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Soap-Making Manual

A practical handbook on the raw materials, their manipulation, analysis
and control in the modern soap plant.

By

_E. G. Thomssen, Ph. D._

ILLUSTRATED


NEW YORK

D. VAN NOSTRAND COMPANY

EIGHT WARREN STREET

1922

COPYRIGHT 1922

BY

D. VAN NOSTRAND COMPANY

Printed in the United States of America

       *       *       *       *       *

Transcriber's note:

This is a series of articles collected into a book. There are
differences in spelling and punctuation in the different chapters (e.g.
cocoanut in one chapter and coconut in another). These differences were
left in the text as they appeared.

For Text: A word surrounded by a tilde such as ~this~ signifies that
the word is bolded in the text. A word surrounded by underscores like
_this_ signifies the word is italics in the text.

For numbers and equations: Parentheses have been added to clarify
fractions. Underscores before bracketed numbers in equations denote a
subscript.

Minor typos have been corrected and footnotes moved to the end of the
chapters.

       *       *       *       *       *


PREFATORY NOTE.


The material contained in this work appeared several years ago in serial
form in the American Perfumer and Essential Oil Review. Owing to the
numerous requests received, it has been decided to now place before
those interested, these articles in book form. While it is true that the
works pertaining to the soapmaking industry are reasonably plentiful,
books are quite rare, however, which, in a brief volume, will clearly
outline the processes employed together with the necessary methods of
analyses from a purely practical standpoint. In the work presented the
author has attempted to briefly, clearly, and fully explain the
manufacture of soap in such language that it might be understood by all
those interested in this industry. In many cases the smaller plants find
it necessary to dispense with the services of a chemist, so that it is
necessary for the soapmaker to make his own tests. The tests outlined,
therefore, are given as simple as possible to meet this condition. The
formulae submitted are authentic, and in many cases are now being used
in soapmaking.

In taking up the industry for survey it has been thought desirable to
first mention and describe the raw materials used; second, to outline
the processes of manufacture; third, to classify the methods and
illustrate by formulae the composition of various soaps together with
their mode of manufacture; fourth, to enumerate the various methods of
glycerine recovery, including the processes of saponification, and,
fifth, to give the most important analytical methods which are of value
to control the process of manufacture and to determine the purity and
fitness of the raw material entering into it.

It is not the intention of the author to go into great detail in this
work, nor to outline to any great extent the theoretical side of the
subject, but rather to make the work as brief as possible, keeping the
practical side of the subject before him and not going into concise
descriptions of machinery as is very usual in works on this subject.
Illustrations are merely added to show typical kinds of machinery used.

The author wishes to take this opportunity of thanking Messrs. L. S.
Levy and E. W. Drew for the reading of proof, and Mr. C. W. Aiken of the
Houchin-Aiken Co., for his aid in making the illustrations a success, as
well as others who have contributed in the compiling of the formulae for
various soaps. He trusts that this work may prove of value to those
engaged in soap manufacture.

E. G. T.

January, 1922




TABLE OF CONTENTS.


CHAPTER I.                                                      Page.

RAW MATERIALS USED IN SOAP MAKING                                1-30

  1. Soap Defined                                                   1

  2. Oils and Fats                                                1-2

  3. Saponification Defined                                       2-3

  4. Fats and Oils Used in Soap Manufacture                       3-4
    Fullers' Earth Process for Bleaching Tallow                   4-6
    Method for Further Improvement of Color in Tallow               6
    Vegetable Oils                                                6-9
    Chrome Bleaching of Palm Oil                                 9-12
    Air Bleaching of Palm Oil                                   12-16

  5. Rancidity of Oils and Fats                                 16-18
    Prevention of Rancidity                                        18

  6. Chemical Constants of Oils and Fats                        18-19

  7. Oil Hardening or Hydrogenating                             19-21

  8. Grease                                                     21-22

  9. Rosin (Colophony, Yellow Rosin, Resina)                    22-23

  10. Rosin Saponification                                      23-24

  11. Naphthenic Acids                                          24-25

  12. Alkalis                                                   25-26
    Caustic Soda                                                   26
    Caustic Potash                                              26-28
    Sodium Carbonate (Soda Ash)                                 28-29
    Potassium Carbonate                                            29

  13. Additional Material Used in Soap Making                   29-30


CHAPTER II.

CONSTRUCTION AND EQUIPMENT OF A SOAP PLANT                      31-34


CHAPTER III.

CLASSIFICATION OF SOAP MAKING METHODS                           35-46

  1. Full Boiled Soaps                                          36-42

  2. Cold Process                                               43-44

  3. Carbonate Saponification                                   45-46


CHAPTER IV.

CLASSIFICATION OF SOAPS                                        47-104

  1. Laundry Soap                                                  48
    Semi-Boiled Laundry Soap                                    49-50
    Settled Rosin Soap                                          50-54

  2. Chip Soap                                                  54-55
    Cold Made Chip Soap                                         55-56
    Unfilled Chip Soap                                             56

  3. Soap Powders                                               56-59
    Light Powders                                               60-61

  4. Scouring Powders                                              61

  5. Scouring Soap                                              61-62

  6. Floating Soap                                              62-65

  7. Toilet Soap                                                65-68
    Cheaper Toilet Soaps                                        68-69
    Run and Glued-up Soaps                                      69-71
    Curd Soap                                                   71-72
    Cold Made Toilet Soaps                                      72-73
    Perfuming and Coloring Toilet Soaps                         73-75
    Coloring Soap                                               75-76

  8. Medicinal Soaps                                            76-77
    Sulphur Soaps                                                  77
    Tar Soap                                                       77
    Soaps Containing Phenols                                    77-78
    Peroxide Soap                                                  78
    Mercury Soaps                                                  78
    Less Important Medicinal Soaps                              78-79

  9. Castile Soap                                               79-81

  10. Eschweger Soap                                            81-82

  11. Transparent Soap                                          82-84
    Cold Made Transparent Soap                                  84-87

  12. Shaving Soaps                                             87-90
    Shaving Powder                                                 90
    Shaving Cream                                               90-93

  13. Pumice or Sand Soaps                                      93-94

  14. Liquid Soaps                                              94-95

  15. Use of Hardened Oils in Toilet Soaps                      96-98

  16. Textile Soaps                                                98
    Scouring and Fulling Soaps for Wool                        98-100
    Wool Thrower's Soap                                       100-101
    Worsted Finishing Soaps                                       101
    Soaps Used in the Silk Industry                           101-103
    Soaps Used for Cotton Goods                               103-104

  17. Sulphonated Oils                                        104-105


CHAPTER V.

GLYCERINE RECOVERY                                            105-126

  1. Methods of Saponification                                105-106
     Recovery of Glycerine from Spent Lye                     106-113
     Twitchell Process                                        113-118
     Autoclave Saponification                                     118
     Lime Saponification                                      118-120
     Acid Saponification                                      120-121
     Aqueous Saponification                                       121
     Splitting Fats with Ferments                             121-123
     Krebitz Process                                          123-125

  2. Distillation of Fatty Acids                              125-126


CHAPTER VI.

ANALYTICAL METHODS                                            127-164

  1. Analysis of Oils and Fats                                    128
     Free Fatty Acids                                         128-130
     Moisture                                                     130
     Titer                                                    130-132
     Determination of Unsaponifiable Matter                   132-133
     Test for Color of Soap                                   133-134
     Testing of Alkalis Used in Soap Making                   134-137

  2. Soap Analysis                                            137-138
     Moisture                                                 138-139
     Free Alkali or Acid                                      139-142
     Insoluble Matter                                             143
     Starch and Gelatine                                      143-144
     Total Fatty and Resin Acids                                  144
     Determination of Rosin                                   144-147
     Total Alkali                                             147-148
     Unsaponifiable Matter                                        148
     Silica and Silicates                                     148-149
     Glycerine in Soap                                        149-150
     Sugar in Soap                                                150

  3. Glycerine Analysis                                       150-151
     Sampling                                                     151
     Analysis                                                 151-154
     Acetin Process for the Determination of Glycerol         155-156
     The Method                                               156-159
     Ways of Calculating Actual Glycerol Contents             159-160
     Bichromate Process for Glycerol Determination
       Reagents Required                                      160-161
     The Method                                               161-162
     Sampling Crude Glycerine                                 162-164


CHAPTER VII

STANDARD METHODS FOR THE SAMPLING AND ANALYSIS OF
COMMERCIAL FATS AND OILS                                      165-195

  1. Scope, Applicability and Limitations of the Methods      165-166
    Scope                                                         165
    Applicability                                                 166
    Limitations                                                   166
    Sampling                                                  166-169
    Tank Cars                                                 166-167
    Barrels, Tierces, Casks, Drums, and Other Packages            168

  2. Analysis                                                 169-183
    Sample                                                        169
    Moisture and Volatile Matter                              170-172
    Insoluble Impurities                                      172-173
    Soluble Mineral Matter                                        173
    Free Fatty Acids                                              174
    Titer                                                     174-175
    Unsaponifiable Matter                                     176-177
    Iodine Number-Wijs Method                                 177-181
    Saponification Number (Koettstorfer Number)                   181
    Melting Point                                             181-182
    Cloud Test                                                182-184

  3. Notes of the Above Methods                               184-196
    Sampling                                                      183
    Moisture and Volatile Matter                              184-187
    Insoluble Impurities                                          187
    Soluble Mineral Matter                                    187-188
    Free Fatty Acid                                           188-189
    Titer                                                         189
    Unsaponified Matter                                       190-193
    Melting Point                                             193-196

Plant and Machinery                                           198-219
    Illustrations of Machinery and Layouts of the Plant
    of a Modern Soap Making Establishment                     198-219

Appendix                                                      219-237

    Useful Tables

Index                                                             239




CHAPTER I

Raw Materials Used in Soap Making.


Soap is ordinarily thought of as the common cleansing agent well known
to everyone. In a general and strictly chemical sense this term is
applied to the salts of the non-volatile fatty acids. These salts are
not only those formed by the alkali metals, sodium and potassium, but
also those formed by the heavy metals and alkaline earths. Thus we have
the insoluble soaps of lime and magnesia formed when we attempt to wash
in "hard water"; again aluminum soaps are used extensively in polishing
materials and to thicken lubricating oils; ammonia or "benzine" soaps
are employed among the dry cleaners. Commonly, however, when we speak of
soap we limit it to the sodium or potassium salt of a higher fatty acid.

It is very generally known that soap is made by combining a fat or oil
with a water solution of sodium hydroxide (caustic soda lye), or
potassium hydroxide (caustic potash). Sodium soaps are always harder
than potassium soaps, provided the same fat or oil is used in both
cases.

The detergent properties of soap are due to the fact that it acts as an
alkali regulator, that is, when water comes into contact with soap, it
undergoes what is called hydrolytic dissociation. This means that it is
broken down by water into other substances. Just what these substances
are is subject to controversy, though it is presumed caustic alkali and
the acid alkali salt of the fatty acids are formed.


OILS AND FATS.

There is no sharp distinction between fat and oil. By "oil" the layman
has the impression of a liquid which at warm temperature will flow as a
slippery, lubricating, viscous fluid; by "fat" he understands a greasy,
solid substance unctuous to the touch. It thus becomes necessary to
differentiate the oils and fats used in the manufacture of soap.

Inasmuch as a soap is the alkali salt of a fatty acid, the oil or fat
from which soap is made must have as a constituent part, these fatty
acids. Hydrocarbon oils or paraffines, included in the term "oil," are
thus useless in the process of soap-making, as far as entering into
chemical combination with the caustic alkalis is concerned. The oils and
fats which form soap are those which are a combination of fatty acids
and glycerine, the glycerine being obtained as a by-product to the
soap-making industry.


NATURE OF A FAT OR OIL USED IN SOAP MANUFACTURE.

Glycerine, being a trihydric alcohol, has three atoms of hydrogen which
are replaceable by three univalent radicals of the higher members of the
fatty acids, _e. g._,

                OH                       OR
    C_{3} H_{5} OH + 3 ROH = C_{3} H_{5} OR + 3 H_{2}O
                OH                       OR

Glycerine plus 3 Fatty Alcohols equals Fat or Oil plus 3 Water.

Thus three fatty acid radicals combine with one glycerine to form a true
neutral oil or fat which are called triglycerides. The fatty acids which
most commonly enter into combination of fats and oils are lauric,
myristic, palmitic, stearic and oleic acids and form the neutral oils or
triglycerides derived from these, _e. g._, stearin, palmatin, olein.
Mono and diglycerides are also present in fats.


SAPONIFICATION DEFINED.

When a fat or oil enters into chemical combination with one of the
caustic hydrates in the presence of water, the process is called
"saponification" and the new compounds formed are soap and glycerine,
thus:

               OR                       OH
    C_{3}H_{5} OR + 3 NaOH = C_{3}H_{5} OH + 3 NaOR
               OR                       OH

Fat or Oil plus 3 Sodium Hydrate equals Glycerine plus 3 Soap.

It is by this reaction almost all of the soap used today is made.

There are also other means of saponification, as, the hydrolysis of an
oil or fat by the action of hydrochloric or sulfuric acid, by autoclave
and by ferments or enzymes. By these latter processes the fatty acids
and glycerine are obtained directly, no soap being formed.


FATS AND OILS USED IN SOAP MANUFACTURE.

The various and most important oils and fats used in the manufacture of
soap are, tallow, cocoanut oil, palm oil, olive oil, poppy oil, sesame
oil, soya bean oil, cotton-seed oil, corn oil and the various greases.
Besides these the fatty acids, stearic, red oil (oleic acid) are more or
less extensively used. These oils, fats and fatty acids, while they vary
from time to time and to some extent as to their color, odor and
consistency, can readily be distinguished by various physical and
chemical constants.

Much can be learned by one, who through continued acquaintance with
these oils has thoroughly familiarized himself with the indications of a
good or bad oil, by taste, smell, feel and appearance. It is, however,
not well for the manufacturer in purchasing to depend entirely upon
these simpler tests. Since he is interested in the yield of glycerine,
the largest possible yield of soap per pound of soap stock and the
general body and appearance of the finished product, the chemical tests
upon which these depend should be made. Those especially important are
the acid value, percentage unsaponifiable matter and titer test.

A short description of the various oils and fats mentioned is sufficient
for their use in the soap industry.

_Tallow_ is the name given to the fat extracted from the solid fat or
"suet" of cattle, sheep or horses. The quality varies greatly, depending
upon the seasons of the year, the food and age of the animal and the
method of rendering. It comes to the market under the distinction of
edible and inedible, a further distinction being made in commerce as
beef tallow, mutton tallow or horse tallow. The better quality is white
and bleaches whiter upon exposure to air and light, though it usually
has a yellowish tint, a well defined grain and a clean odor. It consists
chiefly of stearin, palmitin and olein. Tallow is by far the most
extensively used and important fat in the making of soap.

In the manufacture of soaps for toilet purposes, it is usually necessary
to produce as white a product as possible. In order to do this it often
is necessary to bleach the tallow before saponification. The method
usually employed is the Fuller's Earth process.


FULLER'S EARTH PROCESS FOR BLEACHING TALLOW.

From one to two tons of tallow are melted out into the bleaching tank.
This tank is jacketed, made of iron and provided with a good agitator
designed to stir up sediment or a coil provided with tangential downward
opening perforations and a draw-off cock at the bottom. The coil is the
far simpler arrangement, more cleanly and less likely to cause trouble.
By this arrangement compressed air which is really essential in the
utilization of the press (see later) is utilized for agitation. A dry
steam coil in an ordinary tank may be employed in place of a jacketed
tank, which lessens the cost of installation.

The tallow in the bleaching tank is heated to 180° F. (82° C.) and ten
pounds of dry salt per ton of fat used added and thoroughly mixed by
agitation. This addition coagulates any albumen and dehydrates the fat.
The whole mass is allowed to settle over night where possible, or for at
least five hours. Any brine which has separated is drawn off from the
bottom and the temperature of the fat is then raised to 160° F. (71° C).

Five per cent. of the weight of the tallow operated upon, of dry
Fuller's earth is now added and the whole mass agitated from twenty to
thirty minutes.

The new bleached fat, containing the Fuller's earth is pumped directly
to a previously heated filter press and the issuing clear oil run
directly to the soap kettle.

One of the difficulties experienced in the process is the heating of the
press to a temperature sufficient to prevent solidification of the fat
without raising the press to too great a temperature. To overcome this
the first plate is heated by wet steam. Air delivered from a blower and
heated by passage through a series of coils raised to a high temperature
by external application of heat (super-heated steam) is then substituted
for the steam. The moisture produced by the condensation of the steam is
vaporized by the hot air and carried on gradually to each succeeding
plate where it again condenses and vaporizes. In this way the small
quantity of water is carried through the entire press, raising its
temperature to 80°-100° C. This temperature is subsequently maintained
by the passage of hot air. By this method of heating the poor
conductivity of hot air is overcome through the intermediary action of a
liquid vapor and the latent heat of steam is utilized to obtain the
initial rise in temperature. To heat a small press economically where
conditions are such that a large output is not required the entire
press may be encased in a small wooden house which can be heated by
steam coils. The cake in the press is heated for some time after the
filtration is complete to assist drainage. After such treatment the cake
should contain approximately 15 per cent. fat and 25 per cent. water.
The cake is now removed from the press and transferred to a small tank
where it is treated with sufficient caustic soda to convert the fat
content into soap.

Saturated brine is then added to salt out the soap, the Fuller's earth
is allowed to settle to the bottom of the tank and the soap which
solidifies after a short time is skimmed off to be used in a cheap soap
where color is not important. The liquor underneath may also be run off
without disturbing the sediment to be used in graining a similar cheap
soap. The waste Fuller's earth contains about 0.1 to 0.3 per cent. of
fat.


METHOD FOR FURTHER IMPROVEMENT OF COLOR.

A further improvement of the color of the tallow may be obtained by
freeing it from a portion of its free fatty acids, either with or
without previous Fuller's earth bleaching.

To carry out this process the melted fat is allowed to settle and as
much water as possible taken off. The temperature is then raised to 160°
F. with dry steam and enough saturated solution of soda ash added to
remove 0.5 per cent. of the free fatty acids, while agitating the mass
thoroughly mechanically or by air. The agitation is continued ten
minutes, the whole allowed to settle for two hours and the foots drawn
off. The soap thus formed entangles a large proportion of the impurities
of the fat.


VEGETABLE OILS.

_Cocoanut Oil_, as the name implies, is obtained from the fruit of the
cocoanut palm. This oil is a solid, white fat at ordinary temperature,
having a bland taste and a characteristic odor. It is rarely
adulterated and is very readily saponified. In recent years the price of
this oil has increased materially because cocoanut oil is now being used
extensively for edible purposes, especially in the making of
oleomargarine. Present indications are that shortly very little high
grade oil will be employed for soap manufacture since the demand for
oleomargarine is constantly increasing and since new methods of refining
the oil for this purpose are constantly being devised.

The oil is found in the market under three different grades: (1) Cochin
cocoanut oil, the choicest oil comes from Cochin (Malabar). This
product, being more carefully cultivated and refined than the other
grades, is whiter, cleaner and contains a smaller percentage of free
acid. (2) Ceylon cocoanut oil, coming chiefly from Ceylon, is usually of
a yellowish tint and more acrid in odor than Cochin oil. (3) Continental
cocoanut oil (Copra, Freudenberg) is obtained from the dried kernels,
the copra, which are shipped to Europe in large quantities, where the
oil is extracted. These dried kernels yield 60 to 70 per cent oil. This
product is generally superior to the Ceylon oil and may be used as a
very satisfactory substitute for Cochin oil, in soap manufacture,
provided it is low in free acid and of good color. The writer has
employed it satisfactorily in the whitest and finest of toilet soaps
without being able to distinguish any disadvantage to the Cochin oil.
Since continental oil is usually cheaper than Cochin oil, it is
advisable to use it, as occasion permits.

Cocoanut oil is used extensively in toilet soap making, usually in
connection with tallow. When used alone the soap made from this oil
forms a lather, which comes up rapidly but which is fluffy and dries
quickly. A pure tallow soap lathers very much slower but produces a more
lasting lather. Thus the advantage of using cocoanut oil in soap is
seen. It is further used in making a cocoanut oil soap by the cold
process also for "fake" or filled soaps. The fatty acid content readily
starts the saponification which takes place easily with a strong lye
(25°-35° B.). Where large quantities of the oil are saponified care must
be exercised as the soap formed suddenly rises or puffs up and may boil
over. Cocoanut oil soap takes up large quantities of water, cases having
been cited where a 500 per cent. yield has been obtained. This water of
course dries out again upon exposure to the air. The soap is harsh to
the skin, develops rancidity and darkens readily.

_Palm Kernel Oil_, which is obtained from the kernels of the palm tree
of West Africa, is used in soap making to replace cocoanut oil where the
lower price warrants its use. It resembles cocoanut oil in respect to
saponification and in forming a very similar soap. Kernel oil is white
in color, has a pleasant nutty odor when fresh, but rapidly develops
free acid, which runs to a high percentage.

_Palm Oil_ is produced from the fruit of the several species of the palm
tree on the western coast of Africa generally, but also in the
Philippines. The fresh oil has a deep orange yellow tint not destroyed
by saponification, a sweetish taste and an odor of orris root or violet
which is also imparted to soap made from it. The methods by which the
natives obtain the oil are crude and depend upon a fermentation, or
putrefaction. Large quantities are said to be wasted because of this
fact. The oil contains impurities in the form of fermentable fibre and
albuminous matter, and consequently develops free fatty acid rapidly.
Samples tested for free acid have been found to have hydrolized
completely and one seldom obtains an oil with low acid content. Because
of this high percentage of free fatty acid, the glycerine yield is
small, though the neutral oil should produce approximately 12 per cent.
glycerine. Some writers claim that glycerine exists in the free state
in palm oil. The writer has washed large quantities of the oil and
analyzed the wash water for glycerine. The results showed that the
amount present did not merit its recovery. Most soap makers do not
attempt to recover the glycerine from this oil, when used alone for soap
manufacture.

There are several grades of palm oil in commerce, but in toilet soap
making it is advisable to utilize only Lagos palm oil, which is the best
grade. Where it is desired to maintain the color of the soap this oil
produces, a small quantity of the lower or "brass" grade of palm oil may
be used, as the soap made from the better grades of oil gradually
bleaches and loses its orange yellow color.

Palm oil produces a crumbly soap which cannot readily be milled and is
termed "short." When used with tallow and cocoanut oil, or 20 to 25 per
cent. cocoanut oil, it produces a very satisfactory toilet soap. In the
saponification of palm oil it is not advisable to combine it with tallow
in the kettle, as the two do not readily mix.

Since the finished soap has conveyed to it the orange color of the oil,
the oil is bleached before saponification. Oxidation readily destroys
the coloring matter, while heat and light assist materially. The methods
generally employed are by the use of oxygen developed by bichromates and
hydrochloric acid and the direct bleaching through the agency of the
oxygen of the air.


CHROME BLEACHING OF PALM OIL.

The chrome process of bleaching palm oil is more rapid and the oxygen
thus derived being more active will bleach oils which air alone cannot.
It depends upon the reaction:

    Na_{2}Cr_{2}O_{7} + 8HCl = Cr_{2}Cl_{6} + 2NaCl + 7O.

in which the oxygen is the active principle. In practice it is found
necessary to use an excess of acid over that theoretically indicated.

