights. It has thus a range of 900 divisions, and expresses specific gravities at the temperature of 62° Fahr. In order to render this instrument so accurate a measurer of the specific gravity, at the standard temperature, as to involve no error of an appreciable amount, Mr. Bate has constructed the weights (which in this instrument are immersed in the fluid of different specific gravities) so that each successive weight should have an increase of bulk over the preceding weight equal to that part of the stem occupied by the scale, and an increase of weight sufficient to take the whole of the scale, and no more, down to the liquid. This arrangement requires great accuracy of workmanship, and enhances the price of the instrument. But it allows of increased strength in the ball, where it is very much required, and it gives, upon inspection only, the indication (apparent specific gravity) by which the general table is to be examined and the result ascertained. Fig. 5. represents this instrument and two of its nine ballast weights. It comprehends all specific gravities between 820 and 1000. It indicates true specific gravity with almost perfect accuracy at the temperature of 62° Fahr.; but it does not exclude other instruments from being used in conjunction with tables. The latter are, in fact, independent of the instrument, and may be used with gravimeters, or any instrument affording indications by specific gravity at a given temperature.

The commercial value of spirituous liquors being much lower in France than in England, a less sensible instrument becomes sufficient for the wants of that country. Baumé’s and Cartier’s hydrometers, with short arbitrary scales, are very much employed, but they have been lately superseded by an ingenious and ready instrument contrived by M. Gay Lussac, and called by him an alcoomètre. He takes for the term of comparison pure alcohol by volume, at the temperature of 15° Cent., and represents the strength of it by 100 centimes, or by unity. Consequently, the strength of a spirituous liquid is the number of centimes in volume of pure alcohol which that liquid contains at the temperature of 15° Cent. The instrument is formed like a common hydrometer, and is graduated for the temperature of 15° Cent. Its scale is divided into 100 parts or degrees, each of which denotes a centime of alcohol; the division 0 at the bottom of the stem corresponds to pure water, and the division 100 at its top, to pure alcohol. When immersed in a spirituous liquor at 15° Cent. (59° Fahr.) it announces its strength directly. For example: if in spirits supposed at the temperature of 15° Cent. it sinks to the division 50, it indicates that the strength of this liquor is 50 per cent., or that it contains 50 centimes of pure alcohol. In our new British proof spirit, it would sink to nearly 57, indicating 57 by volume of pure alcohol, allowing for condensation, or 50 by weight. A table of correction is given for temperature, which he calls “Table of real strength of spirituous liquors.” The first vertical column of this table contains the temperatures, from 0° to 30° Cent., and the first horizontal line the indications of the alcoomètre. In the same table we have most ingeniously inserted a correction for the volume of the spirits when the temperature differs from 15° Cent. If we take 1000 litres or gallons, measured at the temperature of 2°, of a spirituous liquor whose apparent strength is 44c; its real strength at 15° will from the preceding mode of correction be 49c. On heating this liquid to 15°, in order to find its real specific gravity or strength, its bulk will become greater; and, instead of 1000 litres or gallons, which it measured at 2°, we shall have 1009 at 15° C. This number is inscribed in smaller characters in the same square cell with the real force, precisely under 49c. All the numbers in small characters, printed under each real strength, indicate the volume which 1000 litres of a spirituous liquor would have, when measured at the temperature at which its apparent strength is taken. In the above example, the quantity in litres or gallons of pure alcohol contained in 1000 litres or gallons of the spirits, measured at the temperature of 2°, will be, therefore,—1009 lit. × 0·49 = 494 lit. 41.

This quantity of pure alcohol, thus estimated, is called richness of spirit in alcohol, or simply richness.

Let us take an example similar to the preceding, but at a higher temperature than 15° Cent. Suppose we have 1000 litres measured, at the temperature of 25°, of spirits whose apparent strength is 53c, what is the real quantity of pure alcohol which this spirit contains at the temperature of 15°? We shall find in the table, first of all, that the real strength of the spirits is 49c·3. As to its bulk or volume, it is very clear that the 1000 litres in cooling from 25° to 15°, will occupy a smaller space. This [24]volume will be 993 litres; it is inscribed directly below 49c·3, the real strength. We shall therefore have of pure alcohol, contained in the 1000 litres of spirits, measured at the temperature of 25°, or their richness, 993 lit. × 0·493 = 489 lit. 55.


Alcometrical Table of real Strength, by M. Gay Lussac.

31c 32c 33c 34c 35c 36c 37c 38c 39c 40c 41c 42c 43c 44c 45c 46c 47c 48c 49c 50c 51c 52c 53c 54c 55c 56c 57c 58c 59c 60c 61c 62c 63c 64c 65c 66c 67c 68c 69c 70c 71c 72c 73c 74c 75c 76c 77c 78c 79c 80c 81c 82c 83c 84c 85c 86c 87c 88c 89c 90c
10 33·0 34 35 36 37 38 39 40 41 42 43 44 45 46 46·9 47·9 48·9 49·9 50·9 51·8 52·8 53·8 54·8 55·8 56·8 57·8 58·8 59·7 60·7 61·7 62·7 63·7 64·7 65·7 66·7 67·6 68·6 69·6 70·6 71·6 72·6 73·5 74·5 75·5 76·5 77·5 78·5 79·5 80·5 81·5 82·4 83·4 84·4 85·4 86·4 87·4 88·3 89·3 90·2 91·2
1002 1002 1003 1003 1003 1003 1003 1003 1003 1003 1003 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005
11 32·6 33·6 34·6 35·6 36·6 37·6 38·6 39·6 40·6 41·6 42·6 43·6 44·6 45·6 46·6 47·6 48·6 49·5 50·5 51·5 52·5 53·5 54·4 55·4 56·4 57·4 58·4 59·4 60·4 61·4 62·4 63·4 64·4 65·4 66·4 67·3 68·3 69·3 70·3 71·3 72·3 73·2 74·2 75·2 76·2 77·2 78·2 79·2 80·2 81·2 82·2 83·1 84·1 85·1 86·1 87·1 88 89 90 91
1002 1002 1002 1002 1002 1002 1002 1002 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004
12 32·2 33·2 34·2 35·2 36·2 37·2 38·2 39·2 40·2 41·2 42·2 43·2 44·2 45·2 46·2 47·2 48·2 49·2 50·2 51·1 52·1 53·1 54·1 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 72·9 73·9 74·9 75·9 76·9 77·9 78·9 79·9 80·9 81·9 82·9 83·9 84·8 85·8 86·8 87·8 88·7 89·7 90·7
1001 1001 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003
13 31·8 32·8 33·8 34·8 35·8 36·8 37·8 38·8 39·8 40·8 41·8 42·8 43·8 44·8 45·8 46·8 47·8 48·8 49·8 50·8 51·8 52·7 53·7 54·7 55·7 56·7 57·7 58·7 59·7 60·7 61·7 62·7 63·7 64·7 65·7 66·7 67·7 68·7 69·6 70·6 71·6 72·6 73·6 74·6 75·6 76·6 77·6 78·6 79·6 80·6 81·6 82·6 83·6 84·6 85·5 86·5 87·5 88·5 89·5 90·5
1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1092 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002
14 31·4 32·4 33·4 34·4 35·4 36·4 37·4 38·4 39·4 40·4 41·4 42·4 43·4 44·4 45·4 46·4 47·4 48·4 49·4 50·4 51·4 52·3 53·3 54·3 55·3 56·3 57·3 58·3 59·3 60·3 61·3 62·3 63·3 64·3 65·3 66·3 67·3 68·3 69·3 70·3 71·3 72·3 73·3 74·3 75·3 76·3 77·3 78·3 79·3 80·3 81·3 82·3 83·3 84·3 85·3 86·3 87·3 88·2 89·2 90·2
1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1000 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001
15 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
16 30·6 31·6 32·5 33·5 34·5 35·5 36·5 37·5 38·5 39·5 40·6 41·6 42·6 43·6 44·6 45·6 46·6 47·6 48·6 49·6 50·6 51·6 52·6 53·6 54·6 55·6 56·6 57·6 58·6 59·6 60·6 61·7 62·7 63·7 64·7 65·7 66·7 67·7 68·7 69·7 70·7 71·7 72·7 73·7 74·7 75·7 76·7 77·7 78·7 79·7 80·7 81·7 82·7 83·7 84·7 85·7 86·7 87·7 88·7 89·7
1000 1000 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999
17 30·2 31·2 32·1 33·1 34·1 35·1 36·1 37·1 38·1 39·1 40·2 41·2 42·2 43·2 44·9 45·2 46·2 47·2 48·2 49·2 50·3 51·3 52·3 53·3 54·3 55·3 56·3 57·3 58·3 59·3 60·3 61·3 62·3 63·3 64·3 65·3 66·3 67·3 68·3 69·3 70·3 71·3 72·3 73·3 74·3 75·4 76·4 77·4 78·4 79·4 80·4 81·4 82·4 83·4 84·4 85·4 86·4 87·4 88·4 89·5
999 999 999 999 999 999 999 999 999 999 999 999 999 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998
18 29·8 30·8 31·7 32·7 33·7 34·7 35·7 36·7 37·7 38·7 39·8 40·8 41·8 42·8 43·8 44·9 45·9 46·9 47·9 48·9 49·9 50·9 51·9 52·9 53·9 54·9 55·9 56·9 57·9 58·9 59·9 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75·1 76·1 77·1 78·1 79·1 80·1 81·1 82·1 83·1 84·1 85·2 86·2 87·2 88·2 89·2
999 999 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 998 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997
19 29·4 30·4 31·3 32·3 33·3 34·3 35·3 36·3 37·3 38·3 39·4 40·4 41·4 42·5 43·5 44·5 45·5 46·5 47·5 48·5 49·5 50·6 51·6 52·6 53·6 54·6 55·6 56·6 57·6 58·6 59·6 60·6 61·6 62·7 63·7 64·7 65·7 66·7 67·7 68·7 69·7 70·7 71·7 72·7 73·7 74·7 75·8 76·8 77·8 78·8 79·8 80·8 81·9 82·9 83·9 84·9 85·9 86·9 87·9 88·9
998 998 998 998 998 998 998 998 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 997 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996
20 29 30 30·9 31·9 32·9 33·9 34·9 35·9 36·9 37·9 39 40 41 42·1 43·1 44·1 45·1 46·1 47·2 48·2 49·2 50·2 51·2 52·2 53·2 54·2 55·2 56·2 57·2 58·2 59·2 60·3 61·3 62·3 63·3 64·3 65·4 66·4 67·4 68·4 69·4 70·4 71·4 72·4 73·4 74·4 75·5 76·5 77·5 78·5 79·5 80·5 81·6 82·6 83·6 84·6 85·6 86·6 87·7 88·7
998 998 997 997 997 997 997 997 997 997 997 997 997 997 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 996 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995
21 28·6 29·6 30·5 31·5 32·5 33·5 34·5 35·5 36·5 37·5 38·6 39·6 40·6 41·7 42·7 43·7 44·8 45·8 46·8 47·8 48·8 49·8 50·8 51·8 52·9 53·9 54·9 55·9 56·9 57·9 58·9 59·9 61 62 63 64 65 66 67 68·1 69·1 70·1 71·1 72·1 73·1 74·1 75·2 76·2 77·2 78·2 79·2 80·2 81·3 82·3 83·3 84·3 85·3 86·4 87·4 88·4
997 997 997 997 997 997 997 996 996 996 996 996 996 996 996 996 996 996 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 995 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994
22 28·2 29·2 30·1 31·1 32·1 33·1 34·1 35·1 36·1 37·1 38·2 39·2 40·2 41·3 42·3 43·3 44·3 45·3 46·4 47·4 48·4 49·4 50·4 51·4 52·5 53·5 54·5 55·5 56·5 57·5 58·5 59·5 60·6 61·6 62·7 63·7 64·7 65·7 66·7 67·7 68·8 69·8 70·8 71·8 72·8 73·8 74·8 75·9 76·9 77·9 78·9 79·9 81 82 83 84 85 86·1 87·1 88·2
997 997 996 996 996 996 996 996 996 996 996 995 995 995 995 995 995 995 995 995 995 995 995 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 994 993 993 993 993 993 993 993 993 993 993 993 993 993 993 993 993
23 27·8 28·8 29·7 30·7 31·7 32·7 33·7 34·7 35·7 36·7 37·8 38·8 39·8 40·9 41·9 42·9 43·9 44·9 46 47 48 49·1 50·1 51·1 52·1 53·1 54·1 55·1 56·1 57·1 58·1 59·2 60·2 61·3 62·3 63·3 64·3 65·4 66·4 67·4 68·4 69·4 70·5 71·5 72·5 73·5 74·5 75·5 76·6 77·6 78·6 79·6 80·7 81·7 82·7 83·8 84·8 85·8 86·8 87·9
996 996 996 996 996 996 996 995 995 995 995 995 995 994 994 994 994 994 994 994 994 994 994 994 994 994 994 993 993 993 993 993 993 993 993 993 993 993 993 993 993 993 993 993 992 992 992 992 992 992 992 992 992 992 992 992 992 992 992 992
24 27·4 28·4 29·3 30·3 31·3 32·3 33·3 34·3 35·3 36·3 37·4 38·4 39·4 40·5 41·5 42·5 43·6 44·6 45·6 46·6 47·6 48·7 49·7 50·7 51·8 52·8 53·8 54·8 55·8 56·8 57·8 58·9 59·9 61 62 63 64 65 66 67·1 68·1 69·1 70·1 71·2 72·2 73·2 74·2 75·2 76·3 77·3 78·3 79·3 80·4 81·4 82·4 83·5 84·5 85·5 86·5 87·6
996 996 995 995 995 995 995 995 995 994 994 994 994 994 994 994 994 994 993 993 993 993 993 693 993 993 993 993 993 992 992 992 992 992 992 992 992 992 992 992 992 992 992 992 992 992 992 991 991 991 991 991 991 991 991 991 991 991 991 991
25 27 28 28·9 29·9 30·9 31·9 32·9 33·9 34·9 35·9 37 38 39 40·1 42·1 42·2 43·2 44·2 45·2 46·3 47·3 48·3 49·3 50·3 51·4 52·4 53·4 54·4 55·5 56·5 57·5 58·5 59·5 60·6 61·6 62·6 63·7 64·7 65·7 66·7 67·8 68·8 69·8 70·8 71·8 72·8 73·9 74·9 76 77 78 79 80·1 81·1 82·1 83·2 84·2 85·2 86·3 87·4
995 995 995 995 995 994 994 994 994 994 994 994 993 993 993 993 993 993 993 993 993 993 993 992 992 992 992 992 992 992 992 992 992 991 991 991 991 991 991 991 991 991 991 991 991 991 991 991 991 991 991 991 990 990 990 990 990 990 990 990
31c 32c 33c 34c 35c 36c 37c 38c 39c 40c 41c 42c
10 33·0 34 35 36 37 38 39 40 41 42 43 44
1002 1002 1003 1003 1003 1003 1003 1003 1003 1003 1003 1004
11 32·6 33·6 34·6 35·6 36·6 37·6 38·6 39·6 40·6 41·6 42·6 43·6
1002 1002 1002 1002 1002 1002 1002 1002 1003 1003 1003 1003
12 32·2 33·2 34·2 35·2 36·2 37·2 38·2 39·2 40·2 41·2 42·2 43·2
1001 1001 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002
13 31·8 32·8 33·8 34·8 35·8 36·8 37·8 38·8 39·8 40·8 41·8 42·8
1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001
14 31·4 32·4 33·4 34·4 35·4 36·4 37·4 38·4 39·4 40·4 41·4 42·4
1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001
15 31 32 33 34 35 36 37 38 39 40 41 42
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
16 30·6 31·6 32·5 33·5 34·5 35·5 36·5 37·5 38·5 39·5 40·6 41·6
1000 1000 999 999 999 999 999 999 999 999 999 999
17 30·2 31·2 32·1 33·1 34·1 35·1 36·1 37·1 38·1 39·1 40·2 41·2
999 999 999 999 999 999 999 999 999 999 999 999
18 29·8 30·8 31·7 32·7 33·7 34·7 35·7 36·7 37·7 38·7 39·8 40·8
999 999 998 998 998 998 998 998 998 998 998 998
19 29·4 30·4 31·3 32·3 33·3 34·3 35·3 36·3 37·3 38·3 39·4 40·4
998 998 998 998 998 998 998 998 997 997 997 997
20 29 30 30·9 31·9 32·9 33·9 34·9 35·9 36·9 37·9 39 40
998 998 997 997 997 997 997 997 997 997 997 997
21 28·6 29·6 30·5 31·5 32·5 33·5 34·5 35·5 36·5 37·5 38·6 39·6
997 997 997 997 997 997 997 996 996 996 996 996
22 28·2 29·2 30·1 31·1 32·1 33·1 34·1 35·1 36·1 37·1 38·2 39·2
997 997 996 996 996 996 996 996 996 996 996 995
23 27·8 28·8 29·7 30·7 31·7 32·7 33·7 34·7 35·7 36·7 37·8 38·8
996 996 996 996 996 996 996 995 995 995 995 995
24 27·4 28·4 29·3 30·3 31·3 32·3 33·3 34·3 35·3 36·3 37·4 38·4
996 996 995 995 995 995 995 995 995 994 994 994
25 27 28 28·9 29·9 30·9 31·9 32·9 33·9 34·9 35·9 37 38
995 995 995 995 995 994 994 994 994 994 994 994
43c 44c 45c 46c 47c 48c 49c 50c 51c 52c 53c 54c
10 45 46 46·9 47·9 48·9 49·9 50·9 51·8 52·8 53·8 54·8 55·8
1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004
11 44·6 45·6 46·6 47·6 48·6 49·5 50·5 51·5 52·5 53·5 54·4 55·4
1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003
12 44·2 45·2 46·2 47·2 48·2 49·2 50·2 51·1 52·1 53·1 54·1 55
1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002
13 43·8 44·8 45·8 46·8 47·8 48·8 49·8 50·8 51·8 52·7 53·7 54·7
1001 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002
14 43·4 44·4 45·4 46·4 47·4 48·4 49·4 50·4 51·4 52·3 53·3 54·3
1001 1001 1001 1001 1001 1001 1001 1000 1001 1001 1001 1001
15 43 44 45 46 47 48 49 50 51 52 53 54
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
16 42·6 43·6 44·6 45·6 46·6 47·6 48·6 49·6 50·6 51·6 52·6 53·6
999 999 999 999 999 999 999 999 999 999 999 999
17 42·2 43·2 44·9 45·2 46·2 47·2 48·2 49·2 50·3 51·3 52·3 53·3
999 998 998 998 998 998 998 998 998 998 998 998
18 41·8 42·8 43·8 44·9 45·9 46·9 47·9 48·9 49·9 50·9 51·9 52·9
998 998 998 998 998 998 998 998 998 998 998 998
19 41·4 42·5 43·5 44·5 45·5 46·5 47·5 48·5 49·5 50·6 51·6 52·6
997 997 997 997 997 997 997 997 997 997 997 997
20 41 42·1 43·1 44·1 45·1 46·1 47·2 48·2 49·2 50·2 51·2 52·2
997 997 996 996 996 996 996 996 996 996 996 996
21 40·6 41·7 42·7 43·7 44·8 45·8 46·8 47·8 48·8 49·8 50·8 51·8
996 996 996 996 996 996 995 995 995 995 995 995
22 40·2 41·3 42·3 43·3 44·3 45·3 46·4 47·4 48·4 49·4 50·4 51·4
995 995 995 995 995 995 995 995 995 995 995 994
23 39·8 40·9 41·9 42·9 43·9 44·9 46 47 48 49·1 50·1 51·1
995 994 994 994 994 994 994 994 994 994 994 994
24 39·4 40·5 41·5 42·5 43·6 44·6 45·6 46·6 47·6 48·7 49·7 50·7
994 994 994 994 994 994 993 993 993 993 993 693
25 39 40·1 42·1 42·2 43·2 44·2 45·2 46·3 47·3 48·3 49·3 50·3
993 993 993 993 993 993 993 993 993 993 993 992
55c 56c 57c 58c 59c 60c 61c 62c 63c 64c 65c 66c
10 56·8 57·8 58·8 59·7 60·7 61·7 62·7 63·7 64·7 65·7 66·7 67·6
1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004
11 56·4 57·4 58·4 59·4 60·4 61·4 62·4 63·4 64·4 65·4 66·4 67·3
1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003
12 56 57 58 59 60 61 62 63 64 65 66 67
1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002
13 55·7 56·7 57·7 58·7 59·7 60·7 61·7 62·7 63·7 64·7 65·7 66·7
1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002
14 55·3 56·3 57·3 58·3 59·3 60·3 61·3 62·3 63·3 64·3 65·3 66·3
1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001
15 55 56 57 58 59 60 61 62 63 64 65 66
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
16 54·6 55·6 56·6 57·6 58·6 59·6 60·6 61·7 62·7 63·7 64·7 65·7
999 999 999 999 999 999 999 999 999 999 999 999
17 54·3 55·3 56·3 57·3 58·3 59·3 60·3 61·3 62·3 63·3 64·3 65·3
998 998 998 998 998 998 998 998 998 998 998 998
18 53·9 54·9 55·9 56·9 57·9 58·9 59·9 61 62 63 64 65
998 998 998 997 997 997 997 997 997 997 997 997
19 53·6 54·6 55·6 56·6 57·6 58·6 59·6 60·6 61·6 62·7 63·7 64·7
997 997 997 997 997 997 997 997 997 997 997 997
20 53·2 54·2 55·2 56·2 57·2 58·2 59·2 60·3 61·3 62·3 63·3 64·3
996 996 996 996 996 996 996 996 996 996 996 996
21 52·9 53·9 54·9 55·9 56·9 57·9 58·9 59·9 61 62 63 64
995 995 995 995 995 995 995 995 995 995 995 995
22 52·5 53·5 54·5 55·5 56·5 57·5 58·5 59·5 60·6 61·6 62·7 63·7
994 994 994 994 994 994 994 994 994 994 994 994
23 52·1 53·1 54·1 55·1 56·1 57·1 58·1 59·2 60·2 61·3 62·3 63·3
994 994 994 993 993 993 993 993 993 993 993 993
24 51·8 52·8 53·8 54·8 55·8 56·8 57·8 58·9 59·9 61 62 63
993 993 993 993 993 992 992 992 992 992 992 992
25 51·4 52·4 53·4 54·4 55·5 56·5 57·5 58·5 59·5 60·6 61·6 62·6
992 992 992 992 992 992 992 992 992 991 991 991
67c 68c 69c 70c 71c 72c 73c 74c 75c 76c 77c 78c
10 68·6 69·6 70·6 71·6 72·6 73·5 74·5 75·5 76·5 77·5 78·5 79·5
1004 1004 1004 1004 1004 1004 1005 1005 1005 1005 1005 1005
11 68·3 69·3 70·3 71·3 72·3 73·2 74·2 75·2 76·2 77·2 78·2 79·2
1003 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004
12 68 69 70 71 72 72·9 73·9 74·9 75·9 76·9 77·9 78·9
1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003
13 67·7 68·7 69·6 70·6 71·6 72·6 73·6 74·6 75·6 76·6 77·6 78·6
1002 1002 1002 1002 1002 1002 1002 1002 1092 1002 1002 1002
14 67·3 68·3 69·3 70·3 71·3 72·3 73·3 74·3 75·3 76·3 77·3 78·3
1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001
15 67 68 69 70 71 72 73 74 75 76 77 78
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
16 66·7 67·7 68·7 69·7 70·7 71·7 72·7 73·7 74·7 75·7 76·7 77·7
999 999 999 999 999 999 999 999 999 999 999 999
17 66·3 67·3 68·3 69·3 70·3 71·3 72·3 73·3 74·3 75·4 76·4 77·4
998 998 998 998 998 998 998 998 998 998 998 998
18 66 67 68 69 70 71 72 73 74 75·1 76·1 77·1
997 997 997 997 997 997 997 997 997 997 997 997
19 65·7 66·7 67·7 68·7 69·7 70·7 71·7 72·7 73·7 74·7 75·8 76·8
997 997 996 996 996 996 996 996 996 996 996 996
20 65·4 66·4 67·4 68·4 69·4 70·4 71·4 72·4 73·4 74·4 75·5 76·5
996 996 996 996 996 996 995 995 995 995 995 995
21 65 66 67 68·1 69·1 70·1 71·1 72·1 73·1 74·1 75·2 76·2
995 995 995 995 995 995 995 994 994 994 994 994
22 64·7 65·7 66·7 67·7 68·8 69·8 70·8 71·8 72·8 73·8 74·8 75·9
994 994 994 994 994 994 994 994 993 993 993 993
23 64·3 65·4 66·4 67·4 68·4 69·4 70·5 71·5 72·5 73·5 74·5 75·5
993 993 993 993 993 993 993 993 992 992 992 992
24 64 65 66 67·1 68·1 69·1 70·1 71·2 72·2 73·2 74·2 75·2
992 992 992 992 992 992 992 992 992 992 992 991
25 63·7 64·7 65·7 66·7 67·8 68·8 69·8 70·8 71·8 72·8 73·9 74·9
991 991 991 991 991 991 991 991 991 991 991 991
79c 80c 81c 82c 83c 84c 85c 86c 87c 88c 89c 90c
10 80·5 81·5 82·4 83·4 84·4 85·4 86·4 87·4 88·3 89·3 90·2 91·2
1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005 1005
11 80·2 81·2 82·2 83·1 84·1 85·1 86·1 87·1 88 89 90 91
1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004 1004
12 79·9 80·9 81·9 82·9 83·9 84·8 85·8 86·8 87·8 88·7 89·7 90·7
1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003 1003
13 79·6 80·6 81·6 82·6 83·6 84·6 85·5 86·5 87·5 88·5 89·5 90·5
1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002 1002
14 79·3 80·3 81·3 82·3 83·3 84·3 85·3 86·3 87·3 88·2 89·2 90·2
1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001 1001
15 79 80 81 82 83 84 85 86 87 88 89 90
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
16 78·7 79·7 80·7 81·7 82·7 83·7 84·7 85·7 86·7 87·7 88·7 89·7
999 999 999 999 999 999 999 999 999 999 999 999
17 78·4 79·4 80·4 81·4 82·4 83·4 84·4 85·4 86·4 87·4 88·4 89·5
998 998 998 998 998 998 998 998 998 998 998 998
18 78·1 79·1 80·1 81·1 82·1 83·1 84·1 85·2 86·2 87·2 88·2 89·2
997 997 997 997 997 997 997 997 997 997 997 997
19 77·8 78·8 79·8 80·8 81·9 82·9 83·9 84·9 85·9 86·9 87·9 88·9
996 996 996 996 996 996 996 996 996 996 996 996
20 77·5 78·5 79·5 80·5 81·6 82·6 83·6 84·6 85·6 86·6 87·7 88·7
995 995 995 995 995 995 995 995 995 995 995 995
21 77·2 78·2 79·2 80·2 81·3 82·3 83·3 84·3 85·3 86·4 87·4 88·4
994 994 994 994 994 994 994 994 994 994 994 994
22 76·9 77·9 78·9 79·9 81 82 83 84 85 86·1 87·1 88·2
993 993 993 993 993 993 993 993 993 993 993 993
23 76·6 77·6 78·6 79·6 80·7 81·7 82·7 83·8 84·8 85·8 86·8 87·9
992 992 992 992 992 992 992 992 992 992 992 992
24 76·3 77·3 78·3 79·3 80·4 81·4 82·4 83·5 84·5 85·5 86·5 87·6
991 991 991 991 991 991 991 991 991 991 991 991
25 76 77 78 79 80·1 81·1 82·1 83·2 84·2 85·2 86·3 87·4
991 991 991 991 990 990 990 990 990 990 990 990


I consider the preceding table, which I have extracted from the longer tables of M. Gay Lussac, as an important addition to the resources of British dealers and manufacturing chemists. With the aid of his little instrument, which may be got for a trifle from its ingenious maker, M. Collardeau, Rue Faubourg St. Martin, at Paris, or constructed by one of the London hydrometer artists, the per centage of real alcohol, and the real value of any spirituous liquor, may be determined to sufficient nicety for most purposes, in a far easier manner than by any instruments now used in this country. It has been adopted by the Swedish government, with M. Gay Lussac’s tables.

M. Gay Lussac’s table gives, by inspection, the true bulk of the spirits as corrected for temperature; that is, their volume, if of the normal temperature of 15° Cent. (59° Fahr.). Now this is important information; for, if a person buys 1000 gallons of spirits in hot weather, and pays for them exactly according to their strength corrected for temperature, he will not have 1000 gallons when the weather is in its mean state. He may lose, in this way, several gallons without being aware of it from his hydrometer.

Sometimes, after moist autumns, when damaged grain abounds, the alcohol distilled from its fermented wash contains a peculiar volatile body. When we apply our nose to this species of spirits in its hot state, the volatile substance dissolved in it irritates the eyes and nostrils: it has very nearly the same smell as an alcoholic solution of cyanogen, as any chemist may discover by standing near the discharge pipe of the refrigeratory worm of a raw-grain whisky still. Such spirits intoxicate more strongly than pure spirits of the same strength, and excite, in many persons, even temporary frenzy. It is a volatile fatty matter, of a very fetid odour, when obtained by itself, as I have procured it in cold weather at some of the great distilleries in Scotland. It does not combine with bases. At the end of a few months, it spontaneously decomposes in the spirits, and leaves them in a less nauseous and noxious state. By largely diluting the spirits with water, and distilling at a moderate temperature, the greater part of this oil may be separated. Part of it comes over with the strongest alcohol, and part with the latter runnings, which are called by the distillers strong and weak feints. The intermediate portion is purer spirit. The feints are always more or less opalescent, or become so on dilution with water, and then throw up an oily pellicle upon their surface. The charcoals of light wood, such as pine or willow, well calcined, and infused in sufficient quantity with the spirits prior to rectification, will deprive them of the greater part of that oily contamination. Animal charcoal, well calcined, has also been found useful; but it must be macerated for some time with the empyreumatic spirits, before distillation. Another mode of separating that offensive oil is, to agitate the impure spirits with a quantity of a fat oil, such as olive oil, or oil of almonds, to decant off the oil, and re-distil the spirits with a little water.

Some foreign chemists direct empyreumatic or rank spirits, to be rectified with the addition of chloride of lime. I have tried this method in every way, and on a considerable scale, but never found the spirits to be improved by it. They were rather deteriorated. See Brandy, Distillation, Fermentation, Gin, Rum, Whisky.

Anhydrous or absolute alcohol, when swallowed, acts as a mortal poison, not only by its peculiar stimulus on the nervous system, but by its abstracting the aqueous particles from the soft tissue of the stomach, with which it comes in contact, so as to destroy its organisation. Alcohol of 0·812 consists, by experiments, of 3 atoms of carbon, 6 of hydrogen, and 2 of oxygen; absolute alcohol consists, probably, of 2 of carbon, 3 of hydrogen, and 1 of oxygen.

ALE. The fermented infusion of pale malted barley, usually combined with infusion of hops. See Beer.

ALEMBIC, a Still; which see.

ALEMBROTH, salt of. The salt of wisdom, of the alchemists; a compound of bichloride of mercury and sal ammoniac, from which the old white precipitate of mercury is made.

ALGAROTH, powder of. A compound of oxide and chloride of antimony, being a precipitate obtained by pouring water into the acidulous chloride of that metal.

ALIZARINE. See Madder.

ALKALI. A class of chemical bodies, distinguished chiefly by their solubility in water, and their power of neutralising acids, so as to form saline compounds. The alkalis of manufacturing importance are, ammonia, potash, soda, and quinia. These alkalis change the purple colour of red cabbage and radishes to a green, the reddened tincture of litmus to a purple, and the colour of turmeric and many other yellow dyes to a brown. Even when combined with carbonic acid, the first three alkalis exercise this discolouring power, which the alkaline earths, lime and barytes, do not. The same three alkalis have an acrid, and somewhat urinous taste; the first two are energetic solvents of animal matter; and the three combine with oils, so as to form soaps. They unite with water in every proportion, and also with alcohol; and the first three combine with water after being carbonated.


ALKALIMETER. An instrument for measuring the alkaline force or purity of any of the alkalis of commerce. It is founded on the principle, that the quantity of real alkali present in any sample, is proportional to the quantity of acid which a given weight of it can neutralize. See the individual alkalis, Potash, and Soda.

ALKANA, is the name of the root and leaves of Lausania inermis, which have been long employed in the East, to dye the nails, teeth, hair, garments, &c. The leaves, ground and mixed with a little limewater, serve for dyeing the tails of horses in Persia and Turkey.

ALKANET, the root of. (Anchusa tinctoria.) A species of bugloss, cultivated chiefly in the neighbourhood of Montpellier. It affords a fine red colour to alcohol and oils; but a dirty red to water. Its principal use is for colouring ointments, cheeses, and pommades. The spirituous tincture gives to white marble a beautiful deep stain.

ALLIGATION. An arithmetical formula, useful, on many occasions, for ascertaining the proportion of constituents in a mixture, when they have undergone no change of volume by chemical action. When alcoholic liquors are mixed with water, there is a condensation of bulk, which renders that arithmetical rule inapplicable. The same thing holds, in some measure, in the union of metals by fusion. See Alloy.

ALLOY. (Alliage, Fr.; Legirung, Germ.) This term formerly signified a compound of gold and silver, with some metal of inferior value, but it now means any compound of any two or more metals whatever. Thus, bronze is an alloy of copper and tin; brass, an alloy of copper and zinc; and type metal, an alloy of lead and antimony. All the alloys possess metallic lustre, even when cut or broken to pieces; they are opaque; are excellent conductors of heat and electricity; are frequently susceptible of crystallising; are more or less ductile, malleable, elastic, and sonorous. An alloy which consists of metals differently fusible is usually malleable in the cold, and brittle when hot, as is exemplified with brass and gong metal.

Many alloys consist of definite or equivalent proportions of the simple component metals, though some alloys seem to form in any proportion, like combinations of salt or sugar with water. It is probable that peculiar properties belong to the equivalent or atomic ratio, as is exemplified in the superior quality of brass made in that proportion.

One metal does not alloy indifferently with every other metal, but it is governed in this respect by peculiar affinities; thus, silver will hardly unite with iron, but it combines readily with gold, copper, and lead. In comparing the alloys with their constituent metals, the following differences may be noted; in general, the ductility of the alloy is less than that of the separate metals, and sometimes in a very remarkable degree; on the contrary, the alloy is usually harder than the mean hardness of its constituents. The mercurial alloys or amalgams are, perhaps, exceptions to this rule.

The specific gravity is rarely the mean between that of each of its constituents, but is sometimes greater and sometimes less, indicating, in the former case, an approximation, and in the latter, a recedure, of the particles from each other in the act of their union. The following tables of binary alloys exhibit this circumstance in experimental detail:—

Alloys having a density greater than
the mean of their constituents.
Alloys having a density less than
the mean of their constituents.
Gold and zinc Gold and silver
Gold and tin Gold and iron
Gold and bismuth Gold and lead
Gold and antimony Gold and copper
Gold and cobalt Gold and iridium
Silver and zinc Gold and nickel
Silver and lead Silver and copper
Silver and tin Silver and lead
Silver and bismuth Iron and bismuth
Silver and antimony Iron and antimony
Copper and zinc Iron and lead
Copper and tin Tin and lead
Copper and palladium Tin and palladium
Copper and bismuth Tin and antimony
Lead and antimony Nickel and arsenic
Platinum and molybdenum Zinc and antimony.
Palladium and bismuth.  

It would be hardly possible to infer the melting point of an alloy from that of each of its constituent metals; but, in general, the fusibility is increased by mutual affinity in their state of combination. Of this, a remarkable instance is afforded in the fusible metal consisting of 8 parts of bismuth, 5 of lead, and 3 of tin, which melts at the[30] heat of boiling water or 212° Fahr., though the melting point deduced from the mean of its components should be 514°. This alloy may be rendered still more fusible by adding a very little mercury to it, when it forms an excellent material for certain anatomical injections, and for filling the hollows of carious teeth. Nor do the colours of alloys depend, in any considerable degree, upon those of the separate metals; thus, the colour of copper, instead of being rendered paler by a large addition of zinc, is thereby converted into the rich-looking pinchbeck metal.

By means of alloys, we multiply, as it were, the numbers of useful metals, and sometimes give usefulness to such as are separately of little value. Since these compounds can be formed only by fusion, and since many metals are apt to oxidise readily at their melting temperature, proper precautions must be taken in making alloys to prevent this occurrence, which is incompatible with their formation. Thus, in combining tin and lead, rosin or grease is usually put on the surface of the melting metals, the carbon produced by the decomposition of which protects them, in most cases, sufficiently from oxidisement. When we wish to combine tin with iron, as in the tinning of cast-iron tea kettles, we rub sal ammoniac upon the surfaces of the hot metals in contact with each other, and thus exclude the atmospheric oxygen by means of its fumes. When there is a notable difference in the specific gravities of the metals which we wish to combine, we often find great difficulties in obtaining homogeneous alloys; for each metal may tend to assume the level due to its density, as is remarkably exemplified in alloys of gold and silver made without adequate stirring of the melting metals. If the mass be large, and slow of cooling after it is cast in an upright cylindrical form, the metals sometimes separate, to a certain degree, in the order of their densities. Thus, in casting large bells and cannons with copper alloys, the bottom of the casting is apt to contain too much copper and the top too much tin, unless very dexterous manipulation in mixing the fused materials have been employed immediately before the instant of pouring out the melted mass. When such inequalities are observed, the objects are broken and re-melted, after which they form a much more homogeneous alloy. This artifice of a double melting is often had recourse to, and especially in casting the alloys for the specula of telescopes.

When we wish to alloy three or more metals, we often experience difficulties, either because one of the metals is more oxidable, or denser, or more fusible, than the others, or because there is no direct affinity between two of the metals. In the latter predicament, we shall succeed better by combining the three metals, first in pairs, for example, and then melting the two pairs together. Thus, it is difficult to unite iron with bronze directly; but if, instead of iron, we use tin plate, we shall immediately succeed, and the bronze, in this manner, acquires valuable qualities from the iron. Thus, also, to render brass better adapted for certain purposes, a small quantity of lead ought to be added to it, but this cannot be done directly with advantage: it is better to melt the lead first along with the zinc, and then to add this alloy to the melting copper, or the copper to that alloy, and fuse them together.

We have said that the difference of fusibility was often an obstacle to metallic combination; but this circumstance may also be turned to advantage in decomposing certain alloys by the process called eliquation. By this means silver may be separated from copper, if a considerable quantity of lead be first alloyed with the said copper; this alloy is next exposed to a heat just sufficient to melt the lead, which then sweats out, so to speak, from the pores of the copper, and carries along with it the greater part of the silver, for which it has a strong affinity. The lead and the silver are afterwards separated from each other, in virtue of their very different oxidability, by the action of heat and air.

One of the alloys most useful to the arts is brass; it is more ductile and less easily oxidised than even its copper constituent, notwithstanding the opposite nature of the zinc. This alloy may exist in many different proportions, under which it has different names, as tombac, similor, pinchbeck, &c. Copper and tin form, also, a compound of remarkable utility, known under the names of hard brass, for the bushes, steps, and bearings of the axles, arbours, and spindles in machinery; and of bronze, bell-metal, &c. Gold and silver, in their pure state, are too soft and flexible to form either vessels or coins of sufficient strength and durability; but when alloyed with a little copper, they acquire the requisite hardness and stiffness for these and other purposes.

When we have occasion to unite several pieces of the same or of different metals, we employ the process called soldering, which consists in fixing together the surfaces by means of an interposed alloy, which must be necessarily more fusible than the metal or metals to be joined. That alloy must also consist of metals which possess a strong affinity for the substances to be soldered together. Hence each metal would seem to require a particular kind of solder, which is, to a certain extent, true. Thus, the solder for gold trinkets and plate is an alloy of gold and silver, or gold and copper; that of silver trinkets, is an alloy of silver and copper; that of copper is either fine tin, for pieces that must not be exposed to the fire, or a brassy alloy called hard solder, of which[31] the zinc forms a considerable proportion. The solder of lead and tinplate is an alloy of lead and tin, and that of tin is the same alloy with a little bismuth. Tinning, gilding, and silvering may also be reckoned a species of alloys, since the tin, gold, and silver are superficially united in these cases to other metals.

Metallic alloys possess usually more tenacity than could be inferred from their constituents; thus, an alloy of twelve parts of lead with one of zinc has a tenacity double that of zinc. Metallic alloys are much more easily oxidised than the separate metals, a phenomenon which may be ascribed to the increase of affinity for oxygen which results from the tendency of the one of the oxides to combine with the other. An alloy of tin and lead heated to redness takes fire, and continues to burn for some time like a piece of bad turf.

Every alloy is, in reference to the arts and manufactures, a new metal, on account of its chemical and physical properties. A vast field here remains to be explored. Not above sixty alloys have been studied by the chemists out of many hundred which may be made; and of these very few have yet been practically employed. Very slight modifications often constitute very valuable improvements upon metallic bodies. Thus, the brass most esteemed by turners at the lathe contains from two to three per cent. of lead; but such brass does not work well under the hammer; and, reciprocally, the brass which is best under the hammer is too tough for turning.

That metallic alloys tend to be formed in definite proportions of their constituents is clear from the circumstance that the native gold of the auriferous sands is an alloy with silver, in the ratios of 1 atom of silver united to 4, 5, 6, 12 atoms of gold, but never with a fractional part of an atom. Also, in making an amalgam of 1 part of silver with 12 or 15 of mercury, and afterwards squeezing the mixture through chamois leather, the amalgam separates into 2 parts: one, containing a small proportion of silver and much mercury, passes through the skin; and the other, formed of 1 of silver and 8 of mercury, is a compound in definite proportions, which crystallises readily, and remains in the knot of the bag. An analogous separation takes place in the tinning of mirrors; for on loading them with the weights, a liquid amalgam of tin is squeezed out, while another amalgam remains in a solid form composed of tin and mercury in uniform atomic proportions. But, as alloys are generally soluble, so to speak, in each other, this definiteness of combination is masked and disappears in most cases.

M. Chaudet has made some experiments on the means of detecting the metals of alloys by the cupelling furnace, and they promise useful applications. The testing depends upon the appearances exhibited by the metals and their alloys when heated on a cupel. Pure tin, when heated this way, fuses, becomes of a greyish black colour, fumes a little, exhibits incandescent points on its surface, and leaves an oxide, which, when withdrawn from the fire, is at first lemon-yellow, but when cold, white. Antimony melts, preserves its brilliancy, fumes, and leaves the vessel coloured lemon-yellow when hot, but colourless when cold, except a few spots of a rose tint. Zinc burns brilliantly, forming a cone of oxide; and the oxide, much increased in volume, is, when hot, greenish, but when cold, perfectly white. Bismuth fumes, becomes covered with a coat of melted oxide, part of which sublimes, and the rest enters the pores of the cupel; when cold, the cupel is of a fine yellow colour, with spots of a greenish hue. Lead resembles bismuth very much; the cold cupel is of a lemon-yellow colour. Copper melts, and becomes covered with a coat of black oxide; sometimes spots of a rose tint remain on the cupel.

Alloys.—Tin 75, antimony 25, melt, become covered with a coat of black oxide, have very few incandescent points; when cold, the oxide is nearly black, in consequence of the action of the antimony: a 1400 part of antimony may be ascertained in this way in the alloy. An alloy of antimony, containing tin, leaves oxide of tin in the cupel: a 1100 part of tin may be detected in this way. An alloy of tin and zinc gives an oxide which, whilst hot, is of a green tint, and resembles philosophic wool in appearance. An alloy containing 99 tin, 1 zinc, did not present the incandescent points of pure tin, and gave an oxide of greenish tint when cold. Tin 95, bismuth 5 parts, gave an oxide of a grey colour. Tin and lead give an oxide of a rusty brown colour. An alloy of lead and tin, containing only 1 per cent. of the latter metal, when heated, does not expose a clean surface, like lead, but is covered at times with oxide of tin. Tin 75, and copper 25, did not melt, gave a black oxide: if the heat be much elevated, the under part of the oxide is white, and is oxide of tin; the upper is black, and comes from the copper. The cupel becomes of a rose colour. If the tin be impure from iron, the oxide produced by it is marked with spots of a rust colour.

The degree of affinity between metals may be in some measure estimated by the greater or less facility with which, when of different degrees of fusibility or volatility, they unite, or with which they can, after union, be separated by heat. The greater or less tendency to separate into differently proportioned alloys, by long-continued fusion, may also give some information upon this subject. Mr. Hatchett remarked, in his[32] elaborate researches on metallic alloys, that gold made standard with the usual precautions, by silver, copper, lead, antimony, &c., and then cast, after long fusion, into vertical bars, was by no means an uniform compound; but that the top of the bar, corresponding to the metal at the bottom of the crucible, contained the larger proportion of gold. Hence, for a more thorough combination, two red-hot crucibles should be employed, and the liquefied metals should be alternately poured from the one into the other. To prevent unnecessary oxidisement from the air, the crucibles should contain, besides the metal, a mixture of common salt and pounded charcoal. The metallic alloy should also be occasionally stirred up with a rod of pottery ware.

The most direct evidence of a chemical change having been effected in alloys is, when the compound melts at a lower temperature than the mean of its ingredients. Iron, which is nearly infusible, acquires almost the fusibility of gold when alloyed with this precious metal. The analogy is here strong with the increase of solubility which salts acquire by mixture, as is exemplified in the difficulty of crystallising residuums of saline solutions, or mother waters, as they are called.

In common cases the specific gravity affords a good criterion whereby to judge of the proportion of two metals in an alloy. But a very fallacious rule has been given in some respectable works for computing the specific gravity that should result from the alloying of given quantities of two metals of known densities, supposing no chemical condensation or expansion of volume to take place. Thus, it has been taught, that if gold and copper be united in equal weights, the computed specific gravity is merely the arithmetical mean between the numbers denoting the two specific gravities. Whereas, the specific gravity of any alloy must be computed by dividing the sum of the two weights by the sum of the two volumes, compared, for conveniency sake, to water reckoned unity. Or, in another form, the rule may be stated thus:—Multiply the sum of the weights into the products of the two specific-gravity numbers for a numerator; and multiply each specific gravity-number into the weight of the other body, and add the two products together for a denominator. The quotient obtained by dividing the said numerator by the denominator, is the truly computed mean specific gravity of the alloy. On comparing with that density, the density found by experiment, we shall see whether expansion or condensation of volume has attended the metallic combination. Gold having a specific gravity of 19·36, and copper of 8·87, when they are alloyed in equal weights, give, by the fallacious rule of the arithmetical mean of the densities 19·36 + 8·872 = 14·11; whereas the rightly computed mean density is only 12·16. It is evident that, on comparing the first result with experiment, we should be led to infer that there had been a prodigious condensation of volume, though expansion has actually taken place. Let W, w be the two weights; P, p the two specific gravities, then M, the mean specific gravity, is given by the formula

(W + w)PpPw + pW ∴ 2Δ = - (P - p)2P + p =

twice the error of the arithmetical mean; which is therefore always in excess.

ALMOND. (Amande, Fr.; Mandel, Germ.) There are two kinds of almond which do not differ in chemical composition, only that the bitter, by some mysterious reaction of its constituents, generates in the act of distillation a quantity of a volatile oil, which contains hydrocyanic acid. Vogel obtained from bitter almonds 8·5 per cent. of husks. After pounding the kernels, and heating them to coagulate the albumen, he procured, by expression, 28 parts of an unctuous oil, which did not contain the smallest particle of hydrocyanic acid. The whole of the oil could not be extracted in this way. The expressed mass, treated with boiling water, afforded sugar and gum, and, in consequence of the heat, some of that acid. The sugar constitutes 6·5 per cent. and the gum 3. The vegetable albumen extracted, by means of caustic potash, amounted to 30 parts: the vegetable fibre to only 5. The poisonous aromatic oil, according to Robiquet and Boutron-Charlard, does not exist ready-formed in the bitter almond, but seems to be produced under the influence of ebullition with water. These chemists have shown that bitter almonds deprived of their unctuous oil by the press, when treated first by alcohol, and then by water, afford to neither of these liquids any volatile oil. But alcohol dissolves out a peculiar white crystalline body, without smell, of a sweetish taste at first, and afterwards bitter, to which they gave the name of amygdaline. This substance does not seem convertible into volatile oil.

Sweet almonds by the analysis of Boullay, consist of 54 parts of the bland almond oil, 6 of uncrystallisable sugar, 3 of gum, 24 of vegetable albumen, 24 of woody fibre, 5 of husks, 3·5 of water, 0·5 of acetic acid, including loss. We thus see that sweet almonds contain nearly twice as much oil as bitter almonds do.

ALMOND OIL. A bland fixed oil, obtained usually from bitter almonds by the action of a hydraulic press, either in the cold, or aided by hot iron plates. See Oil.


ALOE. A series of trials has been made within a few years at Paris to ascertain the comparative strength of cables made of hemp and of the aloe from Algiers; and they are said to have all turned to the advantage of the aloe. Of cables of equal size, that made of aloe raised a weight of 2,000 kilogrammes (2 tons nearly); that made of hemp, a weight of only 400 kilogrammes. At the exposition of objects of national industry, two years ago, in Brussels, I saw aloe cordage placarded, as being far preferable to hempen. See Rope.

ALUDEL. A pear-shaped vessel open at either end, of which a series are joined for distilling mercury in Spain. See Mercury.

ALUM. (Alun, Fr.; Alaum, Germ.) A saline body, consisting of the earth of clay, called alumina by the chemists, combined with sulphuric acid and potash, or sulphuric acid and ammonia, into a triple compound. It occurs in the crystallised form of octahedrons, has an acerb subacid taste, and reddens the blue colour of litmus or red cabbage.

Alum works existed many centuries ago at Roccha, formerly called Edessa, in Syria, whence the ancient name of Roch alum given to this salt. It was afterwards made at Foya Nova, near Smyrna, and in the neighbourhood of Constantinople. The Genoese, and other trading people of Italy, imported alum from these places into western Europe, for the use of the dyers of red cloth. About the middle of the fifteenth century, alum began to be manufactured at La Tolfa, Viterbo, and Volaterra, in Italy; after which time the importation of oriental alum was prohibited by the pope, as detrimental to the interests of his dominions. The manufacture of this salt was extended to Germany at the beginning of the sixteenth century, and to England at a somewhat later period, by Sir Thomas Chaloner, in the reign of Elizabeth. In its pure state, it does not seem to have been known to the ancients; for Pliny, in speaking of something like plumose alum, says, that it struck a black colour with pomegranate juice, which shows that the green vitriol was not separated from it. The stypteria of Dioscorides, and the alumen of Pliny, comprehended, apparently, a variety of saline substances, of which sulphate of iron, as well as alumina, was probably a constituent part. Pliny, indeed, says, that a substance called in Greek Ὑγρα, or watery, probably from its very soluble nature, which was milk-white, was used for dyeing wool of bright colours. This may have been the mountain butter of the German mineralogists, which is a native sulphate of alumina, of a soft texture, waxy lustre, and unctuous to the touch.

The only alum manufactories now worked in Great Britain, are those of Whitby, in England, and of Hurlett and Campsie, near Glasgow, in Scotland; and these derive the acid and earthy constituents of the salt from a mineral called alum slate. This mineral has a bluish or greenish-black colour, emits sulphurous fumes when heated, and acquires thereby an aluminous taste. The alum manufactured in Great Britain contains potash as its alkaline constituent; that made in France contains, commonly, ammonia, either alone, or with variable quantities of potash. Alum may in general be examined by water of ammonia, which separates from its watery solutions its earthy basis, in the form of a light flocculent precipitate. If the solution be dilute, this precipitate will float long as an opalescent cloud.

If we dissolve alum in 20 parts of water, and drop this solution slowly into water or caustic ammonia till this be nearly, but not entirely, saturated, a bulky white precipitate will fall down, which, when properly washed with water, is pure aluminous earth or clay, and dried forms 10·82 per cent. of the weight of the alum. If this earth, while still moist, be dissolved in dilute sulphuric acid, it will constitute, when as neutral as possible, the sulphate of alumina, which requires only two parts of cold water for its solution. If we now decompose this solution, by pouring into it water of ammonia, there appears an insoluble white powder, which is subsulphate of alumina, or basic alum; and contains three times as much earth as exists in the neutral sulphate. If, however, we pour into the solution of the neutral sulphate of alumina a solution of sulphate of potash, a white powder will fall if the solutions be concentrated, which is true alum; but if the solutions be dilute, by evaporating their mixture, and cooling it, crystals of alum will be obtained.

When newly precipitated alumina is boiled in a solution of alum, a portion of the earth enters into combination with the salt, constituting an insoluble compound, which falls in the form of a white powder. The same combination takes place, if we decompose a boiling hot solution of alum with a solution of potash, till the mixture appears nearly neutral by litmus paper. This insoluble or basic alum exists native in the alum-stone of Tolfa, near Civita Vecchia, and it consists in 100 parts of 19·72 parts of sulphate of potash, 61·99 basic sulphate of alumina, and 18·29 water. When this mineral is treated with a due quantity of sulphuric acid, it dissolves, and is converted into the crystallisable alum of commerce.

These experimental facts develope the principles of the manufacture of alum, which is prosecuted under various modifications, for its important uses in the arts. Alum seldom occurs ready-formed in nature; occasionally, as an efflorescence on stones, and in[34] certain mineral waters in the East Indies. The alum of European commerce is fabricated artificially, either from the alum schists or stones, or from clay. The mode of manufacture differs according to the nature of these earthy compounds. Some of them, such as the alum stone, contain all the elements of the salt, but mixed with other matters, from which it must be freed. The schists contain only the elements of two of the constituents, namely, clay and sulphur, which are convertible into sulphate of alumina, and this may be then made into alum by adding the alkaline ingredient. To this class belong the alum slates, and other analogous schists, containing brown coal.

1. Manufacture of Alum from the Alum Stone.—The alum-stone is a rare mineral, being found in moderate quantity at Tolfa, and in larger in Hungary, at Bereghszasz, and Muszag, where it forms entire beds in a hard substance, partly characterised by numerous cavities, containing drusy crystallisations of alum-stone or basic alum. The larger lumps contain more or fewer flints disseminated through them, and are, according to their quality, either picked out to make alum, or are thrown away. The sorted pieces are roasted or calcined, by which operation apparently the hydrate of alumina, associated with the sulphate of alumina, loses its water, and, as burnt clay, loses its affinity for alum. It becomes, therefore, free; and during the subsequent exposure to the weather the stone gets disintegrated, and the alum becomes soluble in water.

The calcination is performed in common lime-kilns in the ordinary way. In the regulation of the fire it is requisite, here, as with gypsum, to prevent any fusion or running together of the stones, or even any disengagement of sulphuric or sulphurous acids, which would cause a corresponding defalcation in the product of alum. For this reason the contact of the ignited stones with carbonaceous matter ought to be avoided.

The calcined alum-stones, piled in heaps from 2 to 3 feet high, are to be exposed to the weather, and meanwhile they must be continually kept moist by sprinkling them with water. As the water combines with the alum the stones crumble down, and fall, eventually, into a pasty mass, which must be lixiviated with warm water, and allowed to settle in a large cistern. The clear supernatant liquor, being drawn off, must be evaporated, and then crystallised. A second crystallisation finishes the process, and furnishes a marketable alum. Thus the Roman alum is made, which is covered with a fine red film of peroxide of iron.

2. Alum Manufacture from Alum Schist.—The greater portion of the alum found in British commerce is made from alum-slate and analogous minerals. This slate contains more or less iron pyrites, mixed with coaly or bituminous matter, which is occasionally so abundant as to render them somewhat combustible. In the strata of brown coal and bituminous wood, where the upper layers lie immediately under clay beds, they consist of the coaly substance rendered impure with clay and pyrites. This triple mixture constitutes the essence of all good alum schists, and it operates spontaneously towards the production of sulphate of alumina. The coal serves to make the texture open, and to allow the air and moisture to penetrate freely, and to change the sulphur and iron present into acid and oxide. When these schists are exposed to a high temperature in contact with air, the pyrites loses one half of its sulphur, in the form of sublimed sulphur or sulphurous acid, and becomes a black sulphuret of iron, which speedily attracts oxygen, and changes to sulphate of iron, or green vitriol. The brown coal schists contain, commonly, some green vitriol crystals spontaneously formed in them. The sulphate of iron transfers its acid to the clay, progressively, as the iron, by the action of the air with a little elevation of temperature, becomes peroxidised; whereby sulphate of alumina is produced. A portion of the green vitriol remains, however, undecomposed, and so much the more as there may happen to be less of other salifiable bases present in the clay slate. Should a little magnesia or lime be present, the vitriol gets more completely decomposed, and a portion of Epsom salt and gypsum is produced.

The manufacture of alum from alum schists may be distributed under the six following heads:—1. The preparation of the alum slate. 2. The lixiviation of the slate. 3. The evaporation of the lixivium. 4. The addition of the saline ingredients, or the precipitation of the alum. 5. The washing of the aluminous salts; and 6. The crystallisation.

1. Preparation of the Alum Slate.—Some alum slates are of such a nature that, being piled in heaps in the open air, and moistened from time to time, they get spontaneously hot, and by degrees fall into a pulverulent mass, ready to be lixiviated. The greater part, however, require the process of ustulation, from which they derive many advantages. The cohesion of the dense slates is thereby so much impaired that their decomposition becomes more rapid; the decomposition of the pyrites is quickened by the expulsion of a portion of the sulphur; and the ready-formed green vitriol is partly decomposed by the heat, with a transference of its sulphuric acid to the clay, and the production of sulphate of alumina.

Such alum-slates as contain too little bitumen or coal for the roasting process must be interstratified with layers of small coal or brushwood over an extensive surface. At[35] Whitby the alum rock, broken into small pieces, is laid upon a horizontal bed of fuel, composed of brushwood; but at Hurlett small coal is chiefly used for the lower bed. When about four feet of the rock is piled on, fire is set to the bottom in various parts; and whenever the mass is fairly kindled, more rock is placed over the top. At Whitby this piling process is continued till the calcining heap is raised to the height of 90 or 100 feet. The horizontal area is also augmented at the same time till it forms a great bed nearly 200 feet square, having therefore about 100,000 yards of solid measurement. The rapidity of the combustion is tempered by plastering up the crevices with small schist moistened. When such an immense mass is inflamed, the heat is sure to rise too high, and an immense waste of sulphur and sulphuric acid must ensue. This evil has been noticed at the Whitby works. At Hurlett the height to which the heap is piled is only a few feet, while the horizontal area is expanded; which is a much more judicious arrangement. At Whitby 130 tons of calcined schist produce on an average 1 ton of alum. In this humid climate it would be advisable to pile up on the top of the horizontal strata of brushwood or coal, and schist, a pyramidal mass of schist, which having its surface plastered smooth, with only a few air-holes, will protect the mass from the rains, and at the same time prevent the combustion from becoming too vehement. Should heavy rains supervene, a gutter must be scooped out round the pile for receiving the aluminous lixivium, and conducting it into the reservoir.

It may be observed, that certain alum schists contain abundance of combustible matter, to keep up a suitable calcining heat after the fire is once kindled; and therefore nothing is needed but the first layer of brushwood, which, in this case, may be laid over the first bed of the bituminous schist.

A continual, but very slow, heat, with a smothered fire, is most beneficial for the ustulation of alum slate. When the fire is too brisk, the sulphuret of iron may run with the earthy matters into a species of slag, or the sulphur will be dissipated in vapour, by both of which accidents the product of alum will be impaired. Those bituminous alum schists which have been used as fuel under steam boilers have suffered such a violent combustion that their ashes yield almost no alum. Even the best regulated calcining piles are apt to burn too briskly in high winds, and should have their draught-holes carefully stopped under such circumstances. It may be laid down as a general rule, that the slower the combustion the richer the roasted ore will be in sulphate of alumina. When the calcination is complete, the heap diminishes to one half its original bulk; it is covered with a light reddish ash, and is open and porous in the interior, so that the air can circulate freely throughout the mass. To favour this access of air, the masses should not be too lofty; and in dry weather a little water should be occasionally sprinkled on them, which, by dissolving away some of the saline matter, will make the interior more open to the atmosphere.

When the calcined mineral becomes thoroughly cold, we may proceed to the lixiviation. But as, from the first construction of the piles or beds till their complete calcination, many weeks, or even months, may elapse, care ought to be taken to provide a sufficient number or extent of them, so as to have an adequate supply of material for carrying on the lixiviating and crystallising processes during the course of the year, or at least during the severity of the winter season, when the calcination may be suspended, and the lixiviation becomes unsatisfactory. The beds are known to be sufficiently decomposed by the efflorescence of the salt which appears upon the stones, from the strong aluminous taste of the ashes, and from the appropriate chemical test of lixiviating an aliquot average portion of the mass, and seeing how much alum it will yield to solution of muriate or sulphate of potash.

2. The Lixiviation.—The lixiviation is best performed in stone-built cisterns; those of wood, however strong at first, are soon decomposed, and need repairs. They ought to be erected in the neighbourhood of the calcining heaps, to save the labour of transport, and so arranged that the solutions from the higher cisterns may spontaneously flow into the lower. In this point of view, a sloping terrace is the best situation for an alum work. In the lowest part of this terrace, and in the neighbourhood of the boiling-house, there ought to be two or more large deep tanks, for holding the crude lixivium, and they should be protected from the rain by a proper shed. Upon a somewhat higher level the cisterns of the clear lixivium may be placed. Into the highest range of cisterns the calcined mineral is to be put, taking care to lay the largest lumps at the bottom, and to cover them with lighter ashes. A sufficient quantity of water is now to be run over it, and allowed to rest for some time. The lixivium may then be drawn off, by a stopcock connected with a pipe at the bottom of the cistern, and run into another cistern at a somewhat lower level. Fresh water must now be poured on the partly exhausted schist, and allowed to remain for a sufficient time. This lixivium, being weak, should be run off into a separate tank. In some cases a third addition of fresh water may be requisite, and the weak lixivium which is drawn off may be reserved for a fresh portion of calcined mineral. In order to save evaporation, it is always requisite to strengthen weak[36] leys by employing them instead of water for fresh portions of calcined schist. Upon the ingenious disposition and form of these lixiviating cisterns much of the economy and success of an alum work depend. The hydrometer should be always used to determine the degree of concentration which the solutions acquire.

The lixiviated stone being thus exhausted of its soluble ingredients, is to be removed from the cisterns, and piled up in a heap in any convenient place, where it may be left either spontaneously to decompose, or, after drying, may be subjected to another calcination.

The density of the solution may be brought, upon an average, up to the sp. gr. of from 1·09 to 1·15. The latter density may always be obtained by pumping up the weaker solutions upon fresh calcined mine. This strong liquor is then drawn off, when the sulphate of lime, the oxide of iron, and the earths are deposited. It is of advantage to leave the liquor exposed for some time, whereby the green vitriol may pass into a persulphate of iron with the deposition of some oxide, while the liberated acid may combine with some of the clay present, so as to increase the quantity of sulphate of alumina. The manufacture of alum is the more imperfect, as the quantity of sulphate of iron left undecomposed is greater, and therefore every expedient ought to be tried to convert the sulphate of iron into sulphate of alumina.

3. The evaporation of the Schist Lixivium.—As the aluminous liquors, however well settled at first, are apt, on the great scale, to deposit earthy matters in the course of their concentration by heat, they are best evaporated by a surface fire, such as that employed at Hurlett and Campsie. A water-tight stone cistern must be built, having a layer of well rammed clay behind the flags or tiles which line its bottom and sides. This cistern may be 4 or 6 feet wide, 2 or 3 feet deep, and 30 or 40 feet long, and it is covered in by an arch of stone or brickwork. At one extremity of this tunnel, or covered canal, a fire-grate is set, and at the other a lofty chimney is erected. The cistern being filled to the brim with the alum ley, a strong fire is kindled in the reverberatory grate, and the flame and hot air are forced to sweep along the surface of the liquor, so as to keep it in constant ebullition, and to carry off the aqueous parts in vapour. The soot which is condensed in the process falls to the bottom, and leaves the body of the liquor clear. As the concentration goes on, more of the rough lixivium is run in from the settling cistern, placed on a somewhat higher level, till the whole gets charged with a clear liquor of a specific gravity sufficiently high for transferring into the proper lead boilers.

At Whitby, the lead pans are 10 feet long, 4 feet 9 inches wide, 2 feet 2 inches deep at the one end, and 2 feet 8 inches deep at the other. This increase of depth and corresponding slope, facilitates the decantation of the concentrated lixivium by means of a syphon, applied at the lower end. The bottom of the pan is supported by a series of parallel iron bars, placed very near each other. In these lead pans the liquor is concentrated, at a brisk boiling heat, by means of the flame of a flue beneath them. Every morning the pans are emptied into a settling cistern of stone or lead. The specific gravity of the liquor should be about 1·4 or 1·5, being a saturated solution of the saline matters present. The proper degree of density must vary, however, with different kinds of lixivia, and according to the different views of the manufacturer. For a liquor which consists of two parts of sulphate of alumina, and one part of sulphate of iron, a specific gravity of 1·25 may be sufficient; but for a solution which contains two parts of sulphate of iron to one of sulphate of alumina, so that the green vitriol must be withdrawn first of all by crystallisation, a specific gravity of 1·4 may be requisite.

The construction of an evaporating furnace well adapted to the concentration of aluminous and other crude lixivia, is described under Soda. The liquor basin may be made of tiles or flags puddled in clay, and secured at the seams with a good hydraulic cement. A mortar made of quicklime mixed with the exhausted schist in powder, and iron turnings, is said to answer well for this purpose. Sometimes over the reverberatory furnace a flat pan is laid, instead of the arched top, into which the crude liquor is put for neutralisation and partial concentration. In Germany, such a pan is made of copper, because iron would waste too fast, and lead would be apt to melt. From this preparation basin the under evaporating trough is gradually supplied with hot liquor. At one side of this lower trough, there is sometimes a door, through which the sediment may be raked out as it accumulates upon the bottom. Such a contrivance is convenient for this mode of evaporation, and it permits, also, any repairs to be readily made; but, indeed, an apparatus of this kind, well mounted at first, will serve for many years.

In the course of the final concentration of the liquors, it is customary to add some of the mother waters of a former process, the quantity of which must be regulated by a proper analysis and knowledge of their contents. If these mother waters contain much free sulphuric acid, from the peroxidation of their sulphate of iron, they may prove useful in dissolving a portion of the alumina of the sediment which is always present in greater or less quantity.


4. The precipitation of the Alum by adding Alkaline Salts.—As a general rule, it is most advantageous to separate, first of all, from the concentrated clear liquors, the alum in the state of powder or small crystals, by addition of the proper alkaline matter, and to leave the mingled foreign salts, such as the sulphate of iron or magnesia, in solution, instead of trying to abstract these salts by a previous crystallisation. In this way we not only simplify and accelerate the manufacture of alum, and leave the mother waters to be worked up at any convenient season, but we also avoid the risk of withdrawing any of the sulphate of alumina with the sulphate of iron or magnesia. On this account, the concentration of the liquor ought not to be pushed so far as that, when it gets cold, it should throw out crystals, but merely to the verge of this point. This density may be determined by suitable experiments.

The clear liquor should now be run off into the precipitation cistern, and have the proper quantity of sulphate or muriate of potash, or impure sulphate or carbonate of ammonia added to it. The sulphate of potash, which is the best precipitant, forms 18·34 parts out of 100 of crystallised alum; and therefore that quantity of it, or its equivalent in muriate of potash, or other potash or ammoniacal salts, must be introduced into the aluminous liquor. Since sulphate of potash takes 10 parts of cold water to dissolve it, but is much more soluble in boiling water, and since the precipitation of alum is more abundant the more concentrated the mingled solutions are, it would be prudent to add the sulphate solution as hot as may be convenient; but, as muriate of potash is fully three times more soluble in cold water, it is to be preferred as a precipitant, when it can be procured at a cheap rate. It has, also, the advantage of decomposing the sulphate of iron present into a muriate, a salt very difficult of crystallisation, and, therefore, less apt to contaminate the crystals of alum. The quantity of alkaline salts requisite to precipitate the alum, in a granular powder, from the lixivium, depends on their richness in potash or ammonia, on the one hand, and on the richness of the liquors in sulphate of alumina on the other; and it must be ascertained, for each large quantity of product, by a preliminary experiment in a precipitation glass. Here, an aliquot measure of the aluminous liquor being taken, the liquid precipitant must be added in successive portions, as long as it causes any cloud, when the quantity added will be indicated by the graduation of the vessel. A very exact approximation is not practicable upon the great scale; but, as the mother waters are afterwards mixed together in one cistern, any excess of the precipitant, at one time, is corrected by excess of aluminous sulphate at another, and the resulting alum meal is collected at the bottom. When the precipitated saline powder is thoroughly settled and cooled, the supernatant mother water must be drawn off by a pump, or rather a syphon or stopcock, into a lower cistern. The more completely this drainage is effected, the more easily and completely will the alum be purified.

This mother liquor has, generally, a specific gravity of 1·4 at a medium temperature of the atmosphere, and consists of a saturated solution of sulphate or muriate of black and red oxide of iron, with sulphate of magnesia, in certain localities, and muriate of soda, when the soaper’s salt has been used as a precipitant, as also a saturated solution of sulphate of alumina. By adding some of it, from time to time, to the fresh lixivia, a portion of that sulphate is converted into alum; but, eventually, the mother water must be evaporated, so as to obtain from it a crop of ferruginous crystals; after which it becomes capable, once more, of giving up its alum to the alkaline precipitants.

When the aluminous lixivia contain a great deal of sulphate of iron, it may be good policy to withdraw a portion of it by crystallisation before precipitating the alum. With this view, the liquors must be evaporated to the density of 1·4, and then run off into crystallising stone cisterns. After the green vitriol has concreted, the liquor should be pumped back into the evaporating pan, and again brought to the density of 1·4. On adding to it, now, the alkaline precipitants, the alum will fall down from this concentrated solution, in a very minute crystalline powder, very easy to wash and purify. But this method requires more vessels and manipulation than the preceding, and should only be had recourse to from necessity; since it compels us to carry on the manufacture of both the valuable alum and the lower priced salts at the same time; moreover, the copperas extracted at first from the schist liquors carries with it, as we have said, a portion of the sulphate of alumina, and acquires thereby a dull aspect; whereas the copperas obtained after the separation of the alum is of a brilliant appearance.

5. The washing, or edulcoration, of the Alum Powder.—This crystalline pulverulent matter has a brownish colour, from the admixture of the ferruginous liquors; but it may be freed from it by washing with very cold water, which dissolves not more than one sixteenth of its weight of alum. After stirring the powder and the water well together, the former must be allowed to settle, and then the washing must be drawn off. A second washing will render the alum nearly pure. The less water is employed, and the more effectually it is drained off, the more complete is the process. The second water may be used in the first washing of another portion of[38] alum powder, in the place of pure water. These washings may be added to the schist lixivia.

6. The crystallisation.—The washed alum is put into a lead pan, with just enough water to dissolve it at a boiling heat; fire is applied, and the solution is promoted by stirring. Whenever it is dissolved in a saturated state, it is run off into the crystallising vessels, which are called roching casks. These casks are about five feet high, three feet wide in the middle, somewhat narrower at the ends; they are made of very strong staves, nicely fitted to each other, and held together by strong iron hoops, which are driven on pro tempore, so that they may be easily knocked off again, in order to take the staves asunder. The concentrated solution, during its slow cooling in these close vessels, forms large regular crystals, which hang down from the top, and project from the sides, while a thick layer or cake lines the whole interior of the cask. At the end of eight or ten days, more or less, according to the weather, the hoops and staves are removed, when a cask of apparently solid alum is disclosed to view. The workman now pierces this mass with a pickaxe at the side near the bottom, and allows the mother water of the interior to run off on the sloping stone floor into a proper cistern, whence it is taken and added to another quantity of washed powder to be crystallised with it. The alum is next broken into lumps, exposed in a proper place to dry, and is then put into the finished bing for the market. There is sometimes a little insoluble basic alum (subsulphate) left at the bottom of the cask. This being mixed with the former mother liquors, gets sulphuric acid from them; or, being mixed with a little sulphuric acid, it is equally converted into alum.

When, instead of potash or its salts, the ammoniacal salts are used, or putrid urine, with the aluminous lixivia, ammoniacal alum is produced, which is perfectly similar to the potash alum in its appearance and properties. At a gentle heat both lose their water of crystallisation, amounting to 4512 per cent. for the potash alum, and 48 for the ammoniacal. The quantity of acid is the same in both, as, also, very nearly the quantity of alumina, as the following analyses will show:

Potash alum. Ammonia alum.
Sulphate of potash 18·34 Sulphate of ammonia 12·88
Sulphate of alumina 36·20 Sulphate of alumina 38·64
Water 45·46 Water 48·48
100·00 100·00
Or otherwise, Potash alum. Ammonia alum.
1 atom sulphate of potash 1089·07 1 atom sulphate of ammonia 716·7
1 atom sulphate of alumina 2149·80 1 atom sulphate of alumina 2149·8
24 water 2669·52 24 water 2699·5
5938·39 5566·0
Or, Potash alum. Ammonia alum.
Alumina 10·82 Alumina 11·90
Potash 9·94 Ammonia 3·89
Sulphuric Acid 33·77 Sulphuric acid 36·10
Water 45·47 Water 48·11
100·00 100·00

When heated pretty strongly, the ammoniacal alum loses its sulphuric acid and ammonia, and only the earth remains. This is a very convenient process for procuring pure alumina. Ammoniacal alum is easily distinguished from the other by the smell of ammonia which it exhales when triturated with quicklime. The Roman alum, made from alum stone, possesses most of the properties of the schist-made alums, but it has a few peculiar characters: it crystallises always in opaque cubes, whereas the common alum crystallises in transparent octahedrons. It is probable that Roman alum is a sulphate of alumina and potash, with a slight excess of the earthy ingredient. It is permanent when dissolved in cold water; for after a slow evaporation it is recovered in a cubical form. But when it is dissolved in water heated to 110° Fahr. and upwards, or when its solution is heated above this pitch, subsulphate of alumina falls, and on evaporation octahedral crystals of common alum are obtained. The exact composition of the Roman alum has not been determined, as far as I know. It probably differs from the other also in its water of crystallisation. The Roman alum contains, according to MM. Thenard and Roard, only 12200 of sulphate of iron, while the common commercial[39] alums contain 11000. It may be easily purified by solution, granulation, crystallisation, and washing, as has been already explained.

Alum is made extensively in France from an artificial sulphate of alumina. For this purpose clays are chosen as free as possible from carbonate of lime and oxide of iron. They are calcined in a reverberatory furnace, in order to expel the water, to peroxidise the iron, and to render the alumina more easily acted on by the acid. The expulsion of the water renders the clay porous and capable of absorbing the sulphuric acid by capillary attraction. The peroxidation of the iron renders it less soluble in the sulphuric acid; and the silica of the clay, by reacting on the alumina, impairs its aggregation, and makes it more readily attracted by the acid. The clay should, therefore, be moderately calcined; but not so as to indurate it like pottery ware, for it would then suffer a species of siliceous combination which would make it resist the action of acids. The clay is usually calcined in a reverberatory furnace, the flame of which serves thereafter to heat two evaporating pans and a basin for containing a mixture of the calcined clay and sulphuric acid. As soon as the clay has become friable in the furnace it is taken out, reduced to powder, and passed through a fine sieve. With 100 parts of the pulverised clay, 45 parts of sulphuric acid, of sp. gr. 1·45, are well mixed, in a stone basin, arched over with brickwork. The flame and hot air of a reverberatory furnace are made to play along the mixture, in the same way as described for evaporating the schist liquors. See Soda. The mixture, being stirred from time to time, is, at the end of a few days, to be raked out, and to be set aside in a warm place, for the acid to work on the clay, during six or eight weeks. At the end of this time it must be washed, to extract the sulphate of alumina. With this view, it may be treated like the roasted alum ores above described. If potash alum is to be formed, this sulphate of alumina is evaporated to the specific gravity of 1·38; but if ammonia alum, to the specific gravity of only 1·24; because the sulphate of ammonia, being soluble in twice its weight of water, will cause a precipitation of pulverulent alum from a weaker solution of sulphate of alumina than the less soluble sulphate of potash could do.

The alum stone, from which the Roman alum is made, contains potash. The following analysis of alunite, by M. Cordier, places this fact in a clear light:—

Sulphate of potash 18·53
Sulphate of alumina 38·50
Hydrate of alumina 42·97

To transform this compound into alum, it is merely necessary to abstract the hydrate of alumina. The ordinary alum stone, however, is rarely so pure as the above analysis would seem to show; for it contains a mixture of other substances; and the above are in different proportions.

Alum is very extensively employed in the arts, most particularly in dyeing, lake making, dressing sheep-skins, pasting paper, in clarifying liquors, &c. Its purity for the dyer may be tested by prussiate of potash, which will give solution of alum a blue tint in a few minutes if it contain even a very minute portion of iron. A bit of nut-gall is also a good test of iron.

AMADOU. The French name of the spongy combustible substance, called in German zunderschwamm, prepared from a species of agaric, the boletus igniarius, a kind of mushroom, which grows on the trunks of old oaks, ashes, beeches, &c. It must be plucked in the months of August and September. It is prepared by removing the outer bark with a knife, and separating carefully the spongy substance of a yellow brown colour, which lies within it, from the ligneous matter below. This substance is cut into thin slices, and beat with a mallet to soften it, till it can be easily pulled asunder between the fingers. In this state the boletus is a valuable substance for stopping oozing hemorrhages, and some other surgical purposes. To convert it into tinder it must receive a finishing preparation, which consists in boiling it in a strong solution of nitre; drying it, beating it anew, and putting it a second time into the solution. Sometimes, indeed, to render it very inflammable, it is imbued with gunpowder, whence the distinction of black and brown amadou.

All the puff balls of the lycopodium genus of plants, which have a fleshy or filamentous structure, yield a tinder quite ready for soaking in gunpowder water. The Hindoos employ a leguminous plant, which they call solu, for the same purpose. Its thick spongy stem, being reduced to charcoal, takes fire like amadou.

AMALGAM. When mercury is alloyed with any metal, the compound is called an amalgam of that metal; as, for example, an amalgam of tin, bismuth, &c.

AMALGAMATION. This is a process used extensively in extracting silver and gold from certain of their ores, founded on the property which mercury has to dissolve these[40] metals as disseminated in the minerals, and thus to separate them from the earthy matters. See Mercury, Metallurgy, and Silver.

AMBER. (Succin, Fr.; Bernstein, Germ.) A mineral solid, of a yellow colour of various shades, which burns quite away with flame, and consists of carbon, hydrogen, and oxygen, in nearly the same proportions, and the same state of combination, as vegetable resin. Its specific gravity varies, by my trials, from 1·080 to 1·085. It becomes negatively and powerfully electrical by friction. When applied to a lighted candle it takes fire, swells considerably, and exhales a white smoke of a pungent odour; but does not run into drops. Copal, which resembles it in several respects, differs in being softer, and in melting into drops at the flame; and mellite, or honey-stone, which is a mineral of a similar colour, becomes white when laid on a red-hot coal.

The texture of amber is resino-vitreous, its fracture conchoidal, and lustre glassy. It is perfectly homogeneous; sufficiently hard to scratch gypsum, and to take a fine polish. It is, however, scratched by calcareous spar. When amber is distilled in a retort, crystalline needles of succinic acid sublime into the dome, and oil of amber drops from the beak into the receiver. Fossil resins, such as that of Highgate, found in the London clay formation, do not afford succinic acid by heat; nor does copal. Amber is occasionally found of a whitish and brownish colour.

The most interesting fact relative to this vegeto-mineral is its geological position, which is very characteristic and well determined. It is found almost uniformly in separate nodules, disseminated in the sand, clay, or fragments of lignite of the plastic clay, and lignite formation, situated between the calcaire grossier (crag limestone) of the tertiary strata above, and the white chalk below. The size of these nodules varies from a nut to a man’s head; but this magnitude is very rare in true amber. It does not occur either in continuous beds, like the chalk flints, nor in veins; but it lies at one time in the earthy or friable strata, which accompany or include the lignites; at another, entangled in the lignites themselves; and is associated with the minerals which constitute this formation, principally the pyrites, the most abundant of all. The pieces of amber found in the sands, and other formations evidently alluvial, those met with on the sea-coasts of certain countries, and especially Pomerania, come undoubtedly from the above geological formation; for the organic matters found still adhering to the amber leave no doubt as to its primitive place. Amber does not, therefore, belong to any postdiluvian or modern soil, since its native bed is covered by three or four series of strata, often of considerable thickness, and well characterised; proceeding upwards from the plastic clay which includes the amber: these are, the crag limestone, the bone gypsum, with its marls, the marly limestone, the upper marl sandstone, which covers it, and, lastly, the freshwater or lacustrine formation, often so thick, and composed of calcareous and siliceous rocks.

The amber bed is not, however, always covered with all these strata; and it is even rare to see a great mass of one of them above the ground which contains it; because, were it buried under such strata, it would be difficult to meet with such circumstances as would lay it spontaneously open to the day. But by comparing observations made in different places, relatively to the patches of these formations, which cover the amber deposits, we find that no other mineral formations have been ever seen among them except those above detailed, and thus learn that its geological locality is completely determined.

The proper yellow amber, therefore, or the Borussic, from the country where it has been most abundantly found, belongs to the plastic clay formation, intermediate, in England, between the chalk and the London clay. It is sometimes interposed in thin plates between the layers of the lignites, but more towards the bark of the fibrous lignites, which retain the form of the wood, than towards the middle of the trunk of the tree; a position analogous to that of the resinous matters in our existing ligneous vegetables. The fibrous lignites which thus contain amber belong to the dicotyledinous woods. Hence that substance seems to have been formed during the life of the vegetable upon which it is now encrusted. It must be remembered that the grounds containing the amber are often replete with the sulphates of iron, alumina, and lime, or at least with the pyritous elements of these salts. Some specimens of amber have a surface figured with irregular meshes, indicating a sort of shrinkage from consolidation, and consequently a matter that was at one time fluid, viscid, or merely soft. From optical examination, Dr. Brewster has concluded amber to be of vegetable origin.

The different bodies included in the amber, distinguishable from its transparence, demonstrate, indeed, in the most convincing manner, its primitive state of liquidity or softness. These bodies have long exercised the skill of naturalists. They are generally insects, or remains of insects, and sometimes leaves, stalks, or other portions of vegetables. Certain families of insects occur more abundantly than others. Thus the hymenoptera, or insects with four naked membranaceous wings, as the bee and wasp, and the diptera, or insects with two wings, as gnats, flies, gadflies, &c.; then come the spider tribe;[41] some coleoptera (insects with crustaceous shells or elytra, which shut together, and form a longitudinal suture down the back,) or beetles, principally those which live on trees; such as the elaterides, or leapers, and the chrysomelida. The lepidoptera, or insects with four membranaceous wings, and pterigostea covered with mail-like scales, are very rare in amber. We perceive from this enumeration, which results from the labours of Germar, Schweiger, &c., that the insects enveloped in this resinous matter are in general such as sit on the trunks of trees, or live in the fissures of their bark. Hitherto, it has not been found possible to refer them to any living species; but it has been observed in general that they resemble more the insects of hot climates than those of the temperate zones.

The districts where amber occurs in a condition fit for mining operations are not numerous; but those in which it is met with in small scattered bits are very abundant. Its principal exploitation is in Eastern Prussia, on the coasts of the Baltic sea, from Memel to Dantzick, particularly in the neighbourhood of Konigsberg, along the shore which runs north and south from Grossdirschheim to Pillau, and in several other places near Dantzick.

It is collected upon this coast in several ways; 1. In the beds of small streams which run near the villages, and in rounded fragments without bark, or in the sand-banks of rivers, in pieces thrown back by the sea, and rounded by the waves. 2. If the pieces thrown up by the waters are not numerous, the fishers, clothed in a leather dress, wade into the sea up to the neck, seek to discover the amber by looking along its surface, and seize it with bag nets, hung at the end of very long poles. They conclude that a great deal of amber has been detached from the cliffs by the sea, when many pieces of lignite (wood coal) are seen afloat. This mode of collecting amber is not free from danger, and the fishers, therefore, advance in troops, to lend each other aid in case of accident; but their success, even thus, is most precarious. 3. The third method of searching for amber is a real mining operation: it consists in digging pits upon the borders of the sandy downs, sometimes to a depth of more than 130 feet. 4. The last mode is by exploring the precipitous sea cliffs in boats, and detaching masses of loose soil from them with long poles terminating in iron hooks; a very hazardous employment. They search the cliffs with great care at the level, where the amber nodules commonly lie, and loosen the seams with their hooks; in which business the boats are sometimes broken against the precipices, or sunk by an avalanche of rubbish.

Amber occurs in Sicily, disseminated in beds of clay and marl, which lie below the crag limestone. It is accompanied with bitumen; and, though a scanty deposit, it is mined for sale. The pieces are coated with a kind of whitish bark, present a variety of colours, and include many insects. Amber is found in a great many places in the sandy districts of Poland, at a very great distance from the sea, where it is mixed with cones of the pine. In Saxony it is met with in the neighbourhood of Pretsch and Wittemberg, in a bituminous clay mingled with lignite. At the embouchure of the Jenissey, in Siberia, it occurs likewise along with lignite; as also in Greenland.

Fine amber is considerably valued for making ornamental objects, and the coarser kinds for certain uses in chemistry, medicine, and the arts. The oriental nations prize more highly than the people of Europe trinkets made of amber; and hence the chief commerce of the Pomeranian article is with Turkey. The Prussian government is said to draw an annual revenue of 17,000 dollars from amber. A good piece of a pound weight fetches 50 dollars. A mass weighing 13 pounds was picked up not long since in Prussia, for which 5000 dollars were offered, and which would bring, in the opinion of the Armenian merchants, from 30,000 to 40,000 dollars at Constantinople. At one time it was customary to bake the opaque pieces of amber in sand, at a gentle heat, for several hours, in order to make it transparent, or to digest it in hot rapeseed oil, with the same view; but how far these processes were advantageous does not appear.

When amber is to be worked into trinkets, it is first split on a leaden plate at a lathe (see Gems, Cutting of), and then smoothed into shape on a Swedish whetstone. It is polished on the lathe with chalk and water, or vegetable oil, and finished by friction with flannel. In these processes the amber is apt to become highly electrical, very hot, and even to fly into fragments. Hence, the artists work the pieces time about, so as to keep each of them cool, and feebly excited. The men are often seized with nervous tremors in their wrists and arms from the electricity. Pieces of amber may be neatly joined by smearing their edges with linseed oil, and pressing them strongly together, while they are held over a charcoal fire. Solid specimens of amber, reported to have been altogether fused by a particular application of heat, are now shown in the royal cabinet of Dresden.

A strong and durable varnish is made by dissolving amber in drying linseed oil. For this purpose, however, the amber must be previously heated in an iron pot, over a clear red fire, till it soften and be semi-liquefied. The oil, previously heated, is to be now poured in, with much stirring, in the proportion of 10 ounces to the pound of amber;[42] and after the incorporation is complete, and the liquid somewhat cooled, a pound of oil of turpentine must be added. Some persons prescribe 2 ounces of melted shellac, though by this means they are apt to deepen the colour, already rendered too dark by the roasting.

The fine black varnish of the coachmakers is said to be prepared by melting 16 ounces of amber in an iron pot, adding to it half a pint of drying linseed oil, boiling hot, of powdered resin and asphaltum 3 ounces each: when the materials are well united, by stirring over the fire, they are to be removed, and, after cooling for some time, a pint of warm oil of turpentine is to be introduced.

The oil of amber enters into the composition of the old perfume called eau de luce; and is convertible, by the action of a small quantity of strong nitric acid, into a viscid mass like shoemakers’ rosin, which has a strong odour of musk, and, under the name of artificial musk, has been prescribed, in alcoholic solution, as a remedy against hooping cough, and other spasmodic diseases.

Acid of amber (succinic acid) is a delicate reagent, in chemistry, for separating red oxide of iron from compound metallic solutions.

AMBERGRIS. (Ambregric, Fr.; Ambra, Germ.).—A morbid secretion of the liver of the spermaceti whale (physeter macrocephalus), found usually swimming upon the sea. It occurs upon the coasts of Coromandel, Japan, the Moluccas, and Madagascar, and has sometimes been extracted from the rectum of whales in the South Sea fishery. It has a gray-white colour, often with a black streak, or is marbled, yellow and black; has a strong but rather agreeable smell, a fatty taste, is lighter than water, melts at 60° C. (140° F.), dissolves readily in absolute alcohol, in ether, and in both fat and volatile oils. It contains 85% of the fragrant substance called ambreine. This is extracted from ambergris by digestion with alcohol of 0·827, filtering the solution, and leaving it to spontaneous evaporation. It is thus obtained in the form of delicate white tufts: which are convertible into ambreic acid by the action of nitric acid. Ambergris is used in perfumery.

AMIANTHUS. A mineral in silky filaments, called also Asbestus.

AMMONIA. A chemical compound, called also volatile alkali. This substance, in its purest state, is a highly pungent gas, possessed of all the mechanical properties of the air, but very condensable with water. It consists of 3 volumes of hydrogen and 1 of azote condensed into two volumes; and hence its density is 0·591, atmospheric air being 1·000. By strong compression and refrigeration it may be liquefied into a fluid, whose specific gravity is 0·76 compared to water 1·000.

Ammonia gas is composed by weight of 82·53 azote and 17·47 hydrogen in 100 parts. It is obtained by mixing muriate of ammonia, commonly called sal ammoniac, with quicklime, in a retort or still, applying a moderate heat, and receiving the gas either over mercury for chemical experiments, or in water to make liquid ammonia for the purposes of medicine and the arts. Woulfe’s apparatus is commonly employed for this condensation.

Ammonia is generated in a great many operations, and especially in the decomposition of many organic substances, by fire or fermentation. Urine left to itself for a few days is found to contain much carbonate of ammonia, and hence this substance was at one time collected in great quantities for the manufacture of certain salts of ammonia, and is still used for its alkaline properties in making alum, scouring wool, &c. When woollen rags, horns, bones, and other animal substances are decomposed in close vessels by fire, they evolve a large quantity of ammonia, which distils over in the form of a carbonate. The main source of ammonia now in this country, for commercial purposes, is the coal gas works. A large quantity of watery fluid is condensed in their tar pits, which contains, chiefly ammonia combined with sulphuretted hydrogen and carbonic acid. When this water is saturated with muriatic acid and evaporated it yields muriate of ammonia, or sal ammoniac, somewhat impure, which is afterwards purified by sublimation. See Carbonate of Ammonia and Sal Ammoniac.

The soot of chimnies where coal is burned contains both sulphate and carbonate of ammonia, and was extensively employed, at one time, to manufacture these salts.

In making water of ammonia on the great scale, a cast iron still should be preferred, and equal weights of quicklime and sal ammoniac should be brought to the consistence of a pap, with water, before the heat is applied. In this case, a refrigeratory worm or globe should be interposed between the adopter tube of the capital of the still and the bottles of Woulfe’s apparatus. The muriate of lime, or chloride of calcium, which is left in the still when the whole ammonia is expelled, is of no value. Water is capable of condensing easily about one third of its weight of ammonia gas, or 460 times its bulk. The following table of the quantity of ammonia in 100 parts by weight of its aqueous combinations, at successive densities, is the result of very careful experiments made by me, and recorded in the Philosophical Magazine for March, 1821.


Table of Water of Ammonia or Volatile Alkali, by Dr. Ure.

Equivalent primes.
100 26·500 73·500 0·9000    
95 25·175 74·825 0·9045 0·90452   Wat. Am.
90 23·850 76·150 0·9090 0·90909 24 + 76, 6 to 1
85 22·525 77·475 0·9133 0·91370  
80 21·200 78·800 0·9177 0·91838 21·25 + 78·75, 7 to 1
75 19·875 80·125 0·9227 0·92308  
70 18·550 81·450 0·9275 0·92780 19·1 + 80·9, 8 to 1
65 17·225 82·775 0·9320 0·93264 17·35 + 82·65, 9 to 1
60 15·900 84·100 0·9363 0·93750 15·9 + 84·1, 10 to 1
55 14·575 85·425 0·9410 0·94241 14·66 + 85·34, 11 to 1
50 13·250 86·750 0·9455 0·94737 13·60 + 86·40, 12 to 1
45 11·925 88·075 0·9510 0·95238 11·9 + 88·1, 14 to 1
40 10·600 89·400 0·9564 0·95744 11·2 + 88·8, 15 to 1
35 9·275 90·725 0·9614 0·96256  
30 7·950 92·050 0·9662 0·96774 8·63 + 91·37, 20 to 1
25 6·625 93·375 0·9716 0·97297 7 + 93, 25 to 1
20 5·300 94·700 0·9768 0·97826 6 + 94, 30 to 1
15 3·975 96·025 0·9828 0·98360 4·5 + 95·5, 40 to 1
10 2·650 97·350 0·9887 0·98900 3 + 97, 60 to 1
5 1·325 98·675 0·9945 0·99447  

AMMONIAC, gum-resin. This is the inspissated juice of an umbelliferous plant (the dorema armeniacum) which grows in Persia. It comes to us either in small white tears clustered together, or in brownish lumps, containing many impurities. It possesses a peculiar smell, somewhat like that of assafœtida, and a bitterish taste. It is employed in medicine. Its only use in the arts is for forming a cement to join broken pieces of china and glass, which may be prepared as follows: Take isinglass 1 ounce, distilled water 6 ounces, boil together down to 3 ounces, and add 112 ounce of strong spirit of wine;—boil this mixture for a minute or two; strain it; add, while hot, first, half an ounce of a milky emulsion of gum ammoniac, and then five drams of an alcoholic solution of resin mastic. This resembles a substance sold in the London shops, under the name of diamond cement. The recipe was given me by a respectable dispensing chemist.