For the best results an oil should be chosen containing under 2 per
cent. impurities and a low percentage of free fatty acids. Lagos oil is
best adapted to these requirements. The oil is melted by open steam from
a jet introduced through the bung, the melted oil and condensed water
running to the store tank through two sieves (about 1/8 inch mesh) to
remove the fibrous material and gross impurities. The oil thus obtained
contains fine earthy and fibrous material and vegetable albuminous
matter which should be removed, as far as possible, since chemicals are
wasted in their oxidation and they retard the bleaching. This is best
done by boiling the oil for one hour with wet steam and 10 per cent.
solution of common salt (2 per cent. dry salt on weight of oil used) in
a lead-lined or wooden tank. After settling over night the brine and
impurities are removed by running from a cock at the bottom of the vat
and the oil is run out into the bleaching tank through an oil cock,
situated about seven inches from the bottom.

The bleaching tank is a lead-lined iron tank of the approximate
dimensions of 4 feet deep, 4 feet long and 3-1/2 feet wide, holding
about 1-1/2 tons. The charge is one ton. A leaden outlet pipe is fixed
at the bottom, to which is attached a rubber tube closed by a screw
clip. A plug also is fitted into the lead outlet pipe from above. Seven
inches above the lower outlet is affixed another tap through which the
oil is drawn off.

The tank is further equipped with a wet steam coil and a coil arranged
to allow thorough air agitation, both coils being of lead. A good
arrangement is to use one coil to deliver either air or steam. These
coils should extend as nearly as possible over the entire bottom of the
tank and have a number of small downward perforations, so as to spread
the agitation throughout the mass.

The temperature of the oil is reduced by passing in air to 110° F. and
40 pounds of fine common salt per ton added through a sieve. About
one-half of the acid (40 pounds of concentrated commercial hydrochloric
acid) is now poured in and this is followed by the sodium bichromate in
concentrated solution, previously prepared in a small lead vat or
earthen vessel by dissolving 17 pounds of bichromate in 45 pounds
commercial hydrochloric acid. This solution should be added slowly and
should occupy three hours, the whole mass being thoroughly agitated with
air during the addition and for one hour after the last of the bleaching
mixture has been introduced. The whole mixture is now allowed to settle
for one hour and the exhausted chrome liquors are then run off from the
lower pipe to a waste tank. About 40 gallons of water are now run into
the bleached oil and the temperature raised by open steam to 150° to
160° F. The mass is then allowed to settle over night.

One such wash is sufficient to remove the spent chrome liquor
completely, provided ample time is allowed for settling. A number of
washings given successively with short periods of settling do not remove
the chrome liquors effectually. The success of the operation depends
entirely upon the completeness of settling.

The wash water is drawn off as before and the clear oil run to storage
tanks or to the soap kettle through the upper oil cock.

The waste liquors are boiled with wet steam and the oil skimmed from the
surface, after which the liquors are run out through an oil trap.

By following the above instructions carefully it is possible to bleach
one ton of palm oil with 17 pounds of bichromate of soda and 85 pounds
hydrochloric acid.

The spent liquors should be a bright green color. Should they be of a
yellow or brownish shade insufficient acid has been allowed and more
must be added to render the whole of the oxygen available.

If low grade oils are being treated more chrome will be necessary, the
amount being best judged by conducting the operation as usual and after
the addition of the bichromate, removing a sample of the oil, washing
the sample and noting the color of a rapidly cooled sample.

A little practice will enable the operator to judge the correspondence
between the color to be removed and the amount of bleaching mixture to
be added.

To obtain success with this process the method of working given must be
adhered to even in the _smallest detail_. This applies to the
temperature at which each operation is carried out particularly.


AIR BLEACHING OF PALM OIL.

The method of conducting this process is identical with the chrome
process to the point where the hydrochloric acid is to be added to the
oil. In this method no acid or chrome is necessary, as the active
bleaching agent is the oxygen of the air.

The equipment is similar to that of the former process, except that a
wooden tank in which no iron is exposed will suffice to bleach the oil
in. The process depends in rapidity upon the amount of air blown through
the oil and its even distribution. Iron should not be present or exposed
to the oil during bleaching, as it retards the process considerably.

After the impurities have been removed, as outlined under the chrome
process, the temperature of the oil is raised by open steam to boiling.
The steam is then shut off and air allowed to blow through the oil until
it is completely bleached, the temperature being maintained above 150°
F. by occasionally passing in steam. Usually a ton of oil is readily and
completely bleached after the air has been passed through it for 18 to
20 hours, provided the oil is thoroughly agitated by a sufficient flow
of air.

If the oil has been allowed to settle over night, it is advisable to run
off the condensed water and impurities by the lower cock before
agitating again the second day.

When the oil has been bleached to the desired color, which can be
determined by removing a sample and cooling, the mass is allowed to
settle, the water run off to a waste tank from which any oil carried
along may be skimmed off and the supernatant clear oil run to the
storage or soap kettle.

In bleaching by this process, while the process consumes more time and
is not as efficient in bleaching the lower grade oils, the cost of
bleaching is less and with a good oil success is more probable, as there
is no possibility of any of the chrome liquors being present in the oil.
These give the bleached oil a green tint when the chrome method is
improperly conducted and they are not removed.

Instead of blowing the air through it, the heater oil may be brought
into contact with the air, either by a paddle wheel arrangement, which,
in constantly turning, brings the oil into contact with the air, or by
pumping the heated oil into an elevated vessel, pierced with numerous
fine holes from which the oil continuously flows back into the vessel
from which the oil is pumped. While in these methods air, light and heat
act simultaneously in the bleaching of the oil, the equipment required
is too cumbersome to be practical.

Recent investigations[1] in bleaching palm oil by oxygen have shown that
not only the coloring matter but the oil itself was affected. In
bleaching palm oil for 30 hours with air the free fatty acid content
rose and titer decreased considerably.

_Olive Oil_, which comes from the fruit of the olive trees, varies
greatly in quality, according to the method by which it is obtained and
according to the tree bearing the fruit. Three hundred varieties are
known in Italy alone. Since the larger portion of olive oil is used for
edible purposes, a lower grade, denatured oil, denatured because of the
tariff, is used for soap manufacture in this country. The oil varies in
color from pale green to golden yellow. The percentage of free acid in
this oil varies greatly, though the oil does not turn rancid easily. It
is used mainly in the manufacture of white castile soap.

Olive oil foots, which is the oil extracted by solvents after the better
oil is expressed, finds its use in soap making mostly in textile soaps
for washing and dyeing silks and in the production of green castile
soaps.

Other oils, as poppy seed oil, sesame oil, cottonseed oil, rape oil,
peanut (arachis) oil, are used as adulterants for olive oil, also as
substitutes in the manufacture of castile soap, since they are cheaper
than olive oil.

_Cottonseed Oil_ is largely used in the manufacture of floating and
laundry soaps. It may be used for toilet soaps where a white color is
not desired, as yellow spots appear on a finished soap in which it has
been used after having been in stock a short time.

_Corn Oil and Soya Bean Oil_ are also used to a slight extent in the
manufacture of toilet soaps, although the oils form a soap of very
little body. Their soaps also spot yellow on aging.

Corn oil finds its greatest use in the manufacture of soap for washing
automobiles. It is further employed for the manufacture of cheap liquid
soaps.

_Fatty Acids_ are also used extensively in soap manufacture. While the
soap manufacturer prefers to use a neutral oil or fat, since from these
the by-product glycerine is obtained, circumstances arise where it is
an advantage to use the free fatty acids. Red oil (oleic acid, elaine)
and stearic acid are the two fatty acids most generally bought for soap
making. In plants using the Twitchell process, which consists in
splitting the neutral fats and oils into fatty acids and glycerine by
dilute sulphuric acid and producing their final separation by the use of
so-called aromatic sulphonic acids, these fatty acids consisting of a
mixture of oleic, stearic, palmitic acids, etc., are used directly after
having been purified by distillation, the glycerine being obtained from
evaporating the wash water.

Oleic acid (red oil) and stearic acid are obtained usually by the
saponification of oils, fats and greases by acid, lime or water under
pressure or Twitchelling. The fatty acids thus are freed from their
combination with glycerine and solidify upon cooling, after which they
are separated from the water and pressed at a higher or lower
temperature. The oleic acid, being liquid at ordinary temperature,
together with some stearic and palmitic acid, is thus pressed out. These
latter acids are usually separated by distillation, combined with the
press cake further purified and sold as stearic acid.

The red oil, sometimes called saponified red oil, is often semi-solid,
resembling a soft tallow, due to the presence of stearic acid. The
distilled oils are usually clear, varying in color from light to a deep
brown. Stearic acid, which reaches the trade in slab form, varies in
quality from a soft brown, greasy, crumbly solid of unpleasant odor to a
snow white, wax-like, hard, odorless mass. The quality of stearic acid
is best judged by the melting point, since the presence of any oleic
acid lowers this. The melting point of the varieties used in soap
manufacture usually ranges from 128° to 132° F. Red oil is used in the
manufacture of textile soaps, replacing olive oil foots soap for this
purpose, chlorophyll being used to color the soap green. Stearic acid,
being the hard firm fatty acid, may be used in small quantities to give
a better grade of soap body and finish. In adding this substance it
should always be done in the crutcher, as it will not mix in the kettle.
It finds its largest use for soap, however, in the manufacture of
shaving soaps and shaving creams, since it produces the non-drying
creamy lather so greatly desired for this purpose. Both red oil and
stearic acid being fatty acids, readily unite with the alkali
carbonates, carbon dioxide being formed in the reaction and this method
is extensively used in the formation of soap from them.


RANCIDITY OF OILS AND FATS.

Rancidity in neutral oils and fats is one of the problems the soap
manufacturer has to contend with. The mere saying that an oil is rancid
is no indication of its being high in free acid. The two terms rancidity
and acidity are usually allied. Formerly, the acidity of a fat was
looked upon as the direct measure of its rancidity. This idea is still
prevalent in practice and cannot be too often stated as incorrect. Fats
and oils may be _acid_, or _rancid_, or _acid and rancid_. In an acid
fat there has been a hydrolysis of the fat and it has developed a rather
high percentage of free acid. A rancid fat is one in which have been
developed compounds of an odoriferous nature. An acid and rancid fat is
one in which both free acid and organic compounds of the well known
disagreeable odors have been produced.

It cannot be definitely stated just how this rancidity takes place, any
more than just what are the chemical products causing rancidity. The
only conclusion that one may draw is that the fats are first hydrolyzed
or split up into glycerine and free fatty acids. This is followed by an
oxidation of the products thus formed.

Moisture, air, light, enzymes (organized ferments) and bacteria are all
given as causes of rancidity.

It seems very probable that the initial splitting of the fats is caused
by enzymes, which are present in the seeds and fruits of the vegetable
oils and tissue of animal fats, in the presence of moisture. Lewkowitsch
strongly emphasizes this point and he is substantiated in his idea by
other authorities. Others hold that bacteria or micro-organisms are the
cause of this hydrolysis, citing the fact that they have isolated
various micro-organisms from various fats and oils. The acceptance of
the bacterial action would explain the various methods of preservation
of oils and fats by the use of antiseptic preparations. It cannot,
however, be accepted as a certainty that bacteria cause the rancidity of
fats.

The action of enzymes is a more probable explanation.

The hydrolysis of fats and oils is accelerated when they are allowed to
remain for some time in the presence of organic non-fats. Thus, palm
oil, lower grades of olive oil, and tallow, which has been in contact
with the animal tissue for a long time, all contain other nitrogenous
matter and exhibit a larger percentage of free fatty acid than the oils
and fats not containing such impurities.

Granting this initial splitting of the fat into free fatty acids and
glycerine, this is not a sufficient explanation. The products thus
formed must be acted upon by air and light. It is by the action of these
agents that there is a further action upon the products, and from this
oxidation we ascertain by taste and smell (chemical means are still
unable to define rancidity) whether or not a fat is rancid. While some
authorities have presumed to isolate some of these products causing
rancidity, we can only assume the presence of the various possible
compounds produced by the action of air and light which include oxy
fatty acids, lactones, alcohols, esters, aldehydes and other products.

The soap manufacturer is interested in rancidity to the extent of the
effect upon the finished soap. Rancid fats form darker soaps than fats
in the neutral state, and very often carry with them the disagreeable
odor of a rancid oil. Further, a rancid fat or oil is usually high in
free acid. It is by no means true, however, that rancidity is a measure
for acidity, for as has already been pointed out, an oil may be rancid
and not high in free acid.

The percentage of free fatty acid is of even greater importance in the
soap industry. The amount of glycerine yield is dependent upon the
percentage of free fatty acid and is one of the criterions of a good fat
or oil for soap stock.


PREVENTION OF RANCIDITY.

Since moisture, air, light and enzymes, produced by the presence of
organic impurities, are necessary for the rancidity of a fat or oil, the
methods of preventing rancidity are given. Complete dryness, complete
purification of fats and oils and storage without access of air or light
are desirable. Simple as these means may seem, they can only be
approximated in practice. The most difficult problem is the removal of
the last trace of moisture. Impurities may be lessened very often by the
use of greater care. In storing it is well to store in closed barrels or
closed iron tanks away from light, as it has been observed that oils and
fats in closed receptacles become rancid less rapidly than those in open
ones, even though this method of storing is only partially attained.
Preservatives are also used, but only in edible products, where their
effectiveness is an open question.


CHEMICAL CONSTANTS OF OILS AND FATS.

Besides the various physical properties of oils and fats, such as
color, specific gravity, melting point, solubility, etc., they may be
distinguished chemically by a number of chemical constants. These are
the iodine number, the acetyl value, saponification number,
Reichert-Meissl number for volatile acids, Hehner number for insoluble
acids. These constants, while they vary somewhat with any particular oil
or fat, are more applicable to the edible products and are criterions
where any adulteration of fat or oil is suspected. The methods of
carrying out the analyses of oils and fats to obtain these constants are
given in the various texts[2] on oils and fats, and inasmuch as they are
not of great importance to the soap industry they are merely mentioned
here.


OIL HARDENING OR HYDROGENATING.

It is very well known that oils and fats vary in consistency and
hardness, depending upon the glycerides forming same. Olein, a
combination of oleic acid and glycerine, as well as oleic acid itself
largely forms the liquid portion of oils and fats. Oleic acid
(C_{18}H_{34}O_{2}) is an unsaturated acid and differs from stearic acid
(C_{18}H_{36}O_{2}), the acid forming the hard firm portion of oils and
fats, by containing two atoms of hydrogen less in the molecule.
Theoretically it should be a simple matter to introduce two atoms of
hydrogen into oleic acid or olein, and by this mere addition convert
liquid oleic acid and olein into solid stearic acid and stearine.

For years this was attempted and all attempts to apply the well known
methods of reduction (addition of hydrogen) in organic chemistry, such
as treatment with tin and acid, sodium amalgam, etc., were unsuccessful.
In recent years, however, it has been discovered that in the presence of
a catalyzer, nickel in finely divided form or the oxides of nickel are
usually employed, the process of hydrogenating an oil is readily
attained upon a practical basis.

The introduction of hardened oils has opened a new source of raw
material for the soap manufacturer in that it is now possible to use
oils in soap making which were formerly discarded because of their
undesirable odors. Thus fish or train oils which had up to the time of
oil hydrogenating resisted all attempts of being permanently deodorized,
can now be employed very satisfactorily for soap manufacture. A Japanese
chemist, Tsujimoto[3] has shown that fish oils contain an unsaturated
acid of the composition C_{18}H_{28}O_{2}, for which he proposed the
name clupanodonic acid. By the catalytic hardening of train oils this
acid passes to stearic acid and the problem of deodorizing these oils is
solved.[4]

At first the introduction of hardened oils for soap manufacture met with
numerous objections, due to the continual failures of obtaining a
satisfactory product by the use of same. Various attempts have now shown
that these oils, particularly hardened train oils, produce
extraordinarily useful materials for soap making. These replace
expensive tallow and other high melting oils. It is of course impossible
to employ hardened oils alone, as a soap so hard would thus be obtained
that it would be difficultly soluble in water and possess very little
lathering quality. By the addition of 20-25% of tallow oil or some other
oil forming a soft soap a very suitable soap for household use may be
obtained. Ribot[5] discusses this matter fully. Hardened oils readily
saponify, may be perfumed without any objections and do not impart any
fishy odor to an article washed with same. Meyerheim[6] states that
through the use of hydrogenated oils the hardness of soap is
extraordinarily raised, so that soap made from hardened cottonseed oil
is twelve times as hard as the soap made from ordinary cottonseed oil.
This soap is also said to no longer spot yellow upon aging, and as a
consequence of its hardness, is able to contain a considerably higher
content of rosin through which lathering power and odor may be improved.
Hardened oils can easily be used for toilet soap bases, provided they
are not added in too great a percentage.

The use of hardened oils is not yet general, but there is little doubt
that the introduction of this process goes a long way toward solving the
problem of cheaper soap material for the soap making industry.


GREASE.

Grease varies so greatly in composition and consistency that it can
hardly be classed as a distinctive oil or fat. It is obtained from
refuse, bones, hides, etc., and while it contains the same constituents
as tallow, the olein content is considerably greater, which causes it to
be more liquid in composition. Grease differs in color from an off-white
to a dark brown. The better qualities are employed in the manufacture of
laundry and chip soap, while the poorer qualities are only fit for the
cheapest of soaps used in scrubbing floors and such purposes. There is
usually found in grease a considerable amount of gluey matter, lime and
water. The percentage of free fatty acid is generally high.

The darker grades of grease are bleached before being used. This is done
by adding a small quantity of sodium nitrate to the melted grease and
agitating, then removing the excess saltpeter by decomposing with
sulphuric acid. A better method of refining, however, is by
distillation. The chrome bleach is also applicable.


ROSIN (COLOPHONY, YELLOW ROSIN, RESINA).

Rosin is the residue which remains after the distillation of turpentine
from the various species of pines. The chief source of supply is in the
States of Georgia North and South Carolina. It is a transparent, amber
colored hard pulverizable resin. The better grades are light in color
and known as water white (w. w.) and window glass (w. g.). These are
obtained from a tree which has been tapped for the first year. As the
same trees are tapped from year to year, the product becomes deeper and
darker in color until it becomes almost black.

The constituents of rosin are chiefly (80-90%) abietic acid or its
anhydride together with pinic and sylvic acids. Its specific gravity is
1.07-1.08, melting point about 152.5 C., and it is soluble in alcohol,
ether, benzine, carbon disulfide, oils, alkalis and acetic acid. The
main use of rosin, outside of the production of varnishes, is in the
production of laundry soaps, although a slight percentage acts as a
binder and fixative for perfumes in toilet soaps and adds to their
detergent properties. Since it is mainly composed of acids, it readily
unites with alkaline carbonates, though the saponification is not quite
complete and the last portion must be completed through the use of
caustic hydrates, unless an excess of 10% carbonate over the theoretical
amount is used. A lye of 20° B. is best adapted to the saponification of
rosin when caustic hydrates are employed for this purpose, since weak
lyes cause frothing. While it is sometimes considered that rosin is an
adulterant for soap, this is hardly justifiable, as it adds to the
cleansing properties of soap. Soaps containing rosin are of the well
known yellowish color common to ordinary laundry soaps. The price of
rosin has so risen in the last few years that it presents a problem of
cost to the soap manufacturer considering the price at which laundry
soaps are sold.


ROSIN SAPONIFICATION.

As has been stated, rosin may be saponified by the use of alkaline
carbonates. On account of the possibility of the soap frothing over, the
kettle in which the operation takes place should be set flush with the
floor, which ought to be constructed of cement. The kettle itself is an
open one with round bottom, equipped with an open steam coil and skimmer
pipe, and the open portion is protected by a semi-circular rail. A
powerful grid, having a 3-inch mesh, covers one-half of the kettle, the
sharp edges protruding upwards.

The staves from the rosin casks are removed at the edge of the kettle,
the rosin placed on the grid and beaten through with a hammer to break
it up into small pieces.

To saponify a ton of rosin there are required 200 lbs. soda ash, 1,600
lbs. water and 100 lbs. salt. Half the water is run into the kettle,
boiled, and then the soda ash and half the salt added. The rosin is now
added through the grid and the mixture thoroughly boiled. As carbon
dioxide is evolved by the reaction the boiling is continued for one hour
to remove any excess of this gas. A portion of the salt is gradually
added to grain the soap well and to keep the mass in such condition as
to favor the evolution of gas. The remainder of the water is added to
close the soap and boiling continued for one or two hours longer. At
this point the kettle must be carefully watched or it will boil over
through the further escape of carbon dioxide being hindered. The mass,
being in a frothy condition, will rapidly settle by controlling the flow
of steam. The remaining salt is then scattered in and the soap allowed
to settle for two hours or longer. The lyes are then drained off the
top. If the rosin soap is required for toilet soaps, it is grained a
second time. The soap is now boiled with the water caused by the
condensation of the steam, which changes it to a half grained soap
suitable for pumping. A soap thus made contains free soda ash 0.15% or
less, free rosin about 15%. The mass is then pumped to the kettle
containing the soap to which it is to be added at the proper stage. The
time consumed in thus saponifying rosin is about five hours.


NAPHTHENIC ACIDS.

The naphtha or crude petroleum of the various provinces in Europe, as
Russia, Galacia, Alsace and Roumania yield a series of bodies of acid
character upon refining which are designated under the general name of
naphthenic acids. These acids are retained in solution in the alkaline
lyes during the distillation of the naphtha in the form of alkaline
naphthenates. Upon adding dilute sulphuric acid to these lyes the
naphthenates are decomposed and the naphthenic acids float to the
surface in an oily layer of characteristic disagreeable odor and varying
from yellow to brown in color[7]. In Russia particularly large
quantities of these acids are employed in the manufacture of soap.

The soaps formed from naphthenic acids have recently been
investigated[8] and found to resemble the soaps made from cocoanut oil
and palm kernel oil, in that they are difficult to salt out and
dissociate very slightly with water. The latter property makes them
valuable in textile industries when a mild soap is required as a
detergent, e. g., in the silk industry. These soaps also possess a high
solvent power for mineral oils and emulsify very readily. The mean
molecular weight of naphthenic acids themselves is very near that of the
fatty acids contained in cocoanut oil, and like those of cocoanut oil a
portion of the separated acids are volatile with steam. The iodine
number indicates a small content of unsaturated acids.

That naphthenic acids are a valuable soap material is now recognized,
but except in Russia the soap is not manufactured to any extent at the
present time.


ALKALIS.

The common alkali metals which enter into the formation of soap are
sodium and potassium. The hydroxides of these metals are usually used,
except in the so called carbonate saponification of free fatty acids in
which case sodium and potassium carbonate are used. A water solution of
the caustic alkalis is known as lye, and it is as lyes of various
strengths that they are added to oils and fats to form soap. The density
or weight of a lye is considerably greater than that of water, depending
upon the amount of alkali dissolved, and its weight is usually
determined by a hydrometer. This instrument is graduated by a
standardized scale, and while all hydrometers should read alike in a
liquid of known specific gravity, this is generally not the case, so
that it is advisable to check a new hydrometer for accurate work against
one of known accuracy. In this country the Baumé scale has been adopted,
while in England a different graduation known as the Twaddle scale is
used. The strength of a lye or any solution is determined by the
distance the instrument sinks into the solution, and we speak of the
strength of a solution as so many degrees Baumé or Twaddle which are
read to the point where the meniscus of the lye comes on the graduated
scale. Hydrometers are graduated differently for liquids of different
weights. In the testing of lyes one which is graduated from 0° to 50° B.
is usually employed.