AMORPHOUS. Without shape. Said of mineral and other substances which occur in forms not easy to be defined.

ANALYSIS. The art of resolving a compound substance or machine into its constituent parts. Every manufacturer should so study this art, in the proper treatises, and schools of Chemistry or Mechanics, as to enable him properly to understand and regulate his business.


ANCHOR. (Ancre, Fr.; Anker, Germ.) An iron hook of considerable weight and strength, for enabling a ship to lay hold of the ground, and fix itself in a certain situation by means of a rope called the cable. It is an instrument of the greatest importance to the navigator, since upon its taking and keeping hold depends his safety upon[44] many occasions, especially near a lee shore, where he might be otherwise stranded or shipwrecked. Anchors are generally made of wrought iron, except among nations who cannot work this metal well, and who therefore use copper. The mode in which an anchor operates will be understood from inspection of fig. 6., where, from the direction of the strain, it is obvious that the anchor cannot move without ploughing up the ground in which its hook or fluke is sunk. When this, however, unluckily takes place, from the nature of the ground, from the mode of insertion of the anchor, or from the violence of the winds or currents, it is called dragging the anchor. When the hold is good, the cable or the buried arm will sooner break than the ship will drive. Anchors are of different sizes, and have different names, according to the purposes they serve; thus there are, sheet, best bower, small bower, spare, stream, and kedge anchors. Ships of the first class have seven anchors, and smaller vessels, such as brigs and schooners, three.

Parts of anchor

The manufacture of anchors requires great knowledge of the structure of iron, and skill in the art of working it. I shall give, here, a brief notice of the improved system introduced by Mr. Perring, clerk of the cheque at Plymouth, in which the proportions of the parts are admirably adapted to the strains they are likely to suffer. In fig. 7. A is the shank; B, the arm or fluke; C, the palm; D, the blade; E, the square; F, the nut; G, the ring; H, the crown.

Formerly the shank was made of a number of square iron rods, laid parallel together in a cylindrical form, and bound by iron hoops. When they were welded into one bar, the exterior rods could not fail to be partially burned and wasted by the strong heat. Mr. Perring abated this evil by using bars of the whole breadth of the shank, and placing them right over each other, hooping them and welding them together at two heats into one solid mass. To any one who has seen the working of puddled iron, with a heavy mill hammer, this operation will not appear difficult.

He formed the crown with bars similarly distributed with those of the shank. His mode of uniting the flukes to the crown is probably the most valuable part of his invention. The bars and half the breadth of the anchor are first welded separately, and then placed side by side, where the upper half is worked into one mass, while the lower part is left disunited, but has carrier iron bars, or porters, as these prolongation rods are commonly called, welded to the extremity of each portion. The lower part is now heated and placed in the clamping machine, which is merely an iron plate firmly bolted to a mass of timber, and bearing upon its surface four iron pins. One end of the crown is placed between the first of these pins, and passed under an iron strap; the other end is brought between the other pins, and is bent by the leverage power of the elongated rods or porters.

Thus a part of the arm being formed out of the crown gives much greater security that a true union of fibres is effected, than when the junction was made merely by a short scarf.

The angular opening upon the side opposite B H, fig. 7., is filled with the chock, formed of short iron bars placed upright. When this has been firmly welded, the truss-piece is brought over it. This piece is made of plates similar to the above, except that their edges are here horizontal. The truss-piece is half the breadth of the arm; so that when united to the crown, it constitutes, with the other parts, the total breadth of the arms at those places.

The shank is now shut upon the crown; the square is formed, and the nuts welded to it; the hole is punched out for the ring, and the shank is then fashioned.

The blade is made much in the way above described. In making the palm, an iron rod is first bent into the approximate form, notching it so that it may more readily take the desired shape. To one end a porter rod is fastened, by which the palm is carried and turned round in the fire during the progress of the fabrication. Iron plates are next laid side by side upon the rod, and the joint at the middle is broken by another plate laid over it. When the mass is worked, its under side is filled up by similar plates, and the whole is completely welded; pieces being added to the sides, if necessary, to form the angles of the palm. The blade is then shut on to the palm, after which the part of the arm attached to the blade is united to that which constitutes the crown. The smith-work of the anchor is now finished.

The junction, or shutting on, as the workmen call it, of the several members of an anchor, is effected by an instrument called a monkey, which is merely a mass of iron raised to a certain height, between parallel uprights, as in the pile engine or vertical ram, and let fall upon the metal previously brought to a welding heat.


The monkey and the hercules, both silly, trivial names, are similar instruments, and are usually worked, like a portable pile engine, by the hands of several labourers, pulling separate ropes. Many other modes of manufacturing anchors have been devised, in which mechanical power is more extensively resorted to.

The upper end of the shank F (fig. 7.) is squared to receive and hold the stock steadily, and keep it from turning. To prevent it shifting along, there are two knobs or tenon-like projections. The point of the angle H, between the arms and the shank, is sometimes called the throat. The arm B C generally makes an angle of 56° with the shank A; it is either round or polygonal, and about half the length of the shank.

The stock of the anchor (fig. 6.) is made of oak. It consists of two beams which embrace the square, and are firmly united by iron bolts and hoops, as shown in the figure. The stock is usually somewhat longer than the shank, has in the middle a thickness about one-twelfth of its length, but tapers at its under side to nearly one half this thickness at the extremities. In small anchors the stock is frequently made of iron; but in this case it does not embrace the anchor, but goes through a hole made in the square, which is swelled out on purpose.

The weight of anchors for different vessels is proportioned to the tonnage; a good rule being to make the anchor in hundredweights one-twentieth of the number of tons of the burden. Thus a ship of 1000 tons would require a sheet anchor of 50 cwts. Ships of war are provided with somewhat heavier anchors.

Several new forms and constructions of anchors were proposed under Mr. Piper’s patent of November, 1822, by the adoption of which great advantages as to strength were anticipated over every other form or construction previously made.

The particular object was to preserve such a disposition of the fibres of the metal as should afford the greatest possible strength; in doing which the crossing or bending of the fibres at the junctions of the shank, flukes, and crown, where great strength is required, has been avoided as much as possible, so that the fibres are not disturbed or injured.

In this respect most anchors are defective; for in connecting the shanks to the crown-pieces, the grain of the metal is either crossed, or so much curved, as to strain the fibre, and consequently induce a weakness where the greatest strength is required. And, further, the very considerable thicknesses of metal which are to be brought into immediate contact by means of the hammer in forging anchors upon the old construction, render it highly probable that faulty places may be left within the mass, though they be externally imperceptible. Mr. Piper’s leading principle was, that the fibre of the metal should run nearly straight in all the parts where strength is particularly required.


Fig. 8. shows an anchor with one tumbling fluke, which passes through the forked or branched part of the shank. The lower part of this anchor, answering to the crown, has a spindle through it, upon which the fluke turns, and a pin is there introduced for the purpose of confining the fluke when in a holding position. This shank is formed of a solid piece of wrought iron, the fibres of which run straight, and at the crown holes are pierced, which merely bulge the metal without bending the fibres round so as to strain them. The arm and fluke, also, are formed of one piece punched through without curling or crossing the fibre, and the spindle which holds the arm to the crown is likewise straight. This spindle extends some distance on each side of the anchor, and is intended to answer the purpose of a stock; for when either of the ends of the spindle comes in contact with the ground, the anchor will be thrown over into a holding position; or an iron stock may be introduced near the shackle, instead of these projecting ends. In the descent of the anchor, the fluke will fall over towards that side which is nearest the ground, and will there be ready to take hold when the anchor is drawn forward.


Fig. 9. is another anchor upon the same principle, but slightly varied in form from the last. In this the forked part of the shank is closer than in the former, and there are two arms or flukes connected to the crown-pieces, one of which falls into its holding position as the anchor comes to the ground, and is held at its proper angle by the other fluke stopping against the shank.


Fig. 10. represents another variation in the form of these improved anchors, having two tumbling flukes, which are both intended to take hold of the ground at the same time. The shank is here, as before, made without crossing the grain of the iron, and the eyes for admitting the bolt at the crown and at the shackle are punched out of the solid, not formed by welding or turning the iron round. In this form a guard is introduced at[46] the crown, to answer the purpose of a stock, by turning the flukes over into a holding position. The arms and flukes are made, as before described, of the straight fibre of the iron punched through, and the flukes are fixed to the spindle, which passes through the crown-piece.


Fig. 11. has a shank without any fork, but formed straight throughout; the guard here is an elongated frame of iron, for the same purpose as a stock, and is, with the tumbling flukes, fastened to the spindle, which passes through the crown of the anchor, and causes the flukes to fall into their holding position.

The principles of these new anchors are considered to consist in shanks which are made of straight lengths of metal, and finished so that the fibres of the iron shall not be injured by cross-shuts or uncertain welding; also each arm and palm is made in one solid piece, and finished in straight lines, so that the fibres will not be altered, and the shaft-pin or spindle will also be in one straight line; and this is the improvement claimed. These anchors being made in separate pieces, give a great advantage to the workman to execute each part perfectly; for he will not have such heavy weights to lift when hot, which will render these anchors much stronger, with less weight; and if any accident should happen to them, any part may be taken separate from the others to be repaired, and several of those parts of the anchor which may be likely to break may be carried on board, in case of accident. This anchor is so contrived that one of thirty hundred weight may be taken to pieces and put together again, by one man, in twenty minutes; it may also be dismounted, and stowed in any part of the ship, in as little room as straight bars of iron, and speedily put together again.


The anchor (fig. 12.) patented by Mr. Brunton, in February, 1822, has its stock introduced at the crown part, for the purpose of turning it over into a holding position. The shank is perforated through the solid, in two places, with elliptical apertures, for the purpose of giving it a greater stability, and more effectually resisting the strain to which the anchor may be subjected. The stock is a cylindrical iron rod, held at its extremities by lateral braces, which are bolted to the shank.

Fig. 12. shows the form of the anchor. The shank is seen upright, with one of the flukes projecting in its front; the horizontal iron stock is at bottom; and the oblique braces are bolted to both shank and stock. The ends of the stock, from the shoulder, are formed dove-tailed, and oval in the vertical direction, and are protruded through apertures in the braces, also oval, but in the horizontal direction, and counter sunk. When the ends of the stock have been thus introduced through the holes, the braces are securely bolted to the shank; the ends of the stock are then spread, by hammering into the counter-sunk holes of the braces, and by that means they are made firm.

An anchor of this description is considered by the patentee to possess considerable advantage, particularly in point of stability, over the ordinary construction of anchors, and is economical, inasmuch as a less weight of metal will give, upon this plan, an equal degree of strength.

An ingenious form of anchor was made the subject of a patent, by Lieutenant Rodgers, of the Royal Navy, in 1828, and was afterwards modified by him in a second patent, obtained in August, 1829. The whole of the parts of the anchor are to be bound together by means of iron bands or hoops, in place of bolts or pins.


Fig. 13. is a side view of a complete anchor, formed upon his last improved construction, and fig. 14., a plan of the same; fig. 15., an end view of the crown and flukes, or arms; fig. 16. represents the two principal iron plates, a, a, of which the shank is constructed, but so as to form parts of the stump arms to which the flukes are to be connected.

The crown piece is to be welded to the stump piece, c c, fig. 16., as well as to the[47] end l of the centre piece h h, and the scarfs m m are to be cut to receive the arms or flukes. Previously, however, to uniting the arms or flukes with the stump arms, the crown and throat of the anchor are to be strengthened, by the application of the crown slabs n n, fig. 16., which are to be welded upon each side of the crown, overlapping the end of the pillar h, and the throat or knees of the stump arms and the crown piece. The stump arms are then to be strengthened in a similar manner, by the thin flat pieces p p, which are to be welded upon each side. The palms are united to the flukes in the usual way, and the flukes are also united to the stump arms by means of the long scarfs m m. When the shank of the anchor has been thus formed, and united with the flukes, the anchor smith’s work may be said to be complete.


Another of the improvements in the construction of anchors, claimed under this patent, consists in a new method of affixing the stock upon the shank of the anchor, which is effected in the following manner: in fig. 14. the stock is shown affixed to the anchor; in fig. 17. it is shown detached. It may be made either of one or two pieces of timber, as may be found most convenient. It is, however, to be observed that the stock is to be completed before fitting on to the shank. After the stock is shaped, a hole is to be made through the middle of it, to fit that part of the shank to which it is to be affixed. Two stock plates are then to be let in, one on each side of the stock, and made fast by counter sunk nails and straps, or hoops; other straps or hoops of iron are also to be placed round the stock, as usual.

In place of nuts, formed upon the shank of the anchor, it is proposed to secure the stock by means of a hoop and a key, shown above and below J, in fig. 14. By this contrivance, the stock is prevented from going nearer to the crown of the anchor than it ought to do, and the key prevents it from sliding towards the shackle.

Since fitting the stock to the shank of an anchor, by this method, prevents the use of a ring, as in the ordinary manner, the patentee says that he in all cases substitutes a shackle for the ring, and which is all that is required for a chain cable; but, when a hempen cable is to be used, he connects a ring to the usual shackle, by means of a joining shackle, as in figs. 13. and 14.

Mr. Rodgers proposes, under another patent, dated July, 1833, to alter the size and form of the palms; having found from experience that anchors with small palms will not only hold better than with large ones, but that the arms of the anchor, even without any palms, have been found to take more secure hold of the ground than anchors of the old construction, of similar weight and length. He has, accordingly, fixed upon one-fifth of the length of the arm, as a suitable proportion for the length or depth of the palm. He makes the palms, also, broader than they are long or deep.

ANIMÉ. A resin of a pale brown yellow colour, transparent and brittle. It exudes from the courbaril of Cayenne, a tree which grows also in various parts of South America. It occurs in pieces of various sizes, and it often contains so many insects belonging to living species, as to have merited its name, as being animated. It contains about a fifth of one per cent. of a volatile oil, which gives it an agreeable odour. Alcohol does not dissolve the genuine animé, as I have ascertained by careful experiments; nor does caoutchoucine; but a mixture of the two, in equal parts, softens it into a tremulous jelly, though it will not produce a liquid solution. When reduced to this state, the insects can be easily picked out, without injury to their most delicate parts.

The specific gravity of the different specimens of animé which I tried, varied from 1·054 to 1·057. When exposed to heat, in a glass retort over a spirit flame, it softens, and, by careful management, it may be brought into liquid fusion, without discolouration. It then exhales a few white vapours, of an ambrosiacal odour, which being condensed in water, and the liquid being tested, is found to be succinic acid. Author.

It is extensively used by the varnish makers, who fuse it at a pretty high heat, and in this state combine it with their oils, or other varnishes.

ANKER. A liquid measure of Amsterdam, which contains 32 gallons English.

ANNEALING or NEALING. (Le recuit, Fr.; das anlassen, Germ.) A process by which glass is rendered less frangible; and metals, which have become brittle, either in consequence of fusion, or long-continued hammering, are again rendered malleable. When a glass vessel is allowed to cool immediately after being made, it will often sustain the shock of a pistol-bullet, or any other blunt body falling into it from a considerable height; while a small splinter of flint, or an angular fragment of quartz, dropped gently into it, makes it sometimes immediately, sometimes after a few minutes, fly to pieces with great violence. This extreme fragility is prevented by annealing, or placing the vessels in an oven, where they take several hours or even some days to cool. Similar phenomena are exhibited in a higher degree by glass-tears, or Prince Rupert’s drops. They are procured by letting drops of melted glass fall into cold water. Their form resembles that of a pear, rounded at one extremity, and tapering to a very slender tail at the other. If a part of the tail be broken off, the whole drop flies to pieces with a loud explosion; and yet the tail of a drop may be cut away by a glass-cutter’s wheel, or the thick end[48] may be struck smartly with a hammer, without the fear of sustaining any injury. When heated to redness, and permitted to cool gradually in the open air, they lose these peculiarities, and do not differ sensibly from common glass.

The properties of unannealed glass depend on a peculiar structure, extending uniformly through its whole substance; and the bursting of a glass drop by breaking off the tail, or of an unannealed glass vessel, by dropping a piece of flint into it, arises from a crack being thus begun, which afterwards extends its ramifications in different directions throughout the glass.

When metals have been extended to a certain degree under the hammer, they become brittle, and incapable of being further extended without cracking. In this case the workman restores their malleability by annealing, or heating them red-hot. The rationale of this process seems to be, that the hammering and extension of the metal destroy the kind of arrangement which the particles of the metal had previous to the hammering; and that the annealing, by softening the metal, enables it to recover its original structure.

Of late years a mode has been discovered of rendering cast iron malleable, without subjecting it to the action of puddling. The process is somewhat similar to that employed in annealing glass. The metal is kept for several hours at a temperature a little below its fusing point, and then allowed to cool slowly. In this manner vessels are made of cast iron which can sustain considerable violence, without being broken. See Steel, softening of.

ANNOTTO. (Rocou, or roucou, Fr.; orleans, Germ.) A somewhat dry and hard paste, brown without, and red within. It is usually imported in cakes of two or three pounds weight, wrapped up in leaves of large reeds, packed in casks, from America, where it is prepared from the seeds of a certain tree, the bixa orellana, of Linnæus.

The pods of the tree being gathered, their seeds are taken out and bruised; they are then transferred to a vat, which is called the steeper, where they are mixed with as much water as covers them. Here the substance is left for several weeks, or even months; it is now squeezed through sieves placed above the steeper, that the water containing the colouring matter in suspension may return, into the vat. The residuum is preserved under the leaves of the anana (pine-apple) tree, till it becomes hot by fermentation. It is again subjected to the same operation, and this treatment is continued till no more colour remains.

The substance thus extracted is passed through sieves, in order to separate the remainder of the seeds, and the colour is allowed to subside. The precipitate is boiled in coppers till it be reduced to a consistent paste; it is then suffered to cool, and dried in the shade.

Instead of this long and painful labour, which occasions diseases by the putrefaction induced, and which affords a spoiled product, Leblond proposes simply to wash the seeds of annotto till they be entirely deprived of their colour, which lies wholly on their surface; to precipitate the colour by means of vinegar or lemon juice, and to boil it up in the ordinary manner, or to drain it in bags, as is practised with indigo.

The experiments which Vauquelin made on the seeds of annotto imported by Leblond, confirmed the efficacy of the process which he proposed; and the dyers ascertained that the annotto obtained in this manner was worth at least four times more than that of commerce; that, moreover, it was more easily employed; that it required less solvent; that it gave less trouble in the copper, and furnished a purer colour.

Annotto dissolves better and more readily in alcohol than in water, when it is introduced into the yellow varnishes for communicating an orange tint.

The decoction of annotto in water has a strong peculiar odour, and a disagreeable taste. Its colour is yellowish-red, and it remains a little turbid. An alkaline solution renders its orange-yellow clearer and more agreeable, while a small quantity of a whitish substance is separated from it, which remains suspended in the liquid. If annotto be boiled in water along with an alkali, it dissolves much better than when alone, and the liquid has an orange hue.

The acids form with this liquor an orange-coloured precipitate, soluble in alkalies, which communicate to it a deep orange colour. The supernatant liquor retains only a pale yellow hue.

When annotto is used as a dye, it is always mixed with alkali, which facilitates its solution, and gives it a colour inclining less to red. The annotto is cut in pieces, and boiled for some instants in a copper with its own weight of crude pearl ashes, provided the shade wanted do not require less alkali. The cloths may be thereafter dyed in this bath, either by these ingredients alone, or by adding others to modify the colour; but annotto is seldom used for woollen, because the colours which it gives are too fugitive, and may be obtained by more permanent dyes. Hellot employed it to dye a stuff, prepared with alum and tartar; but the colour acquired had little permanence. It is almost solely used for silks.


For silks intended to become aurora and orange, it is sufficient to scour them at the rate of 20 per cent. of soap. When they have been well cleansed, they are immersed in a bath prepared with water, to which is added a quantity of alkaline solution of annotto, more or less considerable according to the shade that may be wanted. This bath should have a mean temperature, between that of tepid and boiling water.

When the silk has become uniform, one of the hanks is taken out, washed, and wrung, to see if the colour be sufficiently full; if it be not so, more solution of annotto is added, and the silk is turned again round the sticks: the solution keeps without alteration.

When the desired shade is obtained, nothing remains but to wash the silk, and give it two beetlings at the river, in order to free it from the redundant annotto, which would injure the lustre of the colour.

When raw silks are to be dyed, those naturally white are chosen, and dyed in the annotto bath, which should not be more than tepid, or even cold, in order that the alkali may not attack the gum of the silk, and deprive it of the elasticity which it is desirable for it to preserve.

What has been now said regards the silks to which the aurora shades are to be given; but to make an orange hue, which contains more red than the aurora, it is requisite, after dyeing with annotto, to redden the silks with vinegar, alum, or lemon juice. The acid, by saturating the alkali employed for dissolving the annotto, destroys the shade of yellow that the alkali had given, and restores it to its natural colour, which inclines a good deal to red.

For the deep shades, the practice at Paris, as Macquer informs us, is to pass the silks through alum; and if the colour be not red enough, they are passed through a faint bath of brazil wood. At Lyons, the dyers who use carthamus, sometimes employ old baths of this ingredient for dipping the deep oranges.

When the orange hues have been reddened by alum, they must be washed at the river; but it is not necessary to beetle them, unless the colour turns out too red.

Shades may be obtained also by a single operation, which retain a reddish tint, employing for the annotto bath a less proportion of alkali than has been pointed out.

Guhliche recommends to avoid heat in the preparation of annotto. He directs it to be placed in a glass vessel, or in a glazed earthen one; to cover it with a solution of pure alkali; to leave the mixture at rest for 24 hours; to decant the liquor, filter it, and add water repeatedly to the residuum, leaving the mixture each time at rest for two or three days, till the water is no longer coloured; to mix all these liquors, and preserve the whole for use in a well-stopped vessel.

He macerates the silk for 12 hours in a solution of alum, at the rate of an eighth of this salt for one part of silk, or in a water rendered acidulous by the aceto-citric acid above described; and he wrings it well on its coming out of this bath.

Silk thus prepared is put into the annotto bath quite cold. It is kept in agitation there till it has taken the shade sought for; or the liquor may be maintained at a heat far below ebullition. On being taken out of the bath, the silk is to be washed and dried in the shade.

For lighter hues, a liquor less charged with colour is taken; and a little of the acid liquid which has served for the mordant may be added, or the dyed silk may be passed through the acidulous water.

We have seen the following preparation employed for cotton velvet:—one part of quicklime, one of potash, two of soda.

Of these a ley is formed, in which one part of annotto is dissolved; and the mixture is boiled for an hour and a half. This bath affords the liveliest and most brilliant auroras. The buff (chamois) fugitive dye is also obtained with this solution. For this purpose only a little is wanted; but we must never forget, that the colours arising from annotto are all fugitive.

Dr. John found in the pulp surrounding the unfermented fresh seeds, which are about the size of little peas, 28 parts of colouring resinous matter, 26·5 of vegetable gluten, 20 of ligneous fibre, 20 of colouring extractive matter, 4 formed of matters analogous to vegetable gluten and extractive, and a trace of spicy and acid matters.

The Gloucestershire cheese is coloured with annotto, in the proportion of one cwt. to an ounce of the dye.

When used in calico-printing, it is usually mixed with potash or ammonia and starch.

It is an appropriate substance for tingeing varnishes, oils, spirits, &c.

The import duty upon annotto is 1s. per cwt. for flag, and 4s. for other sorts. In 1834, 252,981 lbs. were imported; and in 1835, 163,421 lbs. The revenue from this drug in these two years, was 180l. and 98l. respectively.

ANTHRACITE, from ανθραξ, coal, is a species of coal found in the transition rock formation, and is often called stone coal. It has a grayish black, or iron black colour, an imperfectly metallic lustre, conchoidal fracture, and a specific gravity of from 1·4 to 1·6, being, therefore, much denser than the coal of the proper coal measures. It consists[50] wholly of carbon, with a small and variable proportion of iron, silica, and alumina. It is difficult to kindle in separate masses, and burns when in heaps or grates without smell or smoke, leaving sometimes an earthy residuum. It has been little explored or worked in the old world; but is extensively used in the United States of America, and has become of late years a most valuable mineral to that country, where it is burned in peculiar grates, adapted to its difficult combustion. In Pennsylvania the anthracite coal formation has been traced through a tract many miles in width, and extending across the two entire counties of Luzerne and Schuylkill. At Maunch Chunk, upon the Lehigh, 800 men were employed so far back as 1825, in digging this coal. In that year 750,000 bushels were dispatched for Philadelphia. It is worked there with little cost or labour, being situated on hills from 300 to 600 feet above the level of the neighbouring rivers and canals, and existing in nearly horizontal beds, of from 15 to 40 feet in thickness, covered by only a few feet of gravelly loam. At Portsmouth, in Rhode Island, an extensive stratum of this coal has been worked, with some interruptions, for 20 years; and more recently a mine of anthracite has been opened at Worcester, in Massachusetts, at the head of the Blackstone canal. It has been of late employed in South Wales, for smelting iron, and in a cupola blast furnace, by Mr. Crane.

ANTIGUGGLER. A small syphon of metal, which is inserted into the mouths of casks, or large bottles, called carboys, to admit air over the liquor contained in them, and thus to facilitate their being emptied without agitation or a guggling noise.

ANTIMONY. (Antimoine, Fr.; Spiessglanz, or Spiessglass, Ger.) The only ore of this metal found in sufficient abundance to be smelted, is the sulphuret, formerly called crude antimony. It occurs generally in masses, consisting of needles closely aggregated, of a metallic lustre, a lead-gray colour, inclining to steel-gray, which is unchanged in the streak. The needles are extremely brittle, and melt even in the flame of a candle, with the exhalation of a sulphureous smell. The powder of this sulphuret is very black, and was employed by women in ancient times to stain their eyebrows and eyelids. This ore consists in 100 parts of 72·86 metal, and 27·14 sulphur. Specific gravity from 4·13 to 4·6.

The veins of sulphuret of antimony occur associated with gangues of quartz, sulphate of barytes, and carbonate of lime; those of Allémont occur in the numerous fissures of a mica schist, evidently primitive.

In treating the ore to obtain the metal, the first object is to separate the gangue, which was formerly done by filling crucibles with the mixed materials, placing them on the hearth of an oven, and exposing them to a moderate heat. As the sulphuret easily melts, it ran out through a hole in the bottom of the crucible into a pot placed beneath, and out of the reach of the fire. But the great loss from breakage of the crucibles, has caused another method to be adopted. In this the broken ore, being sorted, is laid on the bottom of a concave reverberatory hearth, where it is reduced.


Figs. 18. 19. represent a wind or flame furnace, for the reduction of antimony. The hearth is formed of sand and clay solidly beat together, and slopes from all sides towards the middle, where it is connected with the orifice a, which is closed with dense coal-ashes; b is the air channel up through the bridge; c, the door for introducing the prepared ore, and running off the slags; d, the bridge; e, the grate; f, the fire or fuel-door; g, the chimney. With 2 or 3 cwt. of ore, the smelting process is completed in from 8 to 10 hours. The metal thus obtained is not pure enough, but must be fused under coal dust, in portions of 20 or 30 pounds, in crucibles, placed upon a reverberatory hearth.

To obtain antimony free from iron, it should be fused with some antimonic oxide in a crucible, whereby the iron is oxidized and separated. The presence of arsenic in antimony is detected by the garlic smell, emitted by such an alloy when heated at the blow-pipe; or, better, by igniting it with nitre in a crucible; in which case, insoluble antimonite and antimoniate of potash will be formed along with soluble arseniate. Water digested upon the mixture, filtered, and then tested with nitrate of silver, will afford the brown-red precipitate characteristic of arsenic acid.

According to Berthier, the following materials afford, in smelting, an excellent product of antimony: 100 parts of sulphuret; 60 of hammerschlag (protoxide of iron from the shingling or rolling mills); 45 to 50 of carbonate of soda; and 10 of charcoal powder. From 65 to 70 parts of metallic antimony or regulus should be obtained. Glauber salts may be used instead of soda. For another mode of smelting antimony, at Malbosc, in the department of Ardèche, in France, see Liquation.

In the works where antimonial ores are smelted, by means of tartar (argol), the alkaline[51] scoriæ, which cover the metallic ingots, are not rejected as useless, for they hold a certain quantity of antimonial oxide in combination; a property of the potash flux, which is propitious to the purity of the metal. These scoriæ, consisting of sulphuret of potassium and antimonite of potash, being treated with water, undergo a reciprocal decomposition; the elements of the water act on those of the sulphuret, and the resulting alkaline hydro-sulphuret re-acts on the antimonial solution, so as to form a species of kermes mineral, which precipitates. This is dried, and sold at a low price as a veterinary medicine, under the name of kermes, by the dry way.

Metallic antimony, as obtained by the preceding process, is the antimony of commerce, but is not absolutely pure; containing frequently minute portions of iron, lead, and even arsenic; the detection and separation of which belong to the sciences of chemistry and pharmacy. Antimony is a brittle metal, of a silvery white colour, with a tinge of blue, a lamellar texture, and crystalline fracture. When heated at the blowpipe, it melts with great readiness, and diffuses white vapours, possessing somewhat of a garlic smell. If thrown in this melted state on a sheet of flat paper, the globule sparkles, and bursts into a multitude of small spheroids, which retain their incandescence for a long time, and run about on the paper, leaving traces of the white oxide produced during the combustion. When this oxide is fused with borax, or other vitrifying matter, it imparts a yellow colour to it. Metallic antimony, treated with hot nitric acid and in a concentrated state, is converted into a powder, called antimonious acid, which is altogether insoluble in the ordinary acid menstrua; a property by which the chemist can separate that metal from lead, iron, copper, bismuth, and silver. According to Bergman, the specific gravity of antimony is 6·86; but Haidinger makes the Swedish native metal only 6·646. The alchemists had conceived the most brilliant hopes of this metal; the facility with which it is alloyed with gold, since its fumes alone render this most ductile metal immediately brittle, led them to assign to it a royal lineage, and to distinguish it by the title of regulus, or the little king.

Its chief employment now is in medicine, and in making the alloys called type metal, stereotype metal, music plates, and Britannia-metal; the first consisting of 6 of lead and 2 of antimony; the second of 6 of lead and 1 of antimony; the third of lead, tin, and antimony; and the fourth also of lead, tin, and antimony, with occasionally a little copper and bismuth.—For Glass of antimony, see Pastes.

ANTISEPTICS. Substances which counteract the spontaneous decomposition of animal and vegetable substances. These are chiefly culinary salt, nitre, spices, and sugar, which operate partly by inducing a change in the animal or vegetable fibres, and partly by rendering the aqueous constituent unsusceptible of decomposition. See Provisions, curing of.

ANVIL. A mass of iron, having a smooth and nearly flat top surface of steel; upon which blacksmiths, and various other artificers, forge metals with the hammer. The common anvil is usually made of seven pieces: 1, the core, or body; 2, 3, 4, 5, the four corner pieces which serve to enlarge its base; 6, the projecting end, which has a square hole for the reception of the tail or shank of a chisel on which iron bars may be cut through; and 7, the beak, or horizontal cone round which rods or slips of metal may be turned into a circular form, as in making rings. These 6 pieces are welded separately to the first, or core, and then hammered into an uniform body. In manufacturing large anvils two hearths are needed, in order to bring each of the two pieces to be welded, to a proper heat by itself; and several men are employed in working them together briskly in the welding state, by heavy swing hammers. The steel facing is applied by welding in the same manner. The anvil is then hardened by heating it to a cherry red, and plunging it into cold water; a running stream being preferable to a pool or cistern. The facing should not be too thick a plate, for, when such, it is apt to crack in the hardening. The face of the anvil is now smoothed upon a grindstone, and finally polished with emery and crocus, for all delicate purposes of art.

The blacksmith, in general, sets his anvil loosely upon a wooden block, and in preference on the root of an oak. But the cutlers and file-makers fasten their anvils to a large block of stone; which is an advantage, for the more firmly and solidly this tool is connected to the earth, the more efficacious will be the blows of the hammer on any object placed upon it.

AQUAFORTIS. Nitric acid, somewhat dilute, was so named by the alchemists on account of its strong solvent and corrosive operation upon many mineral, vegetable, and animal substances. See Nitric Acid.

AQUA REGIA. The name given by the alchemists to that mixture of nitric and muriatic acids which was best fitted to dissolve gold, styled by them the king of the metals. It is now called nitro-muriatic acid.

AQUA VITÆ. The name very absurdly given to alcohol, when used as an intoxicating beverage. It has been the aqua mortis to myriads of the human race; and will, probably, ere long destroy all the native tribes of North America and Australia.


ARCHIL. A violet red paste used in dyeing, of which the substance called cudbear in Scotland (from Cuthbert, its first preparer in that form), is a modification. Two kinds of archil are distinguished in commerce, the archil plant of the Canaries, and that of Auvergne. The first is most esteemed: it is prepared from the lichen rocellus, which grows on rocks adjoining the sea in the Canary and Cape de Verde Islands, in Sardinia, Minorca, &c., as well as on the rocks of Sweden. The second species is prepared from the lichen parellus, which grows on the basaltic rocks of Auvergne.

There are several other species of lichen which might be employed in producing an analogous dye, were they prepared, like the preceding, into the substance called archil. Hellot gives the following method for discovering if they possess this property. A little of the plant is to be put into a glass vessel; it is to be moistened with ammonia and lime-water in equal parts; a little muriate of ammonia (sal ammoniac) is added; and the small vessel is corked. If the plant be of a nature to afford a red dye, after three or four days, the small portion of liquid, which will run off on inclining the vessel, now opened, will be tinged of a crimson red, and the plant itself will have assumed this colour. If the liquor or the plant does not take this colour, nothing need be hoped for; and it is useless to attempt its preparation on the great scale. Lewis says, however, that he has tested in this way a great many mosses, and that most of them afforded him a yellow or reddish brown colour; but that he obtained from only a small number a liquor of a deep red, which communicated to cloth merely a yellowish-red colour.

Prepared archil gives out its colour very readily to water, ammonia, and alcohol. Its solution in alcohol is used for filling spirit-of-wine thermometers; and when these thermometers are well freed from air, the liquor loses its colour in some years, as Abbé Nollet observed. The contact of air restores the colour, which is destroyed anew, in vacuo, in process of time. The watery infusion loses its colour, by the privation of air, in a few days; a singular phenomenon, which merits new researches.

The infusion of archil is of a crimson bordering on violet. As it contains ammonia, which has already modified its natural colour, the fixed alkalies can produce little change on it, only deepening the colour a little, and making it more violet. Alum forms in it a precipitate of a brown red; and the supernatant liquid retains a yellowish-red colour. The solution of tin affords a reddish precipitate, which falls down slowly; the supernatant liquid retains a feeble red colour. The other metallic salts produce precipitates which offer nothing remarkable.

The watery solution of archil applied to cold marble, penetrates it, communicating a beautiful violet colour, or a blue bordering on purple, which resists the air much longer than the archil colours applied to other substances. Dufay says, that he has seen marble tinged with this colour preserve it without alteration at the end of two years.

To dye with archil, the quantity of this substance deemed necessary, according to the quantity of wool or stuff to be dyed, and according to the shade to which they are to be brought, is to be diffused in a bath of water as soon as it begins to grow warm. The bath is then heated till it be ready to boil, and the wool or stuff is passed through it without any other preparation, except keeping that longest in, which is to have the deepest shade. A fine gridelin, bordering upon violet, is thereby obtained; but this colour has no permanence. Hence archil is rarely employed with any other view than to modify, heighten, and give lustre to the other colours. Hellot says, that having employed archil on wool boiled with tartar and alum, the colour resisted the air no more than what had received no preparation. But he obtained from herb archil (l’orseille d’herbe) a much more durable colour, by putting in the bath some solution of tin. The archil thereby loses its natural colour, and assumes one approaching more or less to scarlet, according to the quantity of solution of tin employed. This process must be executed in nearly the same manner as that of scarlet, except that the dyeing may be performed in a single bath.

Archil is frequently had recourse to for varying the different shades and giving them lustre; hence it is used for violets, lilacs, mallows, and rosemary flowers. To obtain a deeper tone, as for the deep soupes au vin, sometimes a little alkali or milk of lime is mixed with it. The suites of this browning may also afford agates, rosemary flowers, and other delicate colours, which cannot be obtained so beautiful by other processes. Alum cannot be substituted for this purpose; it not only does not give this lustre, but it degrades the deep colours.

The herb-archil is preferable to the archil of Auvergne, from the greater bloom which it communicates to the colours, and from the larger quantity of colouring matter. It has, besides, the advantage of bearing ebullition. The latter, moreover, does not answer with alum, which destroys the colour; but the herb archil has the inconvenience of dyeing in an irregular manner, unless attention be given to pass the cloth through hot water as soon as it comes out of the dye.

Archil alone is not used for dyeing silk, unless for lilacs; but silk is frequently passed through a bath of archil, either before dyeing it in other baths or after it has been dyed, in order to modify different colours, or to give them lustre. Examples of this[53] will be given in treating of the compound colours. It is sufficient here to point out how white silks are passed through the archil bath. The same process is performed with a bath more or less charged with this colour, for silks already dyed.

Archil, in a quantity proportioned to the colour desired, is to be boiled in a copper. The clear liquid is to be run off quite hot from the archil bath, leaving the sediment at the bottom, into a tub of proper size, in which the silks, newly scoured with soap, are to be turned round on the skein-sticks with much exactness, till they have attained the wished-for shade. After this they must receive one beetling at the river.

Archil is in general a very useful ingredient in dyeing; but as it is rich in colour, and communicates an alluring bloom, dyers are often tempted to abuse it, and to exceed the proportions that can add to the beauty without at the same time injuring in a dangerous manner the permanence of the colours. Nevertheless, the colour obtained when solution of tin is employed, is less fugitive than without this addition: it is red, approaching to scarlet. Tin appears to be the only ingredient which can increase its durability. The solution of tin may be employed, not only in the dyeing bath, but for the preparation of the silk. In this case, by mixing the archil with other colouring substances, dyes may be obtained which have lustre with sufficient durability.

We have spoken of the colour of the archil as if it were natural to it; but it is, really, due to an alkaline combination. The acids make it pass to red, either by saturating the alkali, or by substituting themselves for the alkali.

The lichen which produces archil is subjected to another preparation, to make turnsole (litmus). This article is made in Holland. The lichen comes from the Canary Islands, and also from Sweden. It is reduced to a fine powder by means of a mill, and a certain proportion of potash is mixed with it. The mixture is watered with urine, and allowed to suffer a species of fermentation. When this has arrived at a certain degree, carbonate of lime in powder is added, to give consistence and weight to the paste, which is afterwards reduced into small parallelopipeds that are carefully dried.

The latest researches on the lichens, as objects of manufacture, are those of Westring of Stockholm. He examined 150 species, among which he found several which might be rendered useful. He recommends that the colouring matter should be extracted in the places where they grow, which would save a vast expense in curing, package, carriage, and waste. He styles the colouring substance itself cutbear, persio, or turnsole; and distributes the lichens as follows:—1st. Those which left to themselves, exposed to moderate heat and moisture, may be fixed without a mordant upon wool or silk; such are the L. cinereus, æmatonta, ventosus, corallinus, westringii, saxatilis, conspassus, barbatus, plicatus, vulpinus, &c.

2. Those which develop a colouring matter fixable likewise without mordant, but which require boiling and a complicated preparation; such are the lichens subcarneus, dillenii, farinaceus, jubatus, furfuraceus, pulmonareus, cornigatus, cocciferus, digitatus, ancialis, aduncus, &c. Saltpetre or sea-salt are requisite to improve the lustre and fastness of the dye given by this group to silk.

3. Those which require a peculiar process to develop their colour; such as those which become purple through the agency of stale urine or ammonia. Westring employed the following mode of testing:—He put three or four drachms of the dried and powdered lichen into a flask; moistened it with three or four measures of cold spring water; put the stuff to be dyed into the mixture, and left the flask in a cool place. Sometimes he added a little salt, saltpetre, quicklime, or sulphate of copper. If no colour appeared, he then moistened the lichen with water containing one twentieth of sal ammoniac, and one tenth of quicklime, and set the mixture aside in a cool place from eight to fourteen days. There appeared in most cases a reddish or violet coloured tint. Thus the lichen cinereus dyed silk a deep carmelite, and wool a light carmelite; the l. physodes gave a yellowish-gray; the pustulatus, a rose red; sanguinarius, gray; tartareus, found on the rocks of Norway, Scotland, and England, dyes a crimson-red. In Jutland, cutbear is made from it, by grinding the dry lichen, sifting it, then setting it to ferment in a close vessel with ammonia. The lichen must be of the third year’s growth to yield an abundant dye; and that which grows near the sea is the best. It loses half its weight by drying. A single person may gather from twenty to thirty pounds a day in situations where it abounds. No less than 2,239,685 pounds were manufactured at Christiansand, Flekkefiort, and Fakrsund, in Norway, in the course of the six years prior to 1812. Since more solid dyes of the same shade have been invented, the archil has gone much into disuse. Federigo, of Florence, who revived its use at the beginning of the fourteenth century, made such an immense fortune by its preparation, that his family became one of the grandees of that city, under the name of Oricellarii, or Rucellarii. For more than a century Italy possessed the exclusive art of making archil, obtaining the lichens from the islands of the Mediterranean. According to an official report of 1831, Teneriffe furnished annually 500 quintals (cwts.) of lichen;[54] the Canary Isles, 400; Fuerta Santura, 300; Lancerot, 300; Gomera, 300; isle of Ferro, 800. This business belonged to the crown, and brought it a revenue of 1500 piastres. The farmers paid from 15 to 20 reals for the right to gather each quintal. At that time the quintal fetched in the London market 4l. sterling.

Archil is perhaps too much used in some cloth factories of England, to the discredit of our dyes. It is said, that by its aid one third of the indigo may be saved in the blue vat; but the colour is so much the more perishable. The fine soft tint induced upon much of the black cloth by means of archil is also deceptive. One half-pound of cutbear will dye one pound of woollen cloth. A crimson red is obtained by adding to the decoction of archil a little salt of tin (muriate), and passing the cloth through the bath, after it has been prepared by a mordant of tin and tartar. It must be afterwards passed through hot water.

ARDENT SPIRIT. Alcohol of moderate strength.

AREOMETER OF BAUMÉ. This scale is much used by the French authors.

Specific Gravity Numbers corresponding with Baumé’s Areometric Degrees.

Liquids denser than Water. Less dense than Water.
0 1·0000 26 1·2063 52 1·5200 10 1·0000 36 0·8488
1 1·0066 27 1·2160 53 1·5353 11 0·9932 37 0·8439
2 1·0133 28 1·2258 54 1·5510 12 0·9865 38 0·8391
3 1·0201 29 1·2358 55 1·5671 13 0·9799 39 0·8313
4 1·0270 30 1·2459 56 1·5833 14 0·9733 40 0·8295
5 1·0340 31 1·2562 57 1·6000 15 0·9669 41 0·8249
6 1·0411 32 1·2667 58 1·6170 16 0·9605 42 0·8202
7 1·0483 33 1·2773 59 1·6344 17 0·9542 43 0·8156
8 1·0556 34 1·2881 60 1·6522 18 0·9480 44 0·8111
9 1·0630 35 1·2992 61 1·6705 19 0·9420 45 0·8066
10 1·0704 36 1·3103 62 1·6889 20 0·9359 46 0·8022
11 1·0780 37 1·3217 63 1·7079 21 0·9300 47 0·7978
12 1·0857 38 1·3333 64 1·7273 22 0·9241 48 0·7935
13 1·0935 39 1·3451 65 1·7471 23 0·9183 49 0·7892
14 1·1014 40 1·3571 66 1·7674 24 0·9125 50 0·7849
15 1·1095 41 1·3694 67 1·7882 25 0·9068 51 0·7807
16 1·1176 42 1·3818 68 1·8095 26 0·9012 52 0·7766
17 1·1259 43 1·3945 69 1·8313 27 0·8957 53 0·7725
18 1·1343 44 1·4074 70 1·8537 28 0·8902 54 0·7684
19 1·1428 45 1·4206 71 1·8765 29 0·8848 55 0·7643
20 1·1515 46 1·4339 72 1·9000 30 0·8795 56 0·7604
21 1·1603 47 1·4476 73 1·9241 31 0·8742 57 0·7656
22 1·1692 48 1·4615 74 1·9487 32 0·8690 58 0·7526
23 1·1783 49 1·4758 75 1·9740 33 0·8639 59 0·7487
24 1·1875 50 1·4902 76 2·0000 34 0·8588 60 0·7449
25 1·1968 51 1·4951     35 0·8538 61 0·7411

ARGILLACEOUS EARTH. The earth of clay, called in chemistry alumina, because it is obtained in greatest purity from alum.

ARGOL. Crude tartar; which see.

ARMS. Weapons of war. See Fire-Arms for an account of this manufacture.

ARRACK. A kind of intoxicating beverage made in India, by distilling the fermented juice of the cocoa-nut, the palmyra tree, and rice in the husk.

ARROW ROOT. The root of the maranta arundinacea, a plant which grows in the West Indies, furnishes, by pounding in mortars and elutriation through sieves, a peculiar species of starch, commonly but improperly called arrow root. It is reckoned more nourishing than the starch of wheat or potatoes, and is generally also freer from peculiar taste or flavour. The fresh root consists, according to Benzon, of 0·07 of volatile oil; 26 of starch (23 of which are obtained in the form of powder, while the other 3 must be extracted from the parenchyma in a paste by boiling water); 1·58 of vegetable albumen; 0·6 of a gummy extract; 0·25 of chloride of calcium; 6 of insoluble fibrine; and 65·6 of water.

The import duty upon arrow root from our own colonies, is 1s. per cwt.; from foreign parts, 2d. per lib. In 1835, 987,966 lbs. were imported, of which only 6267 were exported; leaving 895,406 for home consumption. The total revenue derived that year from arrow root, was 518l. See Starch.

ARSENIC. This metal occurs native, in the state of oxide, and also combined with sulphur under the improper name of yellow and red arsenic, or orpiment and realgar. Arsenic is associated with a great many metallic ores; but it is chiefly extracted from those of cobalt, by roasting, in which case the white oxide of arsenic, or, more correctly, the arsenious acid is obtained. This acid is introduced occasionally in small quantities[55] into the materials of flint glass, either before their fusion, or in the melting pot. It serves to peroxidize the iron oxide in the sand, and thereby to purify the body of the glass; but an excess of it makes the glass milky.

Scheele’s green is a combination of this arsenious acid with oxide of copper, or an arsenite of copper, and is described under this metal.

Arseniate of potash is prepared, in the small way, by exposing to a moderate heat in a crucible, a mixture of equal parts of white arsenic and nitre in powder. After fusion, the crucible is to be cooled; the contents being dissolved in hot water, and the solution filtered, will afford regular crystals on cooling. According to M. Berzelius, they are composed of arsenic acid, 63·87; potash, 26·16; and water, 9·97. It is an acidulous salt, and is hence usually called the binarseniate, to denote that its composition is 2 atoms of arsenic acid, and 1 of potash. This article is prepared upon the great scale, in Saxony, by melting nitre and arsenious acid together in a cylinder of cast-iron. A neutral arseniate also is readily formed, by saturating the excess of acid in the above salt with potash; it does not crystallize. The acid arseniate is occasionally used in calico printing, for preventing certain points of the cotton cloth from taking on the mordant; with which view it is mixed up with gum water and pipe clay into a paste, which is applied to such places with a block.

The extraction of arsenic from the cobalt ores, is performed at Altenberg and Reichenstein, in Silesia, with an apparatus, excellently contrived to protect the health of the smelters from the vapours of this most noxious metallic sublimate.

Arsenical furnace

Figs. 20. to 23. represent the arsenical furnaces at Altenberg. Fig. 20. is a vertical section of the poison tower; fig. 21., a longitudinal section of the subliming furnace A, with the adjoining vault B, and the poison tower in part at n; fig. 22., the transverse section of the furnace A, of fig. 21.; fig. 23., ground plan of the furnace A, where the left half shows the part above, and the right the part below the muffle or oblong retort; B′ is the upper view, B′′ the ground plan of the vault B, of fig. 21.; m, n, the base of the poison tower. In the several figures the same letters denote the same objects: a is the muffle; b is its mouth for turning over the arsenical schlich, or ground ore; c c c, fire draughts or flues; d, an aperture for charging the muffle with fresh schlich; e, the smoke chimney; f, two channels or flues for the ascent of the arsenious fumes, which proceed to other two flues g, and then terminate both in h, which conducts the fumes into the vault B. They issue by the door i, into the conduit k, thence by l into the spaces m, n, o, p, q, r, of the tower. The incondensable gases escape by the chimney, s.[56] The cover t, is removed after completion of the process, in order to push down the precipitate into the lower compartments.

Arsenical furnace

Figs. 21 and 22 enlarged (93 kB)

The arsenious schlichs, to the amount of 9 or 10 cwt. for one operation (1 roast-post, or roasting round), are spread 2 or 3 inches thick upon the bottom of the muffle, heated with a brisk fire to redness, then with a gentler heat, in order to oxidize completely, before subliming, the arsenical ore. With this view the air must have free entrance, and the front aperture of the muffle must be left quite open. After 11 or 12 hours, the calcined materials are raked out by the mouth of the muffle, and fresh ones are introduced by the openings indicated above, which are closed during the sublimation.

The arsenious acid found in these passages, is not marketable till it be re-sublimed in large iron pots, surmounted with a series of sheet iron drums or cast-iron cylinders, upon the sides of which the arsenic is condensed in its compact glassy form. The top cylinder is furnished with a pipe, which terminates in a condensing chamber.

Arsenic furnace

Figs. 24, 25. represent the arsenic refining furnaces at Reichenstein. Fig. 24. shows at A, a vertical section of the furnace, the kettle, and the surmounting drums or cylinders; over B it is seen in elevation; fig. 25. is a ground plan of the four fireplaces. a is the grate; b, the ash pit; c, the openings for firing; d, the fire-place; e, iron pots or kettles which are charged with the arsenious powder; f, the fire flues proceeding to the common chimney g; h, iron cylinders; i, caps; k, pipes leading to the poison vent l; m, openings in the pipes for introducing the probing wires.

Arsenic furnace

The conduct of the process is as follows:—The pot is filled nearly to its brim with 312 cwt. of the arsenic meal, the cylinders are fitted on by means of their handles, and luted together with a mixture of loam, blood, and hair; then is applied first a gentle, and after half an hour, a strong fire, whereby the arsenic is raised partly in the form of a white dust, and partly in crystals; which, by the continuance of the heat, fuse together into a homogeneous mass. If the fire be too feeble, only a sublimate is obtained; but, if too violent, much of the arsenic is volatilized into the pipes. The workmen judge by the heat of the cylinders whether the operation be going on well or not. After 12 hours the furnace is allowed to cool, provided the probe wires show that the sublimation is over. The cylinders are then lifted off, and the arsenious glass is detached from their inner surface. According to the quality of the poison-flour, it yields from 34 to 78 of its weight of the glass or enamel. Should any dark particles of metallic arsenic be intermixed with the glass, a fresh sublimation must be had recourse to.

The following is the product in cwts. of arsenious acid, at Altenberg and Reichenstein, in Silesia, in the years

  1825. 1826. 1827. 1828. 1829. 1830. 1831. 1832.
White arsenic in a glassy state 2632 1703 2686 1900 2070 2961 3337 2730
Sublimed arsenic in powder - 27 33 31 30 44 69 38
Yellow arsenical glass 112 11 56 - 86 313 60 219
Red arsenical glass 3 - - - 28      


ARTESIAN WELLS. Under this name is designated a cylindrical perforation, bored vertically down through one or more of the geological strata of the earth, till it passes into a porous gravel bed containing water, placed under such incumbent pressure as to make it mount up through the perforation, either to the surface or to a height convenient for the operation of a pump. In the first case, these wells are called spouting or overflowing. This property is not directly proportional to the depth, as might at first sight be supposed, but to the subjacent pressure upon the water. We do not know exactly the period at which the borer or sound was applied to the investigation of subterranean fountains, but we believe the first overflowing wells were made in the ancient French province of Artois, whence the name of Artesian. These wells, of such importance to agriculture and manufactures, and which cost nothing to keep them in condition, have been in use, undoubtedly, for several centuries in the northern departments of France, and the north of Italy; but it is not more than 50 or 60 years since they became known in England and Germany. There are now a great many such wells in London and its neighbourhood, perforated through the immensely thick bed of the London clay, and even through some portions of the subjacent chalk. The boring of such wells has given much insight into the geological structure of many districts.

The formation of artesian wells depends on two things, essentially distinct from each other: 1. On an acquaintance with the physical constitution, or nature, of the mineral structure of each particular country; and, 2. On the skilful direction of the processes by which we can reach the water level, and of those by which we can promote its ascent in the tube. We shall first treat of the best method of making the well, and then offer some general remarks on the other subjects.

The operations employed for penetrating the soil are entirely similar to those daily practised by the miner, in boring to find metallic veins; but the well excavator must resort to peculiar expedients to prevent the purer water, which comes from deep strata, mingling with the cruder waters of the alluvial beds near the surface of the ground, as also to prevent the small perforation getting eventually filled with rubbish.

The cause of overflowing wells has been ascribed to a variety of circumstances. But, as it is now generally admitted that the numerous springs which issue from the ground proceed from the infiltration of the waters progressively condensed in rain, dew, snow, &c. upon the surface of our globe, the theory of these interior streamlets becomes by no means intricate; being analogous to that of syphons and water jets, as expounded in the treatises of physics. The waters are diffused, after condensation, upon the surface of the soil, and percolate downwards, through the various pores and fissures of the geological strata, to be again united subterraneously in veins, rills, streamlets, or expanded films, of greater or less magnitude, or regularity. The beds traversed by numerous disjunctions will give occasion to numerous interior currents in all directions, which cannot be recovered, and brought to the day; but when the ground is composed of strata of sand, or gravel very permeable to water, separated by other strata nearly impervious to it, reservoirs are formed to our hand, from which an abundant supply of water may be spontaneously raised. In this case, as soon as the upper stratum is perforated, the waters may rise, in consequence of the hydrostatic pressure upon the lower strata, and even overflow the surface in a constant stream, provided the level from which they proceed be proportionally higher.

The sheets of water occur principally at the separation of two contiguous formations; and, if the succession of the geological strata be considered, this distribution of the water will be seen to be its necessary consequence. In fact, the lower beds are frequently composed of compact sandstone or limestone, and the upper beds of clay. In level countries, the formations being almost always in horizontal-beds, the waters which feed the artesian wells must come from districts somewhat remote, where the strata are more elevated, as towards the secondary and transition rocks. The copious streams condensed upon the sides of these colder lands may be therefore regarded as the proper reservoirs of our wells.

Geological section of earth

Fig. 26. represents the manner in which the condensed water of the heavens distributes itself under the surface of our globe. Here we have a geological section, showing the succession of the several formations, and the sheets or laminæ of water that exist at their boundaries, as well as in their sandy beds. The figure shows also very plainly that the height[58] to which the water reascends in the bore of a well depends upon the height of the reservoir which supplies the sheet of water to which the well is perforated. Thus the well A, having gone down to the aqueous expanse A A, whose waters of supply are derived from the percolation M, will afford rising waters, which will come to the surface; whilst in the well B, supplied by the sheet P, the waters will spout above the surface, and in the well C they will remain short of it. The same figure shows that these wells often traverse sheets of water, which rise to different heights. Thus, in the well C there are five columns of ascending waters, which rise to heights proportional to the points whence they take their origin. Several of these will be spouting or overflowing, but some will remain beneath the surface.

Digging artesian well

The situation of the intended well being determined upon, a circular hole is generally dug in the ground, about 6 or 8 feet deep, and 5 or 6 feet wide. In the centre of this hole the boring is carried on by two workmen below, assisted by a labourer above, as shown in fig. 27.


The handle (fig. 28.) having a female screw in the bottom of its iron shank, with a wooden bar or rail passing through the socket of the shank, and a ring at top, is the general agent to which all the boring implements are to be attached. A chisel (fig. 29.) is first employed, and connected to this handle by its screw at top. If the ground is tolerably soft, the weight of the two workmen bearing upon the cross bar, and occasionally forcing it round, will soon cause the chisel to penetrate; but if the ground is hard or strong, the workmen strike the chisel down with repeated blows, so as to peck their way, often changing their situation by walking round, which breaks the stones, or other hard substances, that may happen to obstruct its progress.

The labour is very considerably reduced, by means of an elastic wooden pole, placed horizontally over the well, from which a chain is brought down, and attached to the ring of the handle. This pole is usually made fast at one end, as a fulcrum, by being set into a heap of heavy loose stones; at the other end the labourer above gives it a slight up and down vibrating motion, corresponding to the beating motion of the workmen below, by which means the elasticity of the pole in rising lifts the handle and pecker, and thereby very considerably diminishes the labour of the workmen. See fig. 27.


When the hole has been thus opened by a chisel, as far as its strength would permit, the chisel is withdrawn, and a sort of cylindrical auger (fig. 30.) attached to the handle (fig. 28.), for the purpose of drawing up the dirt or broken stones which have been disturbed by the chisel. A section of this auger is shown in fig. 31., by which the internal valve will be seen. The auger being introduced into the hole, and turned round by the workman, the dirt or broken stones will pass through the aperture at bottom (shown at[59] fig. 32.), and fill the cylinder, which is then drawn up, and discharged at the top of the auger, the valve preventing its escape at bottom.

Rods and chisels

In order to penetrate deeper into the ground, an iron rod, as a, fig. 33., is now to be attached to the chisel, fig. 29., by screwing on to its upper end, and the rod is also fastened to the handle, fig. 28., by screwing into its socket. The chisel having thus become lengthened, by the addition of the rod, it is again introduced into the hole; and the operation of pecking or forcing it down, is carried on by the workmen as before. When the ground has been thus perforated, as far as the chisel and its rod will reach, they must be withdrawn, in order again to introduce the auger, fig. 30., to collect and bring up the rubbish; which is done by attaching it to the iron rod, in place of the chisel. Thus as the hole becomes deepened, other lengths of iron rods are added, by connecting them together, as a b are in fig. 34. The necessity of frequently withdrawing the rods from the holes, in order to collect the mud, stones, or rubbish, and the great friction produced by the rubbing of the tools against its sides, as well as the lengths of rods augmenting in the progress of the operation, sometimes to the extent of several hundred feet, render it extremely inconvenient, if not impossible, to raise them by hand. A tripedal standard is, therefore, generally constructed by three scaffolding poles tied together, over the hole, as shown fig. 27., from the centre of which a wheel and axle, or a pair of pully blocks is suspended, for the purpose of hauling up the rods, and from which hangs the fork, fig. 35. This fork is to be brought down under the shoulder, near the top of each rod, and made fast to it by passing a pin through two little holes in the claws. The rods are thus drawn up, about seven feet at a time, which is the usual distance between each joint, and at every haul a fork, fig. 36., is laid horizontally over the hole, with the shoulders of the lower rod resting between its claws, by which means the rods are prevented from sinking down into the hole again, while the upper length is unscrewed and removed. In attaching and detaching these lengths of rod, a wrench, fig. 37., is employed, by which they are turned round, and the screws forced up to their firm bearing.


The boring is sometimes performed for the first sixty or a hundred feet, by a chisel of 212 inches wide, and cleared out by a gouge of 214 diameter, and then the hole is widened by a tool, such as is shown at fig. 38. This is merely a chisel, as fig. 29., four inches wide, but with a guide, a, put on at its lower part, for the purpose of keeping it in a perpendicular direction; the lower part is not intended to peck, but to pass down the hole previously made, while the sides of the chisel operate in enlarging the hole to four inches. The process, however, is generally performed at one operation, by a chisel of four inches wide, as fig. 29., and a gouge of three inches and three quarters, as fig. 30.

It is obvious, that placing and displacing the lengths of rod, which is done every time that the auger is required to be introduced or withdrawn, must, of itself, be extremely troublesome, independent of the labour of boring, but yet the operation proceeds, when no unpropitious circumstances attend it, with a facility almost incredible. Sometimes, however, rocks intercept the way, which require great labour to penetrate; but this is always effected by pecking, which slowly pulverises the stone. The most unpleasant circumstance attendant upon this business is the occasional breaking of a rod into the hole, which sometimes creates a delay of many days, and an incalculable labour in drawing up the lower portion.

When the water is obtained in such quantities and of such quality as may be required, the hole is dressed or finished by passing down it a diamond chisel, funnel mouthed, with a triangular bit in its centre; this makes the sides smooth previous to putting in the pipe. This chisel is attached to rods, and to the handle, as before described; and, in its descent, the workmen continually walk round, by which the hole is made smooth and cylindrical. In the progress of the boring, frequent veins of water are passed through; but, as these are small streams, and perhaps impregnated with mineral substances, the operation is carried on until an aperture is made into a main spring, which will flow up to the surface of the earth. This must, of course, depend upon the level of its source, which, if in a neighbouring hill, will frequently cause the water to rise up, and produce a continued fountain. But if the altitude of the distant spring happens to be below the level of the surface of the ground where the boring is effected, it sometimes happens that a well of considerable capacity is obliged to be dug down to that level, in order to form a reservoir, into which the water may flow, and whence it must be raised by a pump; while, in the former instance, a perpetual fountain may be obtained. Hence, it will always be a matter of doubt, in level countries, whether water can be procured, which would flow near to or over the surface; if this cannot be effected, the process of boring will be of little or no advantage, except as an experiment to ascertain the fact.

In order to keep the strata pure, and uncontaminated with mineral springs, the hole is cased, for a considerable depth, with a metallic pipe, about a quarter of an inch[60] smaller than the bore. This is generally made of tin (though sometimes of copper or lead) in convenient lengths; and, as each length is let down, it is held by a shoulder resting in a fork, while another length is soldered to it; by which means a continuous pipe is carried through the bore, as far as may be found necessary, to exclude land springs, and to prevent loose earth or sand from falling in, and choking the aperture.

Mr. John Good, of Tottenham, who had been extensively employed in boring the earth for water, obtained a patent, in Aug. 1823, for certain improved implements contrived by him to facilitate his useful labours; a description of which cannot fail to be interesting.

Good's tools

The figures annexed exhibit these ingenious tools; fig. 39. is an auger, to be connected by the screw-head to the length of rods by which the boring is carried on. This auger is for boring in soft clay or sand; it is cylindrical, and has a slit or opening from end to end, and a bit, or cutting-piece at bottom. When the earth is loose or wet, an auger of the same form is to be employed, but the slit or opening reduced in width, or even without a slit or opening. A similar auger is used for cutting through chalk; but the point or bit at bottom should then project lower, and, for that purpose, some of these cylindrical augers are made with moveable bits, to be attached by screws, which is extremely desirable in grinding them to cutting edges. Fig. 40. is a hollow conical auger, for boring loose sandy soils; it has a spiral cutting edge coiled round it, which, as it turns, causes the loose soil to ascend up the inclined plane, and deposit itself in the hollow within. Fig. 41. is a hollow cylinder or tube, shown in section, with a foot-valve, and a bucket to be raised by a rod and cord attached at the top; this is a pumping tool, for the purpose of getting up water and sand that would not rise by the auger. When this cylinder is lowered to the bottom of the bore, the bucket is lifted up by the rod and cord, and descends again by its own gravity, having a valve in the bucket, opening upwards, like other lift pumps; which, at every stroke, raises a quantity of water and sand in the cylinder equal to the stroke; the ascent and descent of the bucket being limited by a guide-piece at the top of the cylinder, and two small knobs upon the rod, which stop against the cross-guide. Fig. 42. is a tool for getting up broken rods. It consists of a small cylindrical piece at bottom, which the broken rod slips through when it is lowered, and a small catch with a knife-edge, acted upon by a back-spring. In rising, the tool takes hold of the broken rod, and thereby enables the workmen at top to draw it up. Another tool for the same purpose, is shown at fig. 43., which is like a pair of tongs; it is intended to be slidden down the bore, and for the broken rod to pass between the two catches, which, pressed by back-springs, will, when drawn up, take fast hold of the broken rod.

Drilling tools

Fig. 44. is a tool for widening the hole, to be connected, like all the others, to the end of the length of rods passed down the bore; this tool has two cutting-pieces extending on the sides at bottom, by which, as the tool is turned round in the bore, the earth is peeled away. Fig. 45. is a chisel, or punch, with a projecting piece to be used for penetrating through stone; this chisel is, by rising and falling, made to peck the stone, and pulverize it; the small middle part breaking it away first, and afterwards the broad part coming into action. Fig. 46. is another chisel, or punching tool, twisted on its cutting edge, which breaks away a greater portion of the stone as it beats against it.

Pipe extension tools

The manner of forcing down lengths of cast-iron pipe, after the bore is formed, is shown at fig. 47.; the pipe is seen below in the socket, at the end of which a block is inserted; and from this block a rod extends upwards, upon which a weight at top slides. To this weight cords are shown to be attached, reaching to the top of the bore; where the workmen alternately raise the weight and let it fall, which, by striking upon the block in its middle, beats down the pipe by a succession of strokes; and when one length of pipe has, by these means, been forced down, another length is introduced into[61] the socket of the former. Another tool for the same purpose is shown at fig. 48., which is formed like an acorn; the raised part of the acorn strikes against the edge of the pipe, and by that means, it is forced down the bore. When it happens that an auger breaks in the hole, a tool similar to that shown at fig. 49. is introduced; on one side of this tool a curved piece is attached, for the purpose of a guide, to conduct it past the cylindrical auger; and at the end of the other side is a hook, which, taking hold of the bottom edge of the auger, enables it to be drawn up.

Pipe straightening tools

Wrought iron, copper, tin, and lead pipes, are occasionally used for lining the bore; and as these are subject to bends and bruises, it is necessary to introduce tools for the purpose of straightening their sides. One of these tools is shown at fig. 50., which is a bow, and is to be passed down the inside of the pipe, in order to press out any dents. Another tool, for the same purpose, is shown at fig. 51., which is a double bow, and may be turned round in the pipe for the purpose of straightening it all the way down; at fig. 52., is a pair of clams, for turning the pipe round in the hole while driving.

Boring claws

When loose stones lie at the bottom of the hole, which are too large to be brought up by the cylindrical auger, and cannot be conveniently broken, then it is proposed to introduce a triangular claw, as fig. 53., the internal notches of which take hold of the stone, and as the tool rises, bring it up. For raising broken rods, a tool like fig. 54. is sometimes employed, which has an angular claw that slips under the shoulder of the rod, and holds it fast while drawing up.

Pipe raising tools

In raising pipes, it is necessary to introduce a tool into the inside of the pipe, by which it will be held fast. Fig. 55. is a pine-apple tool for this purpose; its surface is cut like a rasp, which passes easily down into the pipe, but catches as it is drawn up; and by that means brings the pipe with it. Fig. 56. is a spear for the same purpose, which easily enters the pipe by springing; at the ends of its prongs there are forks which stick into the metal as it is drawn up, and thereby raise it.

These are the new implements, for which the patent was granted. In the process of boring, there does not appear to be any thing new proposed; but that these several tools are to be employed for boring, packing, and otherwise penetrating, raising the earth, and extracting broken or injured tools. There are also suggestions for employing long buckets, with valves opening upward in their bottoms, for the purpose of drawing water from these wells when the water will not flow over the surface; also lift pumps, with a succession of buckets for the same purpose. But as these suggestions possess little if any novelty, it cannot be intended to claim them as parts of the patent.

ASPHALTUM. Native bitumen, so called from the lake Asphaltites.

ASSAY and ASSAYING. (Coupellation, Fr.; Abtreiben auf der capelle, Germ.) This is the process by which the quality of gold and silver bullion, coin, plate, or trinkets is ascertained with precision, or by which the quantity of either or both these precious metals is determined in any given alloy. It is, therefore, a case of chemical analysis, in which peculiar methods are employed to attain the object in view with accuracy and dispatch. Assaying has been also extended of late years, to determine the quantity of palladium and platina in certain bullion and gold dust brought from Brazil.

The art of assaying gold and silver by the cupel, is founded upon the feeble affinity which these metals have for oxygen, in comparison with copper, tin, and the other cheaper metals; and on the tendency which the latter metals have to oxidize rapidly in contact with lead at a high temperature, and sink with it into any porous earthy vessel in a thin glassy or vitriform state. The porous vessel may be made either of wood-ashes, freed from their soluble matter by washing with water; or, preferably, of burned bones reduced to a fine powder.

The lead added to the silver or gold to be assayed, serves chiefly to dissolve the oxidized copper, whence it appears that the quantity of lead requisite for silver assays, ought to be directly proportional to the quantity which the silver and copper would separately require. It has been found by experiment, that 16 parts of lead are quite sufficient to pass 1 of copper through the cupel; and that 310 of lead presents the most suitable proportion for passing one of silver. From these principles, however, if we should always regard the dose of lead to be employed for any alloy as being equal to (16 × C) + (330 × S) we should certainly commit an error. The phenomena of cupellation is of a more complex nature. Long practice and delicate trials alone can guide to the proper quantity of lead to be employed for every various state of the alloy. The following Table contains the results of M. D’Arcet’s elaborate experiments upon this subject:—


Alloy. Lead for 1
of Alloy.
Ratio of the
Copper to
the Lead.
Silver. Copper.
1000 0 310 0
950 50 3 1 : 60
900 100 7 1 : 70
800 200 10 1 : 50
700 300 12 1 : 40
600 400 14 1 : 35
500 500 16 or 17 1 : 32
400 600 16 — 17 1 : 26·7
300 700 16 — 17 1 : 22·9
200 800 16 — 17 1 : 20
100 900 16 — 17 1 : 17·8
0 1000 16 — 17 1 : 16

Bismuth may be used as a substitute for lead in cupellation; two parts of it being nearly equivalent to three of lead. But its higher prices will prevent its general introduction among assay masters.

We begin this assay process by weighing, in a delicate balance, a certain weight of the metallic alloy; a gramme (= 15·444 gr.) is usually taken in France, and 12 grains in this country. This weight is wrapped up in a slip of lead foil or paper, should it consist of several fragments. This small parcel, thus enveloped, is then laid in a watch glass or a capsule of copper, and there is added to it the proportion of lead suited to the quality of alloy to be assayed; there being less lead, the finer the silver is presumed to be. Those who are much in the habit of cupellation can make good guesses in this way; though it is still guess work, and often leads to considerable error, for if too much lead be used for the proportion of baser metal present, a portion of the silver is wasted; but if too little, then the whole of the copper, &c. is not carried off, and the button of fine silver remains more or less impure. The most expert and experienced assayer by the cupel, produces merely a series of approximate conjectural results, which fall short of chemical demonstration and certainty in every instance. The lead must be, in all cases, entirely free from silver, being such as has been revived from pure litharge; otherwise errors of the most serious kind would be occasioned in the assays.

The best cupels weigh 1212 grammes, or 193 grains. The cupels allow the fused oxides to flow through them as through a fine sieve, but are impermeable to the particles of metals; and thus the former pass readily down into their substance while the latter remain upon their surface; a phenomenon owing to the circumstance of the glassy oxides moistening, as it were, the bone-ash powder, whereas the metals can contract no adherence with it. Hence also the liquid metals preserve a hemispherical shape in the cupels, as quicksilver does in a cup of glass, while the fused oxide spreads over, and penetrates their substance, like water. A cupel may be regarded, in some measure, as a filter permeable only to certain liquids.

If we put into a cupel, therefore, two metals, of which the one is unalterable in the air, the other susceptible of oxidizement, and of producing a very fusible oxide, it is obvious that, by exposing both to a proper degree of heat, we shall succeed in separating them. We should also succeed, though the oxide were infusible, by placing it in contact with another one, which may render it fusible. In both cases, however, the metal from which we wish to part the oxides must not be volatile; it should also melt, and form a button at the heat of cupellation; for otherwise it would continue disseminated, attached to the portion of oxide spread over the cupel, and incapable of being collected.

The furnace and implements used for assaying in the Royal Mint and the Goldsmiths’ Hall, in the city of London, are the following:—

Assaying furnace

A A A A, fig. 58., is a front elevation of an assay furnace; a a, a view of one of the two iron rollers on which the furnace rests, and by means of which it is moved forward or backward; b, the ash-pit; c c are the ash-pit dampers, which are moved in a horizontal direction towards each other for regulating the draught of the furnace; d, the door, or opening, by which the cupels and assays are introduced into the muffle; e, a moveable funnel or chimney by which the draught of the furnace is increased.[63] B B B B, fig. 59., is a perpendicular section of fig. 58.; a a, end view of the rollers; b the ash-pit; c one of the ash-pit dampers; d the grate, over which is the plate upon which the muffle rests, and which is covered with loam nearly one inch thick; f the muffle in section representing the situation of the cupels; g the mouth-plate, and upon it are laid pieces of charcoal, which during the process are ignited, and heat the air that is allowed to pass over the cupels, as will be more fully explained in the sequel; h the interior of the furnace, exhibiting the fuel.

The total height of the furnace is 2 feet 612 inches; from the bottom to the grate, 6 inches; the grate, muffle, plate, and bed of loam, with which it is covered, 3 inches; from the upper surface of the grate to the commencement of the funnel e, fig. 58., 2112 inches; the funnel e, 6 inches. The square of the furnace which receives the muffle and fuel is 1134 inches by 15 inches. The external sides of the furnace are made of plates of wrought iron, and are lined with a 2-inch fire-brick.

Section over grate

C C C C, fig. 60., is a horizontal section of the furnace over the grate, showing the width of the mouth-piece, or plate of wrought iron, which is 6 inches, and the opening which receives the muffle-plate.


Fig. 61. represents the muffle or pot, which is 12 inches long, 6 inches broad inside; in the clear 634: in height 412 inside measure, and nearly 512 in the clear.

Muffle plate

Fig. 62., the muffle-plate, which is of the same size as the bottom of the muffle.

Sliding door

Fig. 63. is a representation of the sliding-door of the mouth-plate, as shewn at d, in fig. 58.

Mouth plate

Fig. 64., a front view of the mouth-plate or piece, d, fig. 58.

Furnace mouth

Fig. 65., a representation of the mode of making, or shutting up with pieces of charcoal, the mouth of the furnace.

Fig. 66., the teaser for cleaning the grate.

Teasers and tongs

Fig. 67., a larger teaser, which is introduced at the top of the furnace, for keeping a complete supply of charcoal around the muffle.

Fig. 68., the tongs used for charging the assays into the cups.

Register board

Fig. 69. represents a board of wood used as a register, and is divided into 45 equal compartments, upon which the assays are placed previously to their being introduced into the furnace. When the operation is performed, the cupels are placed in the furnace in situations corresponding to these assays on the board. By these means all confusion is avoided, and without this regularity it would be impossible to preserve the accuracy which the delicate operations of the assayer require.

Assay furnace

I shall now proceed to a description of a small assay furnace, invented by Messrs. Anfrye and d’Arcet, of Paris. They term it, Le Petit Fourneau à Coupelle. Fig. 70. represents this furnace, and it is composed of a chimney or pipe of wrought iron a, and of the furnace B. It is 1712 inches high, and 714 inches wide. The furnace is formed of three pieces; of a dome A; the body of the furnace B; and the ash-pit C, which is[64] used as the base of the furnace, fig. 70. and 71. The principal piece, or body of the furnace, B, has the form of a hollow tower, or of a hollow cylinder, flattened equally at the two opposite sides parallel to the axis, in such a manner that the horizontal section is elliptical. The foot which supports it is a hollow truncated cone, flattened in like manner upon the two opposite sides, and having consequently for its basis two ellipses of different diameters; the smallest ought to be equal to that of the furnace, so that the bottom of the latter may exactly fit it. The dome, which forms an arch above the furnace, has also its base elliptical, whilst that of the superior orifice by which the smoke goes out preserves the cylindrical form. The tube of wrought iron is 18 inches long and 212 inches diameter, having one of its ends a little enlarged, and slightly conical, that it may be exactly fitted or jointed upon the upper part of the furnace dome d, fig. 70. At the union of the conical and cylindrical parts of the tube, there is placed a small gallery of iron, e, fig. 70, 71. See also a plan of it, fig. 72. This gallery is both ingenious and useful. Upon it are placed the cupels, which are thus annealed during the ordinary work of the furnace, that they may be introduced into the muffle, when it is brought into its proper degree of heat. A little above this gallery is a door f, by which, if thought proper, the charcoal could be introduced into the furnace; above that there is placed at g a throttle valve, which is used for regulating the draught of the furnace at pleasure. Messrs. Anfrye and d’Arcet say, that, to give the furnace the necessary degree of heat so as to work the assays of gold, the tube must be about 18 inches above the gallery, for annealing or heating the cupels. The circular opening h, in the dome, fig. 70., and as seen in the section, fig. 71., is used to introduce the charcoal into the furnace: it is also used to inspect the interior of the furnace, and to arrange the charcoal round the muffle. This opening is kept shut during the working of the furnace, with the mouth-piece, of which the face is seen at n, fig. 71.

The section of the furnace, fig. 71., presents several openings, the principal of which is that of the muffle; it is placed at i; it is shut with the semicircular door m, fig. 70., and seen in the section m, fig. 71. In front of this opening, is the table or shelf, upon which the door of the muffle is made to advance or recede; the letter q, fig. 71., shows the face, side, and cross section of the shelf, which makes part of the furnace. Immediately under the shelf, is a horizontal slit, l, which is pierced at the level of the upper part of the grate, and used for the introduction of a slender rod of iron, that the grate may be easily kept clean. This opening is shut at pleasure, by the wedge represented at k, fig. 70. and 71.

Upon the back of the furnace is a horizontal slit p, fig. 71, which supports the fire-brick, s, and upon which the end of the muffle, if necessary, may rest; u, fig. 71., is the opening in the furnace where the muffle is placed.

Horizontal view of grate

The plan of the grate of the furnace is an ellipse: fig. 73. is a horizontal view of it. The dimensions of that ellipsis determine the general form of the furnace, and thickness of the grate. To give strength and solidity to the grate, it is encircled by a bar or hoop of[65] iron. There is a groove in which the hoop of iron is fixed. The holes of the grate are truncated cones, having the greater base below, that the ashes may more easily fall into the ash-pit. The letter v, fig. 71., shows the form of these holes. The grate is supported by a small bank or shelf, making part of the furnace, as seen at a, fig. 71.

The ash-pit, C, has an opening y in front, fig. 71.; and is shut when necessary by the mouth-piece r, fig. 70. and 71.

To give strength and solidity to the furnace, it is bound with hoops of iron, at b, b, b, b, fig. 70.


Figs. 74. 75. 76. are views of the muffle.

Fig. 77. is a view of a crucible for annealing gold.

Crucible and cupels

Figs. 78. 79. 80. are cupels of various sizes, to be used in the furnace. They are the same as those used by assayers in their ordinary furnaces.


Figs. 81. and 82. are views of the hand-shovels, used for filling the furnace with charcoal; they should be made of such size and form as to fit the opening h, in figs. 70. and 71.

The smaller pincers or tongs, by which the assays are charged into the cupels, and by which the latter are withdrawn from the furnace, as well as the teaser for cleaning the grate of the furnace, are similar to those used in the British Mint.

In the furnace of the Mint above described, the number of assays that can be made at one time, is 45. The same number of cupels are put into the muffle. The furnace is then filled with charcoal to the top, and upon this are laid a few pieces already ignited. In the course of three hours, a little more or less, according to circumstances, the whole is ignited; during which period, the muffle, which is made of fire-clay, is gradually heated to redness, and is prevented from cracking; which a less regular or more sudden increase of temperature would not fail to do: the cupels, also, become properly annealed. All moisture being dispelled, they are in a fit state to receive the piece of silver or gold to be assayed.

The greater care that is exercised in this operation, the less liable is the assayer to accidents from the breaking of the muffle; which it is both expensive and troublesome to fit properly into the furnace.

The cupels used in the assay process, are made of the ashes of burnt bones (phosphate of lime). In the Royal Mint, the cores of ox-horn are selected for this purpose; and the ashes produced are about four times the expense of the bone-ash, used in the process of cupellation upon the large scale. So much depends upon the accuracy of an assay of gold or silver, where a mass of 15lbs. troy in the first, and 60lbs. troy in the second instance, is determined by the analysis of a portion not exceeding 20 troy grains, that every precaution which the longest experience has suggested, is used to obtain an accurate result. Hence the attention paid to the selection of the most proper materials for making the cupels.

The cupels are formed in a circular mould made of cast steel, very nicely turned, by which means they are easily freed from the mould when struck. The bone-ash is used moistened with a quantity of water, sufficient to make the particles adhere firmly together. The circular mould is filled, and pressed level with its surface; after which, a pestle or rammer, having its end nicely turned, of a globular or convex shape, and of a size equal to the degree of concavity wished to be made in the cupel for the reception of the assay, is placed upon the ashes in the mould, and struck with a hammer until the cupel is properly formed. These cupels are allowed to dry in the air for some time before they are used. If the weather is fine, a fortnight will be sufficient.

An assay may prove defective for several reasons. Sometimes the button or bead sends forth crystalline vegetations on its surface with such force, as to make one suppose a portion of the silver may be thrown out of the cupel. When the surface of the bead is dull and flat, the assay is considered to have been too hot, and it indicates a loss of silver in fumes. When the tint of the bead is not uniform, when its inferior surface is bubbly, when yellow scales of oxide of lead remain on the bottom of the cupel, and the bead adheres strongly to it, by these signs it is judged that the assay has been too cold, and that the silver retains some lead.

Lastly, the assay is thought to be good if the bead is of a round form, if its upper surface is brilliant, if its lower surface is granular and of a dead white, and if it separates readily from the cupel.

After the lead is put into the cupel, it gets immediately covered with a coat of oxide, which resists the admission of the silver to be assayed into the melted metal; so that the alloy cannot form. When a bit of silver is laid on a lead bath in this predicament, we see it swim about for a long time without dissolving. In order to avoid this result, the silver is wrapped up in a bit of paper; and the carburetted hydrogen generated by its combustion, reduces the film of the lead oxide, gives the bath immediately a bright metallic lustre, and enables the two metals readily to combine.

As the heat rises, the oxide of lead flows round about over the surface, till it is absorbed[66] by the cupel. When the lead is wasted to a certain degree, a very thin film of it only remains on the silver, which causes the iridescent appearance, like the colours of soap-bubbles; a phenomenon, called by the old chemists, fulguration.

When the cupel cools in the progress of the assay, the oxygenation of the lead ceases; and, instead of a very liquid vitreous oxide, an imperfectly melted oxide is formed, which the cupel cannot absorb. To correct a cold assay, the temperature of the furnace ought to be raised, and pieces of paper ought to be put into the cupel, till the oxide of lead which adheres to it, be reduced. On keeping up the heat, the assay will resume its ordinary train.

Pure silver almost always vegetates. Some traces of copper destroy this property, which is obviously due to the oxygen which the silver can absorb while it is in fusion, and which is disengaged the moment it solidifies. An excess of lead, by removing all the copper at an early stage, tends to cause the vegetation.

The brightening is caused by the heat evolved, when the button passes from the liquid to the solid state. Many other substances present the same phenomenon.

In the above operation it is necessary to employ lead which is very pure, or at least free from silver. That kind is called poor lead.

It has been observed at all times, that the oxide of lead carries off with it, into the cupel, a little silver in the state of an oxide. This effect becomes less, or even disappears, when there is some copper remaining; and the more copper, the less chance there is of any silver being lost. The loss of silver increases, on the other hand, with the dose of lead. Hence the reason why it is so important to proportion the lead with a precision which, at first sight, would appear to be superfluous. Hence, also, the reason of the attempts which have, of late years, been made to change the whole system of silver assays, and to have recourse to a method exempt from the above causes of error.

M. d’Arcet, charged by the Commission of the Mint in Paris, to examine into the justice of the reclamations made by the French silversmiths against the public assays, ascertained that they were well founded; and that the results of cupellation gave for the alloys between 897 and 903 thousandths (the limits of their standard coin) an inferior standard, by from 4 to 5 thousandth parts, from the standard or title which should result from the absolute or actual alloy.

The mode of assay shows, in fact, that an ingot, experimentally composed of 900 thousandths of fine silver, and 100 thousandths of copper, appears, by cupellation, to be only, at the utmost, 896 or 897 thousandths; whereas fine silver, of 1000 thousandths, comes out nearly of its real standard. Consequently a director of the Mint, who should compound his alloy with fine silver, would be obliged to employ 903 or 904 thousandths, in order that, by the assay in the laboratory of the Mint, it should appear to have the standard of 900 thousandths. These 3 or 4 thousandths would be lost to him, since they would be disguised by the mode of assay, the definitive criterion of the quantity of silver, of which the government keeps count from the coiner of the money.

From experiments subsequently made by M. d’Arcet, it appears that silver assays always suffer a loss of the precious metal, which varies, however, with the standard of the alloy. It is 1 thousandth for fine silver,

4·3  thousandths  for  silver  of  900  thousandths,
4·9 for of  800
4·2 for of  500

and diminishes thereafter, progressively, till the alloy contains only 100 thousandths of silver, at which point the loss is only 0·4.

Assays requested by the Commission of the Paris Mint, from the assayers of the principal Royal Mints in Europe, to which the same alloys, synthetically compounded, were sent, afforded the results inscribed in the following table.

Names of the Assayers. Cities where
they reside.
Standards found for
the Mathematical Alloys.
950 mill. 900 mill. 800 mill.
F. de Castenhole, Mint Assayer Vienna 946 ·20 898 ·40 795 ·10
A. R. Vervaëz, Ditto Madrid 944 ·40 893 ·70 789 ·20
D. M. Cabrera, Assayer in Spain Ditto 944 ·40 893 ·70 788 ·60
Assayer Amsterdam 947 ·00 895 ·00 795 ·00
Mr. Bingley, Assay Master London 946 ·25 896 ·25 794 ·25
Mr. Johnson, Assayer Ditto 933 ·33 883 ·50 783 ·33
Inspector of the Mint Utrecht 945 ·00 896 ·50 799 ·00
Assayer of the Mint Naples 945 ·00 891 ·00 787 ·00
Assayer of Trade Ditto 945 ·00 891 ·00 787 ·00
Assayer of the Mint Hamburgh 946 ·1372 897 ·4172 798 ·4472
Ditto Altona 942 ·14 894 ·00 790  


These results, as well as those in still greater numbers, obtained from the ablest Parisian assayers, upon identical alloys of silver and copper, prove that the mode of assay applied to them brings out the standard too low; and further, that the quantity of silver masked or disguised, is not uniform for these different eminent assay masters. An alloy, for example, at the standard of 900 thousandths is judged at

the Mint of  Paris  to have a standard of  895·6
At that of  Vienna  898·4
 Madrid  893·7
 Naples  891·0

The fact thus so clearly made out of a loss in the standard of silver bullion and coin, merits the most serious attention; and it will appear astonishing, perhaps, that a thing recurring every day, should have remained for so long a time in the dark. In reality, however, the fact is not new; as the very numerous and well-made experiments of Tillet from 1760 to 1763, which are related in the memoirs of the Academy of Sciences, show, in the silver assays, a loss still greater than that which was experienced lately in the laboratory of the Commission of the French Mint. But he thought that, as the error was common to the nations in general, it was not worth while or prudent to introduce any innovation.

A mode of assaying, to give, with certainty, the standard of silver bullion, should be entirely independent of the variable circumstances of temperature, and the unknown proportions of copper, so difficult to regulate by the mere judgment of the senses. The process by the humid way, recommended by me to the Royal Mint in 1829, and exhibited as to its principles before the Right Honourable John Herries, then Master, in 1830, has all the precision and certainty we could wish. It is founded on the well-known property which silver has, when dissolved in nitric acid, to be precipitated in a chloride of silver quite insoluble, by a solution of sea salt, or by muriatic acid; but, instead of determining the weight of the chloride of silver, which would be somewhat uncertain and rather tedious, on account of the difficulty of drying it, we take the quantity of the solution of sea salt which has been necessary for the precipitation of the silver. To put the process in execution, a liquor is prepared, composed of water and sea salt in such proportions that 1000 measures of this liquor may precipitate, completely, 12 grains of silver, perfectly pure, or of the standard 1000, previously dissolved in nitric acid. The liquor thus prepared, gives, immediately, the true standard of any alloy whatever, of silver and copper, by the weight of it which may be necessary to precipitate 12 grains of this alloy. If, for example 905 measures have been required to precipitate the 12 grains of alloy, its standard would be 905 thousandths.

The process by the humid way is, so to speak, independent of the operator. The manipulations are so easy; and the term of the operation is very distinctly announced by the absence of any sensible nebulosities on the affusion of sea salt into the silver solution, while there remains in it 12 thousandth of metal. The process is not tedious, and in experienced hands it may rival the cupel in rapidity; it has the advantage over the cupel of being more within the reach of ordinary operators, and of not requiring a long apprenticeship. It is particularly useful to such assayers as have only a few assays to make daily, as it will cost them very little time and expense.

By agitating briskly during two minutes, or thereby, the liquid rendered milky by the precipitation of the chloride of silver, it may be sufficiently clarified to enable us to appreciate, after a few moments of repose, the disturbance that can be produced in it by the addition of 1000 of a grain of silver. Filtration is more efficacious than agitation, especially when it is employed afterwards; it may be sometimes used; but agitation, which is much more prompt, is generally sufficient. The presence of lead and copper, or any other metal, except mercury, has no perceptible influence on the quantity of sea salt necessary to precipitate the silver; that is to say, the same quantity of silver, pure or alloyed, requires for its precipitation a constant quantity of the solution of sea salt.

Supposing that we operate upon a gramme of pure silver, the solution of sea salt ought to be such that 100 centimetres cube may precipitate exactly the whole silver. The standard of an alloy is given by the number of thousandths of solution of sea salt necessary to precipitate the silver contained in a gramme of the alloy.

When any mercury is accidentally present, which is, however, a rare occurrence, it is made obvious by the precipitated chloride remaining white when exposed to daylight, whereas when there is no mercury present, it becomes speedily first grey and then purple. Silver so contaminated must be strongly ignited in fusion before being assayed, and its loss of weight noted. In this case, a cupel assay must be had recourse to.

Preparation of the Normal Solution of Sea Salt, when it is measured by Weight.—Supposing the sea salt pure as well as the water, we have only to take these two bodies in the proportion of 0·5427 k. of salt to 99·4573 k. of water, to have 100 k. of solution,[68] of which 100 grammes will precipitate exactly one gramme of silver. But instead of pure salt, which is to be procured with difficulty, and which besides may be altered readily by absorbing the humidity of the air, a concentrated solution of the sea salt of commerce is to be preferred, of which a large quantity may be prepared at a time, to be kept in reserve for use, as it is wanted. Instruction de Gay Lussac.

Preparation of the Normal Solution of Sea Salt, when measured by Volume.—The measure by weight has the advantage of being independent of temperature, of having the same degree of precision as the balance, and of standing in need of no correction. The measure by volume has not all these advantages; but, by giving it sufficient precision, it is more rapid, and is quite sufficient for the numerous daily assays of the mint. This normal solution is so made, that a volume equal to that of 100 grammes of water, or 100 centimetres cube, at a determinate temperature, may precipitate exactly one gramme of silver. The solution may be kept at a constant temperature, and in this case the assay stands in want of no correction; or if its temperature be variable, the assay must be corrected according to its influence. These two circumstances make no change in the principle of the process, but they are sufficiently important to occasion some modifications in the apparatus. Experience has decided the preference in favour of applying a correction to a variable temperature.

We readily obtain a volume of 100 cubic centimetres by means of a pipette, fig. 83., so gauged that when filled with water up to the mark a, b, and well dried at its point, it will run out, at a continuous efflux, 100 grammes of water at the temperature of 15 C. (59 Fah.). We say purposely at one efflux, because after the cessation of the jet, the pipette may still furnish two or three drops of liquid, which must not be counted or reckoned upon. The weight of the volume of the normal solution, taken in this manner with suitable precautions, will be uniform from one extreme to another, upon two centimetres and a half, at most, or to a quarter of a thousandth, and the difference from the mean will be obviously twice less, or one half. Let us indicate the most simple manner of taking a measure of the normal solution of sea salt.


After having immersed the beak c of the pipette in the solution, we apply suction by the mouth, to the upper orifice, and thereby raise the liquid to d above the circular line a b. We next apply neatly the forefinger of one hand to this orifice, remove the pipette from the liquid, and seize it as represented in fig. 84. The mark a b being placed at the level of the eye, we make the surface of the solution become exactly a tangent to the plane a b. At the instant it becomes a tangent, we leave the beak c of the pipette open, by taking away the finger that had been applied to it, and without changing any thing else in the position of the hands, we empty it into the bottle which should receive the solution, taking care to remove it whenever the efflux has run out.

If after filling the pipette by suction, any one should find a difficulty in applying the forefinger fast enough to the upper orifice, without letting the liquid run down below the mark a b, he should remove the pipette from the solution with its top still closed with his tongue, then apply the middle finger of one of his hands to the lower orifice; after which he may withdraw his tongue, and apply the forefinger of the other hand to the orifice previously wiped. This mode of obtaining a measure of normal solution of sea salt is very simple, and requires no complex apparatus; but we shall indicate another manipulation still easier, and also more exact.