_Caustic soda_ is received by the consumer in iron drums weighing
approximately 700 lbs. each. The various grades are designated as 60,
70, 74, 76 and 77%. These percentages refer to the percentage of sodium
oxide (Na_{2}O) in 100 parts of pure caustic soda formed by the
combination of 77-1/2 parts of sodium oxide and 22-1/2 parts of water,
77-1/2% being chemically pure caustic soda. There are generally
impurities present in commercial caustic soda. These consist of sodium
carbonate, sodium chloride or common salt and sometimes lime. It is
manufactured by treating sodium carbonate in an iron vessel with calcium
hydroxide or slaked lime, or by electrolysis of common salt. The latter
process has yet been unable to compete with the former in price.
Formerly all the caustic soda used in soap making was imported, and it
was only through the American manufacturer using a similar container to
that used by foreign manufacturers that they were able to introduce
their product. This prejudice has now been entirely overcome and most of
the caustic soda used in this country is manufactured here.


CAUSTIC POTASH.

The output of the salts containing potassium is controlled almost
entirely by Germany. Formerly the chief source of supply of potassium
compounds was from the burned ashes of plants, but about fifty years ago
the inexhaustible salt mines of Stassfurt, Germany, were discovered.
The salt there mined contains, besides the chlorides and sulphates of
sodium, magnesium, calcium and other salts, considerable quantities of
potassium chloride, and the Stassfurt mines at present are practically
the entire source of all potassium compounds, in spite of the fact that
other localities have been sought to produce these compounds on a
commercial basis, especially by the United States government.

After separating the potassium chloride from the magnesium chloride and
other substances found in Stassfurt salts the methods of manufacture of
caustic potash are identical to those of caustic soda. In this case,
however, domestic electrolytic caustic potash may be purchased cheaper
than the imported product and it gives results equal to those obtained
by the use of the imported article, opinions to the contrary among soap
makers being many. Most of the caustic potash in the United States is
manufactured at Niagara Falls by the Niagara Alkali Co., and the Hooker
Electrochemical Co., chlorine being obtained as a by-product. The latter
concern employs the Townsend Cell, for the manufacture of electrolytic
potash, and are said to have a capacity for making 64 tons of alkali
daily.

Since the molecular weight of caustic potash (56) is greater than that
of caustic soda (40) more potash is required to saponify a pound of fat.
The resulting potash soap is correspondingly heavier than a soda soap.
When salt is added to a potassium soap double decomposition occurs, the
potassium soap being transformed to a sodium soap and the potassium
uniting with the chlorine to form potassium chloride. This was one of
the earliest methods of making a hard soap, especially in Germany, where
potash was derived from leeching ashes of burned wood and plants.


SODIUM CARBONATE (SODA ASH).

While carbonate of soda is widely distributed in nature the source of
supply is entirely dependent upon the manufactured product. Its uses are
many, but it is especially important to the soap industry in the so
called carbonate saponification of free fatty acids, as a constituent of
soap powders, in the neutralization of glycerine lyes and as a filler
for laundry soaps.

The old French Le Blanc soda process, which consists in treating common
salt with sulphuric acid and reducing the sodium sulphate (salt cake)
thus formed with carbon in the form of charcoal or coke to sodium
sulphide, which when treated with calcium carbonate yields a mixture of
calcium sulphide and sodium carbonate (black ash) from which the
carbonate is dissolved by water, has been replaced by the more recent
Solvay ammonia soda process. Even though there is a considerable loss of
salt and the by-product calcium chloride produced by this process is
only partially used up as a drying agent, and for refrigerating
purposes, the Le Blanc process cannot compete with the Solvay process,
so that the time is not far distant when the former will be considered a
chemical curiosity. In the Solvay method of manufacture sodium chloride
(common salt) and ammonium bicarbonate are mixed in solution. Double
decomposition occurs with the formation of ammonium chloride and sodium
bicarbonate. The latter salt is comparatively difficultly soluble in
water and crystallizes out, the ammonium chloride remaining in solution.
When the sodium bicarbonate is heated it yields sodium carbonate, carbon
dioxide and water; the carbon dioxide is passed into ammonia which is
set free from the ammonium chloride obtained as above by treatment with
lime (calcium oxide) calcium chloride being the by-product.

Sal soda or washing soda is obtained by recrystallizing a solution of
soda ash in water. Large crystals of sal soda containing but 37% sodium
carbonate are formed.


POTASSIUM CARBONATE.

Potassium carbonate is not extensively used in the manufacture of soap.
It may be used in the forming of soft soaps by uniting it with free
fatty acids. The methods of manufacture are the same as for sodium
carbonate, although a much larger quantity of potassium carbonate than
carbonate of soda is obtained from burned plant ashes. Purified
potassium carbonate is known as _pearl ash_.


ADDITIONAL MATERIAL USED IN SOAP MAKING.

Water is indispensable to the soap manufacturer. In the soap factory
_hard_ water is often the cause of much trouble. Water, which is the
best solvent known, in passing through the crevices of rocks dissolves
some of the constituents of these, and the water is known as hard. This
hardness is of two kinds, _temporary_ and _permanent_. Temporarily hard
water is formed by water, which contains carbonic acid, dissolving a
portion of calcium carbonate or carbonate of lime. Upon boiling, the
carbonic acid is driven from the water and the carbonate, being
insoluble in carbon dioxide free water, is deposited. This is the cause
of boiler scale, and to check this a small amount of sal ammoniac may be
added to the water, which converts the carbonate into soluble calcium
chloride and volatile ammonium carbonate. Permanent hardness is caused
by calcium sulphate which is soluble in 400 parts of water and cannot be
removed by boiling.

The presence of these salts in water form insoluble lime soaps which act
as inert bodies as far as their value for the common use of soap is
concerned. Where the percentage of lime in water is large this should be
removed. A method generally used is to add about 5% of 20° B. sodium
silicate to the hard water. This precipitates the lime and the water is
then sufficiently pure to use.

_Salt_, known as sodium chloride, is used to a large extent in soap
making for "salting out" the soap during saponification, as well as
graining soaps. Soap ordinarily soluble in water is insoluble in a salt
solution, use of which is made by adding salt to the soap which goes
into solution and throws any soap dissolved in the lyes out of solution.
Salt may contain magnesium and calcium chlorides, which of course are
undesirable in large amounts. The products on the market, however, are
satisfactory, thus no detail is necessary.

_Filling materials_ used are sodium silicate, or water glass, talc,
silex, pumice, starch, borax, tripoli, etc.

Besides these other materials are used in the refining of the oils and
fats, and glycerine recovery, such as Fuller's earth, bichromates of
soda or potash, sulphate of alumina, sulphuric and hydrochloric acids
and alcohol.

A lengthy description of these substances is not given, as their modes
of use are detailed elsewhere.

FOOTNOTES:

[1] Seifensieder Zeit, 1913, 40, p. 687, 724, 740.

[2] Official Methods, see Bull. 107, A. O. A. C., U. S. Dept. Agricult.

[3] Journ. Coll. of Engin. Tokyo Imper. Univ. (1906), p. 1. Abs. Chem.
Revue f. d. Fett-u. Harz, Ind. 16, p. 84; 20, p. 8.

[4] Meyerheim--Fort. der Chem., Physik. und Physik. Chem. (1913), 8. 6,
p. 293-307.

[5] Seifs. Ztg. (1913), 40, p. 142.

[6] Loc. cit.

[7] Les Matieres Graisses (1914), 7, 69, p. 3367.

[8] Zeit. f. Angew. Chem. (1914), 27, 1, p. 2-4.




CHAPTER II

Construction and Equipment of a Soap Plant.


No fixed plan for the construction and equipment of a soap plant can be
given. The specifications for a soap factory to be erected or remodeled
must suit the particular cases. Very often a building which was
constructed for a purpose other than soap manufacture must be adapted
for the production of soap. In either case it is a question of
engineering and architecture, together with the knowledge obtained in
practice and the final decision as to the arrangement is best solved by
a conference with those skilled in each of these branches.

An ideal soap plant is one in which the process of soap making, from the
melting out of the stock to the packing and shipping of the finished
product, moves downward from floor to floor, since by this method it is
possible to utilize gravitation rather than pumping liquid fats and
fluid soaps. Convenience and economy are obtained by such an
arrangement.

The various machinery and other equipment for soap manufacture are well
known to those connected with this industry. It varies, of course,
depending upon the kind of soap to be manufactured, and full
descriptions of the necessary machinery are best given in the catalogs
issued by the manufacturers of such equipment, who in this country are
most reliable.

To know just what equipment is necessary can very easily be described by
a brief outline of the process various soaps undergo to produce the
finished article. After the saponification has taken place in the _soap
kettle_ the molten soap is run directly into the soap _frames_, which
consist of an oblong compartment, holding anywhere from 400 to 1,200
pounds, with removable steel sides and mounted upon trucks, in which it
solidifies. In most cases it is advisable to first run the soap into a
_crutcher_ or mixer which produces a more homogeneous mass than if this
operation is omitted. Color and perfume may also be added at this point,
although when a better grade of perfume is added it must be remembered
that there is considerable loss due to volatilization of same. When a
_drying machine_ is employed the molten soap is run directly upon the
rollers of this machine, later adding about 1.0% zinc oxide to the soap
from which it passes continuously through the drying chamber and is
emitted in chip form ready for milling. After the soap has been framed,
it is allowed to cool and solidify, which takes several days, and then
the sides of the frame are stripped off. The large solid cake is cut
with wires by hand or by a _slabber_ into slabs of any desired size.
These slabs are further divided into smaller divisions by the _cutting
table_. In non-milled soaps (laundry soaps, floating soaps, etc.), these
are pressed at this stage, usually by automatic presses, after a thin
hard film has been formed over the cake by allowing it to dry slightly.
In making these soaps they are not touched by hand at any time during
the operation, the pressing, wrapping and packing all being done by
machinery. For a milled soap the large slabs are cut into narrow oblong
shapes by means of the cutting table to readily pass into the feeder of
the _chipper_, the chips being spread upon _trays_ and dried in a _dry
house_ until the moisture content is approximately 15%.

The process of milling is accomplished by passing the dried soap chips
through a _soap mill_, which is a machine consisting of usually three or
four contiguous, smooth, granite rollers operated by a system of gears
and set far enough apart to allow the soap to pass from a hopper to the
first roller, from which it is constantly conveyed to each succeeding
roller as a thin film, and finally scraped from the last roller to fall
into the _milling box_ in thin ribbon form. These mills are often
operated in tandem, which necessitates less handling of soap by the
operator. The object of milling is to give the soap a glossy, smooth
finish and to blend it into a homogeneous mass. The perfume, color,
medication or any other material desired are added to the dried soap
chips prior to milling. Some manufacturers use an _amalgamator_ to
distribute these uniformly through the soap, which eliminates at least
one milling. When a white soap is being put through the mill, it is
advisable to add from 0.5% to 1% of a good, fine quality of zinc oxide
to the soap, if this substance has not been previously added. This
serves to remove the yellowish cast and any translucency occasioned by
plodding. Too great a quantity of this compound added, later exhibits
itself by imparting to the soap a dead white appearance. Inasmuch as the
milling process is one upon which the appearance of a finished cake of
toilet soap largely depends, it should be carefully done. The number of
times a soap should be milled depends upon the character of a soap being
worked. It should of course be the object to mill with as high a
percentage of moisture as possible. Should the soap become too dry it is
advisable to add water directly, rather than wet soap, since water can
more easily be distributed through the mass. As a general statement it
may be said it is better policy to overmill a soap, rather than not mill
it often enough.

After the soap has been thoroughly milled it is ready for plodding. A
_plodder_ is so constructed as to take the soap ribbons fed into the
hopper by means of a worm screw and continuously force it under great
pressure through a jacketed cylinder through which cold water circulates
in the rear to compensate the heat produced by friction and hot water at
the front, to soften and polish the soap which passes out in solid form
in bars of any shape and size depending upon the form of the _shaping
plate_ through which it is emitted. The bars run upon a _roller board_,
are cut into the required length by a special _cake cutting table_,
allowed to dry slightly and pressed either automatically or by a foot
power _press_ in any suitable soap _die_. The finished cake is then
ready for wrapping and after due time in stock reaches the consumer.

Besides the various apparatus mentioned above there are many other parts
for the full equipment of a modern soap plant, such as remelters, pumps,
mixers, special tanks, power equipment, etc. As has been stated,
however, practical experience will aid in judging the practicability as
to installation of these. The various methods of powdering soap are,
however, not generally known. Where a coarse powder is to be produced,
such as is used for common washing powders, no great difficulty is
experienced with the well known Blanchard mill. In grinding soap to an
impalpable powder the difficulties increase. The methods adapted in
pulverizing soaps are by means of disintegrators, pebble mills and
chaser mills. The disintegrator grinds by the principle of attrition,
that is, the material is reduced by the particles being caused to beat
against each other at great velocity; a pebble mill crushes the
substance by rubbing it between hard pebbles in a slowly revolving
cylinder; the chaser mill first grinds the material and then floats it
as a very fine powder above a curb of fixed height. The last method is
particularly adapted for the finest of powder (140 mesh and over).




CHAPTER III

Classification of Soap-Making Methods.


In the saponification of fats and oils to form soap through the agency
of caustic alkalis, as has been stated, the sodium or potassium salts of
the mixed fatty acids are formed. Sodium soaps are usually termed hard
soaps, and potassium soaps soft. There are, however, a great many
varieties of soaps the appearance and properties of which depend upon
their method of manufacture and the oils or fats used therein.

The various methods adopted in soap making may be thus classified:

1. Boiling the fats and oils in open kettles by open steam with
indefinite quantities of caustic alkali solutions until the finished
soap is obtained; ordinarily named _full boiled soaps_. These may be
sub-divided into (a) hard soaps with sodium hydrate as a base, in which
the glycerine is recovered from the spent lyes; (b) hard soaps with soda
as a base, in which the glycerine remains in the soap, e. g., marine
cocoanut oil soaps; (c) soft potash soaps, in which the glycerine is
retained by the soap.

2. Combining the required amount of lye for complete saponification of a
fat therewith, heating slightly with dry heat and then allowing the
saponification to complete itself. This is known as the _cold process_.

3. Utilizing the fatty acid, instead of the neutral fat, and combining
it directly with caustic alkali or carbonate, which is incorrectly
termed _carbonate saponification_, since it is merely neutralizing the
free fatty acid and thus is not a saponification in the true sense of
the word. No glycerine is directly obtained by this method, as it is
usually previously removed in the clearage of the fat by either the
Twitchell or autoclave saponification method.

In the methods thus outlined the one most generally employed is the full
boiled process to form a sodium soap. This method of making soap
requires close attention and a knowledge which can only be obtained by
constant practice. The stock, strength of lyes, heat, amount of salt or
brine added, time of settling, etc., are all influencing factors.

The principles involved in this process are briefly these:

The fat is partly saponified with weak lyes (usually those obtained from
a previous boiling in the strengthening change are used), and salt is
added to grain the soap. The mass is then allowed to settle into two
layers. The upper layer is partly saponified fat; the lower layer, or
spent lye, is a solution of salt, glycerine, and contains any albuminous
matter or any other impurity contained in the fat. This is known as the
_killing_ or glycerine change. Strong lyes are now added and the fat
entirely saponified, which is termed the _strengthening change_. The
mass is then allowed to settle and the fluid soap run off above the
"nigre." This operation is called the finish or _finishing_ change.

The method may be more fully illustrated by a concrete example of the
method of manufacture of a tallow base:

    Charge--

    Tallow              88 per cent.
    Cocoanut oil        10 per cent.
    Rosin w. w.          2 per cent.

        Amount charge   10 tons

About five tons of tallow and one ton of cocoanut oil are pumped or run
into the soap kettle and brought to a boil with wet steam until it
briskly comes through the hot fat. The caustic soda (strengthening lyes
from former boilings may be used here) is gradually added by the
distributing pipe, any tendency to thicken being checked by the
introduction of small quantities of brine ("salt pickle"). If the lye is
added too rapidly the soap assumes a granular appearance, indicating
that the addition of same must be discontinued. Water should then be
added and the mass boiled through until it again closes. When the
addition of the proper amount of caustic soda is nearing its completion
the soap gradually thins. The steam is now cut down to about one turn of
the valve, and brine is rapidly added or salt shoveled in. In ten to
fifteen minutes the steam again breaks through and, from the appearance
of the soap, it can be seen whether sufficient brine has been added. A
sample taken out by means of a long wooden paddle should show the soap
in fine grains with the lyes running from it clear. The steam is then
shut off and the soap allowed to settle from one and one-half to two
hours. In all settlings the longer time this operation is permitted to
continue, the better will the subsequent operations proceed.

The mixture now consists of a partly saponified layer of fat above the
spent lyes. The lyes are drawn off until soap makes its appearance at
the exit pipe. The valve is then closed and the soap blown back into the
kettle by steam. The lyes thus obtained are known as _spent lyes_, from
which the glycerine is recovered. They should show an alkalinity of
approximately 0.5 per cent. if the operation is carefully carried out.

The remaining tallow is now added and the above operations repeated.

After the spent lyes have been drawn off, the soap is closed with water
and the proper percentage of rosin soap previously formed, or rosin
itself is added to the mass in the kettle. More lye is then allowed to
flow in until the mixture is up to "strength." This is usually tested
by the "bite" on the tongue of a small cooled sample. After boiling
until the steam comes through, the mass is grained with salt as before
and allowed to settle one and one-half to three hours. These lyes, known
as _strengthening lyes_ are run to storage to be used subsequently with
fresh fat to take up the caustic soda contained therein.

The soap is now ready for finishing and is first boiled through and
tried for strength. A drop of phenolphthalein (1 per cent.
phenolphthalein in 98 per cent. alcohol) is allowed to drop on the
molten soap taken up on a trowel. The red color should be instantly
produced and develop to a full deep crimson in a few seconds, or more
lye must be added until this condition is realized. Should it flash a
deep crimson immediately it is on the strong side. This cannot be
conveniently remedied; it can only serve as a guide for the next boil,
but in any case it is not of any serious consequence, unless it is too
strong.

With the steam on, the soap is now examined with a trowel which must be
thoroughly heated by working it about under the surface of the hot soap.
The appearance of the soap as it runs from the face of the trowel
indicates its condition. It is not possible to absolutely describe the
effect, which can only be properly judged by practice, yet the following
points may serve as a guide. The indications to be noticed are the shape
and size of the flakes of soap as the sample on the trowel breaks up and
runs from the hot iron surface, when the latter is turned in a vertical
position, as well as the condition of the iron surface from which the
soap flakes have fallen. A closed soap will run slowly into a
homogeneous sheet, leaving the trowel's surface covered with a thin
layer of transparent soap; a grained mass will run rapidly down in tiny
grains, about one-half an inch in diameter or less, leaving the hot
trowel absolutely dry. The object of the finish is to separate the
soaps of the lower fatty acids from those of the higher, and both from
excess of liquid. A point midway between "open" and "closed" is required
to arrive at this point.

Having arrived at the above condition, the soap is allowed to settle
anywhere from one to three days and then run off through the skimmer
pipes to the nigre and framed or pumped to the tank feeding the drying
machine.

The stock thus obtained should be fairly white, depending upon the grade
of tallow used and slightly alkaline to an alcoholic phenolphthalein
solution. If removed at exactly the neutral point or with a content of
free fat the soap will sooner or later develop rancidity. The soap thus
obtained is an ordinary tallow base, and the one by far greatest used in
the manufacture of toilet soaps. The percentage of cocoanut oil
indicated is not fixed and may readily be varied, while in fine toilet
soap the rosin is usually eliminated.

In the manufacture of full boiled soda soaps in which no glycerine is
obtained as a by-product, it being retained in the soap itself, the soap
formed is known as a "run" soap. The process is used most extensively in
the manufacture of marine soaps by which the method may be best
illustrated. This soap is known as marine soap because of its property
of readily forming a lather with salt water and is mostly consumed
aboard vessels.

Marine soaps are manufactured by first placing in the kettle a
calculated amount of lye of 25 deg. to 35 deg. B., depending upon the
amount of moisture desired in the finished soaps, plus a slight excess
required to saponify a known weight of cocoanut oil. With open steam on,
the cocoanut oil is then gradually added, care being taken that the soap
does not froth over. Saponification takes place readily and when the oil
is entirely saponified the finished soap is put through the process
known as running. This consists in constantly pumping the mass from the
skimmer pipe back into the top of the kettle, the object being to
prevent any settling of the nigre or lye from the soap, as well as
producing a homogeneous mass. It is customary to begin the
saponification in the morning, which should be completed by noon. The
soap is then run for about three hours and framed the next morning.
After having remained in the frame the time required to solidify and
cool, the soap is slabbed and cut into cakes. This process is difficult
to carry out properly, and one not greatly employed, although large
quantities of marine soap are purchased by the government for use in the
navy and must fulfill certain specifications required by the purchasing
department.

In making potash soaps it is practically impossible to obtain any
glycerine directly because of the pasty consistency of the soap, and no
graining is possible because the addition of salt to a soft soap, as
already explained, would form a soda soap. Large quantities of soft
soaps are required for the textile industries who desire mostly a strong
potash soap, and the large number of automobiles in use at the present
time has opened a field for the use of a soft soap for washing these. A
soap for this purpose must be neutral so as not to affect the varnish or
paint of automobiles.

A suitable soap for textile purposes may be made as follows:

    Red oil                         80     parts
    House grease                    20     parts
    Caustic soda lye, 36 degs. B.    3     parts
    Carbonate of potash              5-1/2 parts
    Caustic potash                  23-1/4 parts

Olive oil, corn oil, soya bean oil, olive oil foots or cottonseed oil
may replace any of the above oils. A large quantity of cottonseed oil
will cause the soap to fig.

To carry out the process, the caustic potash and carbonate of potash are
dissolved and placed in the kettle together with the soda lye, and the
oils added. This is most satisfactorily accomplished by being finished
the day before the boiling is begun. The next day the boiling is begun
and water added to bring the soap up to the desired percentage of fatty
acid, due allowance being made for the water formed by the condensation
of the open steam in boiling. Care must be taken that the soap in the
kettle does not swell and run over during the saponification. A good
procedure is to use open steam for a period of about two hours, then
close the valve and allow the saponification to continue without
boiling, and repeat this until it is entirely saponified. After the
saponification has been completed the soap is briskly boiled all day and
the proper corrections made; that is, if too alkaline, more oil is
added, and if free fat is present, more potash. About 2 per cent.
carbonate of potash is the proper amount for a soap containing 50 per
cent. fatty acid. The soap is sampled by allowing it to drop on a clean,
cold glass surface. In so doing, the soap should not slide or slip over
the glass surface when pressed thereon, but should adhere to the glass,
or it is too alkaline. A sample worked between the fingers showing too
much stringiness should have more strong potash and oil added. A sample
taken out in a pail and allowed to cool over night will serve as a guide
as to the body of the soap in the kettle. When the soap has thus been
properly finished it is run into barrels.

For an automobile soap the following is a good working formula:

    Corn oil                       1,000 parts
    Potash lye, 31-1/2 degs. B.      697 parts

Proceed as in the directions just given for textile soap in placing
charge in the kettle. When the kettle is boiling up well, shut off the
steam and the saponification will complete itself. The soap may be run
into the barrels the next day.