In this new process the pipette is filled from the top like a bottle, instead of being filled by suction, and it is moreover fixed. Fig. 85. represents the apparatus. D and D′ are two sockets separated by a stop cock R. The upper one, tapped interiorly, receives, by means of a cork stopper L, the tube T, which admits the solution of sea salt. The lower socket is cemented on to the pipette; it bears a small air-cock R′, and a screw plug V, which regulates a minute opening intended to let the air enter very slowly into the pipette. Below the stop-cock R′, a silver tube N, of narrow diameter, soldered to the socket, leads the solution into the pipette, by allowing the air, which it displaces, to escape by the stop-cock R′. The screw plug, with the milled head V′, replaces the ordinary screw by which the key of the stop-cock may be made to press, with more or less force, upon its conical seat.



Fig. 86. represents, in a side view, the apparatus just described. We here remark an air-cock R, and an opening m. At the extremity Q of the same figure, the conical pipe T enters, with friction. It is by this pipe that the air is sucked into the pipette, when it is to be filled from its beak.


The pipette is supported by two horizontal arms H K (fig. 87.) moveable about a common axis A A, and capable of being drawn out or shortened by the aid of two longitudinal slits. They are fixed steadily by two screw nuts e e′, and their distance may be varied by means of round bits of wood or cork interposed, or even by opposite screw nuts o o′. The upper arm H is pierced with a hole, in which is fixed, by the pressure of a wooden screw v, the socket of the pipette. The corresponding hole of the lower arm is larger; and the beak of the pipette is supported in it by a cork stopper L. The apparatus is fixed by its tail-piece P, by means of a screw to the corner of a wall, or any other prop.

The manner of filling the pipette is very simple. We begin by applying the fore-finger of the left hand to the lower aperture c; we then open the two stop-cocks R and R′. Whenever the liquor approaches the neck of the pipette, we must temper its influx, and when it has arrived at some millimetres above the mark a b, we close the two stop-cocks, and remove our forefinger. We have now nothing more to do than to regulate the pipette; for which purpose the liquid must touch the line a b, and must simply adhere externally to the beak of the pipette.


This last circumstance is easily adjusted. After taking away the finger which closed the aperture c of the pipette, we apply to this orifice a moist sponge m, fig. 88., wrapped up in a linen rag, to absorb the superfluous liquor as it drops out. This sponge is called the handkerchief (mouchoir), by M. Gay Lussac. The pipette is said to be wiped when there is no liquor adhering to its point exteriorly.

For the convenience of operating, the handkerchief is fixed by friction in a tube of tin plate, terminated by a cup, open at bottom to let the droppings flow off into the cistern C, to which the tube is soldered. It may be easily removed for the purpose of washing it; and, if necessary, a little wedge of wood, o, can raise it towards the pipette.

To complete the adjustment of the pipette, the liquid must be made merely to descend to the mark a, b. With this view, and whilst the handkerchief is applied to the beak of the pipette, the air must be allowed to enter very slowly by unscrewing the plug V, fig. 85.; and at the moment of the contact the handkerchief must be removed, and the bottle F, destined to receive the solution, must be placed below the orifice of the pipette, fig. 88. As the motion must be made rapidly, and without hesitation, the bottle is placed in a cylinder of tin-plate, of a diameter somewhat greater, and forming one body with the cistern and the handkerchief. The whole of this apparatus has for a basis a plate of tinned iron, moveable between two wooden rulers R R, one of which bears a groove, under which the edge of the plate slips. Its traverses are fixed by two abutments b b, placed so that when it is stopped by one of them, the beak of the pipette corresponds to the centre of the neck of the bottle, or is a tangent to the handkerchief. This arrangement, very convenient for wiping the pipette and emptying it, gives the apparatus sufficient solidity, and allows of its being taken away, and replaced without deranging any thing. It is obvious that it is of advantage, when once the entry of the air into the pipette has been regulated by the screw V, to leave it constantly open, because the[70] motion from the handkerchief to the bottle is performed with sufficient rapidity to prevent a drop of the solution from collecting and falling down.


Temperature of the Solution.—After having described the manner of measuring by volume the normal solution of the sea salt, we shall indicate the most convenient means of taking the temperature. The thermometer is placed in a tube of glass T, fig. 89., which the solution traverses to arrive at the pipette. It is suspended in it by a piece of cork, grooved on the four sides to afford passage to the liquid. The scale is engraved upon the tube itself, and is repeated at the opposite side, to fix the eye by the coincidence of this double division at the level of the thermometric column. The tube is joined below to another narrower one, through which it is attached by means of a cork stopper B, in the socket of the stop-cock of the pipette. At its upper part it is cemented into a brass socket, screw-tapped in the inside, which is connected in its turn by a cock, with the extremity, also tapped, of the tube above T, belonging to the reservoir of the normal solution. The corks employed here as connecting links between the parts of the apparatus, give them a certain flexibility, and allow of their being dismounted and remounted in a very short time; but it is indispensable to make them be traversed by a hollow tube of glass or metal, which will hinder them from being crushed by the pressure they are exposed to. If the precaution be taken to grease them with a little suet and to fill their pores, they will suffer no leakage.

Preservation of the Normal Solution of Sea Salt in metallic Vessels.—M. Gay Lussac uses for this purpose a cylindrical vessel or drum of copper, of a capacity of about 110 litres, having its inside covered with a rosin and wax cement.

Preparation of the Normal Solution of Sea Salt, measuring it by Volume.—If the drum contains 110 litres, we should put only 105 into it, in order that sufficient space may be left for agitating the liquor without throwing it out. According to the principle that 100 centimetres cube, or 110 of a litre of the solution should contain enough of sea salt to precipitate a gramme of pure silver; and, admitting moreover, 13·516 for the prime equivalent of silver, and 7·335 for that of sea salt, we shall find the quantity of pure salt that should be dissolved in the 105 litres of water, and which corresponds to 105 × 10 = 1050 grammes of silver, to be by the following proportion:—

13·516 : 7·335 ∷ 1050 gramm. : x = 569·83 gr.

And as the solution of the sea salt of commerce, formerly mentioned, contains approximately 250 grammes per kilogramme, we must take 2279·3 grammes of this solution to have 569·83 gram. of salt. The mixture being perfectly made, the tubes and the pipette must be several times washed by running the solution through them, and putting it into the drum. The standard of the solution must be determined after it has been well agitated, supposing the temperature to remain uniform.

To arrive more conveniently at this result, we begin by preparing two decimes solutions; one of silver, and another of sea salt.

The decime solution of silver is obtained by dissolving 1 gramme of silver in nitric acid, and diluting the solution with water till its volume become a litre.

The decime solution of sea salt may be obtained by dissolving 0·543 grammes of pure sea salt in water, so that the solution shall occupy a litre; but we shall prepare it even with the normal solution which we wish to test, by mixing a measure of it with 9 measures of water; it being understood that this solution is not rigorously equivalent to that of silver, and that it will become so, only when the normal solution employed for its preparation shall be finally of the true standard. Lastly, we prepare beforehand several stoppered phials, in each of which we dissolve 1 gramme of silver in 8 or 10 grammes of nitric acid. For brevity’s sake we shall call these tests.

Now to investigate the standard of the normal solution, we must transfer a pipette of it into one of these test phials; and we must agitate the liquors briskly to clarify them. After some instants of repose, we must pour in 2 thousandths of the decime solution of sea salt, which, we suppose, will produce a precipitate. The normal liquor is consequently too feeble; and we should expect this, since the sea salt employed was not perfectly pure. We agitate and add 2 fresh thousandths, which will also produce a precipitate. We continue thus by successive additions of 2 thousandths, till the last produces no precipitation. Suppose that we have added 16 thousandths: the last two should not be reckoned, as they produced no precipitate; the preceding two were necessary, but only in part; that is to say, the useful thousandths added are above 12 and below 14, or otherwise they are on an average equal to 13.

Thus, in the condition of the normal solution, we require 1013 parts of it to precipitate one gramme of silver, while we should require only 1000. We shall find the quantity of concentrated solution of sea salt that we should add, by noting that the quantity of solution of sea salt, at first employed, viz. 2279·3 grammes, produced a standard of only 987 thousandths = 1000 - 13; and by using the following proportion:

987 : 2279·3 ∷ 13 : x = 30·02 grammes.


This quantity of the strong solution of salt, mixed with the normal solution in the drum, will correct its standard, and we shall now see by how much.

After having washed the tubes and the pipette, with the new solution, we must repeat the experiment upon a fresh gramme of silver. We shall find, for example, in proceeding only by a thousandth at a time, that the first causes a precipitate, but not the second. The standard of the solution is still too weak, and is comprised between 1000 and 1001; that is to say, it may be equal to 100012, but we must make a closer approximation.

We pour into the test bottle 2 thousandths of the decime solution of silver, which will destroy, perceptibly, two thousandths of sea salt, and the operation will have retrograded by two thousandths; that is to say, it will be brought back to the point at which it was first of all. If, after having cleared up the liquor, we add half a thousandth of the decime solution, there will necessarily be a precipitate, as we knew beforehand, but a second will cause no turbidity. The standard of the normal liquor will be consequently comprehended between 1000 and 100012, or equal to 100014.

We should rest content with this standard, but if we wish to correct it, we may remark that the two quantities of solution of salt added, viz. 2279·3 gr. + 30·02 gr. = 2309·32 gr. have produced only 999·75 thousandths, and that we must add a new quantity of it corresponding to 14 of a thousandth. We make, therefore, the proportion

999·75 : 2309·32 ∷ 0·25 : x.

But since the first term differs very little from 1000, we may content ourselves to have x by taking the 0·251000 of 2309·32, and we shall find 0·577 gr. for the quantity of solution of sea salt to be added to the normal solution.

It is not convenient to take exactly so small a quantity of solution of sea salt by the balance, but we shall succeed easily by the following process. We weigh 50 grammes of this solution, and we dilute it with water; so that it occupies exactly half a litre, or 500 centimetres cube. A pipette of this solution, one centimetre cube in volume, will give a decigramme of the primitive solution, and as such a small pipette is divided into twenty drops, each drop, for example, will represent 5 milligrammes of the solution. We should arrive at quantities smaller still by diluting the solution with a proper quantity of water; but greater precision would be entirely needless.

The testing of the normal liquor just described, is, in reality, less tedious than might be supposed. It deserves also to be remarked, that liquor has been prepared for more than 1000 assays; and that, in preparing a fresh quantity, we shall obtain directly its true standard, or nearly so, if we bear in mind the quantities of water and solution of salt which had been employed.

Correction of the Standard of the Normal Solution of Sea Salt, when the Temperature changes.—We have supposed, in determining the standard of the normal solution of sea salt, that the temperature remained uniform. The assays made in such circumstances, have no need of correction; but if the temperature should change, the same measure of the solution will not contain the same quantity of sea salt. Supposing that we have tested the solution of the salt at the temperature of 15° C.; if, at the time of making the experiment, the temperature is 18° C., for example, the solution will be too weak on account of its expansion, and the pipette will contain less of it by weight; if, on the contrary, the temperature has fallen to 12°, the solution will be thereby concentrated and will prove too strong. It is therefore proper to determine the correction necessary to be made, for any variation of temperature.

To ascertain this point, the temperature of the solution of sea salt was made successively to be 0°, 5°, 10°, 15°, 20°, 25°, and 30° C.; and three pipettes of the solution were weighed exactly at each of these temperatures. The third of these weighings gave the mean weight of a pipette. The corresponding weights of a pipette of the solution, were afterwards graphically interpolated from degree to degree. These weights form the second column of the following table, intitled, Table of Correction for the Variations in the Temperature of the Normal Solution of the Sea Salt. They enable us to correct any temperature between 0 and 30 degrees centigrade (32° and 86° Fahr.) when the solution of sea salt has been prepared in the same limits.

Let us suppose, for example, that the solution has been made standard at 15°, and that at the time of using it, the temperature has become 18°. We see by the second column of the table, that the weight of a measure of the solution is 100·099 gr. at 15°, and 100·065 at 18°; the difference 0·034 gr., is the quantity of solution less which has been really taken; and of course we must add it to the normal measure, in order to make it equal to one thousand millièmes. If the temperature of the solution had fallen to 10 degrees, the difference of the weight of a measure from 10 to 15 degrees would be 0·019 gr. which we must on the contrary deduct from the measure, since it had been taken too large. These differences of weight of a measure of solution at 15°, from that of a[72] measure at any other temperature, form the column 15° of the table, where they are expressed in thousandths; they are inscribed on the same horizontal lines as the temperatures to which each of them relates with the sign + plus, when they must be added, and with the sign - minus, when they must be subtracted. The columns 5°, 10°, 20°, 25°, 35°, have been calculated in the same manner for the cases in which the normal solution may have been graduated to each of these temperatures. Thus, to calculate the column 10, the number 100·118 has been taken of the column of weights for a term of departure, and its difference from all the numbers of the same column has been sought.

Table of Correction for the Variations in the Temperature of the Normal Solution of the Sea Salt.

Weight. 10° 15° 20° 25° 30°
  gram. mill. mill. mill. mill. mill. mill.
4 100,109 0·0 - 0·1 + 0·1 + 0·7 + 1·7 + 2·7
5 100,113 0·0 - 0·1 + 0·1 + 0·7 + 1·7 + 2·8
6 100,115 0·0 0·0 + 0·2 + 0·8 + 1·7 + 2·8
7 110,118 + 0·1 0·0 + 0·2 + 0·8 + 1·7 + 2·8
8 100,120 + 0·1 0·0 + 0·2 + 0·8 + 1·8 + 2·8
9 100,120 + 0·1 0·0 + 0·2 + 0·8 + 1·8 + 2·8
10 100,118 + 0·1 0·0 + 0·2 + 0·8 + 1·7 + 2·8
11 100,116 0·0 0·0 + 0·2 + 0·8 + 1·7 + 2·8
12 100,114 0·0 0·0 + 0·2 + 0·8 + 1·7 + 2·8
13 100,110 0·0 - 0·1 + 0·1 + 0·7 + 1·7 + 2·7
14 100,106 - 0·1 - 0·1 + 0·1 + 0·7 + 1·6 + 2·7
15 100,099 - 0·1 - 0·2 - 0·0 + 0·6 + 1·6 + 2·6
16 100,090 - 0·2 - 0·3 - 0·1 + 0·5 + 1·5 + 2·5
17 100,078 - 0·4 - 0·4 - 0·2 + 0·4 + 1·3 + 2·4
18 100,065 - 0·5 - 0·5 - 0·3 + 0·3 + 1·2 + 2·3
19 100,053 - 0·6 - 0·7 - 0·5 + 0·1 + 1·1 + 2·2
20 100,039 - 0·7 - 0·8 - 0·6 0·0 + 1·0 + 2·0
21 100,021 - 0·9 - 1·0 - 0·8 - 0·2 + 0·8 + 1·9
22 100,001 - 1·1 - 1·2 - 1·0 - 0·4 + 0·6 + 1·7
23 99,983 - 1·3 - 1·4 - 1·2 - 0·6 + 0·4 + 1·5
24 99,964 - 1·5 - 1·5 - 1·4 - 0·8 + 0·2 + 1·3
25 99,944 - 1·7 - 1·7 - 1·6 - 1·0 0·0 + 1·1
26 99,924 - 1·9 - 1·9 - 1·8 - 1·2 - 0·2 + 0·9
27 99,902 - 2·1 - 2·2 - 2·0 - 1·4 - 0·4 + 0·7
28 99,879 - 2·3 - 2·4 - 2·2 - 1·6 - 0·7 + 0·4
29 99,858 - 2·6 - 2·6 - 2·4 - 1·8 - 0·9 + 0·2
30 99,836 - 2·8 - 2·8 - 2·6 - 2·0 - 1·1 0·0

Several expedients have been employed to facilitate and abridge the manipulations. In the first place, the phials for testing or assaying the specimens of silver should all be of the same height and of the same diameter. They should be numbered at their top, as well as on their stoppers, in the order 1, 2, 3, &c. They may be ranged successively in tens; the stoppers of the same series being placed on a support in their proper order. Each two phials should, in their turn, be placed in a japanned tin case (fig. 90.) with ten compartments duly numbered. These compartments are cut out anteriorly to about half their height, to allow the bottoms of the bottles to be seen. When each phial has received its portion of alloy, through a wide-beaked funnel, there must be poured into it about 10 grammes of nitric acid, of specific gravity 1·28, with a pipette, containing that quantity; it is then exposed to the heat of a water bath, in order to facilitate the solution of the alloy. The water bath is an oblong vessel made of tin plate, intended to receive the phials. It has a moveable double bottom, pierced with small holes, for the purpose of preventing the phials being broken, as it insulates them from the bottom to which the heat is applied. The solution is rapid; and, since it emits nitrous vapours in abundance, it ought to be carried on under a chimney.

Phial rack and agitator

The agitator.Fig. 91. gives a sufficiently exact idea of it, and may dispense with a lengthened description. It has ten cylindrical compartments, numbered from 1 to 10. The phials, after the solution of the alloy, are arranged in it in the order of their numbers. The agitator is then placed within reach of the pipette, intended to measure out the normal solution of sea salt, and a pipette full of this solution is put into each phial. Each is then closed with its glass stopper, previously dipped in pure water. They are fixed in the cells of the agitator by wooden wedges. The agitator is then suspended[73] to a spring R, and, seizing it with the two hands, the operator gives an alternating rapid movement, which agitates the solution, and makes it, in less than a minute, as limpid as water. This movement is promoted by a spiral spring, B, fixed to the agitator and the ground; but this is seldom made use of, because it is convenient to be able to transport the agitator from one place to another. When the agitation is finished, the wedges are to be taken out, and the phials are placed in order upon a table furnished with round cells destined to receive them, and to screen them from too free a light.

When we place the phials upon this table, we must give them a brisk circular motion, to collect the chloride of silver scattered round their sides; we must lift out their stoppers, and suspend them in wire rings, or pincers. We next pour a thousandth of the decime solution into each phial; and before this operation is terminated, there is formed in the first phials, when there should be a precipitate, a nebulous stratum, very well marked, of about a centimetre in thickness.

At the back of the table there is a black board divided into compartments numbered from 1 to 10, upon each of which we mark, with chalk, the thousandths of the decime liquor put into the correspondent phial. The thousandths of sea salt, which indicate an augmentation of standard, are preceded by the sign +, and the thousandths of nitrate of silver by the sign -.

When the assays are finished, the liquor of each phial is to be poured into a large vessel, in which a slight excess of sea salt is kept; and when it is full, the supernatant clear liquid must be run off with a syphon.

The chloride of silver may be reduced without any perceptible loss. After having washed it well, we immerse pieces of iron or zinc into it, and add sulphuric acid in sufficient quantity to keep up a feeble disengagement of hydrogen gas. The mass must not be touched. In a few days the silver is completely reduced. This is easily recognised by the colour and nature of the product; or by treating a small quantity of it with water of ammonia, we shall see whether there be any chloride unreduced; for it will be dissolved by the ammonia, and will afterwards appear upon saturating the ammonia with an acid. The chlorine remains associated with the iron or the zinc in a state of solution. The first washings of the reduced silver must be made with an acidulous water, to dissolve the oxide of iron which may have been formed, and the other washings with common water. After decanting the water of the last washing, we dry the mass, and add a little powdered borax to it. It must be now fused. The silver being in a bulky powder is to be put in successive portions into a crucible as it sinks down. The heat should be at first moderate; but towards the end of the operation it must be pretty strong to bring into complete fusion the silver and the scoriæ, and to effect their complete separation. In case it should be supposed that the whole of the silver had not been reduced by the iron or zinc, a little carbonate of potash should be added to the borax. The silver may also be reduced by exposing the chloride to a strong heat, in contact with chalk and charcoal.

The following remarks by M. Gay Lussac, the author of the above method, upon the effect of a little mercury in the humid assay, are important:—

It is well known that chloride of silver blackens the more readily as it is exposed to an intense light, and that even in the diffused light of a room, it becomes soon sensibly coloured. If it contains four to five thousandths of mercury, it does not blacken; it remains of a dead white: with three thousandths of mercury, there is no marked discolouring in diffused light; with two thousandths it is slight; with one it is much more marked, but still it is much less intense than with pure chloride. With half a[74] thousandth of mercury the difference of colour is not remarkable, and is perceived only in a very moderate light.

But when the quantity of mercury is so small that it cannot be detected by the difference of colour in the chloride of silver, it may be rendered quite evident by a very simple process of concentration. Dissolve one gramme of the silver supposed to contain 14 of a thousandth of mercury, and let only 14 of it be precipitated, by adding only 14 of the common salt necessary to precipitate it entirely. In thus operating, the 14 thousandth of mercury is concentrated in a quantity of chloride of silver four times smaller: it is as if the silver having been entirely precipitated, four times as much mercury, equal to two thousandths, had been precipitated with it.

In taking two grammes of silver, and precipitating only 14 by common salt, the precipitate would be, with respect to the chloride of silver, as if it amounted to four thousandths. By this process, which occupies only five minutes, because exact weighing is not necessary, 110 of a thousandth of mercury may be detected in silver.

It is not useless to observe, that in making those experiments the most exact manner of introducing small quantities of mercury into a solution of silver, is to weigh a minute globule of mercury, and to dissolve it in nitric acid, diluting the solution so that it may contain as many cubic centimetres as the globule weighs of centigrammes. Each cubic centimetre, taken by means of a pipette, will contain one milligramme of mercury.

If the ingot of silver to be assayed is found to contain a greater quantity of mercury, one thousandth for example, the humid process ought either to be given up in this case, or to be compared with cupellation.

When the silver contains mercury, the solution from which the mixed chlorides are precipitated, does not readily become clear.

Silver containing mercury, put into a small crucible and mixed with lamp black, to prevent the volatilization of the silver, was heated for three quarters of an hour in a muffle, but the silver increased sensibly in weight. This process for separating the mercury, therefore, failed. It is to be observed, that mercury is the only metal which has thus the power of disturbing the analysis by the humid way.

Assaying of Gold.—In estimating or expressing the fineness of gold, the whole mass spoken of is supposed to weigh 24 carats of 12 grains each, either real, or merely proportional, like the assayer’s weights; and the pure gold is called fine. Thus, if gold be said to be 23 carats fine, it is to be understood, that in a mass, weighing 24 carats, the quantity of pure gold amounts to 23 carats.

In such small work as cannot be assayed by scraping off a part and cupelling it, the assayers endeavour to ascertain its fineness or quality by the touch. This is a method of comparing the colour and other properties, of a minute portion of the metal, with those of small bars, the composition of which is known. These bars are called touch needles, and they are rubbed upon a smooth piece of black basaltes or pottery, which, for this reason, is called the touchstone. Black flint slate will serve the same purpose. Sets of gold needles may consist of pure gold; of pure gold, 2312 carats with 12 carat of silver; 23 carats of gold with one carat of silver; 2212 carats of gold with 112 carat of silver; and so on, till the silver amounts to four carats; after which the additions may proceed by whole carats. Other needles may be made in the same manner, with copper instead of silver; and other sets may have the addition, consisting either of equal parts of silver and copper, or of such proportions as the occasions of business require. The examination by the touch may be advantageously employed previous to quartation, to indicate the quantity of silver necessary to be added.

In foreign countries, where trinkets and small work are required to be submitted to the assay of the touch, a variety of needles is necessary; but they are not much used in England. They afford, however, a degree of information which is more considerable than might at first be expected. The attentive assayer compares not only the colour of the stroke made upon the touchstone by the metal under examination, with that produced by his needle, but will likewise attend to the sensation of roughness, dryness, smoothness, or greasiness, which the texture of the rubbed metal excites, when abraded by the stone. When two strokes perfectly alike in colour are made upon the stone, he may then wet them with aquafortis, which will affect them very differently, if they be not similar compositions; or the stone itself may be made red-hot by the fire, or by the blowpipe, if thin black pottery be used; in which case the phenomena of oxidation will differ, according to the nature and quantity of the alloy. Six principal circumstances appear to affect the operation of parting; namely, the quantity of acid used in parting, or in the first boiling; the concentration of this acid; the time employed in its application; the quantity of acid made use of in the reprise, or second operation; its concentration; and the time during which it is applied. From experiment it has been shown, that each of these unfavourable circumstances might easily occasion a loss of from the half of[75] a thirty-second part of a carat, to two thirty-second parts. The assayers explain their technical language by observing, that in the whole mass consisting of twenty-four carats, this thirty-second part denotes 1-768th part of the mass. It may easily be conceived, therefore, that if the whole six circumstances were to exist, and be productive of errors, falling the same way, the loss would be very considerable.

It is therefore indispensably necessary, that one uniform process should be followed in the assays of gold; and it is a matter of astonishment, that such an accurate process should not have been prescribed by government for assayers, in an operation of such great commercial importance, instead of every one being left to follow his own judgment. The process recommended in the old French official report is as follows:—twelve grains of the gold intended to be assayed must be mixed with thirty grains of fine silver, and cupelled with 108 grains of lead. The cupellation must be carefully attended to, and all the imperfect buttons rejected. When the cupellation is ended, the button must be reduced, by lamination, into a plate of 112 inches, or rather more, in length, and four or five lines in breadth. This must be rolled up upon a quill, and placed in a matrass capable of holding about three ounces of liquid, when filled up to its narrow part. Two ounces and a half of very pure aquafortis, of the strength of 20 degrees of Baumé’s areometer, must then be poured upon it; and the matrass being placed upon hot ashes, or sand, the acid must be kept gently boiling for a quarter of an hour: the acid must then be cautiously decanted, and an additional quantity of 112 ounces must be poured upon the metal, and slightly boiled for twelve minutes. This being likewise carefully decanted, the small spiral piece of metal must be washed with filtered river water, or distilled water, by filling the matrass with this fluid. The vessel is then to be reversed, by applying the extremity of its neck against the bottom of a crucible of fine earth, the internal surface of which is very smooth. The annealing must now be made, after having separated the portion of water which had fallen into the crucible; and, lastly, the annealed gold must be weighed. For the certainty of this operation, two assays must be made in the same manner, together with a third assay upon gold of twenty-four carats, or upon gold the fineness of which is perfectly and generally known.

No conclusion must be drawn from this assay, unless the latter gold should prove to be of the fineness of twenty-four carats exactly, or of its known degree of fineness; for, if there be either loss or surplus, it may be inferred, that the other two assays, having undergone the same operation, must be subject to the same error. The operation being made according to this process by several assayers, in circumstances of importance, such as those which relate to large fabrications, the fineness of the gold must not be depended upon, nor considered as accurately known, unless all the assayers have obtained an uniform result, without communication with each other. This identity must be considered as referring to the accuracy of half the thirty-second part of a carat. For, notwithstanding every possible precaution or uniformity, it very seldom happens that an absolute agreement is obtained between the different assays of one and the same ingot; because the ingot itself may differ in its fineness in different parts of its mass.

The phenomena of the cupellation of gold are the same as of silver, only the operation is less delicate, for no gold is lost by evaporation or penetration into the bone-ash, and therefore it bears safely the highest heat of the assay furnace. The button of gold never vegetates, and need not therefore be drawn out to the front of the muffle, but may be left at the further end till the assay is complete. Copper is retained more strongly by gold than it is by silver; so that with it 16 parts of lead are requisite to sweat out 1 of copper; or, in general, twice as much lead must be taken for the copper alloys of gold, as for those of silver. When the copper is alloyed with very small quantities of gold, cupellation would afford very uncertain results; we must then have recourse to liquid analysis.

M. Vauquelin recommends to boil 60 parts of nitric acid at 22° Baumé, on the spiral slip or cornet of gold and silver alloy, for twenty-five minutes, and replace the liquid afterwards by acid of 32°, which must be boiled on it for eight minutes. This process is free from uncertainty when the assay is performed upon an alloy containing a considerable quantity of copper. But this is not the case in assaying finer gold; for then a little silver always remains in the gold. The surcharge which occurs here is 2 or 3 thousandths; this is too much, and it is an intolerable error when it becomes greater, which often happens. This evil may be completely avoided by employing the following process of M. Chaudet. He takes 0·500 of the fine gold to be assayed; cupels it with 1·500 of silver, and 1·000 of lead; forms, with the button from the cupel, a riband or strip three inches long, which he rolls into a cornet. He puts this into a mattrass with acid at 22° B., which he boils for 3 or 4 minutes. He replaces this by acid of 32° B., and boils for ten minutes; then decants off, and boils again with acid of 32°, which must be finally boiled for 8 or 10 minutes.

Gold thus treated is very pure. He washes the cornet, and puts it entire into a small[76] crucible permeable to water; heats the crucible to dull redness under the muffle, when the gold assumes the metallic lustre, and the cornet becomes solid. It is now taken out of the crucible and weighed.

When the alloy contains platinum, the assay presents greater difficulties. In general, to separate the platinum from the gold with accuracy, we must avail ourselves of a peculiar property of platinum; when alloyed with silver, it becomes soluble in nitric acid. Therefore, by a proper quartation of the alloy by cupellation, and boiling the button with nitric acid, we may get a residuum of pure gold. If we were to treat the button with sulphuric acid, however, we should dissolve nothing but the silver. The copper is easily removed by cupellation. Hence, supposing that we have a quaternary compound of copper, silver, platinum, and gold, we first cupel it, and weigh the button obtained; the loss denotes the copper. This button, treated by sulphuric acid, will suffer a loss of weight equal to the amount of silver present. The residuum, by quartation with silver and boiling with nitric acid, will part with its platinum, and the gold will remain pure. For more detailed explanations, see Platinum.

ATOMIC WEIGHTS or ATOMS, are the primal quantities in which the different objects of chemistry, simple or compound, combine with each other, referred to a common body, taken as unity. Oxygen is assumed by some philosophers, and hydrogen by others, as the standard of comparison. Every chemical manufacturer should be thoroughly acquainted with the combining ratios which are, for the same two substances, not only definite, but multiple; two great truths, upon which are founded not merely the rationale of his operations, but also the means of modifying them to useful purposes. The discussion of the doctrine of atomic weights, or prime equivalents, belongs to pure chemistry; but several of its happiest applications are to be found in the processes of art, as pursued upon the greatest scale. For many instructive examples of this proposition, the various chemical manufactures may be consulted in this Dictionary.

ATTAR OF ROSES. See Oils, Volatile, and Perfumery.

AURUM MUSIVUM. Mosaic gold, a preparation of tin; which see.

AUTOMATIC, a term which I have employed to designate such economic arts as are carried on by self-acting machinery. The word “manufacture,” in its etymological sense, means any system, or objects of industry, executed by the hands; but in the vicissitude of language, it has now come to signify every extensive product of art which is made by machinery, with little or no aid of the human hand, so that the most perfect manufacture is that which dispenses entirely with manual labour.[4] It is in our modern cotton and flax mills that automatic operations are displayed to most advantage; for there the elemental powers have been made to animate millions of complex organs, infusing into forms of wood, iron, and brass, an intelligent agency. And as the philosophy of the fine arts, poetry, painting, and music, may be best studied in their individual master-pieces, so may the philosophy of manufactures in these its noblest creations.[5]

[4] Philosophy of Manufactures, p. 1.

[5] Ibid., p. 2.

The constant aim and effect of these automatic improvements in the arts are philanthropic, as they tend to relieve the workmen either from niceties of adjustment, which exhaust his mind and fatigue his eyes, or from painful repetition of effort, which distort and wear out his frame. A well arranged power-mill combines the operation of many work-people, adult and young, in tending with assiduous skill, a system of productive machines continuously impelled by a central force. How vastly conducive to the commercial greatness of a nation, and the comforts of mankind, human industry can become, when no longer proportioned in its results to muscular effort, which is by its nature fitful and capricious, but when made to consist in the task of guiding the work of mechanical fingers and arms regularly impelled, with equal precision and velocity, by some indefatigable physical agent, is apparent to every visitor of our cotton, flax, silk, wool, and machine factories. This great era in the useful arts is mainly due to the genius of Arkwright. Prior to the introduction of his system, manufactures were every where feeble and fluctuating in their development; shooting forth luxuriantly for a season, and again withering almost to the roots like annual plants. Their perennial growth then began, and attracted capital, in copious streams, to irrigate the rich domains of industry. When this new career commenced, about the year 1770, the annual consumption of cotton in British manufactures was under four millions of pounds’ weight, and that of the whole of Christendom was probably not more than ten millions. Last year the consumption in Great Britain and Ireland was about two hundred and seventy millions of pounds, and that of Europe and the United States together, four hundred and eighty millions. In our spacious factory apartments the benignant power of steam summons around him his myriads of willing menials, and assigns to each the regulated task, substituting, for painful muscular effort upon their part, the energies of his own gigantic arm, and demanding, in return, only attention and dexterity to correct such little aberrations as casually occur in his workmanship. Under his auspices,[77] and in obedience to Arkwright’s polity, magnificent edifices, surpassing far in number, value, usefulness, and ingenuity of construction, the boasted monuments of Asiatic, Egyptian, and Roman despotism, have, within the short period of fifty years, risen up in this kingdom, to show to what extent capital, industry, and science, may augment the resources of a state, while they meliorate the condition of its citizens. Such is the automatic system, replete with prodigies in mechanics and political economy, which promises, in its future growth, to become the great minister of civilisation to the terraqueous globe, enabling this country, as its heart, to diffuse, along with its commerce, the life-blood of knowledge and religion to myriads of people still lying “in the region and shadow of death.”[6] Of these truths, the present work affords decisive evidence in almost every page.

[6] Philosophy of Manufactures, p. 18.

AUTOMATON. In the etymological sense, this word (self-working) signifies every mechanical construction which, by virtue of a latent intrinsic force, not obvious to common eyes, can carry on, for some time, certain movements more or less resembling the results of animal exertion, without the aid of external impulse. In this respect, all kinds of clocks and watches, planetariums, common and smoke jacks, with a vast number of the machines now employed in our cotton, silk, flax, and wool factories, as well as in our dyeing and calico printing works, may be denominated automatic. But the term, automaton, is, in common language, appropriated to that class of mechanical artifices in which the purposely concealed power is made to imitate the arbitrary or voluntary motions of living beings. Human figures, of this kind, are sometimes styled Androides, from the Greek term, like a man.

Although, from what we have said, clock-work is not properly placed under the head automaton, it cannot be doubted that the art of making clocks in its progressive improvement and extension, has given rise to the production of automata. The most of these, in their interior structure, as well as in the mode of applying the moving power, have a distinct analogy with clocks; and these automata are frequently mounted in connection with watch work. Towards the end of the 13th century, several tower clocks, such as those at Strasburg, Lubeck, Prague, Olmutz, had curious mechanisms attached to them. The most careful historical inquiry proves that automata, properly speaking, are certainly not older than wheel-clocks; and that the more perfect structures of this kind are subsequent to the general introduction of spring clocks. Many accounts of ancient automata, such as the flying doves of Archytas of Tarentum, Regiomontanus’s iron flies, the eagle which flew towards the emperor Maximilian, in Nurenberg, in the year 1470, were deceptions, or exaggerated statements; for, three such masterpieces of art would form now, with every aid of our improved mechanisms, the most difficult of problems. The imitation of flying creatures is extremely difficult, for several reasons. There is very little space for the moving power, and the only material possessed of requisite strength being metal, must have considerable weight. Two automata, of the celebrated French mechanician, Vaucauson, first exhibited in the year 1738, have been greatly admired; namely a flute-player, five and a half feet high, with its cubical pedestal, which played several airs upon the German flute; and that, not by any interior tube-work, but through the actual blowing of air into the flute, the motion of the tongue, and the skilful stopping of the holes with the fingers; as also a duck, which imitated many motions of a natural kind in the most extraordinary manner. This artist has had many imitators, of whom the brothers, Droz of Chaux de Fonds, were the most distinguished. Several very beautiful clock mechanisms of theirs are known. One of them with a figure which draws; another playing on the piano; a third which writes, besides numerous other combined automata. Frederick Von Knauss completed a writing machine at Vienna, in the year 1760. It is now in the model cabinet of the Polytechnic Institute, and consists of a globe 2 feet in diameter, containing the mechanism upon which a figure 7 inches high sits, and writes upon a sheet of paper fixed to a frame, whatever has been placed beforehand upon a regulating cylinder. At the end of every line, it rises and moves its hand sideways, in order to begin a new line.

Very complete automata have not been made of late years, because they are very expensive; and by soon satisfying curiosity, they cease to interest. Ingenious mechanicians find themselves better rewarded by directing their talents to the self-acting machinery of modern manufactures. We may notice here, however, the mechanical trumpeter of Mälzl, at Vienna, and a similar work of Kauffmann, at Dresden. In French Switzerland some artists continue to make minute automata which excite no little wonder; such as singing canary birds, with various movements of a natural kind; also little birds, sometimes hardly three quarters of an inch long, in snuff-boxes and watches of enamelled gold. Certain artificial figures which have been denominated automata, hardly deserve the name; since trick and confederacy are more or less concerned[78] in their operation. To this head belong a number of figures apparently speaking by mechanism; a clock which begins to strike, or to play, when a person makes a sign of holding up his finger; this effect being probably produced by a concealed green-finch, or other little bird, instructed to set off the détente of the wheel-work at a signal. It is likely, also, that the chess player of Von Kempelen, which excited so much wonder in the last century, had a concealed confederate. Likewise, the very ingenious little figures of Tendler, father and son, which imitated English horsemen and rope-dancers, constructed at Eisenerz, in Styria, are probably no more true automata than the fantoccini, or figures of puppets which are exhibited in great perfection in many towns of Italy, especially at Rome.

The moving power of almost all automata is a wound-up steel spring; because, in comparison with other means of giving motion, it takes up the smallest room, is easiest concealed, and set a going. Weights are seldom employed, and only in a partial way. The employment of other moving powers is more limited; sometimes fine sand is made to fall on the circumference of a wheel, by which the rest of the mechanism is moved. For the same purpose water has been employed; and, when it is made to fall into an air-chamber, it causes sufficient wind to excite musical sounds in pipes. In particular cases quicksilver has been used, as, for example, in the Chinese tumblers, which is only a physical apparatus to illustrate the doctrine of the centre of gravity.

Figures are frequently constructed for playthings, which move by wheels hardly visible. An example of this simplest kind of automaton which may be introduced here, as illustrating the self-acting principles of manufactures, is shown in the figure.


Fig. 92. exhibits the outlines of an automaton, representing a swan, with suitably combined movements. The mechanism may be described, for the sake of clearness of explanation, under distinct heads. The first relates to the motion of the whole figure. By means of this part it swims upon the water, in directions changed from time to time without exterior agency. Another construction gives to the figure the faculty of bending its neck on several occasions, and, to such an extent, that it can plunge the bill and a portion of the head under water. Lastly, it is made to move its head and neck slowly from side to side.

On the barrel of the spring, exterior to the usual ratchet wheel, there is a main-wheel, marked 1, which works into the pinion of the wheel 2. The wheel 2 moves a smaller one, shown merely in dotted lines, and on the long axis of the latter, at either end there is a rudder, or water-wheel, the paddles of which are denoted by the letter a. Both of these rudder-wheels extend through an oblong opening in the bottom of the figure down into the water. They turn in the direction of the arrow, and impart a straight-forwards movement to the swan. The chamber, in which these wheels revolve, is made water tight, to prevent moisture being thrown upon the rest of the machinery. By the wheel 4, motion is conveyed to the fly-pinion 5; the fly itself 6, serves to regulate the working of the whole apparatus, and it is provided with a stop bar, not shown in the engraving, to bring it to rest, or set it a-going at pleasure. Here, as we may imagine, the path pursued is rectilinear, when the rudder-wheels are made to work in a square direction. An oblique bar, seen only in section at b, movable about its middle point, carries at each end a web foot c, so that the direction of the bar b, and of both feet towards the rudder wheels, determines the form of the path which the figure will describe. The change of direction of that oblique bar is effected without other agency. For this purpose, the wheel 1 takes into the pinion 7, and this carries round the crown-wheel 8, which is fixed, with an eccentric disc 9, upon a common axis. While the crown-wheel moves in the direction of the arrow, it turns the smaller eccentric portion of the elliptic disc towards the lever m, which, pressed upon incessantly by its spring, assumes, by degrees, the position corresponding with the middle line of the figure, and afterwards an oblique position; then it goes back again, and reaches its first situation; consequently through the reciprocal turning of the bar h, and the swim-foot, is determined and varied the path which the swan must pursue. This construction is available with all automata, which work by wheels; and it is obvious,[79] that we may, by different forms of the disc 9, modify, at pleasure, the direction and the velocity of the turnings. If the disc is a circle for instance, then the changes will take place less suddenly; if the disc has an outward and inward curvature, upon whose edge the end of the lever presses with a roller, the movement will take place in a serpentine line.

The neck is the part which requires the most careful workmanship. Its outward case must be flexible, and the neck itself should therefore be made of a tube of spiral wire, covered with leather, or with a feathered bird-skin. The double line in the interior, where we see the triangles e e e, denotes a steel spring made fast to the plate 10, which forms the bottom of the neck; it stands loose, and needs to be merely so strong as to keep the neck straight, or to bend it a little backwards. It should not be equally thick in all points, but it should be weaker where the first graceful bend is to be made; and, in general, its stiffness ought to correspond to the curvature of the neck of this bird. The triangles e are made fast at their base to the front surface of the spring; in the points of each there is a slit, in the middle of which a movable roller is set, formed of a smoothly turned steel rod. A thin catgut string f, runs from the upper end of the spring, where it is fixed over all these rollers, and passes through an aperture pierced in the middle of 10, into the inside of the rump. If the catgut be drawn straight back towards f, the spring, and consequently the neck, must obviously be bent, and so much the more, the more tightly f is pulled, and is shortened in the hollow of the neck. How this is accomplished by the wheel-work will presently be shown. The wheel 11 receives its motion from the pinion s, connected with the main wheel 1. Upon 11 there is, moreover, the disc 12, to whose circumference a slender chain is fastened. When the wheel 11 turns in the direction of the arrow, the chain will be so much pulled onwards through the corresponding advance at the point at 12, till this point has come to the place opposite to its present situation, and, consequently, 11 must have performed half a revolution. The other end of the chain is hung in the groove of a very movable roller 14; and this will be turned immediately by the unwinding of the chain upon its axis. There turns, in connection with it, however, the large roller 13, to which the catgut f is fastened; and as this is pulled in the direction of the arrow, the neck will be bent until the wheel 11 has made a half revolution. Then the drag ceases again to act upon the chain and the catgut; the spring in the neck comes into play: it becomes straight, erects the neck of the animal, and turns the rollers 13 and 14, back into their first position.

The roller 13 is of considerable size, in order that through the slight motion of the roller 14, a sufficient length of the catgut may be wound off, and the requisite shortening of the neck may be effected; which results from the proportion of the diameters of the rollers 11, 13, and 14. This part of the mechanism is attached as near to the side of the hollow body as possible, to make room for the interior parts, but particularly for the paddle-wheels. Since the catgut, f, must pass downwards on the middle from 10, it is necessary to incline it sideways and outwards towards 13, by means of some small rollers.

The head, constituting one piece with the neck, will be depressed by the complete flexure of this; and the bill, being turned downwards in front of the breast, will touch the surface of the water. The head will not be motionless; but it is joined on both sides by a very movable hinge, with the light ring, which forms the upper part of the clothing of the neck. A weak spring, g, also fastened to the end of the neck, tends to turn the head backwards; but in the present position it cannot do so, because a chain at g, whose other end is attached to the plate 10, keeps it on the stretch. On the bending of the neck, this chain becomes slack; the spring g comes into operation, and throws the head so far back, that, in its natural position, it will reach the water.

Finally, to render the turning of the head and the neck practicable, the latter is not closely connected with the rump, while the plate 10 can turn in a cylindrical manner upon its axis, but cannot become loose outwardly. Moreover, there is upon the axis of the wheel 1, and behind it (shown merely as a circle in the engraving) a bevel wheel, which works into a second similar wheel, 15, so as to turn it in a horizontal direction. The pin 16, of the last wheel, works upon a two-armed lever 19, movable round the point h, and this lever moves the neck by means of the pin 17. The shorter arm of the lever 19 has an oval aperture in which the pin 16 stands. As soon as this, in consequence of the movement of the bevel-wheel 15, comes into the dotted position, it pushes the oval ring outwards on its smaller diameter, and thereby turns the lever upon the point h, into the oblique direction shown by the dotted lines. The pin 16, having come on its way right opposite to its present position, sets the lever again straight. Then the lever, by the further progress of the pin in its circular path, is directed outwards to the opposite side; and, at last, when 15 has made an entire revolution, it is quite straight. The longer arm of the lever follows, of course, these alternating movements, so that it turns the neck upon its plate 10, by means of the pin 17; and, as 18 denotes the bill,[80] this comes into the dotted position. It may be remarked in conclusion, that the drawing of fig. 92. represents about half the size of which the automaton may be constructed, and that the body may be formed of thin sheet-copper or brass.

Automaton details

Fig. 93, 94, 95. show the plan of a third automaton. A horse which moves its feet in a natural way, and draws a carriage with two figures sitting in it. The man appears to drive the horse with a whip; the woman bends forwards from him in front. The four wheels of the carriage have no connection with the moving mechanism. In fig. 95., some parts are represented upon a larger scale. The wheel 1, in fig. 93. operates through the two carrier wheels upon the wheels marked 4 and 5. By means of the axis of these two wheels, the feet are set in motion. The left fore-foot, a, then the right hinder foot, move themselves backwards, and take hold of the ground with small tacks in their hoofs, while the two other legs are bent and raised, but no motion of the body takes place. The carriage, however, with which the horse is connected, advances upon its wheels. By studying the mechanism of the foot, a, and the parts connected with it, we can readily understand the principles of the movement. The axis of wheel 4 is crank-shaped, on both sides, where it has to operate directly on the fore feet; but for each foot, it is bent in an opposite direction, as is obvious in the front view fig. 94. This crank, or properly its part furthest from the axis, serves instead of the pin 16, in the swan, and moves like it in an oval spot, p, fig. 93. a two-armed lever, which gives motion through tooth-work, but not as in the swan, by means of a second pin. This wheel-work renders the motion smoother. The above lever has its fulcrum at n, fig. 93., about which it turns alternately, to the one and the other side, by virtue of the rotation of the wheel 4. The toothed arch, or the half-wheel on the under side, lays hold of a shorter lever, in a similar arch, upon the upper joint of the foot, which is moved forwards and backwards upon the pivot m. In virtue of the motions in the direction of the arrow, the foot a will move itself first obliquely backwards, without bending, and the body will thereby bend itself forwards. When the right hind foot makes the same motion, both the other feet are raised and bent. The joints of the foot at d and e are formed of hinges, which are so constructed that they can yield no farther than is necessary at every oblique position of the foot. With the continued rotation of the wheel 4, the lever turns itself about n, in an inverted direction inwards, and impels the uppermost foot-joint forwards, so that it forms an acute angle with the body in front. The foot is now twice bent upon its joints. This takes place by the traction of the chain t, which is led over rollers (as the drawing shows) to the foot, and is there fastened. As its upper end has its fixed point in the interior of the body, it is therefore drawn by the eccentric pin r standing in the vicinity of m, and thus bends the foot at the hinges. If there were space for it, a roller would answer better than a pin. By the recedure of the uppermost joint into the first position, the tension of the chain t ceases again of itself, while the pin r removes from it, and the foot is again extended in a straight line by the small springs operating upon its two under parts, which were previously bent stiffly by the chain. By the aid of the figures with this explanation, it will be apparent that all the fore feet have a similar construction, that the proper succession of motions will be effected through the toothed arcs, and the position of the cranks on the axis of the wheels 4 and 5, and hence the advance of the figure must follow. The wheel 6 puts the fly 7 in motion, by means of the small wheel marked 1; on the fixed points of the 4 chains, by means of a ratchet-wheel and a catch, the[81] necessary tension will again be produced when the chains have been drawn out a little. There is sufficient room for a mechanism which could give motion to the head and ears, were it thought necessary.