A heavy soap with a smaller percentage of fat may be made as follows:

    Corn oil                       1,000 parts
    Potash lye, 24-1/2 degs. B.      900 parts

Boil until the soap bunches, and shovel the finished soap into barrels.
Upon standing it will clear up. By the addition of more water the yield
of soap per pound of oil may be run up to 300 per cent.

After soft soaps have been allowed to stand for some time the phenomenon
known as "figging" often occurs. This term is applied to a
crystalline-like formation, causing spots of a star-like shape
throughout the soap. This is undoubtedly due to the stearine content of
the soap crystallizing out as it cools, and forming these
peculiarly-shaped spots. It more generally occurs in the winter and may
be produced artificially by adding a small quantity of soda to the
potash lye before saponification.

The oils usually employed in the manufacture of potash soaps are
cottonseed oil, corn oil, soya bean oil, olive oil foots, red oil,
cocoanut oil, grease and the various train oils. The usual percentage
yield is from 225 per cent. to 300 per cent., based upon the weight of
oil used. In calculating the weight of a soft soap it is to be
remembered that since potassium has a higher molecular weight (56) than
sodium (40), the corresponding soap formed is that much greater in
weight when compared with a sodium soap. Rosin may be added to soft
soaps as a cheapening agent.


COLD PROCESS.

The cold process for manufacturing soap is the simplest method of soap
making, and the equipment required is small when compared to the other
methods. All the more expensive equipment that is necessary is a
crutcher, a tank to hold the lye, frames, a slabber or cutting table,
and a press. Yet, in spite of the simplicity of thus making soap, the
disadvantages are numerous for the production of a good piece of soap.
The greatest difficulty is to obtain a thorough combination of oil or
fat and lye so that there will not be an excess of one or the other in
the finished soap. At its best there is either a considerable excess of
free fat which later exhibits itself in producing rancidity or
uncombined caustic, which produces an unpleasant effect on the skin when
the soap is consumed for washing. The latter objection, of course, can
only be applied to toilet soaps.

Cocoanut oil is used very largely in the manufacture of cold-made soaps
as it is well adapted for this purpose, although it is by no means true
that other oils may not be employed. Since by this process of
manufacture no impurity contained in the fat or oil is removed in the
making of the soap, it is necessary that in order to obtain a fine
finished product, any impurity contained in these may be removed if
present, or that the fats be as pure as can be obtained. If inedible
tallow is used for cold-made soap, it is advisable to bleach it by the
Fuller's Earth Process.

The carrying out of this method is best illustrated by an example of a
cold-made cocoanut oil soap.

    Charge:

    Cochin cocoanut oil          846 parts
    Lye (soda), 35 degs. B.      470 parts
    Water                         24 parts

The oil is run into the crutcher and the temperature of the oil raised
to 100 degs. F. by dry steam. The lye and water are at room temperature.
After all the oil is in the crutcher, the lye and water are slowly added
to prevent any graining of the soap. Toward the end the lye may be added
more rapidly. When all the lye is in, the mass is crutched for about
three hours, or until upon stopping the crutcher a finger drawn over the
surface of the soap leaves an impression. If this condition is not
realized, the soap must be mixed until such is the case. Having arrived
at this point, the mixture is dropped into a frame which should remain
uncovered. The heat produced by the further spontaneous saponification
will cause the soap to rise in the middle of the frame. After having set
for some days it is ready to be slabbed and cut into cakes.

A potash soap may be made by the cold process just as readily as a soda
soap. Soaps of this type may be made by either of these formulae in a
crutcher:

    Olive oil foots                                  600
    Potash lye, 18 degs. B. hot, 20 degs. B. cold    660

                    or

    Corn oil                                         800
    Rosin                                            200
    Potash lye, 27 degs. B.                          790
    Water                                            340

Heat the oils to 190 degs. F., add the lye and crutch until the soap
begins to bunch, when it is ready to be run into barrels where the
saponification will be completed.

Semi-boiled soaps differ from those made by the cold process in
temperature. In making semi-boiled soaps the fats are usually heated to
140° F. The addition of the lye raises the temperature to 180°--200° F.
when saponification takes place.


CARBONATE SAPONIFICATION.

The method of the formation of soap by the utilization of the fatty acid
directly, from which the glycerine has already been removed by some
method of saponification other than with caustic soda, and neutralizing
this with alkali, is becoming increasingly popular. The glycerine is
more easily recovered from a previous cleavage of the fats or oils, but
a soap made from the mixed fatty acids thus obtained is seldom white in
color and retains an unpleasant odor. Since soda ash or sodium carbonate
is cheaper than caustic soda and readily unites with a fatty acid, it is
used as the alkali in the carbonate saponification. The process is
similar to that already given under Rosin Saponification. About 19 per
cent. by weight of the fatty acids employed of 58 per cent. soda ash is
dissolved in water until it has a density of 30 degs. B., and the
solution is run into the kettle, which is usually equipped with a
removable agitator. The fatty acids, previously melted, are then slowly
added while the mixture is boiled with open steam and agitated with the
stirring device. The fatty acids instantly unite with the carbonate and
rise in the kettle, due to the generation of carbon dioxide, and care
must be exercised to prevent boiling over. After all the fatty acid has
been added, and the mass is boiled through the saponification must be
completed with caustic soda, as there is as yet no practical method
known which will split a fat entirely into fatty acid and glycerine.
Thus about 10 per cent. of the fatty acids are true neutral fats and
require caustic soda for their saponification. This is then added and
the soap completed, as in full-boiled soaps.

In carrying out this method upon a large scale, large
sue\Neanderthal\doroteer\Neanderthal\Josephine\ quantities of carbon
dioxide are formed during the boiling of the soap, which replaces a
quantity of the air contained therein. The kettle room should therefore
be well ventilated, allowing for a large inflow of fresh air from out of
doors.




CHAPTER IV

Classification of Soaps.


In considering the many different varieties of soaps, their
classification is purely an arbitrary one. No definite plan can be
outlined for any particular brand to be manufactured nor can any very
sharp distinction be drawn between the many soaps of different
properties which are designated by various names. It is really a
question to what use a soap is to be put, and at what price it may be
sold. There is, of course, a difference in the appearance, form and
color, and then there are soaps of special kinds, such as floating
soaps, transparent soaps, liquid soaps, etc., yet in the ultimate sense
they are closely allied, because they are all the same chemical
compound, varying only in their being a potash or soda soap, and in the
fatty acids which enter into combination with these alkalis. Thus we can
take a combination of tallow and cocoanut oil and make a great many
presumably different soaps by combining these substances with caustic
soda, by different methods of manufacture and by incorporating various
other ingredients, as air, to form a floating soap, alcohol to make a
transparent soap, dyestuffs to give a different color, etc., but
essentially it is the same definite compound.

The manufacturer can best judge the brand of soaps he desires to
manufacture, and much of his success depends upon the name, package,
shape, color or perfume of a cake of soap. It is the consumer whom he
must please and many of the large selling brands upon the market today
owe their success to the above mentioned details. The great majority of
consumers of soap know very little concerning soap, except the fact
that it washes or has a pleasant odor or looks pretty, and the
manufacturer of soap must study these phases of the subject even more
carefully than the making of the soap itself.

For a matter of convenience we will classify soap under three general
divisions:

I. Laundry soaps, including chip soaps, soap powders and scouring soaps.

II. Toilet soaps, including floating soap, castile soap, liquid soap,
shaving soap, etc.

III. Textile soaps.


LAUNDRY SOAP.

The most popular household soap is laundry soap. A tremendous amount of
this soap is consumed each day in this country, and it is by far
manufactured in larger quantities than any other soap. It is also a soap
which must be sold cheaper than any other soap that enters the home.

The consumers of laundry soap have been educated to use a full boiled
settled rosin soap and to make a good article at a price this method
should be carried out, as it is the one most advisable to use. The
composition of the fats entering into the soap depends upon the market
price of these, and it is not advisable to keep to one formula in the
manufacture of laundry soap, but rather to adjust the various fatty
ingredients to obtain the desired results with the cheapest material
that can be purchased. It is impossible to use a good grade of fats and
make a profit upon laundry soap at the price at which it must be
retailed. The manufacturer of this grade of soap must look to the
by-product, glycerine, for his profit and he is fortunate indeed if he
realizes the entire benefit of this and still produces a superior piece
of laundry soap.


SEMI-BOILED LAUNDRY SOAPS.

It is advantageous at times to make a laundry soap by a method other
than the full boiled settled soap procedure as previously outlined. This
is especially the condition in making a naphtha soap, in which is
incorporated naphtha, which is very volatile and some of the well known
manufacturers of this class of soap have adopted this process entirely.
A laundry soap containing rosin cannot be advantageously made by the
cold process, as the soap thus made grains during saponification and
drops a portion of the lye and filling materials. By making a
semi-boiled soap this objection is overcome. The half boiled process
differs from the cold process by uniting the fats and alkalis at a
higher temperature.

To carry out this process the following formulae have been found by
experience to give satisfactory results.

                     I.         lbs.

    Tallow                       100
    Rosin                         60
    Soda Lye, 36° B.              80

                    II.

    Tallow                       100
    Rosin                         60
    Silicate of Soda              25
    Soda Lye, 36° B.              85

                    III.

    Tallow                       100
    Rosin                        100
    Lye, 36° B.                  105
    Silicate of Soda              25
    Sal Soda Solution             20

In any of these formulas the sodium silicate (40° B.) may be increased
to the same proportion as the fats used. By so doing, however, twenty
pounds of 36° B. lye must be added for every hundred pounds of silicate
additional to that indicated or in other words, for every pound of
silicate added 20 per cent. by weight of 36° B. lye must be put into the
mixture. The rosin may also be replaced by a previously made rosin soap.

To make a semi-boiled soap, using any of the above formulae, first melt
the rosin with all or part of the fat, as rosin when melted alone
readily decomposes. When the mixture is at 150° F. run it into the
crutcher and add the lye. Turn on sufficient dry steam to keep the
temperature of the soap at about 150° F. in the winter or 130° F. in
summer. After the mass has been mixed for half an hour, by continuously
crutching the soap it will at first thicken, then grain and it may again
become thick before it becomes smooth. When the mass is perfectly smooth
and homogeneous drop into a frame and crutch in the frame by hand to
prevent streaking. After standing the required length of time the soap
is finished into cakes as usual.


SETTLED ROSIN SOAP.

Settled rosin soaps are made from tallow, grease, cottonseed oil,
bleached palm oils of the lower grades, corn oil, soya bean oil, arachis
oil, distilled garbage grease, cottonseed foots or fatty acids together
with an addition of rosin, varying from 24 per cent. to 60 per cent. of
the fatty acids which should titer from 28 to 35. A titer lower than 28
will prevent the finished kettle of soap from being capable of later
taking up the filling materials. As has already been stated under
hardened oils, these being very much higher in titer allow a greater
percentage of rosin to be added. Thus hardened fish oils and cottonseed
oil are gradually being more extensively employed in soaps of this
character.

The procedure of handling the kettle is similar to that given under full
boiled soap. The stock is steamed out into a settling tank and allowed
to settle over night, after which it is pumped into the soap kettle.
Having stocked the kettle, open steam is turned on and 10°-12° B. lye is
run in, while using a steam pressure of ninety to one hundred pounds in
order to prevent too great a quantity of condensation of the steam, the
water thus being formed weakening the lye. If a steam pressure of fifty
to sixty pounds is available, a stronger lye (20° B.) should be added.
Care must be taken not to allow the lye to flow in too rapidly or the
soap will not grain. The saponification is only attained by prolonged
boiling with sufficient lye of proper strength. When saponification has
taken place, the mass begins to clear and a sample taken out with a
paddle and cooled should show a slight pink with a 1 per cent. alcoholic
phenolphthalein solution.

It may be stated here that in using this indicator or any other to test
the alkalinity of soap, the soap should always be cooled and firm, as
whenever water is present, the dissociation of the soap thereby will
always react alkaline. When this state is reached the mass is ready for
graining, which is accomplished by distributing salt brine or pickle or
spreading dry salt over the surface of the soap. The kettle is then
thoroughly boiled until the mass shows a soft curd and the lye drops
clearly from a sample taken out with a trowel or paddle. The steam is
then shut off and the soap allowed to settle over night. The lyes are
then run off to the spent lye tank for glycerine recovery. In
saponifying a freshly stocked kettle it is apt to bunch. To prevent this
salt is added at various times to approximately one per cent. of the fat
used.

If, by any possibility the soap has bunched, this condition may be
remedied by the addition of more strong lye and boiling until it is
taken up. To work a kettle to its full capacity it is advisable to make
two "killing" changes. First add about 75 per cent. of the fat and grain
as directed. Run off the spent lyes and then add the remainder of the
stock and repeat the process. When the spent lye has been run to
storage, the open steam is again turned on and 18° B. lye gradually
allowed to run in. The rosin is now broken up and put into the kettle,
or a previously made rosin soap is pumped in.

Lye is then added until the soap has a sharp taste after about three
hours of continuous boiling, or when the soap is in the closed state.
More lye should then be run into the kettle to grain the soap well, the
grain not being too small. Then allow the soap to settle over night and
draw off the strengthening lye. The next day again boil up the kettle
and add water until the soap thins out and rises or swells high in the
kettle. A sample taken out at this stage upon a hot trowel should run
off in large flakes. The surface of the soap should be bright and shiny.

If the sample clings to the trowel, a slight addition of lye will remedy
this defect. The kettle is then allowed to rest, to drop the nigre and
to cool for some time, depending upon the size of the kettle. The proper
temperature is such that after having been pumped to the crutcher and
the filling materials having been added, a thermometer placed into the
mass should indicate 128°-135° F. after the crutcher has run from ten to
fifteen minutes. The filling material may consist of from 7-9 per cent.
of sal soda solution, 36°-37° B. warm or just enough to close up the
soap and make it rise high in the center of a screw crutcher and make it
cling close to a warm trowel. Other fillers such as outlined below are
added at this point.

An addition of from 2-3 per cent. of a special mineral oil for this
purpose will impart a finish to the soap and 3-5 per cent. starch added
prevents the soap from cracking in the frames. Other filling material as
silicate of soda, borax, talc or silex are used. After the filling
material has been thoroughly crutched through the soap it is framed,
and, after being several days in the frame to solidify and cool the soap
is ready for slabbing, pressing and wrapping.

In order to more definitely illustrate the composition of the mixture of
fats and oils entering into the formation of a laundry soap a typical
formula may be given for such a soap containing 40 per cent. rosin added
to the amount of fats used:

                                  lbs.
    Grease                      7,000
    Tallow                      4,000
    Corn Oil                    7,000
    Cottonseed Oil              3,000
    Rosin                       8,400

The following have been found to be satisfactory filling materials and
are calculated upon the basis of a 1,400-pound frame of soap.

                          I.             lbs.

    Sodium Silicate, 38°-40° B.          100
    Mineral Oil                           25
    Sal Soda Solution, 36° B.             80
    Borax                                  1

                         II.

    Sal Soda Solution, 36° B.             80
    Mineral Oil                           25
    Sodium Silicate                       60

                        III.
    Soda Ash                              10
    Sal Soda                              55
    Sodium Silicate                      115
    Mineral Oil                           40
    Brine (Saturated Solution)            10
    Sodium Silicate, 38°-40° B.          100

                         IV.
    Sodium Silicate                      100
    Silex or Talc                        200
    Soda Ash                              50

                         V.

    Sal Soda Solution, 36° B.             90
    Sodium Silicate                    50-60
    Mineral Oil                           25
    Borax Solution, 25° B. (hot)          15


CHIP SOAP.

Chip soap is used extensively in laundries but is also used largely in
other branches. It may be made either as a settled soap or by the cold
made process.

To make a full boiled settled chip soap, proceed as directed under
settled laundry soap. The kettle is stocked with light grease or a
mixture of grease with corn oil or other cheap oils. For this kind of
soap the rosin is eliminated.

Chip soap may be filled as well as laundry soap. This is done in the
crutcher and the following adulterations are suitable.

                                   lbs.
    Settled Soap                   700
    Soda Ash                        35
    Sodium Silicate                215
                     or
    Settled Soap                   700
    Silicate of Soda               560
    Soda Ash                        18
    Carbonate of Potash, 26° B.     50

The cheapest method of drying is by running this soap through a drying
machine and this is the procedure usually carried out for making dried
chip soap.


COLD MADE CHIP SOAPS.

To make chip soaps by the cold process a sweet tallow of low percentage
of free fatty acid should be employed. The tallow is heated to 120° to
135° F. and the lye run in slowly at first and then the silicate of soda
is added. The mass is then mixed until a finger drawn through the soap
leaves a slight impression, then dropped into frames or barrels. Soaps
containing a small percentage of fat should be well covered in the frame
for twenty-four hours to retain their heat and insure proper
saponification. The following formulae are suitable:

                        I.                lbs.
    Tallow                               1,200
    Soda Lye, 35° B.                       850
    Sodium Silicate                        750

                      II.
    Tallow                                 475
    Ceylon Cocoanut Oil                    100
    Soda Lye, 37° B.                       325
    Potash Lye, 37° B.                      56

                      III.
    Tallow                                 500
    Soda Lye, 37-1/2° B.                   297
    Sodium Silicate                        416
    Potash Lye, 37-1/2° B.                  37-1/2

                       IV.
    Tallow                                 450
    Soda Lye, 37-1/2° B.                   255
    Sodium Silicate                        450
    Potash Lye, 37-1/2° B.                  50

                       V.
    Tallow                                 450
    Soda Lye, 35° B.                       470
    Sodium Silicate                        650

                      VI.
    Tallow                                 420
    Sodium Silicate                        600
    Soda Lye, 37-12° B.                    270


UNFILLED CHIP SOAP.

A very good grade of chip soap is made by employing no filling material
whatsoever, but unfortunately the price of this soap has been cut to
such an extent that these can not compete with a filled chip. A number
of the best soaps of this kind are made from a settled soap using a
light grease with corn oil. A soap of this nature is made as follows.

                                          lbs.
    Settled Soap                           800
    Sal Soda Solution, 36°-37° B.          252
    Soda Ash                               182

If this soap is run into frames it may be stripped and chipped in two
days.


SOAP POWDERS.

Soap powders have become so great a convenience as a general cleansing
agent that to eliminate them from the household necessities would mean
much unnecessary energy and work to the great number of consumers of
this product. They may be manufactured so cheaply and still be
efficient, that their use has almost become universal for cleansing and
scouring purposes. The uses to which soap and scouring powders are
adapted are too well known to enter into a description of their
employment. Since they offer a greater profit to the manufacturer than
ordinary household soap, many brands are extensively advertised.

Numerous combinations for soap powders might be cited and it is a simple
matter to vary the ingredients as to fat content and manufacture a
powder of this sort as low as a cent a pound. Many substances are
incorporated with soap, such as salt, soda ash, tripoli, crushed
volcanic deposits, ground feldspar, infusorial earth of various kinds,
silex, etc. In addition to these various fillers, compounds with true
cleansing and bleaching properties, in addition to soap, are added, such
as the salts of ammonium (sal ammoniac, carbonate of ammonia), sodium
perborate and the peroxides of various metals. The public, however, have
been accustomed to receive a large package of soap or scouring powder
for a small amount of money and it is a difficult matter for the
manufacturer to add more expensive substances of this nature to his
product, to increase its efficiency, without raising the price or
decreasing the size of the package.

In manufacturing soap powders, the dried soap chips might be mixed with
the filler and alkali and then pulverized. This method is not
extensively employed nevertheless. The process which is the most
economical is one whereby the ingredients are mixed in a specially
adapted mixer for heavy material until dry and then run directly to the
crusher and pulverizer, after which it is automatically packed, sealed
and boxed. Another method of procedure is to run out the mixture from
the crutcher to the frames, which are stripped before the soap cools,
and is cut up at once, for if it hardens it could not be cut with wires.
It is better, however, to run the mixture into sheets upon a specially
constructed floor and break up the mass when cool.

Formulae for soap powders which have been found to be suitable for
running dry in the mixer follow:

                        I
    Soda ash, 58 per cent.                   42 lbs.
    Silica                                  220  "
    Settled soap (usually cottonseed).       25  "
    Salt                                     10  "

                       II
    Soap (settled cottonseed)                40 lbs.
    Soda ash, 58 per cent.                   60  "

                      III
    Settled soap                            100 lbs.
    Soda ash, 58 per cent.                  400  "

Fillers in varying proportions may replace the soda ash in the above
formulae. It is of course understood that the soap has been previously
made and run as molten soap into the crutcher.

The following soap powders will not dry up in the crutcher upon running,
but are of the class which may be framed or run on the floor to
solidify:


                         I
    Soap                                 850 lbs.
    Filler                               400  "
    Sal soda solution, 20 degs. B        170  "

                       II
    Soap                                 650 lbs.
    Filler                               550  "
    Sal soda solution, 20 degs. B.       340  "

                      III
    Soap                                  80 lbs.
    Filler                               550  "
    Sal soda solution                    170  "

                      IV
    Soap (settled tallow)                800 lbs.
    Filler                               400  "
    Sal soda solution                    170  "
    Water                                100  "

                       V

First saponify 100 parts house grease and 100 parts ordinary grease and
make a run soap. Then use in crutcher either:

    Soap                                 400 lbs.
    Filler                               575  "
    Hot water                             60  "
                         or
    Soap                                 200 lbs.
    Hot water                            200  "
    Filler                               625  "

It would be a simple matter to write numerous additional formulae, but
the above are typical. The manufacturer must judge for himself just what
filling material to use. The filler indicated in the above formulae is
therefore left open. A few formulae for more expensive powders than
those given recently appeared among others in the "Seifensieder
Zeitung"[9]:


                     I

    Powdered soap                         90 lbs.
    Sodium perborate                      10  "

The perborate should be added when the powder is perfectly dry or it
loses its bleaching properties.

                     II

    Soap powder, 20 per cent. fat.
    Cocoanut oil fatty acids              25 lbs.
    Olein                                 25  "
    Bone fat                              70  "
    Soda lye, 30 degs. B.                 90  "
    Water                                150  "
    Ammonium carbonate                   125  "

                     III

    Soap powder, 10 per cent. fat.
    Cocoanut oil fatty acids              20 lbs.
    Olein                                 10  "
    Bone fat                              20  "
    Soda lye, 30 degs. B.                 30  "
    Water                                175  "
    Ammonium carbonate                   175  "


LIGHT OR FLUFFY POWDERS.

Light or fluffy powders containing 35-45% moisture can be made in two
ways. The first method requiring a minimum equipment is to mix the
powder and sal soda in a mixer, allow it to stand in frames for a week
to crystallize or spread it on the floor for a few hours to dry and then
grinding it.

The continuous method finishes the powder in a few minutes and with a
minimum amount of labor. By this process the various ingredients, soap,
soda ash solution, etc., are measured, run by gravity into the mixer,
mixed and the molten mass run over the crystallizer or chilling rolls
thru which either cold water or brine is pumped. From the roll the
powder is scraped off clean by a knife, passes to a screen which sends
the tailings to a grinder, falls into a storage bin from whence it is
weighed and packed by an automatic weighing machine into cartons made up
in most cases by another machine. Due to the large percentage of
moisture contained in these soap powders the carton is generally wrapped
in wax paper to aid in the prevention of the escape of moisture.


SCOURING POWDERS.

Scouring powders are very similar to soap powders and differ only in the
filler used. We have already considered these fillers under scouring
soap, from which they do not differ materially. They are usually
insoluble in water to aid in scouring. The mixer used for substances of
this kind in incorporating the soap and alkali must be of strong
construction.


SCOURING SOAP.

Scouring soaps resemble soap powders very closely in their composition,
in that they are a combination of soap and filling material. Since more
lather is required from a scouring soap than in soap powders, a cocoanut
oil soap is generally used. The usual filling material used is silex.
The greatest difficulty in the manufacture of scouring soap is the
cracking of the finished cake. This is usually due to the incorporation
of too great an amount of filler, or too high a percentage of moisture.

In manufacturing these soaps the cocoanut oil is saponified in the
crutcher with 38 degs. B. lye, or previously saponified as a run soap,
as already described under "Marine Soaps." To twenty-five parts of soap
are added a percentage of 38 degs. B. sal soda or soda ash solution,
together with a small quantity of salt brine. To this mixture in the
crutcher seventy-five parts of silex are then added, and a sufficient
amount of hot water to make the mass flow readily. Care must be
exercised to not add too great a quantity of water or the mass will
crack when it cools. The mass is then framed and cut before it sets, or
poured into molds and allowed to set. While silex is the most
extensively used filler for scouring soaps, it is feasible to
incorporate other substances of like character, although it is to be
remembered that the consumer is accustomed to a white cake, such as
silex produces. Any other material used to replace silex should also be
as fine as this product.


FLOATING SOAP.

Floating soap occupies a position midway between laundry and toilet
soap. Since it is not highly perfumed and a large piece of soap may be
purchased for small cost, as is the case with laundry soap, it is
readily adaptable to general household use. Floating soap differs from
ordinary soap in having air crutched into it which causes the soap to
float in water. This is often advantageous, especially as a bath soap,
and undoubtedly the largest selling brand of soap on the American market
today is a floating soap.

In the manufacture of floating soap a high proportion of cocoanut oil is
necessary. A most suitable composition is one part cocoanut oil to one
part of tallow. This is an expensive stock for the highest grade of soap
and is usually cheapened by the use of cottonseed or various other
liquid oils. Thus it is possible to obtain a floating soap from a kettle
stocked with 30 per cent. cocoanut oil, 15 per cent. cottonseed oil and
55 per cent. tallow. With this quality of soap, however, there is a
possibility of sweating and rancidity, and of the soap being too soft
and being poor in color.

The process of manufacture is to boil the soap in an ordinary soap
kettle, after which air is worked into the hot soap by a specially
constructed crutcher, after which the soap is framed, slabbed, cut into
cakes and pressed.

Concerning the boiling of the soap, the saponification must be carefully
carried out, as the high proportion of cocoanut oil may cause a violent
reaction in the kettle causing it to boil over.

The method of procedure is the same as for a settled soap up to the
finishing. When the mass is finally settled after the finish, the soap
should be more on the "open" side, and the object should be to get as
long a piece of goods as possible.

Due to its high melting point, a much harder crust forms on the surface
of a floating soap and in a greater proportion than on a settled soap
during the settling. In a large kettle, in fact, it has been found
impossible to break through this crust by the ordinary procedure to
admit the skimmer pipe. Much of the success of the subsequent operations
depends upon the completeness of the settling, and in order to overcome
the difficulties occasioned by the formation of the crust everything
possible should be done in the way of covering the kettle completely to
enable this period of settling to continue as long as possible.

When the soap is finished it is run into a specially constructed U-shape
crutcher, a Strunz crutcher is best adapted to this purpose, although a
rapidly revolving upright screw crutcher has been found to give
satisfaction upon a smaller scale, and a sufficient quantity of air
beaten into the soap to make it light enough to float. Care must be
taken not to run the crutcher too rapidly or the soap will be entirely
too fobby. During this operation the mass of soap increases in bulk,
and after it has been established how much air must be put into the soap
to satisfy the requirements, this increase in bulk is a criterion to
estimate when this process is completed.

It is of course understood that the longer the crutching continues the
greater quantity of air is incorporated and the increase of volume must
be established for a particular composition by sampling, cooling the
sample rapidly and seeing if it floats in water. If the beating is
continued too long an interval of time, the finished soap is too spongy
and useless.

The temperature of the mass during crutching is most important. This
must never exceed 158 degrees F. At 159 degrees F. the operation is not
very successful, yet the thermometer may indicate 140 degrees F. without
interfering with this operation. If, however, the temperature drops too
low, trouble is liable to be met with, by the soap solidifying too
quickly in the frames.

When the crutching is completed, the soap is allowed to drop into frames
through the valve at the bottom of the crutcher and rapidly crutched by
the hand in the frames to prevent large air spaces and then allowed to
cool. It is an improvement to jolt the frames as they are drawn away as
this tends to make the larger air bubbles float to the surface and thus
reduce the quantity of waste. When the soap has cooled, the frame is
stripped and the soap slabbed as usual. At this point a layer of
considerable depth of spongy soap will be found to have formed. This of
course must be cut away and returned to the kettle. The last few slabs
are also often rejected, inasmuch as the weight of the soap above them
has forced out so much of the air that the soap no longer floats. As a
fair average it may be estimated that not more than 50 to 60 per cent.
of the soap in the kettle will come out as finished cakes. the
remaining 40 to 50 per cent. being constituted by the heavy crust in the
kettle, the spongy tops, the bottom slabs and scrapings. This soap is of
course reboiled and consequently not lost, but the actual cakes obtained
are produced at a cost of practically double labor.

It is advisable to add a small quantity of soap blue color to the mass
while crutching to neutralize the yellowish tint a floating soap is
liable to have.

Some manufacturers add a percentage of carbonate of soda, about 3 per
cent., to prevent the soap from shrinking. Floating soap may also be
loaded with sodium silicate to the extent of about 5 per cent.


TOILET SOAP.

It is not a simple matter to differentiate between toilet soaps and
various other soaps, because numerous soaps are adaptable to toilet
purposes. While some soaps of this variety are manufactured by the cold
made or semi-boiled process, and not milled, the consumer has become
accustomed to a milled soap for general toilet use.

The toilet base most extensively employed is a tallow and cocoanut base
made as a full boiled settled soap. The manufacture of this base has
already been outlined and really needs no further comment except that it
is to be remembered that a suitable toilet soap should contain no great
excess of free alkali which is injurious to the skin. Cochin cocoanut
oil is preferable to the Ceylon cocoanut oil or palm kernel oil, to use
in conjunction with the tallow, which should be a good grade and color
if a white piece of goods is desired. The percentage of cocoanut oil may
be anywhere from 10 to 25 per cent., depending upon the kind of lather
required, it being remembered that cocoanut oil increases the lathering
power of the soap.

In addition to a tallow base, numerous other oils are used in the
manufacture of toilet soaps, especially palm oil, palm kernel oil, olive
oil and olive oil foots, and to a much less extent arachis or peanut
oil, sesame oil and poppy seed oil, oils of the class of cottonseed,
corn and soya bean oils are not adapted to manufacturing a milled soap,
as they form yellow spots in a finished cake of soap which has been kept
a short time.

Palm oil, especially the Lagos oil, is much used in making a palm base.
As has already been stated, the oil is bleached before saponification. A
palm base has a yellowish color, a sweetish odor, and a small quantity
added to a tallow base naturally aids the perfume. It is especially good
for a violet soap. The peculiarity of a palm oil base is that this oil
makes a short soap. By the addition of some tallow or twenty to
twenty-five per cent. of cocoanut oil, or both, this objection is
overcome. It is a good plan in using a straight palm base to add a
proportion of yellow color to hold the yellowish tint of this soap, as a
soap made from this oil continues bleaching upon exposure to air and
light.

Olive oil and olive oil foots are used most extensively in the
manufacture of castile soaps. The peculiarity of an olive oil soap is
that it makes a very slimy lather, and like palm oil gives the soap a
characteristic odor. An olive oil soap is usually considered to be a
very neutral soap and may readily be superfatted. Much olive oil soap is
used in bars or slabs as an unmilled soap and it is often made by the
cold process. Peanut oil or sesame and poppy seed oil often replaces
olive oil, as they form a similar soap to olive oil.

In the manufacture of a toilet soap it is hardly practical to lay down a
definite plan for the various bases to be made. From the combination of
tallow, palm oil, cocoanut oil, palm kernel oil, olive oil and olive oil
foots, a great many bases of different proportions might be given. The
simplest method is to make a tallow base, a palm base and an olive oil
base. Then from these it is an easy matter to weigh out any proportion
of these soap bases and obtain the proper mixture in the mill. If,
however, as is often the case, a large quantity of soap base of certain
proportions of these, four or even more of these fats and oils is
required, it is not only more economical to stock the kettle with the
correct proportion of these oils, but a more thorough mixture is thus
obtained by saponifying these in the kettle. In view of the fact that it
is really a question for the manufacturer to decide for himself what
combination of oils he desires for a particular soap we will simply
outline a few typical toilet soap bases in their simplest combination.
It is understood that these soaps are suitable for milled soaps and are
to be made as fully boiled settled soaps. Palm kernel oil may be
substituted for cocoanut oil in all cases.


TALLOW BASE.

    Tallow                       75-90 parts
    Cocoanut oil                 25-10 parts


PALM BASE.

    Bleached Lagos palm oil      75-80 parts
    Cocoanut oil                 25-20 parts

                or

    Tallow                          30 parts
    Palm oil                        60 parts
    Cocoanut oil                    10 parts


OLIVE OIL BASE (WHITE).

    Olive oil                    75-90 parts
    Cocoanut oil                 25-10 parts

                  or

    Olive oil                    40 parts
    Tallow                       40 parts
    Cocoanut                     20 parts

Where a green olive oil base is desired, olive oil foots are substituted
for the olive oil. Peanut oil may replace the olive oil or part of it,
the same being true of sesame oil and poppy seed oil.


PALM AND OLIVE BASE.

    Palm oil                     50 parts
    Olive oil                    30 parts
    Cocoanut oil                 20 parts

                  or

    Palm oil                     20 parts
    Olive oil                    10 parts
    Tallow                       50 parts
    Cocoanut oil                 20 parts


CHEAPER TOILET SOAPS.

It is often necessary to manufacture a cheaper grade of soap for toilet
purposes to meet the demand of a certain class of trade as well as for
export. To accomplish this it is of course necessary to produce a very
inferior product and run down the percentage of fatty acids contained in
the soaps by the addition of fillers or to use cheaper oils in
manufacturing. The most simple method of filling a soap is to load it at
the mill with some substance much less expensive than the soap itself.
Many of the cheaper toilet soaps, however, are not milled and it is,
therefore, necessary to follow out some other procedure.

Milled soaps, as has just been stated, are loaded at the mill. The
consumers of cheaper toilet soaps in this country are accustomed to a
milled soap and this grade of soap for home consumption is very often
filled with numerous substances, but most generally by adding starch
and talc. The addition of such materials of course later exhibit
themselves by imparting to the cake of soap a dead appearance. Talc is
more readily detected in the soap than starch by washing with it, as
talc is insoluble and imparts a roughness to the soap, like sand or
pumice, as the soap wears down. It may readily be added to 20 per cent.
by weight. Starch is to be preferred to talc, in loading a soap, as it
is not so readily noticeable in washing. It leaves the cake itself
absolutely smooth although the lather formed is more shiny. This
substance may be employed to as high a percentage as one-third the
weight of the soap. It is, of course, possible to cheapen the best soap
base by this method and the price may be further lowered by using the
less expensive oils and fats to make the soap base.


RUN AND GLUED UP SOAPS.

A very cheap grade of soap may be made by making a run soap and adding
the filler e. g. sodium silicate in the kettle during saponification.
The percentage of fatty acids may be brought down to 10 per cent.,
although of course a soap of this type shrinks a whole lot upon
exposure.

In making a "glued up" soap the procedure is the same for making the
soap itself as with a settled soap, except that the soap is finished
"curd" and later filled in the crutcher. The percentage of fatty acids
in a soap of this type is seldom below 50 per cent.

The method of "gluing up" a soap is best illustrated by a typical soap
of this character in which the kettle is charged with the following
stock.

    Bleached palm oil                          5 parts
    Distilled grease                           2   "
    Cotton oil foots stock, 63% fatty acid     1   "
    Rosin                                      4   "

The palm oil is first run into the kettle, saponified and washed to
extract any glycerine, then the rest of the fats and finally the rosin.
The soap is then finished and settled as with a boiled settled soap. To
assure success it is absolutely necessary that the soap settle as long a
period as possible, or until the temperature is about 150 degs. F. The
ideal temperature for carrying out the "gluing up" process is 140 degs.
F., as at a lower temperature than this the soap is liable to cool too
quickly and not be thoroughly glued up. A higher temperature than 150
degs. F. causes delay in that the soap does not properly take the filler
at a higher temperature and the soap must be kept in the crutcher until
the temperature drops to the right point.

The soap is run into the crutcher and the percentage of fatty acids run
down to 50-55 per cent. with one of the following mixtures:

    Sodium silicate, 59-1/2° B.     1 part
    Potassium carbonate, 51° B.     1  "

                    or

    Sodium silicate, 59-1/2° B.     1 part
    Potassium carbonate, 51° B.     1  "
    Sodium sulfate, 28° B.          1  "

From 230 to 300 pounds of either of these mixtures are required for a
crutcher holding 2,600 pounds of soap.

The crutching is continued until the mass is well "spiked," that is to
say, a freshly broken surface of the soap, as the crutcher blade is
jerked away, stands up like shattered sheets in triangular form
[Transcriber's note: three triangles]), which retain their shape
perfectly. When this condition is realized the soap is run into frames
which are carefully crutched by hand to remove any air spaces. The
surface of the soap is then smoothed down and heaped up in the center.
After standing a day to contract, the surface is again leveled and a
snugly-fitting board placed on the top of the soap upon which a weight
is placed or upon which the workman treads and stamps until the surface
is flat, thus assuring the further removal of air spaces. The soap
remains in the frame from six to eight days and is then slabbed, barred
and pressed by the usual method employed for soaps thus handled without
milling.

In a soap of this nature no hard and fast rule can be laid down as to
the quantity of solution to be used for "gluing up" or the strength of
the solution. In a soap of the type described the most satisfactory
appearing cake will be obtained from a soap containing 58 per cent.
fatty acids. That is to say, about 8 per cent. to 10 per cent. filling
solution is added per hundred pounds of soap. The filling solutions
given are very satisfactory. Carbonate of soda should be avoided in
connection with sodium silicate as the property of efflorescing on the
surface of the finished cake after a short time will prove detrimental.
To assure successful gluing up it is advisable to experiment upon a
small scale to determine the exact extent to which the filling solution
should be diluted. Various proportions of water are added to a certain
quantity of the filled soap. After the soap has been filled in a small
receptacle a sample is taken and rubbed between the fingers. If the
freshly exposed surface is smooth and glossy, the filling solution is
weak enough, if rough it is too strong. It is of course understood that
the temperature must be correct, 140 degs. to 150 degs. F., or the soap
will be rough. By this means the operator can readily judge the correct
strength of his filling solution. When properly carried out a perfectly
satisfactory soap is obtained.


CURD SOAP.

The object of a soap which is finished "curd" or grained, is to obtain a
harder piece of goods from low titer fat or to increase the percentage
of fatty acids in the finished soap. This is still another method of
producing a cheap grade of soap as by its adoption the cheaper oils and
fats may be used to obtain a firm piece of soap.

A typical charge for curd soap is:

    Red oil        63 parts
    Tallow         10  "
    Rosin          27  "

Cotton seed foots may be employed in place of red oil and a tallow of
too high titer is not suitable for this kind of soap.

The red oil and tallow are first saponified with 15 degs. B. lye, boiler
pressure 80-90 pounds, 18 degs. B. lye for lower steam pressure, and two
washings given to extract the glycerine. The rosin is added at the
strengthening change and at the finish the soap is "pitched," that is to
say, the soap is settled over night only. The next day the lyes are
drawn off and a portion of the nigre pumped to another kettle which
prevents later streaking of the soap. The soap is then boiled with 18
degs. B. lye as with another strengthening change under closed steam.
Salt brine or "pickle," 15 degs. B. is then added and the mass boiled
with closed steam until the brine reaches a density of 18 degs. B. and
the kettle pumped the next day. A soap of this type requires either hand
or power crutching to assure homogeneity and prevention of streaks. To
obviate any air spaces it is advisable to place over the top of the
frame a tightly-fitted board which is heavily weighted down. This soap
is also pressed without any milling.


COLD MADE TOILET SOAPS.

Comparatively little toilet soap is made by the cold or semi-boiled
processes. While these are the simplest methods of manufacturing soaps
the drawbacks of using them are numerous and only in a few cases are
they very extensively employed. To make a toilet soap by the cold
process a combination of good grade tallow and cocoanut oil is required.
It requires 50 per cent. by weight of 36 degs. B. lye to saponify a
given weight of tallow and 50 per cent. of 38 degs. B. lye for cocoanut
oil. The lyes are used full strength or may be reduced slightly with
water and the method of procedure is the same as already given in the
general directions for cold made soaps.

Cold made soaps are readily filled with sodium silicate which is added
at the same time the stock is put into the crutcher. In adding the
silicate it is necessary to add additional lye to that required for
saponifying the fats, about 20 per cent. of 36 degs. B. lye is the
proper amount. There is of course a certain amount of shrinking due to
the addition of this filler and the finished cake is exceedingly hard,
yet the author has seen a good looking cake of cheap soap made from as
high a proportion as 420 parts of tallow to 600 parts of silicate.

Cold made soaps are usually pressed without milling, although it is
readily feasible to mill a cold made soap provided it is not a filled
soap such as has just been described.


PERFUMING AND COLORING TOILET SOAPS.

Equally important as the soap itself or even to a greater extent is the
perfume of a toilet soap. A prominent manufacturer recently made the
statement, which is often the truth, that it makes no difference to the
public what kind of soap you give them, as long as you put plenty of
odor into it. The perfuming of soaps is an art in itself and a subject
to be treated by one versed in this particular branch. We can only take
into account the importance of the perfume as related to toilet soap
not only, but the necessity of adding a certain proportion of the
cheaper products of odoriferous nature to laundry soap to cover and
disguise the odor of even this type of soap.

The price of a cake of toilet soap to a great extent depends upon the
perfume, and the manufacturer should aim to give the best possible
perfume for a certain price. He should not allow his personal likes or
dislikes to enter into the judgment of whether an odor is good or not,
but submit it to a number of persons to obtain the concensus of opinion.
In giving or selling a piece of soap to the consumer, it is second
nature for him to smell it, and in the great majority of cases his
opinion is formed not from any quality the soap itself may have during
use, but from the odor. This only emphasizes the fact that the perfume
must be pleasing, not to one person, but to the majority, and many
brands owe their popularity to nothing more than the enticing perfume.

Perfuming of soap is closely allied to the soap making industry, but as
stated a branch in itself. It is, therefore, not our purpose to give
numerous formulae of how to perfume a soap, but rather to advise to go
for information to some one who thoroughly understands the
characteristics of the numerous essential oils and synthetics and give
positive information for the particular odor desired. Under no
circumstances is it advisable to purchase a perfume already compounded,
but since all perfumes are a blend of several or many essential oils and
synthetics, it is a more positive assurance of obtaining what is
desired, by purchasing the straight oils and blending or mixing them as
one desires.

The perfume is added to a milled soap just before the milling process in
the proper proportion per hundred pounds of soap. In cold made or
unmilled soaps it is added in the crutcher while the soap is still hot.
By this method, of course, a proportion of the perfume is lost due to
its being more or less volatile.


COLORING SOAP.

While much toilet soap is white or natural in color, many soaps are also
artificially colored. The soap colors used for this purpose are mostly
aniline dyestuffs. The price of these dyestuffs is no criterion as to
their quality, as the price is usually regulated by the addition of some
inert, water soluble substance like common salt or sugar.

The main properties that a dyestuff suitable for producing a colored
soap should have are fastness to light and to alkali. They should
further be of such a type that the color does not come off and stain a
wash cloth or the hands when the soap is used and should be soluble in
water. Under no circumstances is it advisable to add these in such a
quantity that the lather produced in the soap is colored. It is
customary to first dissolve the dye in hot water as a standardized
solution. This can then be measured out in a graduate and added to the
soap the same time as the perfume is put in. About one part of color to
fifty parts of water is the proper proportion to obtain a perfect
solution, though this is by no means fixed. In making up a solution thus
it is an improvement to add to the same about one-half of one per cent.
of an alkali either as the hydroxide or carbonate. Then, if there is any
possibility of change of color due to alkalinity of the soap, it will
exhibit itself before the color is added.

A particularly difficult shade to obtain is a purple, as there is up to
the present time no purplish aniline color known which is fast to light.
Very good results in soap may be obtained by mixing a fast blue, as
ultramarine or cobalt blue, with a red as rhodamine or eosine.

Inasmuch as the colors for soap have been carefully tested by most of
the dyestuff manufacturers, and their information, usually reliable, is
open to any one desiring to know about a color for soap, it is better to
depend upon their experience with colors after having satisfied one's
self that a color is what it is represented for a particular shade, than
to experiment with the numerous colors one's self.


MEDICINAL SOAPS.

Soap is often used for the conveyance of various medicants, antiseptics
or other material presumably beneficial for treatment of skin diseases.
While soap is an ideal medium for the carrying of such materials, it is
an unfortunate condition that when incorporated with the soap, all but a
very few of the numerous substances thus employed lose their medicinal
properties and effectiveness for curing skin disorders, as well as any
antiseptic value the substance may have. Soap is of such a nature
chemically that many of the substances used for skin troubles are either
entirely decomposed or altered to such an extent so as to impair their
therapeutic value. Thus many of the claims made for various medicated
soaps fall flat, and really have no more antiseptic or therapeutic merit
than ordinary soap which in itself has certain germicidal and cleaning
value.

In medicating a soap the material used for this purpose is usually added
at the mill. A tallow and cocoanut oil base is best adapted for a soap
of this type. The public have been educated more or less to the use of
colored soap to accentuate its medicinal value, and green is undoubtedly
the most popular shade. This inference, however, is by no means true for
all soaps of this character. Possibly the best method of arranging
these soaps is briefly to outline some medicinal soaps.


SULPHUR SOAPS.

The best known sulphur soaps contain anywhere from one to 20 per cent.
of flowers of sulphur. Other soaps contain either organic or inorganic
sulphur compounds.


TAR SOAP.

The tar used in the manufacturing of tar soap is obtained by the
destructive distillation of wood, the pine tar being the most
extensively employed. While the different wood tars contain numerous
aromatic compounds, such as phenols, phenyl oxides, terpenes and organic
acids, these are present in such a slight proportion so as to render
their effectiveness practically useless. It has, therefore, been tried
to use these various compounds contained in the tar themselves to make
tar soap really effective, yet tar is so cheap a substance that it is
usually the substance used for medicating a tar soap. About 10 per cent.
of tar is usually added to the soap with 2 ounces of lamp black per
hundred pounds of soap.


SOAPS CONTAINING PHENOLS.

Phenol (Carbolic Acid) is most extensively used in soaps of this kind,
which are called carbolic soaps. Carbolic soaps are generally colored
green and contain from 1 to 5 per cent. phenol crystals.

The cresols are also extensively used for making soaps named carbolic.
These substances impart more odor to the soap and really have more
disinfecting powers than phenol when incorporated with soap.

Other soaps, containing the phenol group, which are well known are
resorcinol soap, salol soap, thymol soap, naphthol soap, etc. From one
to five per cent of the compound after which the soap is named is
usually incorporated with the soap.


PEROXIDE SOAP.