The proper cause of the motions may now be explained. In fig. 95., a, is a wheel connected with the wound-up spring, by which the motion of the two human figures, and also, if desired, that of the horse may be effected. The axis of the wheel b carries a disc with pins, which operate upon the two-armed lever with its fulcrum e, and thus cause the bending of the upper part of one of the figures, which has a hinge at f. On the axis of that wheel there is a second disc c, for giving motion to the other figure; which, for the sake of clearness, is shown separate, although it should sit alongside of its fellow. On the upper end of the double-armed lever d, there is a cord whose other end is connected with the moving arm, in the situation i, and raises it whenever a pin in the disc presses the under part of the lever. A spring h brings the arm back into the original position, when a pin has passed from the lever, and has left it behind. The pins at c and d may be set at different distances from the middle of the disc, whereby the motions of the figures by every contact of another pin, are varied, and are therefore not so uniform, and consequently more natural.

For the connexion of both mechanisms, namely, the carriage with the horse, various arrangements may be adopted. Two separate traction springs should be employed; one at a, fig. 95., in the coach-seat; the other in the body of the horse. In the coach-seat at b, the fly with its pinion, as well as a ratchet-wheel, is necessary. By means of the shaft, the horse is placed in connexion with the waggon. It may, however, receive its motion from the spring in the carriage, in which case one spring will be sufficient. Upon the latter plan the following construction maybe adopted:—To the axis of b, fig. 95., a bevel wheel is to be attached, and from this the motion is to be transmitted to the bottom of the carriage with the help of a second bevel wheel s, connected with a third bevel wheel t. This again turns the wheel u, whose long axis v goes to the middle of the horse’s body, in an oblique direction, through the hollow shaft. This axis carries an endless screw 9, fig. 93., with very oblique threads, which works into the little wheel 8, corresponding to the wheel 1, through an opening in the side of the horse, and in this way sets the mechanism of the horse a-going. With this construction of fig. 95., a spring of considerable strength is necessary, or if the height of the carriage-seat does not afford sufficient room, its breadth will answer for placing two weaker springs alongside of each other upon a common barrel.

AXE. A tool much used by carpenters for cleaving, and roughly fashioning, blocks of wood. It is a flat iron wedge, with an oblong steel edge, parallel to which, in the short base, is a hole for receiving and holding fast the end of a strong wooden handle. In the cooper’s adze, the oblong edge is at right angles to the handle, and is slightly curved up, or inflected towards it.

AXLES, of carriages; for their latest improvements, see Wheel Carriages.

AXUNGE. Hog’s lard; see Fat and Oils.

AZOTIZED, said of certain vegetable substances, which, as containing azote, were supposed at one time to partake, in some measure, of the animal nature; most animal bodies being characterised by the presence of much azote in their composition. The vegetable products, indigo, cafeine, gluten, and many others, contain abundance of azote.

AZURE, the fine blue pigment, commonly called smalt, is a glass coloured with oxide of cobalt, and ground to an impalpable powder.

The manufacture of azure, or smalt, has been lately improved in Sweden, by the adoption of the following process:—

The cobalt ore is first roasted till the greater part of the arsenic is driven off. The residuary impure black oxide is mixed with as much sulphuric acid (concentrated) as will make it into a paste, which is exposed at first to a moderate heat, then to a cherry-red ignition for an hour. The sulphate thus obtained is reduced to powder, and dissolved in water. To the solution, carbonate of potash is gradually added, in order to separate the remaining portion of oxide of iron; the quantity of which depends upon the previous degree of calcination. If it be not enough oxidized, the iron is difficult to be got rid of.

When, from the colour of the precipitate, we find that the potash separates merely carbonate of cobalt, it is allowed to settle, the supernatant liquor is decanted, and precipitated, by means of a solution of silicate of potash, prepared as follows:—

Ten parts of potash are carefully mixed with fifteen parts of finely ground flints or sand, and one part of pounded charcoal. This mixture is melted in a crucible of brick clay, an operation which requires steady ignition during 5 or 6 hours. The mass, when melted and pulverized, may be easily dissolved in boiling water, adding to it, by little at a time, the glass previously ground. The filtered solution is colourless, and keeps well in the air, if it contains one part of glass for 5 or 6 of water. The silicate[82] of cobalt, which precipitates upon mixing the two solutions, is the preparation of cobalt most suitable for painting upon porcelain, and for the manufacture of blue glass. See Cobalt.


BABLAH. The rind or shell which surrounds the fruit of the mimosa cineraria; it comes from the East Indies, as also from Senegal, under the name of Neb-neb. It contains gallic acid, tannin, a red colouring matter, and an azotized substance; but the proportion of tannin is smaller than in sumach, galls, and knoppern (gall-nuts of the common oak) in reference to that of gallic acid, which is considerable in the bablah. It has been used, in dyeing cotton, for producing various shades of drab; as a substitute for the more expensive astringent die-stuffs.

BAGASSE. The sugar-cane, in its dry, crushed state, as delivered from the sugar-mill. It is much employed for fuel in the colonial sugar-houses.

BAKING. (Cuire, Fr. Backen, Germ.) The exposure of any body to such a heat as will dry and consolidate its parts without wasting them. Thus wood, pottery, and porcelain, are baked, as well as bread.

BALANCE. To conduct arts, manufactures, and mines, with judgment and success, recourse must be had, at almost every step, to a balance. Experience proves that all material bodies, existing upon the surface of the earth, are constantly solicited by a force which tends to bring them to its centre, and that they actually fall towards it when they are free to move. This force is called gravity. Though the bodies be not free, the effort of gravity is still sensible, and the resultant of all the actions which it exercises upon their material points, constitutes what is popularly called their weight. These weights are, therefore, forces which may be compared together, and by means of machines may be made to correspond or be counterpoised.

To discover whether two weights be equal, we must oppose them to each other in a machine where they act in a similar manner, and then see if they maintain an equilibrium; for example, we fulfil this condition if we suspend them at the two extremities of a lever, supported at its centre, and whose arms are equal. Such is the general idea of a balance. The beam of a good balance ought to be a bar of well-tempered steel, of such form as to secure perfect inflexibility under any load which may be fitly applied to its extremities. Its arms should be quite equal in weight and length upon each side of its point of suspension; and this point should be placed in a vertical line over the centre of gravity; and the less distant it is from it, the more delicate will be the balance. Were it placed exactly in that centre, the beam would not spontaneously recover the horizontal position when it was once removed from it. To render its indications more readily commensurable, a slender rod or needle is fixed to it, at right angles, in the line passing through its centres of gravity and suspension. The point, or rather edge, of suspension, is made of perfectly hard steel, and turns upon a bed of the same. For common uses the arms of a balance can be made sufficiently equal to give satisfactory results; but, for the more refined purposes of science, that equality should never be presumed nor trusted to; and, fortunately, exact weighing is quite independent of that equality. To weigh a body is to determine how many times the weight of that body contains another species of known weight, as of grains or pounds, for example. In order to find it out, let us place the substance, suppose a piece of gold, in the left hand scale of the balance; counterpoise it with sand or shot in the other, till the index needle be truly vertical, or stand in the middle of its scale, proving the beam to be horizontal. Now remove gently the piece of gold, and substitute in its place standard multiple weights of any graduation, English or French, till the needle again resumes the vertical position, or till its oscillations upon either side of the zero point are equal. These weights will represent precisely the weight of the gold, since they are placed in the same circumstances precisely with it, and make the same equilibrium with the weight laid in the other scale.

This method of weighing is obviously independent of the unequal length as well as the unequal weight of the arms of the beam. For its perfection two requisites only are indispensable. The first is that the points of suspension should be rigorously the same in the two operations; for the power of a given weight to turn the beam being unequal, according as we place it at different distances from the centre of suspension, did that point vary in the two consecutive weighings, we would require to employ, in the second, a different weight from that of the piece of gold, in order to form an equilibrium with the sand or shot originally put in the opposite scale; and as there is nothing to indicate such inequality in the states of the beam, great errors would result from it. The best mode of securing against such inequality is to suspend the cords of the scales from sharp-edged rings, upon knife edges, at the ends of the beam, both made of steel so[83] hard tempered as to be incapable of indentation. The second condition is, that the balance should be very sensible, that is, when in equilibrium and loaded, it may be disturbed, and its needle may oscillate, by the smallest weight put into either of the scales. This sensibility depends solely upon the centre or nail of suspension; and it will be the more perfect the less friction there is between that knife-edge surface and the plane which supports it. Both should therefore be as hard and highly polished as possible; and should not be suffered to press against each other, except at the time of weighing. Every delicate balance of moderate size, moreover, should be suspended within a glass case, to protect it from the agitations of the air, and the corroding influence of the weather. In some balances a ball is placed upon the index or needle, (whether that index stand above or below the beam,) which may be made to approach or recede from the beam by a fine-threaded screw, with the effect of varying the centre of gravity relatively to the point of suspension, and thereby increasing, at will, either the sensibility, or the stability of the balance. The greater the length of the arms, the less distant the centre of gravity is beneath the centre of suspension, the better polished its central knife-edge of 30°, the lighter the whole balance, and the less it is loaded; the greater will be its sensibility. In all cases the arms must be quite inflexible. A balance made by Ramsden for the Royal Society, is capable of weighing ten pounds, and turns with one hundredth of a grain, which is the seven-millionth part of the weight. In pointing out this balance to me one evening, Dr. Wollaston told me it was so delicate, that Mr. Pond, then astronomer royal, when making some observations with it, found its indications affected by his relative position before it, although it was inclosed in a glass case. When he stood opposite the right arm, that end of the beam preponderated, in consequence of its becoming expanded by the radiation of heat from his body; and when he stood opposite the left arm, he made this preponderate in its turn. It is probable that Mr. Pond had previously adjusted the centres of gravity and suspension so near to each other as to give the balance its maximum sensibility, consistent with stability. Were these centres made to coincide, the beam, when the weights are equal, would rest in any position, and the addition of the smallest weight would overset the balance, and place the beam in a vertical position, from which it would have no tendency to return. The sensibility in this case would be the greatest possible; but the other two requisites of level and stability would be entirely lost. The case would be even worse if the centre of gravity were higher than the centre of suspension, as the balance when deranged, if free, would make a revolution of no less than a semi-circle. A balance may be made by a fraudulent dealer to weigh falsely though its arms be equal, provided the suspension be as low as the centre of gravity, for he has only to toss his tea, for instance, forcibly into one scale to cause 15 ounces of it, or thereby, to counterpoise a pound weight in the other. Inspectors of weights, &c. are not au fait to this fruitful source of fraud among hucksters.

BALSAMS. (Baumes, Fr. Balsame, Germ.) Are native compounds of ethereal or essential oils, with resin, and frequently benzoic acid. Most of them have the consistence of honey; but a few are solid, or become so by keeping. They flow either spontaneously, or by incisions made from trees and shrubs in tropical climates. They possess peculiar powerful smells, aromatic hot tastes, but lose their odoriferous properties by long exposure to the air. They are insoluble in water; soluble, to a considerable degree, in ether; and completely in alcohol. When distilled with water, ethereal oil comes over, and resin remains in the retort.

1. Balsams with benzoic acid:—

Balsam of Peru is extracted from the myroxylon peruiferum, a tree which grows in Peru, Mexico, &c.; sometimes by incision, and sometimes by evaporating the decoction of the bark and branches of the tree. The former kind is very rare, and is imported in the husk of the cocoa nut, whence it is called balsam en coque. It is brown, transparent only in thin layers, of the consistence of thick turpentine; an agreeable smell, an acrid and bitter taste; formed of two matters, the one liquid, the other granular, and somewhat crystalline. In 100 parts, it contains 12 of benzoic acid, 88 of resin, with traces of a volatile oil.

The second sort, the black balsam of Peru, is much more common than the preceding, translucent, of the consistence of well-boiled syrup, very deep red-brown colour, an almost intolerably acrid and bitter taste, and a stronger smell than the other balsam. Stoltze regards it as formed of 69 parts of a peculiar oil, 20·7 of a resin, little soluble in alcohol, of 6·4 of benzoic acid, of 0·6 of extractive matter, and 0·9 of water.

From its high price, balsam of Peru is often adulterated with copaiba, oil of turpentine, and olive oil. One thousand parts of good balsam, should, by its benzoic acid, saturate 75 parts of crystallised carbonate of soda. It is employed as a perfume for pomatums, tinctures, lozenges, sealing-wax, and for chocolate and liqueurs, instead of vanilla, when this happens to be very dear.


Liquid amber, Storax or Styrax, flows from the leaves and trunk of the liquid amber styraciflua, a tree which grows in Virginia, Louisiana, and Mexico. It is brownish ash-grey, of the consistence of turpentine, dries up readily, smells agreeably, like benzoin, has a bitterish, sharp, burning taste; is soluble in 4 parts of alcohol, and contains only 1·4 per cent. of benzoic acid.

Balsam of Tolu flows from the trunk of the myroxylon toluiferum, a tree which grows in South America; it is, when fresh, of the consistence of turpentine, is brownish-red, dries into a yellowish or reddish brittle resinous mass, of a smell like benzoin; is soluble in alcohol and ether; affords, with water, benzoic acid.

Chinese varnish flows from the bark of the Augia sinensis; it is a greenish yellow turpentine-like substance, smells aromatic, tastes strong and rather astringent, in thin layers dries soon into a smooth shining lac, and consists of resin, ethereous oil, and benzoic acid. It is soluble in alcohol and ether; and has been employed, immemorially, in China, for lacquering and varnishing surfaces, either alone or coloured.

2. Balsams without benzoic acid:—

Copaiva balsam, balsam of copahu or capivi, is obtained from incisions made in the trunk of the Copaifera officinalis, a tree which grows in Brazil and Cayenne. It is pale yellow, middling liquid, clear transparent, has a bitter, sharp, hot taste; a penetrating disagreeable smell; a specific gravity of from 0·950 to 0·996. It dissolves in absolute alcohol, partially in spirit of wine, forms with alkalis, crystalline compounds. It consists of 45·59 ethereous oil, 52·75 of a yellow brittle resin, and 1·66 of a brown viscid resin. The oil contains no oxygen, has a composition like oil of turpentine, dissolves caoutchouc (according to Durand), but becomes oxidised in the air, into a peculiar species of resin. This balsam is used for making paper transparent, for certain lacquers, and in medicine.

Mecca balsam, or opobalsam, is obtained both by incisions of, and by boiling, the branches and leaves of the Balsamodendron Gileadense, a shrub which grows in Arabia Felix, Lesser Asia and Egypt. When fresh it is turbid, whitish, becomes, by degrees, transparent; yellow, thickish, and eventually solid. It smells peculiar, but agreeable; tastes bitter and spicy; does not dissolve completely in hot spirit of wine, and contains 10 per cent. of ethereous oil, of the spec. grav. 0·876.

Japan lac varnish flows from incisions in the trunk of the Rhus Vernix (Melanorrhea usitata) which is cultivated in Japan, and grows wild in North America. The juice becomes black in the air; when purified, dissolves in very little oil; and, mixed with colouring matter, it constitutes the celebrated varnish of the Japanese.

For Benzoin and Turpentine, see these articles in their alphabetical places.

BANDANNA. A style of calico printing, in which white or brightly coloured spots are produced upon a red or dark ground. It seems to have been practised from time immemorial in India, by binding up firmly with thread, those points of the cloth which were to remain white or yellow, while the rest of the surface was freely subjected to the dyeing operations.

Hydraulic press

The European imitations have now far surpassed, in the beauty and precision of the design, the oriental patterns; having called into action the refined resources of mechanical and chemical science. The general principles of producing bright figures upon dark grounds, are explained in the article Calico-printing; but the peculiarities of the Bandanna printing may be conveniently introduced here. In Brande’s Journal for July 1823, I described the Bandanna gallery of Messrs. Monteith at Glasgow, which, when in full action some years ago, might be reckoned the most magnificent and profitable printing apartment in the world. The white spots were produced by a solution of chlorine, made to percolate down through the Turkey red cotton cloth, in certain points, defined and circumscribed by the pressure of hollow lead types in plates, in a hydraulic press. Fig. 96., is an elevation of one press; A, the top or entablature; B B, the cheeks or pillars; C, the upper block for fastening the upper lead perforated pattern to; D, the lower block to which the fellow pattern is affixed, and which moves up and down with the piston of the press; E, the piston or ram; F, the sole or base; G, the water-trough, for the discharged or spotted calico to fall into; H, the small cistern, for the aqueous chlorine or liquor-meter, with glass tubes for indicating the height of liquor inside of the cistern; e e, glass stopcocks, for admitting the liquor into that cistern from the general reservoir; f f, stopcocks for admitting water to wash out the chlorine; g g, the pattern lead-plates, with screws for setting the patterns parallel to each other; m m, projecting angular pieces at each corner, perforated with a half-inch hole to receive the four guide-pins rising from the lower plate, which serve to secure accuracy of adjustment between the two faces of the lead pattern plates; h h, two rollers which seize and pull through the discharged pieces, and deliver them into the water-trough. To the left of D there is a stopcock for filling the trough with water; l, is the waste tube for chlorine liquor and water of washing. The contrivance for blowing a stream of air across the cloth, through the pattern tubes, is not represented in the figure.


Sixteen engines, similar to the above, each possessing the power of pressing with several hundred tons, are arranged in one line, in subdivisions of four; the spaces between each subdivision serving as passages to allow the workmen to go readily from the front to the back of the presses. Each occupies twenty-five feet, so that the total length of the apartment is 100 feet.

To each press is attached a pair of patterns in lead, (or plates as they are called,) the manner of forming which will be described in the sequel. One of these plates is fixed to the upper block of the press. This block is so contrived, that it rests upon a kind of universal joint, which enables this plate to apply more exactly to the under fellow-plate. The latter sits on the moveable part of the press, commonly called the sill. When this is forced up, the two patterns close on each other very nicely, by means of the guide-pins at the corners, which are fitted with the utmost care.

The power which impels this great hydrostatic range is placed in a separate apartment, called the machinery room. This machinery consists of two press cylinders of a peculiar construction, having solid rams accurately fitted to them. To each of these cylinders, three little force-pumps, worked by a steam-engine, are connected.

The piston of the large cylinder is eight inches in diameter, and is loaded with a top-weight of five tons. This piston can be made to rise about two feet through a leather-stuffing or collar. The other cylinder has a piston of only one inch in diameter, which is also loaded with a top-weight of five tons. It is capable, like the other, of being raised two feet through its collar.

Supposing the pistons to be at their lowest point, four of the six small force-pumps are put in action by the steam-engine, two of them to raise the large piston, and two the little one. In a short time, so much water is injected into the cylinders, that the loaded pistons have arrived at their highest points. They are now ready for working the hydrostatic discharge-presses, the water pressure being conveyed from the one apartment to the other, under ground, through strong copper tubes, of small calibre.

Two valves are attached to each press, one opening a communication between the large[86] driving-cylinder and the cylinder of the press, the other between the small driving-cylinder and the press. The function of the first is simply to lift the under-block of the press into contact with the upper-block; that of the second, is to give the requisite compression to the cloth. A third valve is attached to the press, for the purpose of discharging the water from its cylinder, when the press is to be relaxed, in order to remove or draw through the cloth.

From twelve to fourteen pieces of cloth, previously dyed Turkey-red, are stretched over each other, as parallel as possible, by a particular machine. These parallel layers are then rolled round a wooden cylinder, called by the workmen, a drum. This cylinder is now placed in its proper situation at the back of the press. A portion of the fourteen layers of cloth, equal to the area of the plates, is next drawn through between them, by hooks attached to the two corners of the webs. On opening the valve connected with the eight-inch driving-cylinder, the water enters the cylinder of the press, and instantly lifts its lower block, so as to apply the under plate with its cloth, close to the upper one. This valve is then shut, and the other is opened. The pressure of five tons in the one inch prime-cylinder, is now brought to bear on the piston of the press, which is eight inches in diameter. The effective force here will, therefore, be 5 tons × 82 = 320 tons; the areas of cylinders being to each other, as the squares of their respective diameters. The cloth is thus condensed between the leaden pattern-plates, with a pressure of 320 tons, in a couple of seconds;—a splendid example of automatic art.

The next step, is to admit the blanching or discharging liquor, (aqueous chlorine, obtained by adding sulphuric acid to solution of chloride of lime,) to the cloth. This liquor is contained in a large cistern, in an adjoining house, from which it is run at pleasure into small lead cisterns H attached to the presses; which cisterns have graduated index tubes, for regulating the quantity of liquor according to the pattern of discharge. The stopcocks on the pipes and cisterns containing this liquor, are all made of glass.

From the measure-cistern H, the liquor is allowed to flow into the hollows in the upper lead-plate, whence it descends on the cloth, and percolates through it, extracting in its passage the Turkey-red dye. The liquor is finally conveyed into the waste pipe, from a groove in the under block. As soon as the chlorine liquor has passed through, water is admitted in a similar manner, to wash away the chlorine; otherwise, upon relaxing the pressure, the outline of the figure discharged would become ragged. The passage of the discharge liquor, as well as of the water through the cloth, is occasionally aided by a pneumatic apparatus, or blowing machine; consisting of a large gasometer, from which air subjected to a moderate pressure, may be allowed to issue, and act in the direction of the liquid, upon the folds of the cloth. By an occasional twist of the air stopcock, the workman also can ensure the equal distribution of the discharging liquor, over the whole excavations in the upper plate. When the demand for goods is very brisk, the air apparatus is much employed, as it enables the workman to double his product.

The time requisite for completing the discharging process in the first press is sufficient to enable the other three workmen to put the remaining fifteen presses in play. The discharger proceeds now from press to press, admits the liquor, the air, and the water; and is followed at a proper interval by the assistants, who relax the press, move forwards another square of the cloth, and then restore the pressure. Whenever the sixteenth press has been liquored, &c., it is time to open the first press. In this routine, about ten minutes are employed; that is 224 handkerchiefs (16 × 14) are discharged every ten minutes. The whole cloth is drawn successively forward, to be successively treated in the above method.

When the cloth escapes from the press, it is passed between the two rollers in front; from which it falls into a trough of water placed below. It is finally carried off to the washing and bleaching department, where the lustre of both the white and the red is considerably brightened.

By the above arrangement of presses, 1600 pieces, consisting of 12 yards each = 19,200 yards, are converted into Bandannas in the space of ten hours, by the labour of four workmen.

The patterns, or plates, which are put into the presses to determine the white figures on the cloth, are made of lead in the following way. A trellis frame of cast-iron, one inch thick, with turned-up edges, forming a trough rather larger than the intended lead pattern, is used as the solid ground-work. Into this trough, a lead plate about one half inch thick, is firmly fixed by screw nails passing up from below. To the edges of this lead plate, the borders of the piece of sheet-lead are soldered, which covers the whole outer surface of the iron frame. Thus a strong trough is formed, one inch deep. The upright border gives at once great strength to the plate, and serves to confine the liquor. A thin sheet of lead is now laid on the thick lead-plate, in the manner of a veneer on toilette-tables, and is soldered to it round the edges. Both sheets must be made very smooth beforehand, by hammering them on a smooth stone table, and then finishing with a plane: the surface of the thin sheet (now attached), is to be covered with drawing paper, pasted[87] on, and upon this the pattern is drawn. It is now ready for the cutter. The first thing which he does, is to fix down with brass pins all the parts of the pattern which are to be left solid. He now proceeds with the little tools generally used by block-cutters, which are fitted to the different curvatures of the pattern, and he cuts perpendicularly quite through the thin sheet. The pieces thus detached are easily lifted out; and thus the channels are formed which design the white figures on the red cloth. At the bottom of the channels, a sufficient number of small perforations are made through the thicker sheet of lead, so that the discharging liquor may have free ingress and egress. Thus, one plate is finished; from which, an impression is to be taken by means of printers’ ink, on the paper pasted upon another plate. The impression is taken in the hydrostatic press. Each pair of plates constitutes a set, which may be put into the presses, and removed at pleasure.

BARBERRY. The root of this plant contains a yellow colouring matter, which is soluble in water and alcohol, and is rendered brown by alkalis. The solution is employed in the manufacture of Morocco leather.

BARILLA. A crude soda, procured by the incineration of the salsola soda, a plant cultivated for this purpose in Spain, Sicily, Sardinia, &c. Good barilla usually contains, according to my analysis, 20 per cent. of real alkali, associated with muriates and sulphates, chiefly of soda, some lime, and alumina, with very little sulphur. Caustic lyes made from it, are used in the finishing process of the hard soap manufacture. 125,068 cwts. were imported in 1835, of which only 5,807 were exported. The duty is 2s. per cwt. Of the above quantity, 64,174 came from Spain and the Balearic islands, 39,943 from the Canaries, and 20,432 from Italy and the Italian islands.

BARIUM, the metallic basis of Baryta.

BARK OF OAK, for tanning. Unfortunately, the Tables of Revenue published by the Board of Trade, mix up this bark and the dyeing barks together, and give the sum of the whole for 1835, at 826,566 cwts., of which only 2,264 were re-exported. The duty is 1d. per cwt. from British possessions, and 8d. from other parts.

BARLEY (Orge, Fr. Gerste, Germ.) English barley is that with two-rowed ears, or the hordeum vulgare distichon of the botanists; the Scotch beer or bigg, is the hordeum vulgare hexastichon. The latter has two rows of ears, but 3 corns come from the same point, so that it seems to be six-eared. The grains of bigg are smaller than those of barley, and the husks thinner. The specific gravity of English barley varies from 1·25 to 1·33; of bigg from 1·227 to 1·265; the weight of the husk of barley is 16, that of bigg 29. 1000 parts of barley flour contain, according to Einhof, 720 of starch, 56 sugar, 50 mucilage, 36·6 gluten, 12·3 vegetable albumen, 100 water, 2·5 phosphate of lime, 68 fibrous or ligneous matter. Sp. gravity of barley, is 1·235 by my trials.

BARM. The yeasty top of fermenting beer. See Beer, Distillation, Fermentation.

BARYTA or BARYTES, one of the simple earths. It may be obtained most easily by dissolving the native carbonate of barytes (Witherite) in nitric acid, evaporating the neutral nitrate till crystals be formed, draining and then calcining these in a covered platina crucible, at a bright red heat. A less pure baryta may be obtained by igniting strongly a mixture of the carbonate and charcoal, both in fine powder and moistened. It is a grayish white earthy looking substance, fusible only at the jet of the oxy-hydrogen blowpipe, has a sharp caustic taste, corrodes the tongue and all animal matter, is poisonous even in small quantities, has a very powerful alkaline reaction; a specific gravity of 4·0; becomes hot, and slakes violently when sprinkled with water, falling into a fine white powder, called the hydrate of baryta, which contains 1012 per cent. of water, and dissolves in 10 parts of boiling water. This solution lets fall abundant columnar crystals of hydrate of baryta as it cools; but it still retains one twentieth its weight of baryta, and is called baryta water. The above crystals contain 61 per cent. of water, of which, by drying, they lose 50 parts. This hydrate may be fused at a red heat without losing any more water. Of all the bases, baryta has the strongest affinity for sulphuric acid, and is hence employed either in the state of the above water, or in that of one of its neutral salts, as the nitrate or muriate, to detect the presence, and determine the quantity of that acid present in any soluble compound. Its prime equivalent, according to Berzelius, is 956,880, oxygen being 100; or 76,676, hydrogen being 1,000. Native sulphate of baryta, or heavy spar, is fraudulently used to adulterate white lead by the English dealers to a shameful extent.

BASSORINE. A constituent part of a species of gum which comes from Bassora, as also of gum tragacanth, and of some gum resins. It is semi-transparent, difficult to pulverise, swells considerably in cold or boiling water, and forms a thick mucilage without dissolving. Treated with ten times its weight of nitric acid, it affords nearly 23 per cent. of its weight of mucic acid, being much more than is obtainable from gum arabic or cherry-tree gum. Bassorine is very soluble in water slightly acidulated with[88] nitric or muriatic acid. This principle is procured by soaking gum Bassora in a great quantity of cold water, and in removing, by a filter, all the soluble parts.

BATHS. (Bains, Fr. Baden, Germ.) Warm baths have lately come into very general use, and they are justly considered as indispensably necessary in all modern houses of any magnitude, as also in club-houses, hotels, and hospitals. But the mode of constructing these baths, and of obtaining the necessary supplies of hot and cold water, does not appear to have undergone an improvement equal to the extension of their employment.

The several points in regard to warm baths, are,

  1. The materials of which they are constructed.
  2. Their situation.
  3. The supply of cold water.
  4. The supply of hot water.
  5. Minor comforts and conveniences.

1. As to the materials of which they are constructed.—Of these the best are slabs of polished marble, properly bedded with good water-tight cement, in a seasoned wooden case, and neatly and carefully united at their respective edges. These, when originally well constructed, form a durable, pleasant, and agreeable-looking bath; but the expense is often objectionable, and, in upper chambers, the weight may prove inconvenient. If of white or veined marble, they are also apt to get yellow or discoloured by frequent use, and cannot easily be cleansed; so that large Dutch tiles, as they are called, or square pieces of white earthenware, are sometimes substituted; which, however, are difficultly kept water-tight; so that, upon the whole, marble is preferable.

Where there are reasons for excluding marble, copper or tinned iron plate is the usual material resorted to. The former is most expensive in the outfit, but far more durable than the latter, which is, moreover, liable to leakage at the joints, unless most carefully made. Either the one or the other should be well covered outside and inside, with several coats of paint, which may then be marbled, or otherwise ornamented.

Wooden tubs, square or oblong, and oval, are sometimes used for warm baths; and are cheap and convenient, but neither elegant nor cleanly. The wood always contracts a mouldy smell; and the difficulty and nuisance of keeping them water-tight, and preventing shrinkage, are such as to exclude them from all except extemporaneous application.

2. As to the situation of the bath, or the part of the house in which it is to be placed.—In hotels, and club-houses, this is a question easily determined: several baths are usually here required, and each should have annexed to it, a properly warmed dressing-room. Whether they are up stairs or down stairs, is a question of convenience, but the basement story, in which they are sometimes placed, should always be avoided; there is a coldness and dampness belonging to it, in almost all weathers, which is neither agreeable nor salubrious.

In hospitals, there should be at least two or three baths on each side of the house, (the men’s and women’s), and the supply of hot water should be ready at a moment’s notice. The rooms in which the baths are placed should be light and comparatively large and airy; and such conveniences for getting into and out of the bath should be adopted, as the sick are well known to require. The dimensions of these baths should also be larger than usual.

In private houses, the fittest places for warm baths are dressing-rooms annexed to the principal bed-rooms; or, where such convenience cannot be obtained, a separate bath-room, connected with the dressing-room, and always upon the bed-room floor. All newly-built houses should be properly arranged for this purpose, and due attention should be paid to the warming of the bath-room, which ought also to be properly ventilated. A temperature of 70° may be easily kept up in it, and sufficient ventilation is absolutely requisite, to prevent the deposition of moisture upon the walls and furniture.

The objection which formerly prevailed, in respect to the difficulty of obtaining adequate supplies of water, in the upper rooms, has been entirely obviated, by having cisterns at or near the top of the house; and we would just hint that these should be so contrived, as to be placed out of the reach of frost; a provision of the utmost importance in every point of view, and very easily effected in a newly-built house, though it unfortunately happens, that architects usually regard these matters as trifles, and treat them with neglect, as indeed they do the warming and ventilation of buildings generally.

3. The supply of water of proper quality and quantity, is a very important point, as connected with the present subject. The water should be soft, clean, and pure; and as free as possible from all substances mechanically suspended in it. In many cases, it answers to dig a well for the exclusive supply of a large house with water. In most[89] parts of London this may effectually be accomplished, at a comparatively moderate expense; and, if the well be deep enough, the water will be abundant, soft, and pellucid. The labour of forcing it by a pump to the top of the house, is the only drawback; this, however, is very easily done by a horse-engine, or there are people enough about town, glad to undertake it at a shilling a day. I am led to these remarks by observing the filthy state of the water usually supplied, at very extravagant rates, by the water companies. It often partakes more of the appearance of pea-soup than of the pure element; fills our cisterns and pipes with mud and dirt, and, even when cleared by subsidence, is extremely unpalatable. It deposits its nastiness in the pipes connected with warm baths, and throws down a slippery deposit upon the bottom of the vessel itself to such an extent, as often to preclude its being used, at least as a luxury, which a clear and clean bath really is. This inconvenience may, in some measure, be avoided, by suffering the water to throw down its extraneous matters upon the bottom of the cistern, and drawing our supplies from pipes a little above it; there will, however, always be more or less deposit in the pipes themselves; and every time the water runs into the cistern, the grouts are stirred up, and diffused through its mass: this, from some cause or other, has lately become an intolerable nuisance; and he who reflects upon the miscellaneous contents of Thames water, will not have his appetite sharpened by a draught of the Grand Junction beverage, nor feel reanimated and refreshed by bathing in a compound so heterogeneous and unsavoury.

4. and 5. In public bathing establishments, where numerous and constant baths are required, the simplest and most effective means of obtaining hot water for their supply consists in drawing it directly into the baths from a large boiler, placed somewhere above their level. This boiler should be supplied with proper feeding-pipes and gauges; and, above all things, its dimensions should be ample; it should be of wrought iron or copper, except where sea water is used, in which case the latter metal is sometimes objectionable. The hot water should enter the bath by a pipe at least an inch and a half in diameter; and the cold water by one of the same dimension, or somewhat larger, so that the bath may not be long in filling. The relative proportions of the hot and cold water are, of course, to be adjusted by a thermometer, and every bath should have a two-inch waste-pipe, opening about two inches from the top of the bath, and suffering the excess of water freely to run off; so that when a person is immersed in the bath, or when the supplies of water are accidentally left open, there may be no danger of an overflow.

Where there is a laundry in the upper story of the house, or other convenient place for erecting a copper and its appurtenances, a plan similar to the above may often be conveniently adopted in private houses, for the supply of a bath upon the principal bed-room floor. An attempt is sometimes made to place boilers behind the fires of dressing-rooms, or otherwise to erect them in the room itself, for the purpose of supplying warm water; but this plan is always objectionable, from the complexity of the means by which the supply of water is furnished to the boiler, and often dangerous from the flues becoming choaked with soot, and taking fire. Steam is also apt, in such cases, to escape in quantities into the room; so that it becomes necessary to search for other methods of heating the bath; one or two of the least objectionable of which I shall describe.

1. A contrivance of some ingenuity consists in suffering the water for the supply of the bath to flow from a cistern above it, through a leaden pipe of about one inch diameter, which is conducted into the kitchen or other convenient place where a large boiler for the supply of hot water is required. The bath-pipe is immersed in this boiler, in which it makes many convolutions, and, again emerging, ascends to the bath. The operation is simply this:—the cold water passing through the convolutions of that part of the pipe which is immersed in the boiling water, receives there sufficient heat for the purpose required, and is delivered in that state by the ascending pipe into the bath, which is also supplied with cold water and waste-pipes as usual. The pipe may be of lead, as far as the descending and ascending parts are concerned, but the portion forming the worm, or convolutions immersed in the boiler should be copper, in order that the water within it may receive heat without impediment.

This plan is economical only where a large boiler is constantly kept at work in the lower part of the house; otherwise, the trouble and expense of heating such a boiler, for the mere purpose of the bath, render it unavailable. The worm-pipe is also apt to become furred, upon the outside, by the deposition of the earthy impurities of the water in which it is immersed; it then becomes a bad conductor of heat, is cleansed with difficulty, and the plan is rendered ineffective. This system, however, has been adopted, in some particular cases, with satisfaction.

2. A much more simple, economical, and independent mode of heating a warm bath, by a fire placed at a distance from it, is the following, which is found to answer perfectly in private houses, as well as upon a more extended scale in large establishments.[90] It is certainly open to some objections, but these are overbalanced by its advantages. A waggon-shaped boiler, holding about six gallons of water, is properly placed over a small furnace, in any convenient and safe part of the house, as the kitchen, scullery, servants’ hall, or wash-house. The bath itself, of the usual dimensions and construction, is placed where it is wanted, with a due supply of cold water from above. Two pipes issue from within an inch of the bottom of the bath at its opposite extremities; one at the head of the bath, about one inch, and the other at the foot, an inch and one eighth in diameter. These tubes descend to the boiler, the smaller one entering it at the bottom, and the larger one issuing from its top.

Under these circumstances, supposing the pipes and boiler every where perfectly tight, when the bath is filled, the water will descend into and expel the air from the boiler, and completely fill it. Now, upon making a gentle fire under the boiler, an ascending current of warm water will necessarily pass upwards through the larger pipe which issues from its top, and cold water will descend by the pipe which enters at the bottom; and thus, by the establishment of currents, the whole mass of water in the bath will become heated to the desired point; or, if above it, the temperature may easily be lowered by the admixture of cold water.

The advantages of this form of bath are numerous. The shorter the pipes of communication the better, but they may extend forty or fifty feet without any inconvenience beyond that of expense; so that there is no obstacle to the bath being near the bed-room while the boiler is on the basement story. There is but little time required for heating the bath; the water in which may, if requisite, be raised to about 100° in about half an hour from the time of lighting the fire. The consumption of fuel is also trifling.

The following are the chief disadvantages attendant upon this plan, and the means of obviating them:—

It is necessary, when the water has acquired its proper temperature, to withdraw the fire from the boiler, or not to use the bath immediately, as it may go on acquiring some heat from the boiler, so that we may become inconveniently hot in the bath. When, therefore, this bath is used, we may proceed as follows:—heat the water in it an hour before it is wanted, to about 100°, and then extinguish the fire. The water will retain its temperature, or nearly so, for three or four hours, especially if the bath be shut up with a cover; so that when about to use it, cold water may be admitted till the temperature is lowered to the required point, and thus all the above inconveniences are avoided.

Another disadvantage of this bath arises from too fierce a fire being made under the boiler, so as to occasion the water to boil within it, a circumstance which ought always to be carefully avoided. In that case, the steam rising in the upper part of the boiler, and into the top pipe, condenses there, and occasions violent concussions, the noise of which often alarms the whole house, and leads to apprehensions of explosion, which, however, is very unlikely to occur; but the concussions thus produced injure the pipes, and may render them leaky: so that in regard to these, and all other baths, &c., we may remark, that the pipes should pass up and down in such parts of the house as will not be injured if some leakage takes place; and under the bath itself should be a sufficiently large leaden tray with a waste-pipe, to receive and carry off any accidental drippings, which might injure the ceilings of the rooms below. In all newly-built houses, two or three flues should be left in proper places for the passage of ascending and descending water-pipes; and these flues should in some way receive at their lower part a little warm air in winter, to prevent the pipes freezing: the same attention should also be paid to the situation of the cisterns of water in houses, which should be kept within the house, and always supplied with a very ample waste-pipe, to prevent the danger of overflow. Cisterns thus properly placed, and carefully constructed, should be supplied from the water-mains by pipes kept under ground, till they enter the house, and not carried across the area, or immediately under the pavement, where they are liable to freeze.

3. Baths are sometimes heated by steam, which has several advantages: it may either be condensed directly into the water of the bath, or, if the bath be of copper or tinned iron, it may be conducted into a casing upon its outside, usually called a jacket; in the latter case there must be a proper vent for the condensed water, and for the escape of air and waste steam. Steam is also sometimes passed through a serpentine pipe, placed at the bottom of the bath. But none of these methods are to be recommended for adoption in private houses, and are only advisable in hospitals, or establishments where steam boilers are worked for other purposes than the mere heating of baths.

Many copper and tin baths have been lately constructed in London, with a little furnace attached to one end, and surrounded with a case or jacket, into which the water flows and circulates backwards and forwards till the whole mass in the bath gets heated to the due degree. One of the best of these is that constructed by Mr. Benham,[91] of Wigmore Street. The bath must be placed near the fire-grate, and the smoke-pipe of the attached furnace be conducted up the chimney a certain way to secure a sufficient draught to maintain combustion. The above bath, well managed, heats the water from 50° to 98° in about 20 or 25 minutes, as I have experimentally proved. When the proper temperature is attained, the fire must of course be extinguished.

BDELLIUM. A gum resin, produced by an unknown plant which grows in Persia and Arabia. It comes to us in yellowish or reddish pieces, smells faintly, like myrrh, and consists of 59 resin, 9·2 gum, 30·6 bassorine, and 1·2 ethereous oil.

BEER. (Bière, Fr. Bier, Germ.) The fermented infusion of malted barley, flavoured with hops, constitutes the best species of beer; but there are many beverages of inferior quality to which this name is given, such as spruce beer, ginger beer, molasses beer, &c.; all of which consist of a saccharine liquor, partially advanced into the vinous fermentation, and flavoured with peculiar substances.

The ancients were acquainted with beer, and the Romans gave it the appropriate name of Cerevisia (quasi Ceresia), as being the product of corn, the gift of Ceres. The most celebrated liquor of this kind in the old time, was the Pelusian potation, so called from the town where it was prepared at the mouth of the Nile. Aristotle speaks of the intoxication caused by beer; and Theophrastus very justly denominated it the wine of barley. We may, indeed, infer from the notices found in historians, that drinks analogous to our beer were in use among the ancient Gauls, Germans, and in fact almost every people of our temperate zone; and they are still the universal beverage in every land where the vine is not an object of rustic husbandry.

The manufacture of beer, or the art of brewing, may be conveniently considered under five heads:—

1. An examination of the natural productions which enter into its composition; or of barley and hops.

2. The changes which barley must undergo to fit it for making beer; or the processes of malting and mashing.

3. The formation of a proper wort from the mashed malt and hops.

4. The fermentation of that wort; and

5. The fining, ripening, and preservation of the beer.

I. Of the materials.

1. Barley, wheat, maize, and several other kinds of corn are capable of undergoing those fermentative changes, by which beer may be made; but the first substance is by far the fittest. There are two species of barley, the hordeum vulgare or common barley, having two seeds arranged in a row on its spikes; and the hordeum hexastichon, in which three seeds spring from one point, so that its double row has apparently six seeds. The former is the proper barley, and is much the larger sized grain; the latter is little known in England, but is much cultivated in Scotland under the name of bear or big; being a hardy plant adapted to a colder country. The finer the climate in which barley grows the denser and larger its seed, and the thinner its husk; thus the Norfolk and Suffolk barley is distinguished in these respects from that of Aberdeenshire. Big is a less compact grain than barley; the weight of a Winchester bushel (2150·42 cubic inches) of the former is only about 47 libs, while that of a bushel of the latter is nearly 51 libs. Their constituents, however, bear much the same proportion to each other.

The quality of barley is proved not only by its density when dry, but by the increase of volume which it acquires when steeped in water. Thus,

  100  measures  of  average  English barley thereby  swell into  124.
  100 of Scotch  ditto,   121.
  100 of bigg or bear,   118.
Nay,  100  of very fine Suffolk barley have swollen into 183.
While  100  of an inferior Scotch bigg became no more than 109.

This circumstance indicates so nearly the probable yield of malt, that it is carefully attended to by the officers of excise, who gauge the steep cistern, and levy their duty in conformity with the largest volume, 100 pounds of good barley become almost one half heavier by the absorption of moisture; and weigh upon an average 147 pounds; the best of course taking up most water.

By chemical analysis barley flour seems to consist of 67·18 parts of hordeine, or starch and gluten intimately combined, 7·29 of vegetable fibre, 1·15 of coagulated albumen, 3·52 parts of gluten, 5·21 of sugar, 4·62 of gum, 0·24 of phosphate of lime, and 9·37 of water. The loss amounted to 1·42. To these principles should be added a peculiar volatile oil of a concrete nature, which is obtained during the process of distilling fermented malt wash. (See Whiskey.) It may also be extracted from barley flour, by the solvent action of alcohol; and never amounts to more than a few parts in the thousand. The husk also contains some of that fetid oil. Proust thought that he had discovered in barley a peculiar principle, to which he gave the name of hordeine, and which he separated from starch by the action of both cold and boiling water. He found that by treating[92] barley meal successively with water, he obtained from 89 to 90 parts of a farinaceous substance, composed of from 32 to 33 of starch, and from 57 to 58 of hordeine. Einhof obtained from barley seeds, 70·05 of flour, 18·75 of husks or bran, and 11·20 of water.

According to Proust hordeine is a yellowish powder, not unlike fine saw-dust. It contains no azote, for it affords no ammonia by distillation, and is therefore very dissimilar to gluten. In the germination of barley, which constitutes the process of malting, the proportion of hordeine is greatly diminished by its conversion into sugar and starch. Other chemists suppose that the hordeine of Proust is merely a mixture of the bran of the barley with starch and gluten. It is obvious that the subject stands in need of new chemical researches. In barley the husk constitutes from one fourth to one fifth of the whole weight; in oats it constitutes one third; and in wheat, one tenth. From the analysis of barley flour recently made, it appears to consist in 1000 parts: of water, 100; albumine, 22·3; sugar, 56; gum or mucilage, 50; gluten, 37·6; starch, 720; phosphate of lime, 2·5.