Hydrogen peroxide in itself is an excellent disinfectant. It loses all
its medicinal value, however, when added to the soap. To overcome this
objection various metallic peroxides are added to the soap, as sodium
peroxide, zinc peroxide and barium peroxide. These generate hydrogen
peroxide by the addition of water. Sodium perborate is also used in
peroxide soaps, as this substance is decomposed by water into hydrogen
peroxide and sodium metaborate.


MERCURY SOAPS.

Mercuric chloride (corrosive sublimate) is most extensively used for the
production of mercury soaps. Because of its extremely poisonous
properties care should be taken in using it. Since it really eventually
loses any antiseptic value in the soap through forming an insoluble
mercury soap it might better be omitted entirely.


LESS IMPORTANT MEDICINAL SOAPS.

While the above mentioned soaps are probably the best known medicated
soaps, there are numerous other soaps which may be classed under these
kinds of soaps. Thus we have cold cream soap, which can be made by
adding Russian Mineral Oil, 1 to 5 per cent., to the soap; witch hazel
soap, made by the addition of extract of witch hazel; iodine soap, made
by adding iodine or iodoform; formaldehyde soap, made by adding
formaldehyde; tannin soaps, made by adding tannin. In fact, there have
been incorporated in soap so great a number of substances that the list
might be greatly enlarged.

Medicated soaps are not only used in solid form, but in powder, paste
and liquid soap as well. The only difference in a soap like those just
referred to is that the medicant is incorporated with these forms of
soaps as convenience directs.


CASTILE SOAP.

A pure castile soap should be made from olive oil. This, however, is not
always the case, as a number of oils as well as tallow are used to
adulterate this oil to cheapen it, and there are even some soaps called
castile which contain no olive oil at all. Most of the pure castile soap
used in this country is imported, as it is a difficult matter for the
American manufacturer to compete with the pure imported castile soap,
since both labor and oil itself are so much cheaper in the vicinities of
Europe where this oil is produced, that this advantage is more than
compensated by the carrying and custom charges by importing the castile
soap.

Castile soap may be made either by the full boiled or cold process.
There are numerous grades of olive oil, and those used for soap making
are denatured to lower the duty charges. Olive oil makes a hard white
soap, usually sold in bars, and olive oil foots a green soap, due to the
coloring matter contained in this oil.

To make a boiled castile soap, a composition of 10 per cent. Cochin
cocoanut oil and 90 per cent. olive oil may be used. To cheapen this,
peanut oil (Arachis oil) may entirely replace the olive oil, or about 20
per cent. of corn or soya bean oil may be added. The oils are saponified
as usual in making a settled soap and to prevent rancidity the soap is
boiled near the finish for some time in the closed state with
sufficient excess of alkali to give it a sharp taste, then grained with
lye, the lye drawn off, closed with water and then grained with salt.
This process is repeated until the desired strength is reached. The last
graining should not be too great, and on the last change the soap should
not be thinned out, as it will contain too great a quantity of water
when slabbed.

In making a cold castile soap the usual method is pursued as already
directed under cold made soap. When the soap is taken from the crutcher
it is advisable, however, to keep the soap in the frame well covered to
assure complete saponification. Some manufacturers use very small frames
which are placed into compartments, well insulated to retain heat.
Several formulae for cold made castile soaps, follow. It may be noted
that some of these contain practically no olive oil.

                 I

    Olive oil                        2030
    Palm kernel                       674
    Soda lye, 35 per cent. B.        1506

                 II

    Olive oil                        2030
    Cochin cocoanut oil               674
    Soda lye, 36 per cent. B.        1523
    Sodium Silicate                    82

                 III

    Palm kernel oil                  1578
    Tallow                            940
    Olive oil                           7
    Sodium silicate, 20 per cent.     190
    Soda lye, 36 per cent. B.        1507

                 IV

    Olive oil (yellow)               1000
    Soda lye, 37 per cent. B.         500

                 V

    Olive oil                          90
                   or
    Palm kernel            }           10
    Cochin or cocoanut oil }           10
    Lye, 37 per cent. B.               51

If any of the soaps containing a high proportion of cocoanut oil are
boiled the soap will float. It is therefore necessary to keep the
temperature as low as possible.


ESCHWEGER SOAP (BLUE MOTTLED).

Eschweger soap is a colored mottled or marbled soap made to a very
slight extent in this country. Inasmuch as it has been introduced to the
export trade, it is made for this purpose by some manufacturers. A high
percentage of cocoanut oil is usually used together with tallow and
grease. About one-third of each is a typical formula. In a soap of this
character the fact that cocoanut oil soap takes up a large quantity of
water and salts of various kinds and is difficult to salt out is made
use of. The tallow and grease are first saponified as usual, then the
cocoanut oil is pumped and saponified. When the saponification is nearly
completed either silicate or carbonate of soda or common salt are added
to make the soap "short" so as to form the mottle. The finishing of a
soap of this type can only be gained by practice and it is rather
difficult to explain the exact appearance of the kettle at this stage.
The surface of the soap should be bright and lustrous with the steam
escaping in numerous places in rose-like formation. A sample on the
trowel should have a slight sharpness to the tongue and be plastic. When
the soap slides from the trowel it should break short. When the soap has
reached this stage the desired coloring matter, usually ultramarine, is
added to the soap either in the kettle or crutcher and the soap framed.
The yield is 200-215 pounds per hundred pounds of stock.

Several modifications of this general method for Eschweger soap are used
by adopting the half boiled or cold process.


TRANSPARENT SOAP.

Transparent soap is really not a most desirable soap for toilet
purposes, as it contains an excess of free alkali. It has, nevertheless,
met with public approval because of the fact it is novel in being
transparent. Except for this fact very little merit can be claimed for a
soap of this kind.

The transparency of soap is generally due to the presence of alcohol,
sugar or glycerine in the soap when it is made. It is very essential in
a soap of this character, where lightness and clearness of color are
desired, that the material for making the soap be carefully selected as
to color and purity. The perfumes also play an important part in the
color of the soap and many of the tinctures, balsams and infusions used
in perfuming soap may eventually cause trouble by spotting. If the soap
is artificially colored, which is almost always the case, the dyestuffs
used for this purpose should have careful attention and only those
should be used which are known to resist the action of alkalis. Where
rosin is used this product must be of the better grade. Distilled water
is always preferable for use in transparent soap. The government permits
the use of a specially denatured alcohol. This alcohol is not taxed and
consists of grain (ethyl) alcohol denatured with 5 per cent. wood
(methyl) alcohol. Some soapmakers prefer to use a more expensive refined
methyl alcohol, but outside of adding to the cost of the soap, there is
no particular advantage. The glycerine should be chemically pure. As to
the oils and fats these should be low in acid and of good color. Under
no circumstances should the crutcher or kettle in which the soap is made
be rusty or unclean in any way. For a light soap enameled utensils are
to be preferred.

To obtain transparency in soap the following general methods may be
given.

1. Where the transparency is due to sugar.

2. Where alcohol and glycerine produce transparency.

3. Where (1) or (2) is supplemented by the use of castor oil.

4. Where transparency depends upon the percentage of fatty acid in a
soap and the number of times the soap is milled.

Under the first method at least 25 per cent. of the charge should be
cocoanut oil, the other constituent being tallow or any fat or oil
capable of giving a sufficiently hard soap. The soap is boiled and
finished as usual, then run to the crutcher to be mixed with a strong
cane sugar solution, containing 10-20 per cent. sugar of the weight of
the soap. The sugar is dissolved in its own weight of water and the
solution heated to 175 degs. F. before being very slowly added to the
soap. As the water evaporates, soaps of this type show spots due to the
sugar thus being thrown out of solution.

Transparent soap made under the second method may be saponified as usual
and consist of any good toilet base. The soap is run to the crutcher and
mixed with 95 per cent. alcohol in the proportion of one part alcohol to
two parts of fatty acid contained in the soap together with glycerine in
the same proportion.

By the third method castor oil alone may be used to make the soap or
added to any of the above bases up to 33-1/3 per cent. of the charge. If
castor oil only is used, but 2 per cent. or 3 per cent. of sugar is
required.

In the last method a combination of 80 per cent. tallow, very low in
free acid, 20 per cent. cocoanut oil and 5 per cent. W. W. rosin is a
suitable charge. The saponification and finishing is carried out as with
a full boiled soap. The soap is then placed into a jacketed vessel,
provided with dry-steam coils, by which the excess water is evaporated
from the soap until it contains 73 per cent. fatty acids. When the thick
mass reaches this stage it is framed and when cool is suitable for
obtaining a semi transparency which now depends upon the number of times
the soap is milled, it being, of course, inferred that no solid matter
of any sort be added to the soap.


COLD MADE TRANSPARENT SOAP.

While transparent soaps may be made by the above general methods they
are usually made by the semi-boiled or cold process. By this process a
more satisfactory soap is obtained and it is more simple to carry out. A
detailed description of this method is best and most easily given by
using a typical formula.

    Charge:

      Tallow                       193-1/2 lbs.
      Cochin Cocoanut Oil          169-1/2 "
      Castor Oil                    89-1/2 "
      Soda Ash                       7-3/4 "
      Soda Lye, 36 degs. B.        256     "
      Sugar (Cane)                 198     "
      Alcohol                      126     "
      Water (Distilled)             80     "

To proceed, first place into a crutcher or jacketed kettle the oils and
fat and heat to 140 degs. F. Then add the soda ash dissolved in about 30
pounds of the water, after which the lye is added and the mass stirred
until a finger or stick run over the surface leaves an imprint. Where
the soap has reached this stage, it is well covered and allowed to stand
about two hours or until it bulges in the center, after which the rest
of the water which should contain no lime or other mineral substance and
which is preferably distilled water, is added. The sugar is then slowly
shoveled in while the mass is stirring and finally the alcohol is poured
in. The heat is then increased to 160 degs. F. by dry steam and the soap
crutched until dissolved. Under no circumstances should any soap be
allowed to remain above the surface of the mass on the sides of the
mixer. This crutching operation consumes about one hour, and when
finished the soap should stand in the vessel about half an hour when a
small sample is taken out to cool. This sample should be clear and show
an excess of alkali. If it is not clear more alcohol is added, if not of
sufficient strength more lye put in until the desired condition is
reached. The perfume and color are now added.

The soap is then framed and allowed to set after which it is cut,
allowed to dry slightly and then pressed. To obtain a polished cake
transparent soaps are often planed before pressing and after pressing
polished with a soft cloth, dampened with alcohol. Instead of framing
this soap, it is sometimes "tubed," that is to say, the soap from the
crutcher is run into specially constructed tubes of a shape near that of
the desired cake and allowed to cool, after which it is cut and pressed.
All scraps are returned to the crutcher, but in so doing the soap is
slightly darkened in color. It is advisable to expose a finished cake of
transparent soap to the air for some time as by so doing it becomes
clearer.

Other formulae for cold made transparent soaps made as just outlined
follow:

                      I.
    Bleached Tallow                134 lbs.
    Cochin Cocoanut Oil             88  "
    Castor Oil                      20  "
    W. W. Rosin                      7  "
    Cane Sugar                      64  "
    Water                           32  "
    Glycerine                       34  "
    Soda Lye, 38 degs. B.          135  "
    Alcohol                         16 gal.

                     II.
    Tallow                         211   lbs.
    Cochin Cocoanut Oil            185     "
    Castor Oil                      97-1/2 "
    Soda Ash                         8-1/2 "
    Water                          106     "
    Soda Lye, 38 degs. B.          279     "
    Sugar                          216     "
    Alcohol                        137     "

                     III.
    Castor Oil                      60    lbs.
    Cochin Cocoanut Oil            195     "
    Tallow                         120     "
    Alcohol                        115     "
    Sugar                           90     "
    Water                           53     "
    Glycerine                       53     "
    Soda Lye, 38 degs. B.          205-1/2 "

                     IV.
    Tallow                         100 lbs.
    Cochin Cocoanut Oil            100  "
    Castor Oil                      60  "
    Glycerine                       20  "
    Rosin, W. W.                    20  "
    Sugar                           40  "
    Water                           50  "
    Soda Lye, 36 degs. B.          164  "
    Alcohol                          8 gal.

                      V.
    Tallow                         174 lbs.
    Cocoanut Oil                   114  "
    Soda Lye, 38 degs. B.          170  "
    Sugar                           80  "
    Water                           72  "
    Alcohol                         16 gal.

Rosin may be added in this formula up to 20 per cent. of fats used and
the tallow cut down correspondingly.


SHAVING SOAPS.

The requirements of a shaving soap are somewhat different than those of
other soaps. To be a good shaving soap the lather produced therefrom
must be heavy, creamy, but not gummy, and remain moist when formed on
the face. The soap itself should be of a soft consistency so as to
readily adhere to the face when used in stick form. It should
furthermore be neutral or nearly so to prevent the alkali from smarting
during shaving.

Shaving soap is made in the form of a stick, and a tablet for use in the
shaving mug. Some shavers prefer to have the soap as a powder or cream,
which are claimed to be more convenient methods of shaving. While a
liquid shaving soap is not as well known because it has not yet become
popular, some soap for shaving is made in this form.

Formerly shaving soap was extensively made from a charge of about 80
parts tallow and 20 parts cocoanut oil as a boiled settled soap, but
either making the strengthening change with potash lye or using potash
lye in saponifying the stock and graining with salt. Soaps for shaving
made in this manner are very unsatisfactory, as they do not produce a
sufficiently thick or lasting lather and discolor very materially upon
ageing. Potassium stearate forms an ideal lather for shaving, but
readily hardens and hence needs some of the softer oils, or glycerine
incorporated with it to form a satisfactory soap for shaving.

The selection of materials for making a shaving soap is important. The
tallow used should be white and of high titer. Cochin cocoanut oil is to
be preferred to the other kinds, and the alkalis should be the best for
technical use that can be purchased--76 per cent. caustic soda and 88-92
per cent. caustic potash are suitable. By the use of stearic acid it is
a simple matter to reach the neutral point which can be carefully
approximated.

The following are shaving soap formulae which have been found to give
good satisfaction:

                      I.       lbs.
    Tallow                         360
    Stearic acid                    40
    Soda lye, 41° B.               147
    Potash lye, 34° B.              87
    Water                           32
    Gum tragacanth                   1

                     II.       lbs.
    Tallow                         282
    Cocoanut oil                    60
    Stearic acid                    50
    Bayberry wax                    18
    Soda lye, 41° B.               147
    Potash lye, 34° B.              90
    Water                           32

                     III.      lbs.
    Tallow                         400
    Cocoanut oil                   176
    Stearic acid                   415
    Caustic soda, 40° B.           182
    Caustic potash, 38° B.         108

To proceed, first run into the crutcher the tallow, cocoanut oil and
bayberry wax when used, and bring the temperature of the mass up to
140°-160° F. by dry steam. Then add the caustic soda lye and keep on
heat with occasional mixing until it is all taken up. When this stage is
reached gradually add all but about 5 per cent. of the potash lye, and
complete the saponification. This point having been reached, the heat is
turned off; the crutcher is run and the stearic acid, previously melted
by dry steam in a lead-lined or enameled vessel, is run in in a
continuous stream and the crutching continued for fifteen minutes to
half an hour. Samples are taken at this time, cooled and tested by
alcoholic phenolphthalein solution. If too alkaline more stearic acid is
added, if too acid more potash lye from that previously reserved. After
each addition of lye or stearic acid the mass is crutched from 10 to 15
minutes longer, another sample is taken, cooled and again tested. When
the phenolphthalein shows a very light pink after several minutes, the
soap is practically neutral, although at this point one can better judge
by dissolving a sample in hot neutralized alcohol made by putting into
the alcohol a few drops of phenolphthalein, and then adding weak alkali
drop by drop from a burette until a slight pink, not yellow, tint is
obtained, and noting the color of the solution. The solution should show
a very light pink when the soap is properly neutralized. When this stage
is arrived at the gum tragacanth, previously softened in water, is
crutched in if it is to be added. The soap is then framed, stripped in
three or four days, dried and milled.

The formulae as given are for shaving sticks, and do not readily press
unless thoroughly dried. A more satisfactory result is obtained by
adding at the mill 25 per cent. of white tallow base to obtain a
satisfactory mug soap.


SHAVING POWDER.

Shaving powder differs from the soaps just described in being
pulverized, usually adding up to 5 per cent. starch to prevent caking.
Any of the above soaps, dried bone dry, with or without the addition of
tallow base make a satisfactory powder for shaving.


SHAVING CREAM.

Shaving cream is now a very popular shaving medium due to the rapidity
and convenience with which one can shave by the use of this product.
Formerly shaving cream was made from the liquid oils like olive oil and
a soft fat like lard, together with cocoanut oil. Now, however, most of
the popular shaving creams are made from stearic acid and cocoanut oil,
as a far superior product is obtained by the use of these substances. By
using these a more satisfactory cream is obtained, and it is far more
convenient to make. The lather also produced therefrom is more suitable
for shaving, being thick, creamy and remaining moist.

A few typical formulae for shaving creams of this type are as follows:

                          I.       lbs.
    Cochin cocoanut oil             26
    Stearic acid                   165
    Caustic potash lye, 50° B.      69
    Glycerine C. P.                 76
    Water                           38

                          II.      lbs.
    Cochin cocoanut oil             18
    Stearic acid                    73
    Caustic potash lye, 39° B.      54
    Glycerine                       33
    Water                           27

                         III.      lbs.
    Cochin cocoanut oil             18
    Stearic acid                    73
    Caustic potash lye, 39° B.      54
    Glycerine                       20
    Water                           40

                         and       lbs.

    Stearic acid                    60
    Glycerine C. P.                 85
    Water                          165
    Sodium carbonate                50
    Borax                            1

To make a shaving cream by Formula I or II, the cocoanut oil and
glycerine are first put into a suitable mixing apparatus or crutcher,
and heated to 120° F. A part or all the potash lye is then added and the
cocoanut oil saponified. The rest of the potash lye and the water are
then added, and with the mixer running the stearic acid, previously
melted in a lead-lined or enameled vessel, is then poured in in a stream
and the mass stirred until smooth, care being exercised not to aerate it
too much. The cream is then tested for alkalinity, the best method being
by that described under shaving soap, in which the sample is dissolved
in alcohol. Because of the large quantity of water present,
phenolphthalein is unsatisfactory, as dissociation of the soap may show
a pink indication in spite of the fact the mass is on the acid side. For
a quick method of testing the bite on the tongue is a satisfactory
criterion. If a cooled sample bites the tongue more stearic acid is
added until there is a 3% excess of this. When the proper neutralization
has taken place the cream is perfumed and framed in a special frame, or
it may be allowed to cool in the mixer and perfumed the next day. When
cool the cream is strained, or put through an ointment mill, after which
it is ready to fill into tubes.

The procedure for the first part of Formula III is the same as that just
given. The second part of the formula is made the same as a vanishing
cream for toilet purposes. To make this, first melt the stearic acid as
already directed. Dissolve the sodium carbonate and borax in water and
when dissolved add the glycerine and stir. Then heat this solution to
about 100°-120° F. and while stirring in a suitable mixing machine into
which this solution has been poured after being heated, or better still
in which it has been heated by dry steam, add the stearic acid. Continue
mixing until smooth and then allow to cool, or run into frames to cool.

When the shaving cream and vanishing cream are both cool, they are mixed
in the proportion of one of the former to two of the latter. It is
claimed that in thus making a shaving cream a smoother product is
obtained, although it may be said that the vanishing cream is merely a
soft soap and the ultimate result is the same as though the various
ingredients were added in one operation, rather than making two separate
products and then mixing them, thereby considerably increasing the cost
of manufacture.


PUMICE OR SAND SOAPS.

Pumice and sand are at times added to soap to aid in the removal of dirt
in cleansing the hands. In some cases these soaps are made in the form
of a cake, in others they are sold in cans in the form of a paste.

A hand paste is usually made by merely dissolving ordinary tallow base
in two or three times its weight of hot water and mixing in the desired
quantity of pumice or sand and in some instances adding a little
glycerine to keep it soft or a solvent of some kind for grease. It may
also be made by directly incorporating any of these in a potash soap.

A cold made or semi-boiled cocoanut or palm kernel oil soap is the base
used to add the pumice or sand to in making a cake soap of this sort.
The following formulae serve as a guide for these soaps.

                       I.

    Palm Kernel or Ceylon Cocoanut Oil      705 lbs.
    Pumice (Powdered)                       281 "
    Soda Lye, 38° B.                        378 "

                      II.

    Cocoanut Oil                            100 "
    Soda Lye, 38° B.                         55 "
    Water                                     6 "
    Silver Sand (fine)                       60 "

To proceed place the oil in a crutcher and heat to 140° F. Sift in the
pumice and mix thoroughly. The lye is then added which causes a curdling
of the grain. The stirring is continued until the grain closes and the
soap is smooth, after which the desired perfume is added and the soap
dropped into a frame and crutched by hand. When the soap is set, it is
slabbed, cut into cakes, dried slightly and pressed.


LIQUID SOAPS.

Liquid soaps are merely solutions of a potash soap, usually cocoanut oil
soap, although corn oil is used to make a cheap soap. One of the
difficulties encountered in liquid soap is to keep it clear. At a low
temperature a sediment is often formed, but this can be overcome by the
use of sugar and filtering the soap through a filter press at a low
temperature. In order to prevent the soap from freezing, it is necessary
to lower the freezing point by the addition of glycerine or alcohol.

To make liquid soap by any of the formulae given below, the oil is first
run into a jacketed kettle with a stirring device, and heated to about
120° F. The potash lye is then added and the oil saponified. When the
saponification takes place, especially when cocoanut oil is used, the
mass swells rapidly and may foam over the sides of the kettle unless
water is used to check this, or a kettle of about four to five times the
capacity of the total charge of soap is used. When the saponification
has occurred, the sugar, borax and glycerine are added, the water run in
and the mixture stirred until the soap is thoroughly dissolved. Heat
aids materially in dissolving the soap. The soap is then allowed to cool
and if color or perfume is to be added this is stirred in, after which
the soap is cooled and filtered or else run directly into barrels.

Tallow is not suitable for making a clear liquid soap since it is too
high in stearine which when formed into the stearate makes an opaque
solution. The formulae herewith given have been found to give good
practical results.

                   I.               lbs.
    Cocoanut oil                    130
    Caustic potash lye, 28° B.      135
    Sugar                            72
    Borax                             2
    Water                           267

                  II.               lbs.
    Corn oil                        130
    Caustic potash lye, 26° B.      135
    Sugar                            72
    Borax                             2
    Water                           267

                  III.              lbs.
    Cocoanut oil                    100
    Caustic potash lye, 28° B.      102
    Glycerine                       100
    Sugar                            70
    Water                           833

Formulae I and II contain about 20 per cent. fatty acids. It is
possible, of course, to either increase or decrease the percentage of
fatty acid by varying the amount of water. The water used in making
liquid soaps, of course, should be soft, for hard water forms insoluble
soaps which precipitate and cause a sediment.


USE OF HARDENED OILS IN TOILET SOAPS.

While the introduction of the hydrogenation of oils is a decided advance
in the production of suitable cheaper oils for soap making,
comparatively little hardened oil is employed for soap making in America
up to the present time. In Europe, however, considerable advance has
been made by the use of such oils for manufacturing soap therefrom and a
number of plants turn out large quantities of hydrogenated oils for soap
making as well as for edible purposes. Recently a company has been
formed in this country for hardening oils and it is very probable that
the future will see this material extensively used in our own country,
as these appear to be the one present hope of the soap manufacturer as a
check on the ever increasing cost of fats and oils now used in making
soap.

It is an unfortunate condition that hydrogenated oils produced abroad
are sold under names which give absolutely no indication as to the oil
which has been hardened. The softer and cheaper oils like fish oil,
linseed oil, cottonseed oil, etc., are generally hardened for soap
manufacture to different degrees of hardness. While it is impossible to
definitely state just what products as Candelite, Talgol, Krutolin or
several other coined names of hardened oils are, various investigators
have experimented with them as to their adaptability for producing
toilet soaps and found that suitable toilet soaps may be made from them.
While many objections were at first met with concerning soaps made from
these products, as to their unsatisfactory saponification, the poor
lathering quality of the soaps and their odor and consequent difficulty
in perfuming, the results of most investigators along these lines
indicate that these in many cases were due to prejudice against or
unfamiliarity with handling oils of this type for soap making.

In manufacturing soap from hardened oils it is usually necessary to
incorporate with the charge lard, tallow, tallow oil or some other soft
oil of this nature. Satisfactory bases for toilet soaps, made as boiled
settled soap by the use of Talgol (undoubtedly hardened fish oil), are
said to be made by the formulae[10] below.

              I.

    Tallow                  45 parts
    Talgol                  40 "
    Cocoanut Oil            15 "

              II.

    Cocoanut Oil (Ceylon)    6 "
    Tallow                  12 "
    Talgol, Extra           12 "

The method of boiling a soap of this type does not differ materially
from that of making settled tallow soap base. The soap itself has a
different odor than a straight tallow base, but is said to make a very
satisfactory soap for milling and to be of good appearance.

Satisfactory transparent soaps are made from the hardened oil Candelite,
which replaces the tallow in transparent soap formulae such as have
already been given in the section under "Transparent Soaps." The method
of manufacturing a soap by the use of this product varies in no way from
the usual method employed for making these soaps.

Since hydrogenated oils are high in stearine, their use in shaving soaps
is a decided advantage. It has previously been pointed out that
potassium stearate forms an ideal lather for shaving, and in the
hydrogenating process the olein is converted to stearine. Thus a
hardened oil is advantageous in a shaving soap. As an example of a cold
made soap for shaving the following may be taken.[11]

    Talgol Extra            50 lbs.
    Cocoanut Oil            10 "
    Lard                    10 "
    Soda Lye, 38° B.        20 "
    Potash Lye, 37° B.      21 "

This soap may be made in a crutcher by the method generally used in
making soap by the cold process.


TEXTILE SOAPS.

Soap is a very important product to every branch of the textile
industry. For woolen fabrics it is used for scouring, fulling and
throwing the wool; in the silk industry it is necessary for degumming
the raw silk, as well as for dyeing; in the cotton mills it is used to
finish cotton cloth and to some extent in bleaching; it is, furthermore,
employed in a number of ways in the manufacture of linen. Large
quantities of soap are thus consumed in an industry of so great an
extent and the requirements necessitate different soaps for the
different operations. We will, therefore, consider these in detail.


SCOURING AND FULLING SOAPS FOR WOOL.

The soaps used to scour wool and for fulling the woven cloth are usually
made as cheaply as possible. They are, however, generally pure soaps, as
filling material such as sodium silicate does not readily rinse out of
the wool and if used at all must be added very sparingly. Both cold made
and boiled settled soaps are made for this purpose. The soap is
generally sold in barrels, hence is run directly to these from the
crutcher or soap kettle. As cold made soaps the following serve for wool
scouring or fulling.

                 I.

    Palm Oil                         200 lbs.
    Bone Grease                      460 "
    Soda Lye, 36° B.                 357 "
    Water                            113 "
    Soda Ash                          50 "
    Citronella                         2 "

                 II.

    Palm Oil (Calabar, unbleached)   155 "
    House Grease                     360 "
    Soda Lye, 36° B.                 324 "
    Water                            268 "
    Sodium Silicate                   83 "

                 III.

    House Grease                     185 "
    Palm Oil (unbleached)            309 "
    Soda Lye, 36° B.                 309 "
    Water                            391 "
    Soda Ash                          70 "
    Sodium Silicate                   60 "
    Corn Starch                       10 "

These soaps are made in a crutcher by the usual process for cold-made
soaps, crutched until smooth, dropped into a barrel and crutched by hand
the next day or just before cooling.

As a settled soap for these operations the following charge is typical:

    Palm Oil                                               34 parts
    Cottonseed foots or its equivalent in fatty acids      33  "
    Rosin                                                  10  "
    House Grease                                           23  "

The method of boiling such a soap is the same as for any settled soap up
to the strengthening change. When this stage is reached, sufficient lye
is added to strengthen the kettle strongly. It is then boiled down with
closed steam on salt brine or "pickle" until a sample of the lye taken
from the bottom stands at 16°-22° B. The soap is then run into barrels
and after standing therein for a day is hand crutched until cool to
prevent streaking of the soap.

Besides a soap of this type a settled tallow chip soap is used.


WOOL THROWER'S SOAP.

Soaps for wool throwing are sometimes made from olive oil foots but
these are often objected to because of the sulphur-like odor conveyed to
the cloth due to the method by which this oil is extracted with carbon
disulphide. A potash soap hardened somewhat with soda is also used. As a
formula for a suitable soap of this type this may be given.

    Olive Oil Foots              12   parts
    Corn Oil                     46     "
    House Grease                 20     "
    Soda Lye, 36° B.              3     "
    Potassium Carbonate (dry)     5-3/4 "
    Potassium Hydrate (solid)    23     "

This soap is made as a "run" soap by the general directions already
given for a soap thus made. The kettle is boiled with open and closed
steam, adding water very slowly and aiming to obtain a 220-225 per cent.
yield or fatty acid content of the finished soap of 46 per cent. When
the soap is finished a sample cooled on a plate of glass should be
neither slippery or short, but should string slightly. The finished soap
is run directly into barrels.

A soap for wool throwing by the semi-boiled process may be made from
olive oil foots in a crutcher thus:

    Olive Oil Foots          600 lbs.
    Potash Lye, 20° B.        660 "

The oil is heated to 180° F., the lye added and the mass stirred until
it bunches, when it is dropped into barrels.


WORSTED FINISHING SOAPS.

For the finishing of worsted cloth soaps high in cocoanut oil or palm
kernel oil are preferred. These soaps are finished very neutral, being
made as settled soaps, but given an extra wash change after
strengthening strongly. They are then finished as usual and run into
barrels. If framed too hot, the high percentage of cocoanut oil causes
mottling, which is prevented by crutching by hand until the temperature
of the soap is 140°-145° F. Some typical charges, all of which are
saponified with soda lye, follow:

                    I.

    Palm Kernel Oil                      60 parts
    Corn Oil                             40 "

                    II.

    Palm Kernel Oil                      30 "
    Red Oil (single pressed)             70 "

                    III.

    Red Oil                              33-1/3 "
    Corn Oil                             33-1/3 "
    Cocoanut Oil or Palm Kernel Oil      33-1/3 "


SOAPS USED IN THE SILK INDUSTRY.

Soap is used to a very large extent in silk mills, both for degumming
the raw silk and in silk dyeing. Raw silk consists of the true silk
fibre known as fibroin and a gummy coating, sericin, which dulls the
lustre of the silk unless removed. For this purpose a slightly alkaline
olive oil foots soap is best adapted, although palm oil and peanut oil
soaps are sometimes used, as well as soaps made from a combination of
house grease to the extent of 30 per cent., together with red oil or
straight olein soaps, both of which are artificially colored green. In
using house grease, if 30 per cent. is exceeded in combination with red
oil, the titer is raised to such an extent that the soap does not
readily rinse from the silk nor dissolve readily. They are also not
advisable because they impart a disagreeable odor to the silk.

To make a soap for this purpose from olive oil foots it is made as a
settled soap, care being taken to thoroughly boil the mass on the
saponification change in the closed state to assure proper
saponification. The kettle is usually grained with lye and given a good
wash change to remove the excess strength. The change previous to the
finish should not be too heavy or too large a nigre results. The lighter
the grain is, the better the finished kettle is. A yield of 150 per
cent. is usually obtained. This soap is generally run to a frame,
slabbed upon cooling and packed directly into wooden cases.

For silk dyeing the above soap is suitable, although any well-made soap
of good odor and not rancid is useable. While soap alone is often used
in the bath for silk dyeing, certain dyestuffs require the addition of
acetic or sulphuric acid, which sets free the fatty acids. If these be
of bad odor it is taken up by the silk and is difficult to remove. The
most generally used soaps are the just mentioned olive foots soap or a
soap made from a good grade red oil.

Both kinds are extensively used.


SOAPS USED FOR COTTON GOODS.

In the manufacture of cotton goods, as compared to the wool and silk
industries, very much less soap is used and it is only applied to the
finished fabric either to clean the cloth preparatory to dyeing or to
aid in dyeing with certain colors. It is also used in calico printing.
For cleansing the cloth ordinary chip soap is suitable although a more
alkaline soap finished as a curd soap is an advantage in that the free
alkali contained therein aids in removing the dirt and has no harmful
effect on the cotton. For dyeing cotton goods or to brighten certain
colors after dyeing an olive oil foots soap is most generally employed.
In calico printing soap is used to wash and clear the cloth after
printing. A soap for this purpose should be easily soluble in water and
contain no free alkali, rosin or filler. The best soaps for use in
calico printing are either an olive oil foots soap or an olein soap.


SULPHONATED OILS.

While sulphonated oils are not used to any great extent in the
manufacture of soap, they are used very largely in the dyeing and
printing of turkey and alizarine reds on cotton as well as other colors.
Just what action these oils have is not known. Turkey red oil or
sulphonated castor oil is the best known sulphonated oil.

The process of making these oils is simple. The equipment necessary is a
wooden tank or barrel of suitable capacity, approximately two and a half
times the amount of oil to be treated. There are furthermore required
other tanks or vessels to hold the solutions used such as caustic soda,
ammonia and acid. The tank to be used for the preparation of sulphonated
oil should be provided with a valve at the bottom of the tank and a
gauge to measure the quantity of liquid therein.

The process is carried out as follows:

Three hundred pounds of castor oil are placed in the tank and 80 pounds
at 66 deg. B. sulphuric acid are weighed out in another vessel. The acid
is run into the tank containing the oil in a very thin stream while the
oil is well stirred. At no time should the temperature exceed 40 deg. C.
This operation should consume at least an hour and stirring should be
continued half an hour longer to insure the thorough mixing of the oil
with the acid. The mass is then allowed to settle for 24 hours, after
which 40 gallons of water are added and the mixture stirred until it has
a uniform creamy color indicating no dark streaks. This mixing process
should be carefully carried out and when completed allowed to settle 36
hours. At this point the mass will have separated into two layers, the
lower layer consisting of a water solution of acid and the upper layer
of oil. The former is run out through the valve located at the bottom of
the tank. Another wash may now be given or dispensed with as desired. In
this wash the addition of salt or sodium sulphate at the rate of 1-1/2
pounds per gallon of water is advisable. A 24 deg. B. caustic soda
solution is prepared and added slowly to the acidified oil with constant
stirring. The mass first turns creamy, then becomes streaked, increasing
in streaks as the caustic solution is poured in, and finally becomes
clear and transparent. Water is now added to bring the volume to 75
gallons. The oil is now milky in appearance, but the addition of a
little more soda solution restores the transparency.

In some cases ammonia is used in addition to caustic soda in
neutralizing the oil. Three-fourths of the amount of caustic soda
required to complete the neutralization is first added and then the
neutralization is completed with a one to one liquid ammonia and water
solution.

FOOTNOTES:

[9] Seifensieder Ztg., 40, 47, 1266 (1913).

[10] Seifensieder Ztg. (1913), p. 334 and 338.
         "         "   (1912), p. 1229 and 1257.

[11] Seifensieder Ztg. (1912), p. 954.




CHAPTER V

Glycerine Recovery.


The recovery of glycerine is very closely allied with the soap-making
industry, because glycerine is the very valuable by-product obtained in
the saponification of oils and fats. No soap plant is, therefore, fully
equipped unless it has some method whereby the glycerine is recovered
and the importance of recovering this product cannot be too strongly
emphasized.

It has already been pointed out that neutral fats or the glycerides are
a combination of fatty acid with glycerine. These are split apart in the
process of saponification. While by the term _saponification_ as used in
soap making it is inferred that this is the combination of caustic
alkalis with the fatty acids to form soap, this term is by no means
limited to this method of saponification, as there are various other
methods of saponifying a fat. The chemical definition of saponification
is the conversion of an ester, of which glycerides are merely a certain
type, into an alcohol and an acid or a salt of this acid. Thus, if we
use caustic alkali as our saponifying agent for a fat or oil, we obtain
the sodium or potassium salt of the higher fatty acids or soap and the
alcohol, glycerine. On the other hand, if we use a mineral acid as the
saponifying agent, we obtain the fatty acids themselves in addition to
glycerine. While the former is by far the most generally employed for
making soap, other processes consist in saponifying the fats by some
method other than caustic alkalis and then converting the fatty acids
into soap by either neutralizing them with sodium or potassium carbonate
or hydrate.

It is important to again point out here that fats and oils develop free
fatty acid of themselves and that the development of this acid
represents a loss in glycerine. The selection of an oil or fat for soap
making should therefore to a large extent be judged as to its
adaptability by the free fatty acid content, as the higher this content
is, the greater is the loss in the glycerine eventually obtained.
Glycerine often represents the only profit to a soap manufacturer. It is
indeed necessary to determine the percentage of free fatty acid before
purchasing a lot of stock to be made into soap.

In taking up the question of glycerine recovery we will consider the
various methods thus:

1. Where the glycerine is obtained from spent lye by saponifying the
fats or oils with caustic alkali.

2. Where the glycerine is obtained by saponifying the fats or oils by
some other method than the above, of which there are the following:

    (a) Twitchell process.
    (b) Saponification by lime in autoclave.
    (c) Saponification by acid.
    (d) Saponification by water in autoclave.
    (e) Fermentative (Enzymes).
    (f) Krebitz process.


RECOVERY OF GLYCERINE FROM SPENT LYE.

The spent lye obtained from the glycerine changes in making soap varies
greatly, the quality depending upon the stock saponified and the soap
maker's care in handling the operation. No two lyes run exactly alike as
to proportion of the various ingredients, although they are all similar
in containing the same substances either in solution or suspension.
Spent lye is a water solution of mainly glycerine, free alkali either as
caustic alkali or carbonate and salt, including sodium sulfate, but
furthermore contains some soap and albuminous matter either in solution
or suspension. Upon standing in the storage tank the greater part of
the soap usually separates when the lye cools. In order to assure the
greatest economical yield of glycerine by saponifying a fat with caustic
soda it is necessary to obtain a proportion of three parts of water to
every part of fat made into soap. Test runs have shown that this is the
proper proportion and that it is not economical to greatly exceed this
amount, and if a much less proportion is used the full yield of
glycerine is not obtained.

The spent lyes contain varying amounts of glycerine, the first change
being richest in glycerine content, and this being reduced in the
subsequent changes. If the lyes always run high in glycerine it is an
indication that it is not all being obtained. The usual percentage is
from 0.5% to 5% or even more, although the average is somewhere around
2% to 3%. The lye as it comes from the kettle should not contain any
more than 0.5% to 0.6% of free alkali calculated as sodium carbonate,
Na_{2}CO_{3}. If the proportion is higher than this, it shows that the
saponification has been conducted with too high a proportion of alkali,
a condition which should be corrected in the kettle room. An excess of
free alkali does not interfere to any great extent with the successful
recovery of the glycerine, but is a waste of both alkali and the acid
used in neutralizing this. It is, therefore, more economical to run a
strong lye over fresh stock and neutralize the alkali thus, rather than
treating the lye for glycerine recovery.

Before the spent lye can be run into the evaporator it is necessary to
remove the albuminous impurities and soap and to neutralize the excess
alkali to between exactly neutral and 0.02% alkalinity. The lye should
never be fed into the evaporator in the acid condition.

In order to treat the spent lyes for evaporation, they are first allowed
to cool in the storage tank, after which any soap which may have
separated is skimmed off and returned to the soap kettle. This lye is
then pumped to the treatment tank, an ordinary tank equipped with some
method of agitating the liquor, either by a mechanical stirrer, steam
blower or compressed air, until it is about two feet from the top.

After the lye has been skimmed off it is thoroughly agitated and a
sample taken. The amount of lye in the tank is then calculated. Spent
lye is about 1.09 times heavier than water, or weighs about 9 pounds to
the gallon. While the sample is being tested for alkalinity it is
advisable to add sulfate of alumina, which may be dissolving while the
sample is being titrated. This substance should be added in the
proportion of anywhere from 6 to 14 pounds per thousand pounds of lye,
depending upon the amount of impurities contained therein. For a clean
lye six pounds per thousand is sufficient, but for an impure lye a
greater quantity is necessary. The sulfate of alumina used should be
free from arsenic and sulfides and should contain a minimum amount of
grit (silica), as grit reduces the life of the pump valves. This may be
estimated with sufficient accuracy by rubbing the filtered-off portions,
insoluble in water between the fingers and a plate of glass. The object
of adding the sulfate of alumina is to transform the soap contained in
the lye into the insoluble aluminum soaps, and at the same time to
coagulate the albuminous impurities. It must be remembered that the
sulfate of alumina is added only for the fresh lye put into the tank.
Thus if there were 10,000 pounds of lye in the treating tank when the
fresh lye was run in, and 50,000 pounds when the tank is filled, adding
nine pounds of sulfate of alumina per thousand of lye, only 360 pounds
would be added or enough for 40,000 pounds. Sulfate of alumina
neutralizes one-third of its weight of caustic.

To determine the alkali in the sample, 10 cubic centimeters are pipetted
into a beaker, a little distilled water added, then 3 or 4 drops of
phenolphthalein indicator. From a burette, quarter normal (N/4) sulfuric
acid is added until the pink color is just discharged. When this point
is reached 4 to 5 c. c. more of acid are added and the solution is
boiled to expel the carbon dioxide. Should the solution turn pink, it is
necessary to add more acid. After having boiled for 3 to 4 minutes, N/4
caustic soda is added until the pink color just returns and the amount
of caustic soda used is read on the burette. The difference between the
number of cubic centimeters of N/4 sulfuric acid and N/4 caustic soda
gives the amount of alkali in the sample. By using a 10 c. c. sample and
N/4 sulfuric acid and N/4 caustic soda each c. c. obtained by the
difference of these two solutions is equal to one-tenth of one per cent.
(0.1%) of the total alkali in the lye. As an example, say we first used
7.7 c. c. of N/4 sulfuric acid to just discharge the pink, then added 4
c. c. more, or 11.7 c. c. in total. After boiling it required 5.3 c. c.
to bring back a slight pink, the total alkalinity would be 11.7 c. c. -
5.3 c. c. = 6.4 c. c., or 0.64% total alkali in the lye in terms of
caustic soda. If there were 40,000 pounds of lye to be treated then we
should have to neutralize:

40,000 × .0064 = 256 lbs. alkali. Since sulfate of alumina neutralizes
one-third of its weight in caustic, and there are say 9 lbs. of this
added per thousand pounds of lye we would add

40,000 × 9 = 360 lbs. of sulfate of alumina. This would neutralize 360 ×
1/3 = 120 lbs of alkali. There are then 256 - 120 = 136 lbs. of alkali
still to be neutralized. If 60° B. sulfuric acid is used it requires
about 1.54 lbs. of acid to one pound of caustic. Therefore to neutralize
the caustic soda remaining it requires:

136 × 1.54 = 209.44 lbs. 60° B. sulfuric acid to neutralize the total
alkali in the 40,000 pounds of spent lye.

The acid is added and the lye well stirred, after which another sample
is taken and again titrated as before. From this titration the amount of
acid to be added is again calculated and more acid is added if
necessary. Should too much acid have been added, caustic soda solution
is added until the lye is between exactly neutral and 0.02% alkaline.
The filtered lyes at this stage have a slight yellowish cast.

To be sure that the lyes are treated correctly the precipitation test is
advisable. To carry this out filter about 50 c. c. of the treated lye
and divide into two portions in a test tube. To one portion add ammonia
drop by drop. If a cloudiness develops upon shaking, more alkali is
added to the lye in the tank. To the other portion add a few drops of 1
to 5 sulfuric acid and shake the test tube. If a precipitate develops or
the solution clouds, more acid is needed. When the lyes are treated
right no cloudiness should develop either upon adding ammonia or the
dilute acid.

The properly treated lye is then run through the filter press while
slightly warm and the filtered lye is fed to the evaporator from the
filtered lye tank. The lye coming from the filter press should be clear
and have a slight yellowish cast. As the pressure increases it is
necessary to clean the press or some of the press cake will pass through
the cloths. Where sodium silicate is used as a filler, the silicate
scrap should never be returned to the soap kettle until the glycerine
lyes have been withdrawn. This practice of some soapmakers is to be
strongly censured, as it causes decided difficulty in filtering the lye,
since during the treatment of the lye, free silicic acid in colloidal
form is produced by the decomposition of the sodium silicate by acid.
This often prevents filtering the treated lye even at excess pressure
and at its best retards the filtering.

As to the filter press cake, this may be best thrown away in a small
factory. Where, however, the output of glycerine is very large it pays
to recover both the fatty acids and alumina in the press cakes.

In some cases, especially when the lyes are very dirty and the total
residue in the crude glycerine runs high, for which there is a penalty
usually attached, a double filtration of the lye is advisable. This is
carried out by first making the lye slightly acid in reaction by the
addition of alum and acid, then filtering. This filtered lye is then
neutralized to the proper point with caustic, as already described, and
passed through the filter press again.

While in the method of treating the lyes as given sulfuric acid is used
for neutralizing, some operators prefer to use hydrochloric acid, as
this forms sodium chloride or common salt, whereas sulfuric acid forms
sodium sulfate, having 3/5 the graining power of salt, which eventually
renders the salt useless for graining the soap, as the percentage of
sodium sulfate increases in the salt. When the salt contains 25 per
cent. sodium sulfate it is advisable to throw it away. Sulfuric acid,
however, is considerably cheaper than hydrochloric and this more than
compensates the necessity of having to eventually reject the recovered
salt. It may here also be mentioned that recovered salt contains 5-7 per
cent. glycerine which should be washed out in the evaporator before it
is thrown away. The following tables give the approximate theoretical
amounts of acids of various strengths required to neutralize one pound
of caustic soda:

For 1 pound of caustic soda--

    3.25 lbs. 18° B. hydrochloric (muriatic) acid are required.
    2.92  "   20° B.      "            "       "   "     "
    2.58  "   22° B.      "            "       "   "     "

For 1 pound of caustic soda--

    1.93 lbs. 50° B. sulphuric acid are required.
    1.54  "   60° B.     "      "    "     "
    1.28  "   66° B.     "      "    "     "

It is, of course, feasible to neutralize the spent lye without first
determining the causticity by titrating a sample and this is often the
case. The operator under such conditions first adds the sulfate of
alumina, then the acid, using litmus paper as his indicator.
Comparatively, this method of treatment is much slower and not as
positive, as the amount of acid or alkali to be added is at all times
uncertain, for in the foaming of the lyes their action on litmus is
misleading.