2. The hop, humulus lupulus, the female flowers of the plant. Ives first directed attention to a yellow pulverulent substance which invests the scales of the catkins, amounting to about one eighth of their weight; and referred to it the valuable properties which hops impart to beer. We may obtain this substance by drying the hops at a temperature of 86° F., introducing them into a coarse canvass bag, and shaking it so that the yellow powder shall pass through the pores of the canvass. This powder bears some resemblance to lycopodium. Of the 13 parts in 100 of this powder, 4 parts are foreign matters, derived from the scales of the cones; leaving 9 parts of a peculiar granular substance. When distilled with water, this substance affords two per cent. of its weight (210 for 100 times the weight of hops) of a volatile colourless oil, to which the plant owes its peculiar aroma. This oil dissolves in water in considerable quantity. It appears to contain sulphur (for it blackens solutions of silver), and also acetate of ammonia. No less than 65 per cent. of the yellow dust is soluble in alcohol. This solution, treated with water and distilled, leaves a resin, which amounts to 52·5 per cent. It has no bitter taste, and is soluble in alcohol and ether. The watery solution from which the resin was separated contains the bitter substance which has been called lupuline by Payen and Chevallier, mixed with a little tannin and malic acid. To obtain this in a state of purity, the free acid must be saturated with lime, the solution evaporated to dryness, and the residuum must be treated with ether, which removes a little resin; after which the lupuline is dissolved out by alcohol, which leaves the malate of lime. On evaporating away the alcohol, the lupuline remains, weighing from 8·3 to 12·5 per cent. It is sometimes white, or slightly yellowish, and opaque, sometimes orange yellow, and transparent. At ordinary temperatures it is inodorous, but when heated strongly it emits the smell of hops. It possesses the characteristic taste and bitterness of the hop. Water dissolves it only in the proportion of 5 per cent., but it thereby acquires a pale yellow colour. Lupuline is neither acid nor alkaline; it is acted upon neither by the dilute acids nor alkalies, nor by the solutions of the metallic salts: it is quite soluble in alcohol, but hardly in ether. It contains apparently no azote, for it affords no ammonia by destructive distillation; but only an empyreumatic oil.

The yellow dust of hops contains, moreover, traces of a fatty matter, gum, a small quantity of an azotised substance, and several saline combinations in minute quantity. Boiling water dissolves from 19 to 31 per cent., of the contents of the dust, of which a large proportion is resin. Ives thought that the scales of the catkins of hops, when freed from the yellow powder, contained no principles analogous to it; but Payen and Chevallier have proved the contrary. The cones of hop give up to boiling alcohol 36 per cent. of soluble matter; while the same cones, stripped of their yellow powder, yield only 26 per cent.; and further, these chemists found the same principles in the different parts of the hop, but in different proportions.

The packing of the hop catkins or cones is one of the most important operations towards the preservation of this plant; and is probably the cause of the enormous difference in value between the English and French hops after a few years’ keeping. The former, at the end of six years, possess still great value, and may be sold as an article only two or three years old; while the latter have lost the greater part of their value in three years, and are no more saleable at the end of four. In France, it is packed merely by tramping it with the feet in sacks. Under this slight pressure, large interstitial spaces are left amid the mass of the hops, through which the air freely circulates, carrying off the essential oil, and oxygenating some of the other proximate principles, so as to render them inert. By the English method, on the contrary, the hops, after being well rammed into strong sacks hung in frames, are next subjected to the action of a hydraulic press. The valuable yellow powder thus inclosed on every side by innumerable compact scales, is completely screened from the contact of the atmosphere, and from all its vicissitudes of humidity. Its essential oil, in particular the basis of its flavour, is preserved without decay.


According to the experiments of Chevallier and Payen upon the hops of England, Flanders, the Netherlands, and the department of the Vosges, those of the county of Kent afforded the largest cones, and were most productive in useful secreted and soluble matters. Next to them were the hops of Alost.

The best hops have a golden yellow colour, large cones, an agreeable aroma; when rubbed between the hands, they leave yellow traces, powerfully odoriferous, without any broken portions of the plant, such as leaves, stems, and scaly fragments. When alcohol is digested on good hops, from 9 to 12 per cent. of soluble yellow matter may be obtained by evaporating it to dryness. This is a good test of their quality.

The best-flavoured and palest hops are packed in sacks of fine canvass, which are called pockets, and weigh about 112 cwt. each. These are bought by the ale brewer. The stronger-flavoured and darker-coloured hops are packed in bags of a very coarse texture like door-mats, called hop bags: these contain generally about 3 cwt., and are sold to the porter and beer brewers. After the end of a year or two, hops are reckoned to have lost much of their marketable value, and are then sold to the second-rate porter brewers, under the name of old hops. The finest hops are grown in the neighbourhood of Canterbury; but those of Worcester have an agreeable mildness of flavour, greatly admired by many ale drinkers. When the bitter and aromatic principles disappear, the hops are no better than so much chaff; therefore, an accurate chemical criterion of their principles would be a great benefit to the brewer.

II. Malting.—This process consists of three successive operations; the steeping; the couching, sweating, and flooring; and the kiln-drying.

The steeping is performed in large cisterns made of wood or stone, which being filled with clear water up to a certain height, a quantity of barley is shot into them, and well stirred about with rakes. The good grain is heavy, and subsides; the lighter grains, which float on the surface, are damaged, and should be skimmed off; for they would injure the quality of the malt, and the flavour of the beer made with it. They seldom amount to more than two per cent. More barley is successively emptied into the steep cistern, till the water stands only a few inches, about five, above its surface; when this is levelled very carefully, and every light seed is removed. The steep lasts from forty to sixty hours, according to circumstances; new barley requiring a longer period than old, and bigg requiring much less time than barley.

During this steep, some carbonic acid is evolved from the grains, and combines with the water, which, at the same time, acquires a yellowish tinge, and a strawy smell, from dissolving some of the extractive matter of the barley husks. The grain imbibes about one half its weight of water, and increases in size by about one-fifth. By losing this extract, the husk becomes about one seventieth lighter in weight, and paler in colour.

The duration of the steep depends, in some measure, upon the temperature of the air, and is shorter in summer than in winter. In general from 40 to 48 hours will be found sufficient for sound dry grain. Steeping has for its object to expand the farina of the barley with humidity, and thus prepare the seed for germination, in the same way as the moisture of the earth prepares for the growth of the radicle and plumula in seed sown in it. Too long continuance in the steep is injurious; because it prevents the germination at the proper time, and thereby exhausts a portion of the vegetative power: it causes also an abstraction of saccharine matter by the water. The maceration is known to be complete when the grain may be easily transfixed with a needle, and is swollen to its full size. The following is reckoned a good test:—If a barley-corn, when pressed between the thumb and fingers, continues entire in its husk, it is not sufficiently steeped; but if it sheds its flour upon the fingers, it is ready. When the substance exudes in the form of a milky juice, the steep has been too long continued, and the barley is spoiled for germination.

In warm weather it sometimes happens that the water becomes acescent before the grain is thoroughly swelled. This accident, which is manifest to the taste and smell, must be immediately obviated by drawing off the foul water through the tap at the bottom of the cistern, and replacing it with fresh cold water. It does no harm to renew it two or three times at one steep.

The couch.—The water being drawn off, and occasionally a fresh quantity passed through, to wash away any slimy matter which may have been generated in warm weather, the barley is now laid upon the couch floor of stone flags, in square heaps from 12 to 16 inches high, and left in that position for 24 hours. At this period, the bulk of the grain being the greatest, it may be gauged by the revenue officers if they think fit. The moisture now leaves the surface of the barley so completely, that it imparts no dampness to the hand. By degrees, however, it becomes warm; the temperature rising 10° above the atmosphere, while an agreeable fruity smell is evolved. At this time, if the hand be thrust into the heap, it not only feels warm, but it gets bedewed with moisture. At this sweating stage, the germination begins; the fibrils of the radicle first sprout forth from the tip of every grain, and a white elevation appears, that soon[94] separates into three or more radicles, which grow rapidly larger. About a day after this appearance, the plumula peeps forth at the same point, proceeding thence beneath the husk to the other end of the seed, in the form of a green leaflet.

The greatest heat of the couch is usually about 96 hours after the barley has been taken out of the steep. In consequence, the radicles tend to increase in length with very great rapidity, and must be checked by artificial means, which constitute the chief art of the maltster. He now begins to spread the barley thinner on the floor, and turns it over several times in the course of a day, bringing the portions of the interior into the exterior surface. The depth, which was originally 15 or 16 inches, is lowered a little at every turning over, till it be brought eventually down to three or four inches. Two turnings a day are generally required. At this period of spreading or flooring, the temperature in England is about 62°, and in Scotland 5 or 6 degrees lower.

About a day after the radicles appear, the rudiments of the stem, or of the plumula, sprout forth, called by the English maltsters the acrospire. It issues from the same end of the seed as the radicle, but turns round, and proceeds within the husk towards the other end, and would there come forth as a green leaf, were its progress not arrested. The malting, however, is complete before the acrospire becomes a leaf.

The barley couch absorbs oxygen and emits carbonic acid, just as animals do in breathing, but to a very limited extent; for the grain loses only three per cent. of its weight upon the malt floor, and a part of this loss is due to waste particles. As the acrospire creeps along the surface of the seed, the farina within undergoes a remarkable alteration. The gluten and mucilage disappear, in a great measure, the colour becomes whiter, and the substance becomes so friable that it crumbles into meal between the fingers. This is the great purpose of malting, and it is known to be accomplished when the plumula or acrospire has approached the end of the seed. Now the further growth must be completely stopped. Fourteen days may be reckoned the usual duration of the germinating stage of the malting operations in England; but in Scotland, where the temperature of the couch is lower, eighteen days or even twenty-one, are sometimes required. The shorter the period within the above limits, the more advantageous is the process to the maltster, as he can turn over his capital the sooner, and his malt is also somewhat the better. Bigg is more rapid in its germination than barley, and requires to be still more carefully watched. In dry weather it is sometimes necessary to water the barley upon the couch.

Occasionally the odour disengaged from the couch is offensive, resembling that of rotten apples. This is a bad prognostic, indicating either that the barley was of bad quality, or that the workmen, through careless shovelling, have crushed a number of the grains in turning them over. Hence when the weather causes too quick germination, it is better to check it by spreading the heap out thinner than by turning it too frequently over. On comparing different samples of barley, we shall find that the best develope the germ or acrospire quicker than the radicles, and thus occasion a greater production of the saccharine principle; this conversion advances along with the acrospire, and keeps pace with it, so that the portion of the seed to which it has not reached, is still in its unaltered starchy state. It is never complete for any single barleycorn till the acrospire has come to the end opposite to that from which it sprung; hence one part of the corn may be sugary, while the other is still insipid. If the grain were allowed to vegetate beyond this term, the radicles being fully one third of an inch long, the future stem would become visibly green in the exterior; it would shoot forth rapidly, the interior of the grain would become milky, with a complete exhaustion of all its useful constituents, and nothing but the husk would remain.

In France, the brewers, who generally malt their barley themselves, seldom leave it on the couch more than 8 or 10 days, which, even taking into account the warmer climate of their country, is certainly too short a period, and hence they make inferior wort to the English brewer, from the same quantity of malt.

At the end of the germination, the radicles have become 112 longer than the barley, and are contorted so that the corns hook into one another, but the acrospire is just beginning to push through. A moderate temperature of the air is best adapted to malting; therefore it cannot be carried on well during the heat of summer or the colds of winter. Malt-floors should be placed in substantial thick-walled buildings, without access of the sun, so that a uniform temperature of 59° or 60° may prevail inside. Some recommend them to be sunk a little under the surface of the ground, if the situation be dry.

During germination a remarkable change has taken place in the substance of the grain. The glutinous constituent has almost entirely disappeared, and is supposed to have passed into the matter of the radicles, while a portion of the starch is converted into sugar and mucilage. The change is similar to what starch undergoes when dissolved in water, and digested in a heat of about 160°F. along with a little gluten.[95] The thick paste becomes gradually liquid, transparent, and sweet tasted, and the solution contains now, sugar and gum, mixed with some unaltered starch. The gluten suffers a change at the same time, and becomes acescent, so that only a certain quantity of starch can be thus converted by a quantity of gluten. By the artificial growth upon the malt-floor, all the gluten and albumen present in barley are not decomposed, and only about one half of the starch is converted into sugar; the other half, by a continuance of the germination, would only go to the growth of the roots and stems of the plant; but it receives its nearly complete conversion into sugar without any notable waste of substance in the brewer’s operation of mashing.

The kiln-drying.—When the malt has become perceptibly dry to the hand upon the floor, it is taken to the kiln, and dried hard with artificial heat, to stop all further growth, and enable it to be kept, without change, for future use, at any time. The malt-kiln, which is particularly described in the next page, is a round or a square chamber, covered with perforated plates of cast iron, whose area is heated by a stove or furnace, so that not merely the plates on which the malt is laid are warmed, but the air which passes up through the stratum of malt itself, with the effect of carrying off very rapidly the moisture from the grains. The layer of malt should be about 3 or 4 inches thick, and evenly spread, and its heat should be steadily kept at from the 90th to the 100th degree of Fahrenheit’s scale, till the moisture be mostly exhaled from it. During this time the malt must be turned over at first frequently, and latterly every three or four hours. When it is nearly dry, its temperature should be raised to from 145° to 165°F., and it must be kept at this heat till it has assumed the desired shade of colour, which is commonly a brownish-yellow or a yellowish-brown. The fire is now allowed to die out, and the malt is left on the plates till it has become completely cool; a result promoted by the stream of cool air, which now rises up through the bars of the grate; or the thoroughly dry browned malt may, by damping the fire, be taken hot from the plates, and cooled upon the floor of an adjoining apartment. The prepared malt must be kept in a dry loft, where it can be occasionally turned over till it is used. The period of kiln-drying should not be hurried. Many persons employ two days in this operation.

According to the colour and the degree of drying, malt is distributed into three sorts; pale, yellow, and brown. The first is produced when the highest heat to which it has been subjected is from 90° to 100° F.; the amber yellow, when it has suffered a heat of 122°; and the brown when it has been treated as above described. The black malt used by the porter brewer to colour his beer, has suffered a much higher heat, and is partially charred. The temperature of the kiln should, in all cases, be most gradually raised, and most equably maintained. If the heat be too great at the beginning, the husk gets hard dried, and hinders the evaporation of the water from the interior substance; and should the interior be dried by a stronger heat, the husk will probably split, and the farina become of a horny texture, very refractory in the mash-tun. In general, it is preferable to brown malt, rather by a long-continued moderate heat, than by a more violent heat of shorter duration, which is apt to carbonise a portion of the mucilaginous sugar, and to damage the article. In this way, the sweet is sometimes converted into a bitter principle.

During the kiln-drying, the roots and acrospire of the barley become brittle, and fall off; and are separated by a wire sieve whose meshes are too small to allow the malt itself to pass through.

A quantity of good barley, which weighs 100 pounds, being judiciously malted, will weigh, after drying and sifting, 80 pounds. Since the raw grain, dried by itself at the same temperature as the malt, would lose 12 per cent. of its weight in water, the malt process dissipates out of these remaining 88 pounds, only 8 pounds, or 8 per cent. of the raw barley. This loss consists of

1 12  per cent.  dissolved out in the steep water,
3   dissipated in the kiln,
3   by the falling of the fibrils,
  12 of waste.

The bulk of good malt exceeds that of the barley from which it was made, by about 8 or 9 per cent.

The operation of kiln-drying is not confined to the mere expulsion of the moisture from the germinated seeds; but it serves to convert into sugar a portion of the starch which remained unchanged, and that in a twofold way; first, by the action of the gluten upon the fecula at an elevated temperature, as also by the species of roasting which the starch undergoes, and which renders it of a gummy nature. (See Starch.) We shall have a proof of this explanation, if we dry one portion of the malt in a naturally dry atmosphere, and another in a moderately warm kiln; the former will yield less saccharine extract than the latter. Moreover, the kiln-dried malt has a peculiar, agreeable, and faintly burned taste, probably from a small portion of empyreumatic[96] oil formed in the husk, and which not only imparts its flavour to the beer, but also contributes to its preservation. It is therefore obvious, that the skilful preparation of the malt must have the greatest influence both on the quantity and quality of the worts to be made from it. If the germination be pushed too far, a part of the extractible matter is wasted; if it has not advanced far enough, the malt will be too raw, and too much of its substance will remain as an insoluble starch; if it is too highly kiln-dried, a portion of its sugar will be caramelised, and become bitter; and if the sweating was imperfect or irregular, much of the barley may be rendered lumpy and useless. Good malt is distinguishable by the following characters:—

The grain is round and full, breaks freely between the teeth, and has a sweetish taste, an agreeable smell, and is full of a soft flour from end to end. It affords no unpleasant flavour on being chewed; it is not hard, so that when drawn along an oaken table across the fibres, it leaves a white streak, like chalk. It swims upon water, while unmalted barley sinks in it. Since the quality of the malt depends much on that of the barley, the same sort only should be used for one malting. New barley germinates quicker than old, which is more dried up; a couch of a mixture of the two would be irregular, and difficult to regulate.

Malt kiln

Description of the malt kiln.Figs. 97, 98, 99, 100. exhibit the construction of a well-contrived malt kiln. Fig. 97. is the ground plan; fig. 98. is the vertical section; and figs. 99. and 100., a horizontal and vertical section in the line of the malt-plates. The same letters denote the same parts in each of the figures. A cast-iron cupola-shaped oven is supported in the middle, upon a wall of brickwork four feet high; and beneath it, are the grate and its ash-pit. The smoke passes off through two equi-distant pipes into the chimney. The oven is surrounded with four pillars, on whose top a stone lintel is laid: a is the grate, 9 inches below the sole of the oven b; c c c c are the four nine-inch strong pillars of brickwork which bear the lintel m; d d d d d d are strong nine-inch pillars, which support the girder and joists upon which perforated plates repose; e denotes a vaulted arch on each of the four sides of the oven; f is the space between the kiln and the side arch, into which a workman may enter, to inspect and clean the kiln; g g, the walls on either side of the kiln, upon which the arches rest, h, the space for the ashes to fall; k, the fire-door of the kiln; l l, junction-pieces to connect the pipes r r with the kiln; the mode of attaching them is shown in fig. 99. These smoke-pipes lie about three feet under the iron plates, and at the same distance from the side walls; they are supported upon iron props, which are made fast to the arches. In fig. 98., u[97] shows their section; at s s, fig. 99., they enter the chimney, which is provided with two register or damper plates, to regulate the draught through the pipes. These registers are represented by t t, fig. 100., which shows a perpendicular section of the chimney. m, fig. 98., is the lintel which causes the heated air to spread laterally instead of ascending in one mass in the middle, and prevents any combustible particles from falling upon the iron cupola. n n are the main girders of iron for the iron beams o o, upon which the perforated plates p lie; q, fig. 98., is the vapour pipe in the middle of the roof, which allows the steam of the drying malt to escape. The kiln may be heated either with coal or wood.

The size of this kiln is about 20 feet square; but it may be made proportionally either smaller or greater. The perforated floor should be large enough to receive the contents of one steep or couch.

The perforated plate might be conveniently heated by steam pipes, laid zig-zag, or in parallel lines under it; or a wire-gauze web might be stretched upon such pipes. The wooden joists of a common floor would answer perfectly to support this steam-range, and the heat of the pipes would cause an abundant circulation of air. For drying the pale malt of the ale brewer, this plan is particularly well adapted.

The kiln-dried malt is sometimes ground between stones in a common corn mill, like oatmeal; but it is more generally crushed between iron rollers, at least for the purposes of the London brewers.

Crushing mill

The crushing mill.—The cylinder malt-mill is constructed as shown in fig. 101, 102. I is the sloping-trough, by which the malt is let down from its bin or floor to the hopper A of the mill, whence it is progressively shaken in between the rollers B D. The rollers are of iron, truly cylindrical, and their ends rest in bearers of hard brass, fitted into the side frames of iron. A screw E goes through the upright, and serves to force the bearer of the one roller towards that of the other, so as to bring them closer together when the crushing effect is to be increased. G is the square end of the axis, by which one of the rollers may be turned either by the hand or by power; the other derives its rotatory motion from a pair of equal-toothed wheels H, which are fitted to the other end of the axes of the rollers. d is a catch which works into the teeth of a ratchet-wheel on the end of one of the rollers (not shown in this view). The lever c strikes the trough b at the bottom of the hopper, and gives it the shaking motion for discharging the malt between the rollers, from the slide sluice a. e e, fig. 101., are scraper-plates of sheet iron, the edges of which press by a weight against the surfaces of the rollers, and keep them clean.

Instead of the cylinders, some employ a crushing mill of a conical-grooved form like a coffee mill, upon a large scale. (See the general plan, infrà.)

The mashing and boiling.—Mashing is the operation by which the wort is extracted, or eliminated from the malt, and whereby a saccharo-mucilaginous extract is made from it. The malt should not in general be ground into a fine meal, for in that case it would be apt to form a cohesive paste with hot water, or to set, as it is called, and to be difficult to drain. In crushed malt, the husk remains nearly entire, and thus helps to keep the farinaceous particles open and porous to the action of the water. The bulk of the crushed malt is about one-fifth greater than that of the whole, or one bushel of malt gives a bushel and a quarter of crushed malt. This is frequently allowed to lie a few days in a cool place, in order that it may attract moisture from the air, which it does very readily by its hygrometric power. Thus, the farinaceous substance which had been indurated in the kiln, becomes soft, spongy, and fit for the ensuing process of watery extraction.

Mashing has not for its object merely to dissolve the sugar and gum already present in the malt, but also to convert into a sweet mucilage the starch which had remained unchanged during the germination. We have already stated that starch, mixed with gluten, and digested for some time with hot water, becomes a species of sugar. This conversion takes place in the mash-tun. The malted barley contains not only a portion of gluten, but diastase more than sufficient to convert the starch contained in it, by this means, into sugar.


The researches of Payen and Persoz show, that the mucilage formed by the reaction of malt upon starch, may either be converted into sugar, or be made into permanent gum, according to the temperature of the water in which the materials are digested. We take of pale barley malt, ground fine, from 6 to 10 parts, and 100 parts of starch; we heat, by means of a water-bath, 400 parts of water in a copper, to about 80°F.; we then stir in the malt, and increase the heat to 140°F., when we add the starch, and stir well together. We next raise the temperature to 158°, and endeavour to maintain it constantly at that point, or at least to keep it within the limits of 167° on the one side, and 158° on the other. At the end of 20 or 30 minutes, the original milky and pasty solution becomes thinner, and soon after as fluid nearly as water. This is the moment in which the starch is converted into gum, or into that substance which the French chemists call dextrine, from its power of polarising light to the right hand, whereas common gum does it to the left. If this merely mucilaginous solution, which seems to be a mixture of gum with a little liquid starch and sugar, be suitably evaporated, it may serve for various purposes in the arts to which gum is applied, but with this view, it must be quickly raised to the boiling point, to prevent the farther operation of the malt upon it. If we wish, on the contrary, however, to promote the saccharine fermentation, for the formation of beer, we must maintain the temperature at between 158° and 167° for three or four hours, when the greatest part of the gum will have passed into sugar, and by evaporation of the liquid at the same temperature, a starch syrup may be obtained like that procured by the action of sulphuric acid upon starch. The substance, which operates in the formation of sugar, or is the peculiar ferment of the sugar fermentation, may be considered as a residuum of the gluten or vegetable albumen in the germinating grain: it is reckoned by Payen and Persoz, a new proximate principle called diastase, which is formed during malting, in the grains of barley, oats, and wheat, and may be separated in a pure state, if we moisten the malt flour for a few minutes in cold water, press it out strongly, filter the solution, and heat the clear liquid in a water bath, to the temperature of 158°. The greater part of that albuminous azotised substance is thus coagulated, and is to be separated by a fresh filtration; after which, the clear liquid is to be treated with alcohol, when a flocky precipitate appears, which is diastase. To purify it still further, especially from the azotised matter, we should dissolve it in water, and precipitate again with alcohol. When dried at a low temperature, it appears as a solid white substance, which contains no azote; is insoluble in alcohol, but dissolves in water and proof spirit. Its solution is neutral and tasteless; when left to itself, it changes with greater or less rapidity according to the temperature, and becomes sour at a temperature of from 149° to 167°. It has the property of converting starch into gum (dextrine) and sugar, and indeed, when sufficiently pure, with such energy that one part of it disposes 2000 parts of dry starch to that change, but it operates the quicker the greater its quantity. Whenever the solution of diastase with starch or with dextrine is heated to the boiling point, it loses the sugar-fermenting property. One hundred parts of well-malted starch appear to contain about one part of this substance.

We can now understand the theory of malting, and the limits between which the temperature of the liquor, ought to be maintained in this operation; namely, the range between 157° and 160°F. It has been ascertained as a principle in mashing, that the best and soundest extract of the malt, is to be obtained, first of all, by beginning to work with water at the lowest of these heats, and to conclude the mash with water at the highest. Secondly, not to operate the extraction at once with the whole of the water that is to be employed; but with separate portions and by degrees. The first portion is added with the view of penetrating equally the crushed malt, and of extracting the already formed sugar; the next for effecting the sugar fermentation by the action of the diastase. By this means also, the starch is not allowed to run into a cohesive paste, and the extract is more easily drained from the poorer mass, and comes off in the form of a nearly limpid wort. The thicker moreover, or the less diluted the mash is, so much the easier is the wort fined in the boiler or copper by the coagulation of the albuminous matter: these principles illustrate, in every condition, the true mode of conducting the mashing process; but different kinds of malt require a different treatment. Pale and slightly kilned malt requires a somewhat lower heat than malt highly kilned, because the former has more undecomposed starch, and is more ready to become pasty. The former also, for the same reason, needs a more leisurely infusion than the latter, for its conversion into mucilaginous sugar. The more sugar the malt contains, the more is its saccharine fermentation accelerated by the action of the diastase. What has been here said of pale malt, is still more applicable to the case of a mixture of raw grain with malt, for it requires still gentler heats, and more cautious treatment.

III. The mash-tun is a large circular tub with a double bottom; the uppermost of which is called a false bottom, and is pierced with many holes. There is a space of about 2 or 3 inches between the two, into which the stopcocks enter, for letting in the water and drawing off the wort. The holes of the false bottom should be burned, and not bored,[99] to prevent the chance of their filling up by the swelling of the wood, which would obstruct the drainage: the holes should be conical, and largest below, being about 38 of an inch there, and 18 at the upper surface. The perforated bottom must be fitted truly at the sides of the mash-tun, so that no grains may pass through. The mashed liquor is let off into a large back, from which it is pumped into the wort coppers. The mash-tun is provided with a peculiar rotatory apparatus for agitating the crushed grains and water together, which we shall presently describe. The size of the wort copper is proportional to the amount of the brewing, and it must, in general, be at least so large as to operate upon the whole quantity of wort made from one mashing; that is, for every quarter of malt mashed, the copper should contain 140 gallons. The mash-tun ought to be at least a third larger, and of a conical form, somewhat wider below than above. The quantity of water to be employed for mashing, or the extraction of the wort, depends upon the greater or less strength to be given to the beer. The seeds of the crushed malt, after the wort is drawn off, retain still about 32 gallons of water for every quarter of malt. In the boiling, and evaporation from the coolers, 40 gallons of water are dissipated from one quarter of malt; constituting 72 gallons in all. If 13 quarters of barley be taken to make 1500 gallons of beer, 2400 gallons of water must therefore be required for the mashing. This example will give an idea of the proportions for an ordinary quality of beer.

When the mash is to begin, the copper must be filled with water, and heated. As soon as the water has attained the heat of 145° in summer, or 167° in winter, 600 gallons of it are to be run off into the mash-tun, and the 13 quarters of crushed malt are to be gradually thrown in and well intermixed by proper agitation, so that it may be uniformly moistened, and no lumps may remain. After continuing the agitation in this way for one half or three-quarters of an hour, the water in the copper will have approached to its boiling point, when 450 gallons at the temperature of about 200° are to be run into the mash-tun, and the agitation is to be renewed till the whole assumes an equally fluid state: the tun is now to be well covered for the preservation of its heat, and to be allowed to remain at rest for an hour, or an hour and a half. The mean temperature of this mash may be reckoned at about 145°. The time which is necessary for the transmuting heat of the remaining starch into sugar depends on the quality of the malt. Brown malt requires less time than pale malt, and still less than a mixture with raw grain, as already explained. After the mash has rested the proper time, the tap of the tun is opened, and the clear wort is to be drawn out into the under back. If the wort that first flows is turbid, it must be returned into the tun, till it runs clear. The amount of this first wort may be about 675 gallons. Seven hundred and fifty gallons of water at the temperature of 200° are now to be introduced up through the drained malt, into the tun, and the mixture is to be agitated till it becomes uniform, as before. The mash-tun is then to be covered, and allowed to remain at rest for an hour. The temperature of this mash is from 167° to 174°. While the second mash is making, the worts of the first are to be pumped into the wort copper, and set a-boiling as speedily as possible. The wort of the second mash is to be drawn off at the proper time, and added to the copper as fast as it will receive it, without causing the ebullition to stop.

A third quantity of water amounting to 600 gallons, at 200°, is to be introduced into the mash-tun, and after half an hour, is to be drawn off, and either pumped into the wort copper, or reserved for mashing fresh malt, as the brewer may think fit.

The quantity of extract, per barrel weight, which a quarter of malt yields to wort, amounts to about 84 lbs. The wort of the first extract is the strongest; the second contains, commonly, one-half the extract of the first; and the third, one-half of the second; according to circumstances.

To measure the degrees of concentration of the worts drawn off from the tun, a particular form of hydrometer, called a saccharometer, is employed, which indicates the number of pounds weight of liquid contained in a barrel of 36 gallons imperial measure. Now, as the barrel of water weighs 360 lbs., the indication of the instrument when placed in any wort, shows by how many pounds a barrel of that wort is heavier than a barrel of water; thus, if the instrument sinks with its poise till the mark 10 is upon a line with the surface of the liquid, it indicates that a barrel of that wort weighs ten pounds more than a barrel of water. See Saccharometer.

Or, supposing the barrel of wort weighs 396 lbs., to convert that number into specific gravity, we have the following simple rule:—

360 : 396 ∷ 100 : 1·100;

at which density, by my experiments, the wort contains 25 per cent., of solid extract.

Having been employed to make experiments on the density of worts, and the fermentative changes which they undergo, for the information of a committee of the House of Commons, which sat in July and August, 1830, I shall here introduce a short abstract of that part of my evidence which bears upon the present subject.

My first object was to clear up the difficulties which, to common apprehension, hung[100] over the matter, from the difference in the scales of the saccharometers in use among the brewers and distillers of England and Scotland. I found that one quarter of good malt would yield to the porter brewer a barrel Imperial measure of wort, at the concentrated specific gravity of 1·234. Now, if the decimal part of this number be multiplied by 360, being the number of pounds weight of water in the barrel, the product will denote the excess in pounds, of the weight of a barrel of such concentrated wort, over that of a barrel of water, and that product is, in the present case, 84·24 pounds.

Mr. Martineau, jun., of the house of Messrs. Whitbread and Company, and a gentleman connected with another great London brewery, had the kindness to inform me that their average product from a quarter of malt was a barrel of 84 lbs. gravity. It is obvious, therefore, that by taking the mean operation of two such great establishments, I must have arrived very nearly at the truth.

It ought to be remarked that such a high density of wort as 1·234 is not the result of any direct experiment in the brewery, for infusion of malt is never drawn off so strong; that density is deduced by computation from the quantity and quality of several successive infusions; thus, supposing a first infusion of the quarter of malt to yield a barrel of specific gravity 1·112, a second to yield a barrel at 1·091, and a third a barrel at 1·031, we shall have three barrels at the mean of these three numbers, or one barrel at their sum, equal to 1·234.

I may here observe that the arithmetical mean or sum is not the true mean or sum of the two specific gravities; but this difference is either not known or disregarded by the brewers. At low densities this difference is inconsiderable, but at high densities it would lead to serious errors. At specific gravity 1·231, wort or syrup contains one half of its weight of solid pure saccharum, and at 1·1045 it contains one fourth of its weight; but the brewer’s rule, when here applied, gives for the mean specific gravity 1·1155 = 1·231 + 1·0002.

The contents in solid saccharine matter at that density are however 2714 per cent. showing the rule to be 214 lbs. wrong in excess on 100 lbs., or 9 lbs. per barrel.

The specific gravity of the solid dry extract of malt wort is 1·264; it was taken in oil of turpentine, and the result reduced to distilled water as unity. Its specific volume is 0·7911, that is, 10 lbs. of it will occupy the volume of 7·911 lbs. of water. The mean specific gravity, by computation of a solution of that extract in its own weight of water, is 1·1166; but by experiment, the specific gravity of that solution is 1·216, showing considerable condensation of volume in the act of combination with water.

The following Table shows the relation between the specific gravities of solutions of malt extract, and the per-centage of solid extract they contain:

Water. Malt
in 100.
in 100.
600 + 600 50·00 47·00 1·2180
600 + 900 40·0 37·00 1·1670
600 + 1200 33·3 31·50 1·1350
600 + 1500 28·57 26·75 1·1130
600 + 1800 25·00 24·00 1·1000

The extract of malt was evaporated to dryness, at a temperature of about 250° F., without the slightest injury to its quality, or any empyreumatic smell. Bate’s tables have been constructed on solutions of sugar, and not with solutions of extract of malt, or they agree sufficiently well with the former, but differ materially from the latter. Allan’s tables give the amount of a certain form of solid saccharine matter extracted from malt, and dried at 175° F., in correspondence to the specific gravity of the solution; but I have found it impossible to make a solid extract from infusions of malt, except at much higher temperatures than 175° F. Indeed, the numbers on Allan’s saccharometer scale clearly show that his extract was by no means dry: thus, at 1·100 of gravity he assigns 29·669 per cent. of solid saccharine matter; whereas there is at that density of solid extract only 25 per cent. Again, at 1·135, Allan gives 40 parts per cent. of solid extract, whereas there are only 3313 present.

By the triple mashing operations above described, the malt is so much exhausted that it can yield no further extract useful for strong beer or porter. A weaker wort might no doubt still be drawn off for small beer, or for contributing a little to the strength of the next mashing of fresh malt. But this I believe is seldom practised by respectable brewers, as it impoverishes the grains which they dispose of for feeding cattle.

The wort should be transferred into the copper, and made to boil as soon as possible, for if it remains long in the under-back it is apt to become acescent. The steam moreover raised from it in the act of boiling serves to screen it from the oxygenating or acidifying influence of the atmosphere. Until it begins to boil, the air should be excluded by some kind of a cover.


Sometimes the first wort is brewed by itself into strong ale, the second by itself into an intermediate quality; and the third into small beer; but this practice is not much followed in this country.

We shall now treat of the boiling in of the hops. The wort drawn from the mash-tun, whenever it is pumped into the copper, must receive its allowance of hops. Besides evaporating off a portion of the water, and thereby concentrating the wort, boiling has a twofold object. In the first place, it coagulates the albuminous matter, partly by the heat, and partly by the principles in the hops, and thereby causes a general clarification of the whole mass, with the effect of separating the muddy matters in a flocculent form. Secondly, during the ebullition, the residuary starch and hordeine of the malt are converted into a limpid sweetish mucilage, the dextrine above described; while some of the glutinous stringy matter is rendered insoluble by the tannin principle of the hops, which favours still further the clearing of the wort. By both operations the keeping quality of the beer is improved. This boil must be continued during several hours; a longer time for the stronger, and a shorter for the weaker beers. There is usually one seventh or one sixth part of the water dissipated in the boiling copper. This process is known to have continued a sufficient time, if the separation of the albuminous flocks is distinct, and if these are found, by means of a proof gauge suddenly dipped to the bottom, to be collected there, while the supernatant liquor has become limpid. Two or three hours’ boil is deemed long enough in many well-conducted breweries; but in some of those in Belgium, the boiling is continued from 10 to 15 hours, a period certainly detrimental to the aroma derived from the hop.

Many prefer adding the hops when the wort has just come to the boiling point. Their effect is to repress the further progress of fermentation, and especially the passage into the acetous stage, which would otherwise inevitably ensue in a few days. In this respect, no other vegetable production hitherto discovered can be a substitute for the hop. The odorant principle is not so readily volatilised as would at first be imagined; for when hop is mixed with strong beer wort, and boiled for many hours, it can still impart a very considerable degree of its flavour to weaker beer. By mere infusion in hot beer or water, without boiling, the hop loses very little of its soluble principles. The tannin of the hop combines, as we have said, with the vegetable albumen of the barley, and helps to clarify the liquor. Should there be a deficiency of albumen and gluten, in consequence of the mashing having been done at such a heat as to have coagulated them beforehand, the defect may be remedied by the addition of a little gelatine to the wort copper, either in the form of calf’s foot, or of a little isinglass. If the hops be boiled in the wort for a longer period than 5 or 6 hours, they lose a portion of their fine flavour; but if their natural flavour be rank, a little extra boiling improves it. Many brewers throw the hops in upon the surface of the boiling wort, and allow them to swim there for some time, that the steam may penetrate them, and open their pores for a complete solution of their principles when they are pushed down into the liquor. It is proper to add the hops in considerable masses, because in tearing them asunder, some of the lupuline powder is apt to be lost.

The quantity of hop to be added to the wort varies according to the strength of the beer, the length of time it is to be kept, or the heat of the climate where it is intended to be sent. For strong beer, 412 lbs. of hops are required to a quarter of malt, when it is to be highly aromatic and remarkably clear. For the stronger kinds of ale and porter, the rule, in England, is to take a pound of hops for every bushel of malt, or 8 lbs. to a quarter. Common beer has seldom more than a quarter of a pound of hops to the bushel of malt.

It has been attempted to form an extract of hops by boiling in covered vessels, so as not to lose the oil, and to add this instead of the hop itself to the beer. On the great scale this method has no practical advantage, because the extraction of the hop is perfectly accomplished during the necessary boiling of the wort, and because the hop operates very beneficially, as we have explained, in clarifying the beer. Such an extract, moreover, could be easily adulterated.

Of the Coolers.—The contents of the copper are run into what is called the hop-back, on the upper part of which is fixed a drainer, to keep back the hops. The pump is placed in the hop-back, for the purpose of raising the wort to the coolers, usually placed in an airy situation upon the top of the brewery. Two coolers are indispensable when we make two kinds of beer from the same brewing, and even in single brewings, called gyles, if small beer is to be made. One of these coolers ought to be placed above the level of the other. As it is of great consequence to cool the worts down to the fermenting pitch as fast as possible, various contrivances have been made for effecting this purpose. The common cooler is a square wooden cistern, about 6 inches deep, and of such an extent of surface that the whole of one boil may only occupy 2 inches, or thereabouts, of depth in it. For a quantity of wort equal to about 1500 gallons its area should be at least 54 feet long and 20 feet wide. The seams of[102] the cooler must be made perfectly water-tight and smooth, so that no liquor may lodge in them when they are emptied. The utmost cleanliness is required, and an occasional sweetening with lime-water.

The hot wort reaches the cooler at a temperature of from 200° to 208°, according to the power of the pump. Here it should be cooled to the proper temperature for the fermenting tun, which may vary from 54° to 64°, according to circumstances. The refrigeration is accomplished by the evaporation of a portion of the liquor: it is more rapid in proportion to the extent of the surface, to the low temperature, and the dryness of the atmosphere surrounding the cooler. The renewal of a body of cool dry air by the agency of a fan, may be employed with great advantage. The cooler itself must be so placed that its surface shall be freely exposed to the prevailing wind of the district, and be as free as possible from the eddy of surrounding buildings. It is thought by many, that the agitation of the wort during its cooling, is hurtful. Were the roof made moveable, so that the wort could be readily exposed, in a clear night, to the aspect of the sky, it would cool rapidly by evaporation, on the principles explained by Dr. Wells, in his “Essay on Dew.”

When the cooling is effected by evaporation alone, the temperature falls very slowly, even in cold air, if it be loaded with moisture. But when the air is dry, the evaporation is vigorous, and the moisture exhaled does not remain incumbent on the liquor, as in damp weather, but is diffused widely in space. Hence we can understand how wort cools so rapidly in the spring and autumn, when the air is generally dry, and even more quickly than in winter, when the air is cooler, but loaded with moisture. In fact, the cooling process goes on better when the atmosphere is from 50° to 55°, than when it falls to the freezing point, because in this case, if the air be still, the vapours generated remain on the surface of the liquor, and prevent further evaporation. In summer the cooling can take place only during the night.

In consequence of the evaporation during this cooling process, the bulk of the worts is considerably reduced; thus, if the temperature at the beginning was 208°, and if it be at the end 64°, the quantity of water necessary to be evaporated to produce this refrigeration would be nearly 18 of the whole, putting radiation and conduction of heat out of the question. The effect of this will be a proportional concentration of the beer.

The period of refrigeration in a well-constructed cooler, amounts to 6 or 7 hours in favourable weather, but to 12 or 15 in other circumstances. The quality of the beer is much improved by shortening this period; because, in consequence of the great surface which the wort exposes to the air, it readily absorbs oxygen, and passes into the acetous fermentation with the production of various mouldy spots; an evil to which ill-hopped beer is particularly liable. Various schemes have been contrived to cool wort, by transmitting it through the convolutions of a pipe immersed in cold water. The best plan is to expose the hot wort for some hours freely to the atmosphere and the cooler, when the loss of heat is most rapid by evaporation and other means, and when the temperature falls to 100°, or thereby, to transmit the liquor through a zig-zag pipe, laid almost horizontally in a trough of cold water. The various methods described under Refrigerator are more complex, but they may be practised in many situations with considerable advantage.

Whilst the wort reposes in the cooler, it lets fall a slight sediment, which consists partly of fine flocks of coagulated albumen combined with tannin, and partly of starch, which had been dissolved at the high temperature, and separates at the lower. The wort should be perfectly limpid, for a muddy liquor never produces transparent beer. Such beer contains, besides mucilaginous sugar and gum, usually some starch, which even remains after the fermentation, and hinders its clarifying, and gives it a tendency to sour. The wort contains more starch the hotter it has been mashed, the less hops have been added, and the shorter time it has been boiled. The presence of starch in the wort may be made manifest by adding a little solution of iodine in alcohol to it, when it will become immediately blue. We thus see that the tranquil cooling of wort in a proper vessel has an advantage over cooling it rapidly by a refrigeratory apparatus. When the wort is sufficiently cool, it is let down into the fermenting tun. In this transfer, the cooling might be carried several degrees lower, were the wort made to pass down through a tube inclosed in another tube, along which a stream of cold water is flowing in the opposite direction, as we have described in the sequel of Acetic Acid. These fermenting tuns are commonly called gyle-tuns, or working tuns, and are either square or circular, the latter being preferable on many accounts.

IV. Of the Fermentation.—In the great London breweries, the size of these fermenting tuns is such that they contain from 1200 to 1500 barrels. The quantity of wort introduced at a time must, however, be considerably less than the capacity of the vessel, to allow room for the head of yeast which rises during the process; if the vessel be cylindrical, this head is proportional to the depth of the worts. In certain kinds of[103] fermentation, it may rise to a third of that depth. In general, the fermentation proceeds more uniformly and constantly in large masses, because they are little influenced by vicissitudes of temperature; smaller vessels, on the other hand, are more easily handled. The general view of fermentation will be found under that title; I shall here make a few remarks on what is peculiar to beer. During the fermentation of wort, a portion of its saccharine matter is converted into alcohol, and wort thus changed, is beer. It is necessary that this conversion of the sugar be only partial, for beer which contains no undecomposed sugar would soon turn sour, and even in the casks its alcohol undergoes a slow fermentation into vinegar. The amount of this excess of sugar is greater in proportion to the strength of the wort, since a certain quantity of alcohol, already formed, prevents the operation of the ferment on the remaining wort. Temperature has the greatest influence upon the fermentation of wort. A temperature of from 55° to 60° of the liquor, when that of the atmosphere is 55°, is most advantageous for the commencement. The warmth of the wort as it comes into the gyle-tun must be modified by that of the air in the apartment. In winter, when this apartment is cold, the wort should not be cooled under 64° or 60°, as in that case the fermentation would be tedious or interrupted, and the wort liable to spoil or become sour. In summer, when the temperature of the place rises to above 75°, the wort should be cooled, if possible, down to 55°, for which purpose it should be let in by the system of double pipes, above mentioned. The higher the temperature of the wort, the sooner will the fermentation begin and end, and the less is it in our power to regulate its progress. The expert brewer must steer a middle course between these two extremes, which threaten to destroy his labours. In some breweries a convoluted pipe is made to traverse or go round the sides of the gyle-tun, through which warm water is allowed to flow in winter, and cold in summer, so as to modify the temperature of the mass to the proper fermenting pitch. If there be no contrivance of this kind, the apartment may be cooled in summer, by suspending wet canvas opposite the windows in warm weather, and kindling a small stove within it in cold.

When the wort is discharged into the gyle-tun, it must receive its dose of yeast, which has been previously mixed with a quantity of the wort, and left in a warm place till it has begun to ferment. This mixture, called lobb, is then to be put into the tun, and stirred well through the mass. The yeast should be taken from similar beer. Its quantity must depend upon the temperature, strength, and quantity of the wort. In general, one gallon of yeast is sufficient to set 100 gallons of wort in complete fermentation. An excess of yeast is to be avoided, lest the fermentation should be too violent, and be finished in less than the proper period of 6 or 8 days. More yeast is required in winter than summer; for, at a temperature of 50°, a double quantity may be used to that at 68°.

Six or eight hours after adding the yeast, the tun being meanwhile covered, the fermentation becomes active: a white milky-looking froth appears, first on the middle, and spreads gradually over the whole surface; but continues highest in the middle, forming a frothy elevation, the height of which increases with the progress of the fermentation, and whose colour gradually changes to a bright brown, the result, apparently, of the oxidation of the extractive contained in this yeasty top. This covering screens the wort from the contact of the atmospherical air. During this time, there is a perpetual disengagement of carbonic acid gas, which is proportional to the quantity of sugar converted into alcohol. The warmth of the fermenting liquid increases at the same time, and is at a maximum when the fermentation has come to its highest point. This increase of temperature amounts to from 9° to 14° or upwards, and is the greater the more rapid the fermentation. But in general, the fermentation is not allowed to proceed so far in the gyle-tun, for after it is advanced a little way, the beer is cleansed, that is, drawn off into other vessels, which are large barrels set on end, with large openings in their top, furnished with a sloping tray for discharging an excess of yeast into the wooden trough, in which the stillions stand. These stillions are placed in communication with a store-tub, which keeps them always full, by hydrostatic pressure, so that the head of yeast may spontaneously flow over, and keep the body of liquor in the cask clean. This apparatus will be explained in describing the brewery plant. See the figures, infrà.

It must be observed, that the quantity of yeast, and the heat of fermentation, differ for every different quality of beer. For mild ale, when the fermentation has reached 75°, its first flavour begins; at 80° the flavour increases; at 85° it approaches the high flavour; at 90° it is high; but it may be carried to 100° and upwards, for particular purposes. A wort of 30 lbs. per barrel (sp. gr. 1·088), ought to increase about 15°, so that in order to arrive at 80°, it should be set at 65°. The quantity of yeast for such an ale should be from 2 to 3 lbs. per barrel. The higher the heat, the less yeast is necessary. If the heat of the fermentation should at any time fall, it must be raised by a supply of fresh yeast, well stirred in; but this practice is not advisable in general, because rousing the worts in the gyle-tun is apt to communicate a rank flavour of yeast to the ale. It is the practice of many experienced brewers to look every 2 hours into the[104] gyle-tun, chiefly with the view of observing the progress of the heat, which is low at first, but afterwards often increases half a degree per hour, and subsequently declines, as the fermentation approaches its conclusion, till at length the heat becomes uniform, or sometimes decreases, before the fermentation is finished, especially where the quantity operated upon is small.

Some brewers recommend, when the fermentation is carried to its utmost period, to add about 7 lbs. of wheat or bean flour to a gyle-tun of 25 or 30 barrels, at the time of cleansing, so as to quicken the discharge of the yeast, by disengagement of more carbonic acid. The flour should be whisked up in a pail, with some of the beer, till the lumps are broken, and then poured in. By early cleansing, the yeast is preserved longer in a state proper for a perfect fermentation than by a contrary practice.

For old ale, which is to be long kept, the heat of the fermentation should not exceed 75°, but a longer time is required to complete the fermentation and ensure the future good flavour of the ale.

For porter, the general practice is, to use from 4 to 412 lbs. of hops per barrel for keeping; though what is termed mild or mixing porter, has not more than 3 or 312 lbs. The heat of fermentation must not exceed 70°, and begin about 60°. If the heat tend to increase much above that pitch in the gyle-tun, the porter should be cleansed, by means of the stillions. At this period of the fermentation, care should be taken that the sweetness of the malt be removed, for which purpose more yeast may be used than with any other beer of the same strength. The quantity is from 3 to 4 lbs. per barrel, rousing the wort in the gyle-tun every 2 hours in the day-time.

When the plan of cleansing casks is not employed, the yeast is removed from the surface of the fermenting tun by a skimmer, and the clear beer beneath is then drawn off into the ripening tuns, called store-vats, in which it is mixed up with different brewings, to suit the taste of the customers. This transfer must take place whenever the extrication of carbonic acid has nearly ceased; lest the alcohol formed should dissolve some of the floating yeast, acquire thereby a disagreeable taste, and pass partially into the acetous state.

In this process, during the formation of vinous spirit at the expense of the sugar, the albumen and gluten diffused through the beer, being acted upon by the alcohol, become insoluble; one portion of them is buoyed to the top with the carbonic acid gas, to form the frothy yeast; and another portion falls to form the bottom barm. The former consists of the same materials as the wort, with a large proportion of gluten, which forms its active constituent; the latter is a peculiar deposit, consisting of the same gluten mixed with the various dense impurities of the wort, and may be also used as a ferment, but is cruder than the floating yeast. The amount of yeast is proportional to the activity of the fermentation, or extrication of carbonic acid gas, as also to the heat of the mashing process, and the quantity of starch or flour unaltered by germination. Pale malt affords usually, more yeast than malt highly kilned. When the yeast becomes excessive, from too violent fermentation, it should be skimmed off from time to time, which will tend to cool the liquor and moderate the intestine changes.

After the beer is let down into the close store-tuns in the cellar, an obscure fermentation goes on, for a considerable period in its body, which increases its spirituous strength, and keeps up in it a constant impregnation of carbonic acid gas, so as to render it lively and agreeable to the taste, when it is casked off for sale. It would appear, that beer is never stationary in quality, while it is contained in the tuns; for the moment when it ceases to improve by the decomposition of its residuary sugar, it begins to degenerate into vinegar. This result may be produced either by the exhaustion of the saccharine, or by the fermentative matter. The store cellar should therefore be under ground, free from alternations of temperature, vibrations of carriages, and as cool as possible. In the great London breweries, the fermentation is rendered very complete in the cleansing butts; so that a slow and steady ripening is ensured in the great store-tuns. The gyle-tuns are too capacious to permit the fermentation to be finished, with either safety or sufficient dispatch in them.

V. Of ripening different kinds of Beer.—The varieties of beer depend either upon the difference of their materials, or from a different management of the brewing processes.

With regard to the materials, beers differ in the proportion of their malt, hops, and water; and in the different kinds of malt or other grain. To the class of table or small beers, all those sorts may be referred whose specific gravity does not exceed 1·025, which contain about 5 per cent. of malt extract, or nearly 18 pounds per barrel. Beers of middling strength may be reckoned those between the density of 1·025 and 1·040; which contain, at the average, 7 per cent., or 25 pounds per barrel. The latter may be made with 400 quarters of malt to 1500 barrels of beer. Stronger beers have a specific gravity of from 1·050 to 1·080, and take from 45 to 75 quarters of malt to the same quantity of beer. The strongest beer found in the market is some of the English and Scotch ales, for which from 18 to 27 quarters of malt are taken for 1500[105] gallons of beer. Good porter requires from 16 to 18 quarters for that quantity. Beers are sometimes made with the addition of other farinaceous matter to the malt; but when the latter constitutes the main portion of the grain, the malting of the other kinds of corn becomes unnecessary, for the diastase of the barley-malt changes the starch into sugar during the mashing operation. Even with entirely raw grain, beer is made in some parts of the Continent, the brewers trusting the conversion of the starch into sugar to the action of the gluten alone, at a low mashing temperature, on the principle of Saussure’s and Kirchoff’s researches.

The colour of the beer depends upon the colour of the malt, and the duration of the boil in the copper. The pale ale is made, as we have stated, from steam or sun-dried malt, and the young shoots of the hop; the deep yellow ale from a mixture of pale yellow and brown malt; and the dark brown beer from well-kilned and partly carbonised malt, mixed with a good deal of the pale, to give body. The longer and more strongly heated the malt has been in the kiln, the less weight of extract, cæteris paribus, does it afford. In making the fine mild ales, high temperatures ought to be avoided, and the yeast ought to be skimmed off, or allowed to flow very readily from its top, by means of the cleansing butt system, so that little ferment being left in it to decompose the rest of the sugar, the sweetness may remain unimpaired. With regard to porter, in certain breweries, each of the three kinds of malt employed for it is separately mashed, after which the first and the half of the second wort is boiled along with the whole of the hops, and thence cooled and set to ferment in the gyle-tun. The third drawn wort, with the remaining half of the second, is then boiled with the same hops, saved by the drainer, and, after cooling, added to the former in the gyle-tun, when the two must be well roused together.

It is obvious, from the preceding development of principles, that all amylaceous and saccharine materials, such as potatoes, beans, turnips, as well as cane and starch syrup, molasses, &c., may be used in brewing beer. When, however, a superior quality of brown beer is desired, malted barley is indispensable, and even with these substitutes a mixture of it is most advantageous. The washed roots of the common carrot, of the red and yellow beet, or of the potato, must be first boiled in water, and then mashed into a pulp. This pulp must be mixed with water in the copper, along with wheaten or oat meal, and the proper quantity of hops, then boiled during 8 or 9 hours. This wort is to be cooled in the usual way, and fermented, with the addition of yeast. A much better process is that now practised, on a considerable scale, at Strasbourg, in making the ale, for which that city is celebrated. The mashed potatoes are mixed with from a twentieth to a tenth of their weight of finely ground barley malt, and some water. The mixture is exposed, in a water-bath, to a heat of 160° F. for four hours, whereby it passes into a saccharine state, and may then be boiled with hops, cooled, and properly fermented into good beer.

Maize, or Indian corn, has also been employed to make beer; but its malting is somewhat difficult on account of the rapidity and vigour with which its radicles and plumula sprout forth. The proper mode of causing it to germinate is to cover it, a few inches deep, with common soil, in a garden or field, and to leave it there till the bed is covered with green shoots of the plant. The corn must be then lifted, washed, and exposed to the kiln.

The Difference of the Fermentation.—The greater or less rapidity with which the worts are made to ferment has a remarkable influence upon the quality of the beer, especially in reference to its fitness for keeping. The wort is a mucilaginous solution in which the yeastly principles, eliminated by the fermentation, will, if favoured by regular and slow intestine movements, completely rise to the surface, or sink to the bottom, so as to leave the body fine. But, when the action is too violent, these barmy glutinous matters get comminuted and dispersed through the liquor, and can never afterwards be thoroughly separated. A portion of the same feculent matter becomes, moreover, permanently dissolved, during this furious commotion, by the alcohol that is generated. Thus the beer loses not merely its agreeable flavour and limpidity, but is apt to spoil from the slightest causes. The slower, more regularly progressive, and less interrupted, therefore, the fermentation is, so much better will the product be.

Beer, in its perfect condition, is an excellent and healthful beverage, combining, in some measure, the virtues of water, of wine, and of food, as it quenches thirst, stimulates, cheers, and strengthens. The vinous portion of it is the alcohol, proceeding from the fermentation of the malt sugar. Its amount, in common strong ale or beer, is about 4 per cent., or four measures of spirits, specific gravity 0·825 in 100 measures of the liquor. The best brown stout porter contains 6 per cent., the strongest ale even 8 per cent.; but common beer only one. The nutritive part of the beer is the undecomposed gum-sugar, and the starch-gum, not changed into sugar. Its quantity is very variable, according to the original starch of the wort, the length of the fermentation, and the age of the beer.


The main feature of good beer is fine colour and transparency; the production of which is an object of great interest to the brewer. Attempts to clarify it in the cask seldom fail to do it harm. The only thing that can be used with advantage for fining foul or muddy beer, is isinglass. For porter, as commonly brewed, it is frequently had recourse to. A pound of good isinglass will make about 12 gallons of finings. It is cut into slender shreds, and put into a tub with as much vinegar or hard beer as will cover it, in order that it may swell and dissolve. In proportion as the solution proceeds, more beer must be poured upon it, but it need not be so acidulous as the first, because, when once well softened by the vinegar, it readily dissolves. The mixture should be frequently agitated with a bundle of rods, till it acquires the uniform consistence of thin treacle, when it must be equalised still more by passing through a tammy cloth, or a sieve. It may now be made up with beer to the proper measure of dilution. The quantity generally used is from a pint to a quart per barrel, more or less, according to the foulness of the beer. But before putting it into the butt, it should be diffused through a considerable volume of the beer with a whisk, till a frothy head be raised upon it. It is in this state to be poured into the cask, briskly stirred about; after which the cask must be bunged down for at least 24 hours, when the liquor should be limpid. Sometimes the beer will not be improved by this treatment; but this should be ascertained beforehand, by drawing off some of the beer into a cylindric jar or phial, and adding to it a little of the finings. After shaking and setting down the glass, we shall observe whether the feculencies begin to collect in flocky parcels, which slowly subside; or whether the isinglass falls to the bottom without making any impression upon the beer. This is always the case when the fermentation is incomplete, or a secondary decomposition has begun. Mr. Jackson has accounted for this clarifying effect of isinglass in the following way.

The isinglass, he thinks, is first of all rather diffused mechanically, than chemically dissolved, in the sour beer or vinegar, so that when the finings are put into the foul beer, the gelatinous fibres, being set free in the liquor, attract and unite with the floating feculencies, which before this union were of the same specific gravity with the beer, and therefore could not subside alone; but having now acquired additional weight by the coating of fish-glue, precipitate as a flocculent magma. This is Mr. Jackson’s explanation; to which I would add, that if there be the slightest disengagement of carbonic acid gas, it will keep up an obscure locomotion in the particles, which will prevent the said light impurities, either alone or when coated with isinglass, from subsiding. The beer is then properly enough called stubborn by the coopers. But the true theory of the action of isinglass is, that the tannin of the hops combines with the fluid gelatine, and forms a flocculent mass, which envelopes the muddy particles of the beer, and carries them to the bottom as it falls, and forms a sediment. When after the finings are poured in, no proper precipitate ensues, it may be made to appear by the addition of a little decoction of hop.

Mr. Richardson, the author of the well-known brewer’s saccharometer, gives the following as the densities of different kinds of beer:—

Beer. Pounds
Burton ale, 1st sort 40  to  43 1·111 to 1·120
Burton ale, 2d ditto 35  to  40 1·097 to 1·111
Burton ale, 3d ditto 28  to  33 1·077 to 1·092
Common ale 25  to  27 1·070 to 1·073
Ditto ditto   21    1·058
Porter, common sort   18    1·050
Ditto, double   20    1·055
Ditto, brown stout   23    1·064
Ditto, best brown stout   26    1·072
Common small beer     1·014
Good table beer 12  to  14 1·033 to 1·039

Of Returns or Malt Residuums.—When small beer is brewed after ale or porter, only one mash is to be made; but where this is not done, there may be two mashes, in order to economise malt to the utmost. We may let on the water at 160° or 165°, in any convenient quantity, infuse for an hour or thereby, then run it off, and pump into the copper, putting some hops into it, and causing it to boil for an instant; when it may be transferred to the cooler. A second mash or return may be made in the same manner, but at a heat 5° lower; and then disposed of in the boiler with some hops, which may remain in the copper during the night at a scalding heat, and may be discharged into the cooler in the morning. These two returns are to be let down into the under-back immediately before the next brewing, and thence heated in the copper for the next[107] mashing of fresh malt, instead of hot water, commonly called liquor, in the breweries. But allowance must be made, in the calculation of the worts, for the quantity of fermentable matter in these two returns. The nett aggregate saving is estimated from the gravity of the return taken when cold in the cooler. A slight economy is also made in the extra boiling of the used hops. The lapse of a day or two between the consecutive brewings is no objection to the method of returns, because they are too weak in saccharine matter to run any risk of fermentation.

In conclusion, it may be remarked that Mr. Richardson somewhat underrates the gravity of porter, which is now seldom under 20 lbs. per barrel. The criterion for transferring from the gyle-tun to the cleansing butts is the attenuation caused by the production of alcohol in the beer: when that has fallen to 10 lbs. or 11 lbs., which it usually does in 48 hours, the cleansing process is commenced. The heat is at this time generally 75°, if it was pitched at 65°; for the heat and the attenuation go hand in hand.

About thirty years ago, it was customary for the London brewers of porter, to keep immense stocks of it for eighteen months or two years, with the view of improving its quality. The beer was pumped from the cleansing butts into store-vats, holding from twenty to twenty-five gyles or brewings of several hundred barrels each. The store-vats had commonly a capacity of 5000 or 6000 barrels; and a few were double, and one was treble, this size. The porter, during its long repose in these vats, became fine, and by obscure fermentation its saccharine mucilage was nearly all converted into vinous liquor, and dissipated in carbonic acid. Its hop-bitter was also in a great degree decomposed. Good hard beer was the boast of the day. This was sometimes softened by the publican, by the addition of some mild new-brewed beer. Of late years, the taste of the metropolis has undergone such a complete revolution in this respect, that nothing but the mildest porter will now go down. Hence, six weeks is a long period for beer to be kept in London; and much of it is drunk when only a fortnight old. Ale is for the same reason come greatly into vogue; and the two greatest porter houses, Messrs. Barclay, Perkins, & Co., and Truman, Hanbury, & Co., have become extensive and successful brewers of mild ale, to please the changed palate of their customers.

We shall add a few observations upon the brewing of Scotch ale. This beverage is characterised by its pale amber colour, and its mild balsamic flavour. The bitterness of the hop is so mellowed with the malt, as not to predominate. The ale of Preston Pans is, in fact, the best substitute for wine which barley has hitherto produced. The low temperature at which the Scotch brewer pitches his fermenting tun restricts his labours to the colder months of the year. He does nothing during four of the summer months. He is extremely nice in selecting his malt and hops; the former being made from the best English barley, and the latter being the growth of Farnham or East Kent. The yeast is carefully looked after, and measured into the fermenting tun in the proportion of one gallon to 240 gallons of wort.

Only one mash is made by the Scotch ale brewer, and that pretty strong; but the malt is exhausted by eight or ten successive sprinklings of liquor (hot water) over the goods (malt), which are termed in the vernacular tongue, sparges. These waterings percolate through the malt on the mash-tun bottom, and extract as much of the saccharine matter as may be sufficient for the brewing. By this simple method much higher specific gravities may be obtained than would be practicable by a second mash. With malt, the infusion or saccharine fermentation of the diastase is finished with the first mash; and nothing remains but to wash away from the goods the matter which that process has rendered soluble. It will be found on trial that 20 barrels of wort drawn from a certain quantity of malt, by two successive mashings, will not be so rich in fermentable matter as 20 barrels extracted by ten successive sparges of two barrels each. The grains always remain soaked with wort like that just drawn off, and the total residual quantity is three fourths of a barrel for every quarter of malt. The gravity of this residual wort will on the first plan be equal to that of the second mash; but on the second plan, it will be equal only to that of the tenth sparge, and will be more attenuated in a very high geometrical ratio. The only serious objection to the sparging system is the loss of time by the successive drainages. A mash-tun with a steam jacket, promises to suit the sparging system well; as it would keep up an uniform temperature in the goods, without requiring them to be sparged with very hot liquor.

The first part of the Scotch process seems of doubtful economy; for the mash liquor is heated so high as 180°. After mashing for about half an hour, or till every particle of the malt is thoroughly drenched, the tun is covered, and the mixture left to infuse about three hours; it is then drained off into the under-back, or preferably into the wort copper.

After this wort is run off, a quantity of liquor (water), at 180° of heat, is sprinkled uniformly over the surface of the malt; being first dashed on a perforated circular board, suspended horizontally over the mash-tun, wherefrom it descends like a shower[108] upon the whole of the goods. The percolating wort is allowed to flow off, by three or more small stopcocks round the circumference of the mash-tun, to insure the equal diffusion of the liquor.

The first sparge being run off in the course of twenty minutes, another similar one is affused; and thus in succession till the whole of the drainage, when mixed with the first mash-wort, constitutes the density adapted to the quality of the ale. Thus, the strong worts are prepared, and the malt is exhausted either for table beer, or for a return, as pointed out above. The last sparges are made 5° or 6° cooler than the first.

The quantity of hops seldom exceeds four pounds to the quarter of malt. The manner of boiling the worts is the same as that above described; but the conduct of the fermentation is peculiar. The heat is pitched at 50°, and the fermentation continues from a fortnight to three weeks. Were three brewings made in the week, seven or eight working tuns would thus be in constant action; and, as they are usually in one room, and some of them at an elevation of temperature of 15°, the apartment must be propitious to fermentation, however low its heat may be at the commencement. No more yeast is used than is indispensable: if a little more be needed, it is made effective by rousing up the tuns twice a day from the bottom.

When the progress of the attenuation becomes so slack as not to exceed half a pound in the day, it is prudent to cleanse, otherwise the top harm might re-enter the body of the beer, and it would become yeast-bitten. When the ale is cleansed, the head, which has not been disturbed for some days, is allowed to float on the surface till the whole of the then pure ale is drawn off into the casks. This top is regarded as a sufficient preservative against the contact of the atmosphere. The Scotch do not skim their tuns, as the London ale brewers commonly do. The Scotch ale, when so cleansed, does not require to be set upon close stillions. It throws off little or no yeast, because the fermentation was nearly finished in the tun. The strength of the best Scotch ale ranges between 32 and 44 pounds to the barrel; or it has a specific gravity of from 1·088 to 1·122, according to the price at which it is sold. In a good fermentation, seldom more than a fourth of the original gravity of the wort remains at the period of the cleansing. Between one third and one fourth is the usual degree of attenuation. Scotch ale soon becomes fine, and is seldom racked for the home market. The following table will show the progress of fermentation in a brewing of good Scotch ale:—

20  barrels of  mash-worts of  42 12  pounds gravity   =  860 ·6
20 returns 6 110 = 122  
12 ) 982 ·6
pounds weight of extract per quarter of malt = 81  


March 24. pitched the  tun at  51°: yeast 4 gallons.
  Temp. Gravity.
  25.   52°   41  pounds.
  28.   56°   39  
  30.   60°   34  
April 1.   62°   32  
  4.   65°   29  added 1 lb. of yeast.
  5.   66°   25  
  6.   67°   23  
  7.   67°   20  
  8.   66°   18  
  9.   66°   15  
  10.   64°   14 ·5 cleansed[7].

[7] Brewing (Society for diffusing Useful Knowledge), p. 156.

The following table shows the origin and the result of fermentation, in a number of practical experiments:—

of the
Lbs. per
Barrel of
of the Ale.
Lbs. per
Barrel of
1 ·0950 88 ·75 1 ·0500 40 ·25 0 ·478
1 ·0918 85 ·62 1 ·0420 38 ·42 0 ·552
1 ·0829 78 ·125 1 ·0205 16 ·87 0 ·787
1 ·0862 80 ·625 1 ·0236 20 ·00 0 ·757
1 ·0780 73 ·75 1 ·0280 24 ·25 0 ·698
1 ·0700 65 ·00 1 ·0285 25 ·00 0 ·615
1 ·1002 93 ·75 1 ·0400 36 ·25 0 ·613
1[109] ·1025 95 ·93 1 ·0420 38 ·42 0 ·600
1 ·0978 91 ·56 1 ·0307 27 ·00 0 ·705
1 ·0956 89 ·37 1 ·0358 32 ·19 0 ·640
1 ·1130 105 ·82 1 ·0352 31 ·87 0 ·661
1 ·1092 102 ·187 1 ·0302 26 ·75 0 ·605
1 ·1171 110 ·00 1 ·0400 36 ·25 0 ·669
1 ·1030 96 ·40 1 ·0271 23 ·42 0 ·757
1 ·0660 61 ·25 1 ·0214 17 ·80 0 ·709

The second column here does not represent, I believe, the solid extract, but the pasty extract obtained as the basis of Mr. Allen’s saccharometer, and therefore each of its numbers is somewhat too high. The last column, also, must be in some measure erroneous, on account of the quantity of alcohol dissipated during the process of fermentation. It must be likewise incorrect, because the density due to the saccharine matter will be partly counteracted, by the effect of the alcohol present in the fermented liquor. In fact, the attenuation does not correspond to the strength of the wort; being greatest in the third brewing, and smallest in the first. The quantity of yeast for the above ale brewings in the table was, upon an average, one gallon for 108 gallons; but it varied with its quality, and with the state of the weather, which, when warm, permits much less to be used with propriety.

The good quality of the malt, and the right management of the mashing, may be tested by the quantity of saccharine matter contained in the successively drawn worts. With this view, an aliquot portion of each of them should be evaporated by a safety-bath heat to a nearly concrete consistence, and then mixed with twice its volume of strong spirit of wine. The truly saccharine substance will be dissolved, while the starch and other matters will be separated; after which the proportions of each may be determined by filtration and evaporation. Or an equally correct, and much more expeditious, method of arriving at the same result would be, after agitating the viscid extract with the alcohol in a tall glass cylinder, to allow the insoluble fecula to subside, and then to determine the specific gravity of the supernatant liquid by a hydrometer. The additional density which the alcohol has acquired will indicate the quantity of malt sugar which it has received. The following table, constructed by me, at the request of Henry Warburton, Esq., M. P., chairman of the Molasses Committee of the House of Commons in 1830, will show the brewer the principle of this important inquiry. It exhibits the quantity in grains weight of sugar requisite to raise the specific gravity of a gallon of spirit of different densities to the gravity of water = 1·000.

Specific Gravity
of Spirit.
Grains, Weight
of Sugar in the
Gallon Imperial.
0·995 0·980
0·990 1·890
0·985 2·800
0·980 3·710
0·975 4·690
0·970 5·600
0·965 6·650
0·960 7·070
0·955 8·400
0·950 9·310

The immediate purpose of this table was to show the effect of saccharine matter in disguising the presence or amount of alcohol in the weak feints of the distiller. But a similar table might easily be constructed, in which, taking a uniform quantity of alcohol of 0·825, for example, the quantity of sugar in any wort-extract would be shown by the increase of specific gravity which the alcohol received from agitation with a certain weight of the wort, inspissated to a nearly solid consistence by a safety-pan, made on the principle of my patent sugar-pan. (See Sugar.) Thus, the normal quantities being 1000 grain measures of alcohol, and 100 grains by weight of inspissated mash-extract, the hydrometer would at once indicate, by help of the table, first, the quantity per cent. of truly saccharine matter, and next, by subtraction, that of farinaceous matter present in it.

Section of brewery

Fig. 103 enlarged (269 kB)

Plan, Machinery, and Utensils of a great Brewery.Figs. 103. and 104. represent the arrangement of the utensils and machinery in a porter brewery on the largest scale; in which, however, it must be observed that the elevation fig. 103. is in a great degree imaginary as to the plane upon which it is taken; but the different vessels are arranged so as[110] to explain their uses most readily, and at the same time to preserve, as nearly as possible, the relative positions which are usually assigned to each in works of this nature.

The malt for the supply of the brewery is stored in vast granaries or malt-lofts, usually situated in the upper part of the buildings. Of these, I have been able to represent only one, at A, fig. 103.: the others, which are supposed to be on each side of it, cannot[111] be seen in this view. Immediately beneath the granary A, on the ground floor, is the mill; in the upper story above it, are two pairs of rollers, fig. 101, 102, and 103, under a, a, for bruising or crushing the grains of the malt. In the floor beneath the rollers are the mill-stones b, b, where the malt is sometimes ground, instead of being merely bruised by passing between the rollers, under a, a.

The malt, when prepared, is conveyed by a trough into a chest d, to the right of b, from which it can be elevated by the action of a spiral screw, fig. 105., enclosed in the sloping tube e, into the large chest or binn B, for holding ground malt, situated immediately over the mash-tun D. The malt is reserved in this binn till wanted, and it is then let down into the mashing-tun, where the extract is obtained by hot water supplied from the copper G, seen to the right of B.

The water for the service of the brewery is obtained from the well E, seen beneath the mill to the left, by a lifting pump worked by the steam engine; and the forcing-pipe f of this pump conveys the water up to the large reservoir or water-back F, placed at the top of the engine-house. From this cistern, iron pipes are laid to the copper G (on the right-hand side of the figure), as also to every part of the establishment where cold water can be wanted for cleaning and washing the vessels. The copper G can be filled with cold water by merely turning a cock; and the water, when boiled therein, is conveyed by the pipe g into the bottom of the mash-tun D. It is introduced beneath a false bottom, upon which the malt lies, and, rising up through the holes in the false bottom, it extracts the saccharine matter from the malt; a greater or less time being allowed for the infusion, according to circumstances. The instant the water is drawn off from the copper, fresh water must be let into it, in order to be ready for boiling the second mashing; because the copper must not be left empty for a moment, otherwise the intense heat of the fire would destroy its bottom. For the convenience of thus letting down at once as much liquor as will fill the lower part of the copper, a pan or second boiler is placed over the top of the copper, as seen in fig. 103.; and the steam rising from the copper communicates a considerable degree of heat to the contents of the pan, without any expense of fuel. This will be more minutely explained hereafter. (See fig. 107.)

During the process of mashing, the malt is agitated in the mash-tun, so as to expose every part to the action of the water. This is done by a mechanism contained within the mash-tun, which is put in motion by a horizontal shaft above it, H, leading from the mill. The mash machine is shown separately in fig. 106. When the operation of mashing is finished, the wort or extract is drained down from the malt into the vessel I, called the under-back, immediately below the mash-tun, of like dimensions, and situated always on a lower level, for which reason it has received this name. Here the wort does not remain longer than is necessary to drain off the whole of it from the tun above. It is then pumped up by the three-barrelled pump k, into the pan upon the top of the copper, by a pipe which cannot be seen in this section. The wort remains in the pan until the water for the succeeding mashes is discharged from the copper. But this delay is no loss of time, because the heat of the copper, and the steam arising from it, prepare the wort, which had become cooler, for boiling. The instant the copper is emptied, the first wort is let down from the pan into the copper, and the second wort is pumped up from the under-back into the upper pan. The proper proportion of hops is thrown into the copper through the near hole, and then the door is shut down, and screwed fast, to keep in the steam, and cause it to rise up through pipes into the pan. It is thus forced to blow up through the wort in the pan, and communicates so much heat to it, or water, called liquor by the brewers, that either is brought near to the boiling point. The different worts succeed each other through all the different vessels with the greatest regularity, so that there is no loss of time, but every part of the apparatus is constantly employed. When the ebullition has continued a sufficient period to coagulate the grosser part of the extract, and to evaporate part of the water, the contents of the copper are run off through a large cock into the jack-back K, below G, which is a vessel of sufficient dimensions to contain it, and provided with a bottom of cast-iron plates, perforated with small holes, through which the wort drains and leaves the hops. The hot wort is drawn off from the jack-back through the pipe h by the three-barrelled pump, which throws it up to the coolers L, L, L; this pump being made with different pipes and cocks of communication, to serve all the purposes of the brewery except that of raising the cold water from the well. The coolers L, L, L, are very shallow vessels, built over one another in several stages: and that part of the building in which they are contained is built with lattice-work or or shutter flaps, on all sides, to admit free currents of air. When the wort is sufficiently cooled to be put to the first fermentation, it is conducted in pipes from all the different coolers to the large fermenting vessel or gyle-tun M, which, with another similar vessel behind it, is of sufficient capacity to contain all the beer of one day’s brewings.

Whenever the first fermentation is concluded, the beer is drawn off from the great fermenting vessel M, into the small fermenting casks or cleansing vessels N, of which there are a great number in the brewery. They are placed four together, and to each four a common[112] spout is provided to carry off the yeast, and conduct it into the troughs n, placed beneath. In these cleansing vessels the beer remains till the fermentation is completed; and it is then put into the store-vats, which are casks or tuns of an immense size, where it is kept till wanted, and is finally drawn off into barrels, and sent away from the brewery. The store-vats are not represented in the figure: they are of a conical shape, and of different dimensions, from fifteen to twenty feet diameter, and usually from fifteen to twenty feet in depth. The steam-engine which puts all the machine in motion is exhibited in its place, on the left side of the figure. On the axis of the large fly-wheel is a bevelled spur-wheel, which turns another similar wheel upon the end of a horizontal shaft, which extends from the engine-house to the great horse-wheel, set in motion by means of a spur-wheel. The horse-wheel drives all the pinions for the mill-stones b, b, and also the horizontal axis which works the three-barrelled pump k. The rollers a, a, are turned by a bevel wheel upon the upper end of the axis of the horse-wheel, which is prolonged for that purpose; and the horizontal shaft H, for the mashing engine, is driven by a pair of bevel wheels. There is likewise a sack-tackle, which is not represented. It is a machine for drawing up the sacks of malt from the court-yard to the highest part of the building, whence the sacks are wheeled on a truck to the malt-loft A, and the contents of the sacks are discharged.

The horse-wheel is intended to be driven by horses occasionally, if the steam-engine should fail; but these engines are now brought to such perfection that it is very seldom any recourse of this kind is needed.

Section of fermenting house

Fig. 104 enlarged (362 kB)

Fig. 104. is a representation of the fermenting house at the brewery of Messrs. Whitbread and Company, Chiswell Street, London, which is one of the most complete in its arrangement in the world: it was erected after the plan of Mr. Richardson, who conducts the brewing at those works. The whole of fig. 104. is to be considered as devoted to the same object as the large vessel M and the casks N, fig. 103. In fig. 104., r r is the pipe which leads from the different coolers to convey the wort to the great fermenting vessels or squares M, of which there are two, one behind the other; f f represents a part of the great pipe which conveys all the water from the well E, fig. 103, up to the water cistern[113] F. This pipe is conducted purposely up the wall of the fermenting-house, fig. 104, and has a cock in it, near r, to stop the passage. Just beneath this passage a branch-pipe p proceeds, and enters a large pipe x x, which has the former pipe r withinside of it. From the end of the pipe x, nearest to the squares M, another branch n n proceeds, and returns to the original pipe f, with a cock to regulate it. The object of this arrangement is to make all, or any part, of the cold water flow through the pipe x x, which surrounds the pipe r, formed only of thin copper, and thus cool the wort passing through the pipe r, until it is found by the thermometer to have the exact temperature which is desirable before it is put to ferment in the great square M. By means of the cocks at n and p, the quantity of cold water passing over the surface of the pipe r can be regulated at pleasure, whereby the heat of the wort, when it enters into the square, may be adjusted within half a degree.

When the first fermentation in the squares M M is finished, the beer is drawn off from them by pipes marked c, and conducted by its branches W W W, to the different rows of fermenting-tuns, marked N N, which occupy the greater part of the building. In the hollow between every two rows are placed large troughs, to contain the yeast which they throw off. The figure shows that the small tuns are all placed on a lower level than the bottom of the great vessels M, so that the beer will flow into them, and, by hydrostatic equilibrium, will fill them to the same level. When they are filled, the communication-cock is shut; but, as the working off the yeast diminishes the quantity of beer in each vessel, it is necessary to replenish them from time to time. For this purpose, the two large vats O O are filled from the great squares M M, before any beer is drawn off into the small casks N, and this quantity of beer is reserved at the higher level for filling up. The two vessels O O are, in reality, situated between the two squares M M; but I have been obliged to place them thus in the section, in order that they may be seen. Near each filling-up tun O is a small cistern t communicating with the tun O by a pipe, which is closed by a float-valve. The small cisterns t are always in communication with the pipes which lead to the small fermenting vessels N; and therefore the surface of the beer in all the tuns, and in the cisterns, will always be at the same level; and as this level subsides by the working off of the yeast from the tuns, the float sinks and opens the valve, so as to admit a sufficiency of beer from the filling-up tuns O, to restore the surfaces of the beer in all the tuns, and also in the cistern t, to the original level. In order to carry off the yeast which is produced by the fermentation of the beer in the tuns O O, a conical iron dish or funnel is made to float upon the surface of the beer which they contain; and from the centre of this funnel a pipe, o, descends, and passes through the bottom of the tun, being packed with a collar of leather, so as to be water-tight; at the same time that it is at liberty to slide down, as the surface of the beer descends in the tun. The yeast flows over the edge of this funnel-shaped dish, and is conveyed down the pipe to a trough beneath.

Beneath the fermenting-house are large arched vaults, P, built with stone, and lined with stucco. Into these the beer is let down in casks when sufficiently fermented, and is kept in store till wanted. These vaults are used at Mr. Whitbread’s brewery, instead of the great store-vats of which we have before spoken, and are in some respects preferable, because they preserve a great equality of temperature, being beneath the surface of the earth.

The malt-rollers, or machines for bruising the grains of the malt, fig. 101. 102., have been already described. The malt is shot down from A, fig. 103., the malt-loft, into the hopper; and from this it is let out gradually through a sluice or sliding shuttle, a, fig. 103. and falls between the rollers.

Conveyer screw

Fig. 105. is the screw by which the ground or bruised malt is raised up, or conveyed from one part of the brewery to another. K is an inclined box or trough, in the centre of which the axis of the screw H is placed; the spiral iron plate or worm, which is fixed projecting from the axis, and which forms the screw, is made very nearly to fill the inside of the box. By this means, when the screw is turned round by the wheels E F, or by any other means, it raises up the malt from the box d, and delivers it at the spout G.

This screw is equally applicable for conveying the malt horizontally in the trough K, as slantingly; and similar machines are employed in various parts of breweries for conveying the malt wherever the situation of the works require.


Fig. 106. is the mashing-machine. a a is the tun, made of wood staves, hooped together. In the centre of it rises a perpendicular shaft, b, which is turned slowly round by means of the bevelled wheels t u at the top. c c are two arms, projecting from that axis, and supporting the short vertical axis d of the spur-wheel x, which is turned by the spur-wheel w; so that, when the central axis b is made to revolve, it will carry the thick short axle d round the tun in a circle. That axle d is furnished with a number of arms, e e, which have blades placed obliquely to the plane of their[114] motion. When the axis is turned round, these arms agitate the malt in the tun, and give it a constant tendency to rise upwards from the bottom.

The motion of the axle d is produced by a wheel, x, on the upper end of it, which is turned by a wheel, w, fastened on the middle of the tube b, which turns freely round upon its central axis. Upon a higher point of the same tube b is a bevel wheel, o, receiving motion from a bevel wheel, q, fixed upon the end of the horizontal axis n n, which gives motion to the whole machine. This same axis has a pinion, p, upon it, which gives motion to the wheel r, fixed near the middle of a horizontal axle, which, at its left hand end, has a bevel pinion, t, working the wheel u, before mentioned. By these means, the rotation of the central axis b will be very slow compared with the motion of the axle d; for the latter will make seventeen or eighteen revolutions on its own axis in the same space of time that it will be carried once round the tun by the motion of the shaft b. At the beginning of the operation of mashing, the machine is made to turn with a slow motion; but, after having wetted all the malt by one revolution, it is driven quicker. For this purpose, the ascending-shaft f g, which gives[115] motion to the machine, has two bevel wheels, h i, fixed upon a tube, f g, which is fitted upon a central shaft. These wheels actuate the wheels m and o, upon the end of the horizontal shaft n n; but the distance between the two wheels h and i is such, that they cannot be engaged both at once with the wheels m and o; but the tube f g, to which they are fixed, is capable of sliding up and down on its central axis sufficiently to bring either wheel h or i into geer with its corresponding wheel o or m, upon the horizontal shaft; and as the diameters of n o, and i m, are of very different proportions, the velocity of the motion of the machine can be varied at pleasure, by using one or other. k and k are two levers, which are forked at their extremities, and embrace collars at the ends of the tube f g. These levers being united by a rod, l, the handle k gives the means of moving the tube f g, and its wheels h i, up or down, to throw either the one or the other wheel into geer.

The object of boiling the wort is not merely evaporation and concentration, but extraction, coagulation, and, finally, combination with the hops; purposes which are better accomplished in a deep confined copper, by a moderate heat, than in an open shallow pan with a quick fire. The copper being encased above in brickwork, retains its digesting temperature much longer than the pan could do. The waste steam of the close kettle, moreover, can be economically employed in communicating heat to water or weak worts; whereas the exhalations from an open pan would prove a nuisance, and would need to be carried off by a hood. The boiling has a four-fold effect: 1. it concentrates the wort; 2. during the earlier stages of heating, it converts the starch into sugar, dextrine, and gum, by means of the diastase; 3. it extracts the substance of the hops diffused through the wort; 4. it coagulates the albuminous matter present in the grain, or precipitates it by means of the tannin of the hops.

The degree of evaporation is regulated by the nature of the wort, and the quality of the beer. Strong ale and stout for keeping, require more boiling than ordinary porter or table-beer brewed for immediate use. The proportion of the water carried off by evaporation is usually from a seventh to a sixth of the volume. The hops are introduced during the progress of the ebullition. They serve to give the beer not only a bitter aromatic taste, but also a keeping quality, or they counteract its natural tendency to become sour; an effect partly due to the precipitation of the albumen and starch, by their resinous and tanning constituents, and partly to the antifermentable properties of their lupuline, bitter principle, ethereous oil, and resin. In these respects, there is none of the bitter plants which can be substituted for hops with advantage. For strong beer, powerful fresh hops should be selected; for weaker beer, an older and weaker article will suffice.

The hops are either boiled with the whole body of the wort, or extracted with a portion of it; and this concentrated extract added to the rest. The stronger the hops are, the longer time they require for extraction of their virtues; for strong hops, an hour and a half or two hours boiling may be proper; for a weaker sort, half an hour or an hour may be sufficient; but it is never advisable to push this process too far, lest a disagreeable bitterness, without aroma, be imparted to the beer. In our breweries, it is the practice to boil the hops with a part of the wort, and to filter the decoction through a drainer, called the jack hop-back. The proportion of hops to malt is very various; but, in general, from a pound and a quarter to a pound and a half of the former are taken for 100 lbs. of the latter in making good table-beer. For porter and strong ale, 2 pounds of hops are used, or even more; for instance, one pound of hops to a bushel of malt, if the beer be destined for the consumption of India.

During the boiling of the two ingredients, much coagulated albuminous matter, in various states of combination, makes its appearance in the liquid, constituting what is called the breaking or curdling of the wort, when numerous minute flocks are seen floating in it. The resinous, bitter, and oily-ethereous principles of the hops combine with the sugar and gum, or dextrine of the wort; but for this effect they require time and heat; showing that the boil is not a process of mere evaporation, but one of chemical reaction. A yellowish-green pellicle of hop-oil and resin appears upon the surface of the boiling wort, in a somewhat frothy form: when this disappears, the boiling is presumed to be completed, and the beer is strained off into the cooler. The residuary hops may be pressed and used for an inferior quality of beer; or they may be boiled with fresh wort, and be added to the next brewing charge.

Figs. 107, 108. represent the copper of a London brewery. Fig. 107. is a vertical section; fig. 108., a ground-plan of the fire-grate and flue, upon a smaller scale: a is the close copper kettle, having its bottom convex within; b is the open pan placed upon its top. From the upper part of the copper, a wide tube, c, ascends, to carry off the steam generated during the ebullition of the wort, which is conducted through four downwards-slanting tubes, d d (two only are visible in this section), into the liquor of the pan b, in order to warm its contents. A vertical iron shaft or spindle, e, passes down through the tube c, nearly to the bottom of the copper, and is there mounted with an iron arm, called a[116] rouser, which carries round a chain hung in loops, to prevent the hops from adhering to the bottom of the boiler. Three bent stays, f, are stretched across the interior, to support the shaft by a collet at their middle junction. The shaft carries at its upper end a bevel wheel, g, working into a bevel pinion upon the axis h, which may be turned either by power or by hand. The rouser shaft may be lifted by means of the chain i, which, going over two pulleys, has its end passed round the wheel and axle k, and is turned by a winch: l is a tube for conveying the waste steam into the chimney m.

Brewery copper

Fig. 108 enlarged (41 kB)

The heat is applied as follows:—For heating the colossal coppers of the London breweries, two separate fires are required, which are separated by a narrow wall of brickwork, n, fig. 107M, 108. The dotted circle a′ a′ indicates the largest circumference of the copper, and b′ b′ its bottom; o o are the grates upon which the coals are thrown, not through folding doors (as of old), but through a short slanting iron hopper, shown at p, fig. 107., built in the wall, and kept constantly filled with the fuel, in order to exclude the air. Thus the lower stratum of coals gets ignited before it reaches the grate. Above the hopper p, a narrow channel is provided for the admission of atmospherical air, in such quantity merely as may be requisite to complete the combustion of the smoke of the coals. Behind each grate there is a fire-bridge, r, which reflects the flame upwards, and causes it to play upon the bottom of the copper. The burnt air then passes round the copper in a semicircular flue, s s, from which it flows off into the chimney m, on whose under end a sliding damper-plate, t, is placed, for tempering the draught. When cold air is admitted at this orifice, the combustion of the fuel is immediately checked. There is, besides, another slide-plate at the entrance of the slanting flue into the vertical chimney, for regulating the play of the flame under and around the copper. If the plate t be opened, and the other plate shut, the power of the fire is suspended, as it ought to be, at the time of emptying the copper. Immediately over the grate is a brick arch, u, to protect the front edge of the copper from the first impulsion of the flame. The chimney is supported upon iron pillars, v v; w is a cavity closed with a slide-plate, through which the ashes may be taken out from behind, by means of a long iron hook.


Fig. 109. represents one of the sluice-cocks, which are used to make the communications of the pipes with the pumps, or other parts of the brewery. B B represents the pipe in which the cock is placed. The two parts of this pipe are screwed to the side of a box, C C, in which a slider, A, rises and falls, and intercepts, at pleasure, the passage of the pipe. The slider is moved by the rod a. This passes through a stuffing-box,[117] in the top of the box which contains the slider, and has the rack b fastened to it. The rack is moved by a pinion fixed upon the axis of a handle e, and the rack and pinion are contained in a frame d which is supported by two pillars. The frame contains a small roller behind the rack, which bears it up towards the pinion, and keeps its teeth up to the teeth of the pinion. The slider A is made to fit accurately against the internal surface of the box C, and to bear against this surface by the pressure of a spring, so as to make a perfectly close fitting.

Small cock

Fig. 110. is a small cock to be placed in the side of the great store vats, for the purpose of drawing off a small quantity of beer, to taste and try its quality. A is a part of the stave or thickness of the great store vat; into this the tube B of the cock is fitted, and is held tight in its place by a nut, a a, screwed on withinside. At the other end of the tube B, a plug, c, is fitted, by grinding it into a cone, and it is kept in by a screw. This plug has a hole up the centre of it, and from this a hole proceeds sidewise, and corresponds with a hole made through the side of the tube when the cock is open; but when the plug c is turned round, the hole will not coincide, and then the cock will be shut. D is the handle or key of the cock, by which its plug is turned to open or shut it: this handle is put up the bore of the tube (the cover E being first unscrewed and removed), and the end of it is adapted to fit the end of the plug of the cock. The handle has a tube or passage bored up it, to convey the beer away from the cock when it is opened, and from this the passage f, through the handle, leads, to draw the beer into a glass or tumbler. The hole in the side of the plug is so arranged, that, when the handle is turned into a perpendicular direction, with the passage f downwards, the cock will be open. The intention of this contrivance is, that there shall be no considerable projection beyond the surface of the tun; because it sometimes happens that a great hoop of the tun breaks, and, falling down, its great weight would strike out any cock which had a projection; and, if this happened in the night, much beer might be lost before it was discovered. The cock above described, being almost wholly withinside, and having scarcely any projection beyond the outside surface of the tun, is secure from this accident.

Vent peg

Fig. 111. is a small contrivance of a vent peg, to be screwed into the head of a common cask when the beer is to be drawn off from it, and it is necessary to admit some air to allow the beer to flow. A A represents a portion of the head of the cask into which the tube B is screwed. The top of this tube is surrounded by a small cup, from which project the two small handles C C, by which the peg is turned round to screw it into the cask. The cup round the other part of the tube, is filled with water; into this a small cup, D, is inverted; in consequence, the air can gain admission into the cask when the pressure within is so far diminished, that the air will bubble up through the water, and enter beneath the small cup D.

The most efficient substance for fining beer hitherto discovered is isinglass, which is prepared by solution in vinegar or old stale beer, and this solution is afterwards reduced with thin mild beer generally brewed for the purpose, in all large establishments, from a raw or return wort. It must next be passed through a fine hair sieve, by means of rubbing it down with a hard hair-brush, and brought to the proper consistency by thin mild beer. If properly made, it will be clear, transparent, and free from feculencies. Finings serve excellently to remove any extraneous matter that may be found floating in the beer, and thus changes it from bright to brilliant. The common quantity used is from a pint to a quart per barrel, according to the nature of the beer.

To ascertain whether the beer is in a fit state for fining, put it into a long glass cylindric vessel, and add to it a teaspoonful, or thereby, of the fining; then give the mixture a good shake, by turning the vessel up and down, after closing its mouth with[118] the palm of the hand. If the beer has been well brewed, its aptitude to become bright will be soon shown by the mixture getting thick and curdy; a bright portion will generally show itself at the bottom or middle; after which the finings will gradually mount to the top, taking up all the impurities along with them, till the whole becomes brilliant. Some have said that the finings should carry the impurities down to the bottom; but this, according to Mr. Black[8], takes place only with stubborn beer, which would not become thoroughly bright with any quantity of finings which could be introduced. Finings have usually a specific gravity of from 1·010 to 1·016, and, when added to beer in a fit condition for fining, invariably go to the top, and not to the bottom. In fining beer in a barrel laid on its side, if the finings do not make their appearance at the bung-hole, the beer will not become bright. The isinglass must not be dissolved with heat, nor in hot water.

[8] Treatise on Brewing, 8vo, p. 68.

Beer brewed from imperfectly malted grain, or from a mixture of malt and raw corn, gives a fermentation quite different in flavour from that of beer from sound malt. The nose is, in fact, the best guide to the experienced brewer for ascertaining whether his process is going on we