After the lye has been filtered to the filtered lye tank it is fed to
the evaporator, the method of operation of which varies somewhat with
different styles or makes. When it first enters the evaporator the lye
is about 11°-12° B. After boiling the density will gradually rise to 27°
B. and remain at this gravity for some time and during which time most
of the salt is dropped out in the salt filter. As the lye concentrates
the gravity gradually rises to 28°-30° B., which is half crude glycerine
and contains about 60 per cent. glycerine. Some operators carry the
evaporation to this point and accumulate a quantity of half crude before
going on to crude. After half crude is obtained the temperature on the
evaporator increases, the vacuum increases and the pressure on the
condensation drain goes up (using the same amount of live steam). As the
liquor grows heavier the amount of evaporation is less, and less steam
is required necessitating the regulation of the steam pressure on the
drum. When a temperature of 210° F. on the evaporator, with 26 or more
inches vacuum on the pump is arrived at, the crude stage has been
reached and the liquor now contains about 80 per cent. glycerine in
which shape it is usually sold by soap manufacturers. A greater
concentration requires more intricate apparatus. After settling a day in
the crude tank it is drummed.

Crude glycerine (about 80 per cent. glycerol) free from salt is 33° B.,
or has a specific gravity of 1.3. A sample boiled in an open dish boils
at a temperature of 155° C. or over.


TWITCHELL PROCESS.

The Twitchell process of saponification consists of causing an almost
complete cleavage of fats and oils by the use of the Twitchell reagent
or saponifier, a sulfo-aromatic compound. This is made by the action of
concentrated sulfuric acid upon a solution of oleic acid or stearic acid
in an aromatic hydrocarbon. From 0.5 per cent. to 3 per cent. of the
reagent is added and saponification takes place from 12-48 hours by
heating in a current of live steam. The reaction is usually accelerated
by the presence of a few per cent. of free fatty acids as a starter.
Recently the Twitchell double reagent has been introduced through which
it is claimed that better colored fatty acids are obtained and the
glycerine is free from ash.

The advantages claimed for the Twitchell process as outlined by
Joslin[12] are as follows:

1. All the glycerine is separated from the stock before entering the
kettle, preventing loss of glycerine in the soap and removing glycerine
from spent lye.

2. The liquors contain 15-20 per cent. glycerine whereas spent lyes
contain but 3-5 per cent. necessitating less evaporation and
consequently being more economical in steam, labor and time.

3. No salt is obtained in the liquors which makes the evaporation
cheaper and removes the cause of corrosion of the evaporator; also
saves the glycerine retained by the salt.

4. The glycerine liquors are purer and thus the treatment of the lyes is
cheaper and simpler and the evaporation less difficult.

5. The glycerine can readily be evaporated to 90 per cent. crude rather
than 80 per cent. crude, thus saving drums, labor in handling and
freight. The glycerine furthermore receives a higher rating and price,
being known as saponification crude which develops no glycols in
refining it.

6. The fatty acids obtained by the Twitchell saponifier may be converted
into soap by carbonates, thus saving cost in alkali.

7. There is a decrease in the odor of many strong smelling stocks.

8. The glycerine may be obtained from half boiled and cold made soaps as
well as soft (potash) soaps.

While the advantages thus outlined are of decided value in the
employment of the Twitchell process, the one great disadvantage is that
the fatty acids obtained are rather dark in color and are not
satisfactorily employed for the making of a soap where whiteness of
color is desired.

To carry out the process the previously heated oil or fat to be
saponified is run into a lead lined tank. As greases and tallow often
contain impurities a preliminary treatment with sulfuric acid is
necessary. For a grease 1.25 per cent. of half water and half 66° B.
sulfuric acid is the approximate amount. The undiluted 66° B. acid
should never be added directly, as the grease would be charred by this.
The grease should be agitated by steam after the required percentage of
acid, calculated on the weight of the grease, has been added. The wash
lye coming off should be 7°-10° B. on a good clean grease or 15°-22° B.
on cotton oil or a poor grease. As has been stated the grease is heated
before the acid is added or the condensation of the steam necessitates
the addition of more acid. After having boiled for 1-2 hours the grease
is allowed to settle for 12 hours and run off through a swivel pipe.

After the grease has been washed, as just explained, and settled, it is
pumped into a covered wooden tank containing an open brass coil. Some of
the second lye from a previous run is usually left in this tank and the
grease pumped into this. The amount of this lye should be about
one-third to one-half the weight of the grease so that there is about 60
per cent. by weight of grease in the tank after 24 hours boiling. Where
occasions arise when there is no second lye about 50 per cent. by weight
of distilled water to the amount of grease is run into the tank to
replace the lye. The saponifier is then added through a glass or granite
ware funnel after the contents of the tank have been brought to a boil.
If the boiling is to be continued 48 hours, 1 per cent. of saponifier is
added. For 24 hours boiling add 1.5 per cent. The boiling is continued
for 24-48 hours allowing 18 inches for boiling room or the grease will
boil over.

After boiling has continued the required length of time the mass is
settled and the glycerine water is drawn off to the treatment tank.
Should a permanent emulsion have formed, due to adding too great an
amount of saponifier, a little sulfuric acid (0.1 per cent.-0.3 per
cent.) will readily break this. During the time this is being done the
space between the grease and the cover on the tank is kept filled with
steam as contact with the air darkens the fatty acids.

To the grease remaining in the tank distilled water (condensed water
from steam coils) to one-half its volume is added and the boiling
continued 12-24 hours. The grease is then settled and the clear grease
run off through a swivel pipe. A layer of emulsion usually forms between
the clear grease and lye so that it may easily be determined when the
grease has all been run off. To prevent discoloration of the fatty acids
it is necessary to neutralize the lye with barium carbonate. The amount
of this to be added depends upon the percentage of saponifier used.
About 1/10 the weight of saponifier is the right amount. The barium
carbonate is added through the funnel at the top of the tank mixed with
a little water and the lye tested until it is neutral to methyl orange
indicator. When the fatty acids are thus treated they will not darken
upon exposure to the air when run off.

Fresh grease is now pumped into the lye or water remaining in the tank
and the process repeated.

The glycerine water or first lye is run to the treatment tank, the fat
skimmed off and neutralized with lime until it shows pink with
phenolphthalein, after having been thoroughly boiled with steam. About
0.25 per cent. lime is the proper amount to add. The mixture is then
allowed to settle and the supernatant mixture drawn off and run to the
glycerine evaporator feed tank. The lime which holds considerable
glycerine is filtered and the liquor added to the other. The evaporation
is carried out in two stages. The glycerine water is first evaporated to
about 60 per cent. glycerol, then dropped into a settling tank to settle
out the calcium sulfate. The clear liquor is then evaporated to crude
(about 90 per cent. glycerine) and the sediment filtered and also
evaporated to crude.

As to the amount of saponifier to use on various stocks, this is best
determined by experiment as to how high a percentage gives dark colored
fatty acids. For good stock such as clean tallow, prime cottonseed oil,
corn oil, cocoanut oil and stock of this kind 0.75 per cent. saponifier
is sufficient. For poorer grades of tallow, house grease, poor
cottonseed oil, etc., 1 per cent. saponifier is required and for poorer
grade greases higher percentages. The percentage of fatty acids
developed varies in various stocks, and also varies with the care that
the operation is carried out, but is usually between 85 per cent.-95 per
cent. Due to the water taken up in the saponification process there is a
yield of about 103 pounds of fatty acids and glycerine for 100 pounds of
fat.

The Twitchell reagent has undoubtedly caused a decided advance in the
saponification of fats and oils and has been of great value to the soap
manufacturer, because with a small expenditure it is possible to compete
with the much more expensive equipment necessary for autoclave
saponification. The drawback, however, has been that the reagent
imparted a dark color to the fatty acids obtained, due to decomposition
products forming when the reagent is made, and hence is not suitable for
use in soaps where whiteness of color is desired.

There have recently been two new reagents introduced which act as
catalyzers in splitting fats, just as the Twitchell reagent acts, but
the fatty acids produced by the cleavage are of good color. The
saponification, furthermore, takes place more rapidly. These are the
Pfeilring reagent and Kontact reagent.

The Pfeilring reagent is very similar to the Twitchell reagent, being
made from hydrogenated castor oil and naphthalene by sulfonation with
concentrated sulfuric acid. It is manufactured in Germany and is being
extensively used in that country with good success.

The Kontact or Petroff reagent, discovered by Petroff in Russia, is made
from sulfonated mineral oils. Until very recently it has only been
manufactured in Europe, but now that it has been found possible to
obtain the proper mineral constituent from American petroleum, it is
being manufactured in this country, and it is very probable that it will
replace the Twitchell reagent because of the advantages derived by using
it, as compared to the old Twitchell reagent.

The method and equipment necessary for employing either the Pfeilring or
Kontact reagents is exactly the same as in using the Twitchell process.


AUTOCLAVE SAPONIFICATION.

While the introduction of the Twitchell process to a great extent
replaced the autoclave method of saponification for obtaining fatty
acids for soap making, the autoclave method is also used. This process
consists in heating the previously purified fat or oil in the presence
of lime and water, or water only, for several hours, which causes a
splitting of the glycerides into fatty acids and glycerine. The
advantage of autoclave saponification over the Twitchell process is that
a greater cleavage of the fats and oils results in less time and at a
slightly less expense. The glycerine thus obtained is also purer and of
better color than that obtained by Twitchelling the fats.

An autoclave or digestor consists of a strongly constructed, closed
cylindrical tank, usually made of copper, and is so built as to resist
internal pressure. The digestor is usually 3 to 5 feet in diameter and
from 18 to 25 feet high. It may be set up horizontally or vertically and
is covered with an asbestos jacket to retain the heat. Various inlets
and outlets for the fats, steam, etc., as well as a pressure gauge and
safety valve are also a necessary part of the equipment.


LIME SAPONIFICATION.

The saponification in an autoclave is usually carried out by introducing
the fats into the autoclave with a percentage of lime, magnesia or zinc
oxide, together with water. If the fats contain any great amount of
impurities, it is first necessary to purify them either by a treatment
with weak sulfuric acid, as described under the Twitchell process, or by
boiling them up with brine and settling out the impurities from the hot
fat.

To charge the autoclave a partial vacuum is created therein by
condensation of steam just before running the purified oil in from an
elevated tank. The required quantity of unslaked lime, 2 to 4 per cent.
of the weight of the fat, is run in with the molten fat, together with
30 per cent. to 50 per cent. of water. While 8.7 per cent. lime is
theoretically required, practice has shown that 2 per cent. to 4 per
cent. is sufficient. The digestor, having been charged and adjusted,
steam is turned on and a pressure of 8 to 10 atmospheres maintained
thereon for a period of six to ten hours. Samples of the fat are taken
at various intervals and the percentage of free fatty acids determined.
When the saponification is completed the contents of the autoclave are
removed, usually by blowing out the digestor into a wooden settling
tank, or by first running off the glycerine water and then blowing out
the lime, soap and fatty acids. The mass discharged from the digestor
separates into two layers, the upper consisting of a mixture of lime
soap or "rock" and fatty acids, and the lower layer contains the
glycerine or "sweet" water. The glycerine water is first run off through
a clearing tank or oil separator, if this has not been done directly
from the autoclave, and the mass remaining washed once or twice more
with water to remove any glycerine still retained by the lime soap. The
calculated amount of sulfuric acid to decompose the lime "rock" is then
added, and the mass agitated until the fatty acids contained therein are
entirely set free. Another small wash is then given and the wash water
added to the glycerine water already run off. The glycerine water is
neutralized with lime, filtered and concentrated as in the Twitchell
process.

Due to the difficulties of working the autoclave saponification with
lime, decomposing the large amount of lime soap obtained and dealing
with much gypsum formed thereby which collects as a sediment and
necessitates cleaning the tanks, other substances are used to replace
lime. Magnesia, about 2 per cent. of the weight of the fat, is used and
gives better results than lime. One-half to 1 per cent. of zinc oxide of
the weight of the fat is even better adapted and is now being
extensively employed for this purpose. In using zinc oxide it is
possible to recover the zinc salts and use them over again in the
digestor, which makes the process as cheap to work as with lime, with
far more satisfactory results.


ACID SAPONIFICATION.

While it is possible to saponify fats and oils in an autoclave with the
addition of acid to the fat, unless a specially-constructed digestor is
built, the action of the acid on the metal from which the autoclave is
constructed prohibits its use. The acid saponification is therefore
carried out by another method.

The method of procedure for acid saponification, therefore, is to first
purify the fats with dilute acid as already described. The purified, hot
or warm, dry fat is then run to a specially-built acidifier or a
lead-lined tank and from 4 per cent. to 6 per cent. of concentrated
sulfuric acid added to the fat, depending upon its character, the degree
of saponification required, temperature and time of saponification. A
temperature of 110 degrees C. is maintained and the mass mixed from four
to six hours. The tank is then allowed to settle out the tar formed
during the saponification, and the fatty acids run off to another tank
and boiled up about three times with one-third the amount of water. The
water thus obtained contains the glycerine, and after neutralization is
concentrated.


AQUEOUS SAPONIFICATION.

While lime or a similar substance is ordinarily used to aid in splitting
fats in an autoclave, the old water process is still used. This is a
convenient, though slower and more dangerous method, of producing the
hydrolysis of the glyceride, as well as the simplest in that fatty acids
and glycerine in a water solution are obtained. The method consists in
merely charging the autoclave with fats and adding about 30 per cent. to
40 per cent. of their weight of water, depending on the amount of free
fatty acid and subjecting the charge to a pressure of 150 to 300 pounds,
until the splitting has taken place. This is a much higher pressure than
when lime is used and therefore a very strong autoclave is required.
Since fatty acids and pure glycerine water are obtained no subsequent
treatment of the finished charge is necessary except separating the
glycerine water and giving the fatty acids a wash with water to remove
all the glycerine from them.


SPLITTING FATS WITH FERMENTS.

In discussing the causes of rancidity of oils and fats it was pointed
out that the initial splitting of these is due to enzymes, organized
ferments. In the seeds of the castor oil plant, especially in the
protoplasm of the seed, the enzyme which has the property of causing
hydrolysis of the glycerides is found. The ferment from the seeds of the
castor oil plant is now extracted and used upon a commercial basis for
splitting fats.

The equipment necessary to carry out this method of saponification is a
round, iron, lead-lined tank with a conical bottom, preferably about
twice as long as it is wide. Open and closed steam coils are also
necessary in the tank.

The oils are first heated and run into this tank. The right temperature
to heat these to is about 1 degree to 2 degrees above their
solidification point. For liquid oils 23 degrees C. is the proper heat
as under 20 degrees C. the cleavage takes place slowly. Fats titering 44
degrees C. or above must be brought down in titer by mixing with them
oils of a lower titer as the ferment or enzyme is killed at about 45
degrees C. and thus loses its power of splitting. It is also necessary
to have the fat in the liquid state or the ferment does not act. The
proper temperature must be maintained with dry steam.

It is, of course, necessary to add water, which may be any kind desired,
condensed, water from steam coils, well, city, etc. From 30 per cent. to
40 per cent., on the average 35 per cent. of water is added, as the
amount necessary is regulated so as to not dilute the glycerine water
unnecessarily. To increase the hydrolysis a catalyzer, some neutral
salt, usually manganese sulfate is added in the proportion of 0.15 per
cent. appears to vary directly as the saponification number of the fat
or oil. The approximate percentages of fermentive substance to be added
to various oils and fats follow:

    Cocoanut oil          8   %
    Palm Kernel oil       8   %
    Cottonseed oil        6-7 %
    Linseed oil           4-5 %
    Tallow oil            8-10%

The oil, water, manganese sulfate and ferment having been placed in the
tank in the order named, the mixture is agitated with air for about a
quarter of an hour to form an even emulsion, in which state the mass is
kept by stirring occasionally with air while the saponification is
taking place. A temperature is maintained a degree or two above the
titer point of the fat with closed steam which may be aided by covering
the tank for a period of 24 to 48 hours. The splitting takes place
rapidly at first, then proceeds more slowly. In 24 hours 80 per cent. of
the fats are split and in 48 hours 85 per cent. to 90 per cent.

When the cleavage has reached the desired point the mass is heated to 80
degrees-85 degrees C. with live or indirect steam while stirring with
air. Then 0.1 per cent.-0.15 per cent of concentrated sulfuric acid
diluted with water is added to break the emulsion. When the emulsion is
broken the glycerine water is allowed to settle out and drawn off. The
glycerine water contains 12 per cent. to 25 per cent. glycerine and
contains manganese sulfate, sulfuric acid and albuminous matter. Through
neutralization with lime at boiling temperature and filtration the
impurities can almost all be removed after which the glycerine water may
be fed to the evaporator. Should it be desired to overcome the trouble
due to the gypsum formed in the glycerine, the lime treatment may be
combined with a previous treatment of the glycerine water with barium
hydrate to remove the sulfuric acid, then later oxalic acid to
precipitate the lime.

The fatty acids obtained by splitting with ferments are of very good
color and adaptable for soap making.


KREBITZ PROCESS.

The Krebitz process which has been used to some extent in Europe is
based upon the conversion of the fat or oil into lime soap which is
transformed into the soda soap by the addition of sodium carbonate. To
carry out the process a convenient batch of, say, 10,000 pounds of fat
or oil, is run into a shallow kettle containing 1,200 to 1,400 pounds of
lime previously slaked with 3,700 to 4,500 pounds of water. The mass is
slowly heated with live steam to almost boiling until an emulsion is
obtained. The tank is then covered and allowed to stand about 12 hours.
The lime soap thus formed is dropped from the tank into the hopper of a
mill, finely ground and conveyed to a leeching tank. The glycerine is
washed out and the glycerine water run to a tank for evaporation. The
soap is then further washed and these washings are run to other tanks to
be used over again to wash a fresh batch of soap. About 150,000 pounds
of water will wash the soap made from 10,000 pounds of fat which makes
between 15,000 and 16,000 pounds of soap. The first wash contains
approximately 10 per cent. glycerine and under ordinary circumstances
this only need be evaporated for glycerine recovery.

After extracting the glycerine the soap is slowly introduced into a
boiling solution of sodium carbonate or soda ash and boiled until the
soda has replaced the lime. This is indicated by the disappearance of
the small lumps of lime soap. Caustic soda is then added to saponify the
fat not converted by the lime saponification. The soap is then salted
out and allowed to settle out the calcium carbonate. This drops to the
bottom of the kettle as a heavy sludge entangling about 10 per cent. of
the soap. A portion of this soap may be recovered by agitating the
sludge with heat and water, pumping the soap off the top and filtering
the remaining sludge.

While the soap thus obtained is very good, the percentage of glycerine
recovered is greatly increased and the cost of alkali as carbonate is
less. The disadvantages are many. Large quantities of lime are required;
it is difficult to recover the soap from the lime sludge; the operations
are numerous prior to the soap making proper and rather complicated
apparatus is required.


DISTILLATION OF FATTY ACIDS.

The fatty acids obtained by various methods of saponification may be
further improved by distillation.

In order to carry out this distillation, two methods may be pursued,
first, the continuous method, whereby the fatty acids are continually
distilled for five to six days, and, second, the two phase method,
whereby the distillation continues for 16 to 20 hours, after which the
residue is drawn off, treated with acid, and its distillate added to a
fresh charge of fatty acids. The latter method is by far the best, since
the advantages derived by thus proceeding more than compensate the
necessity of cleaning the still. Better colored fatty acids are
obtained; less unsaponifiable matter is contained therein; there is no
accumulation of impurities; the amount of neutral fat is lessened
because the treatment of the tar with acid causes a cleavage of the
neutral fat and the candle tar or pitch obtained is harder and better
and thus more valuable.

The stills are usually built of copper, which are heated by both direct
fire and superheated steam. Distillation under vacuum is advisable. To
begin the distilling operation, the still is first filled with dry hot
fatty acids to the proper level. Superheated steam is then admitted and
the condenser is first heated to prevent the freezing of the fatty
acids, passing over into same. When the temperature reaches 230 deg. C.
the distillation begins. At the beginning, the fatty acids flow from the
condenser, an intense green color, due to the formation of copper soaps
produced by the action of the fatty acids on the copper still. This
color may easily be removed by treating with dilute acid to decompose
the copper soaps.

In vacuum distillation, the operation is begun without the use of
vacuum. Vacuum is introduced only when the distillation has proceeded
for a time and the introduction of this must be carefully regulated,
else the rapid influence of vacuum will cause the contents of the still
to overflow. When distillation has begun a constant level of fatty acids
is retained therein by opening the feeding valve to same, and the heat
is so regulated as to produce the desired rate of distillation. As soon
as the distillate flows darker and slower, the feeding valve to the
still is shut off and the distillation continued until most of the
contents of the still are distilled off, which is indicated by a rise in
the temperature. Distillation is then discontinued, the still shut down,
and in about an hour the contents are sufficiently cool to be emptied.
The residue is run off into a proper receiving vessel, treated with
dilute acid and used in the distillation of tar.

In the distillation of tar the same method as the above is followed,
only distillation proceeds at a higher temperature. The first portion
and last portion of the distillate from tar are so dark that it is
necessary to add them to a fresh charge of fatty acids. By a well
conducted distillation of tar about 50 per cent. of the fatty acids from
the tar can be used to mix with the distilled fatty acids. The residue
of this operation called stearine pitch or candle tar consists of a
hard, brittle, dark substance. Elastic pitch only results where
distillation has been kept constant for several days without
interrupting the process, and re-distilling the tar. In a good
distillation the distillation loss is 0.5 to 1.5% and loss in pitch
1.5%. Fatty acids which are not acidified deliver about 3% of pitch.
Very impure fats yield even a higher percentage in spite of acidifying.
For a long time it was found impossible to find any use for stearine
pitch, but in recent years a use has been found for same in the
electrical installation of cables.

FOOTNOTES:

[12] Journ. Ind. Eng. Chem. (1909), I, p. 654.




CHAPTER VI

Analytical Methods.


While it is possible to attain a certain amount of efficiency in
determining the worth of the raw material entering into the manufacture
of soap through organoleptic methods, these are by no means accurate. It
is, therefore, necessary to revert to chemical methods to correctly
determine the selection of fats, oil or other substances used in soap
making, as well as standardizing a particular soap manufactured and to
properly regulate the glycerine recovered.

It is not our purpose to cover in detail the numerous analytical
processes which may be employed in the examination of fats and oils,
alkalis, soap and glycerine, as these are fully and accurately covered
in various texts, but rather to give briefly the necessary tests which
ought to be carried out in factories where large amounts of soap are
made. Occasion often arises where it is impossible to employ a chemist,
yet it is possible to have this work done by a competent person or to
have someone instruct himself as just how to carry out the more simple
analyses, which is not a very difficult matter. The various standard
solutions necessary to carrying out the simpler titrations can readily
be purchased from dealers in chemical apparatus and it does not take
extraordinary intelligence for anyone to operate a burette, yet in many
soap plants in this country absolutely no attention is paid to the
examining of raw material, though many thousand pounds are handled
annually, which, if they were more carefully examined would result in
the saving of much more money than it costs to examine them or have
them at least occasionally analyzed.


ANALYSIS OF FATS AND OILS.

In order to arrive at proper results in the analysis of a fat or oil, it
is necessary to have a proper sample. To obtain this a sample of several
of the packages of oil or fat is taken and these mixed or molten
together into a composite sample which is used in making the tests. If
the oil or fat is solid, a tester is used in taking the sample from the
package and if they are liquid, it is a simple matter to draw off a
uniform sample from each package and from these to form a composite
sample.

In purchasing an oil or fat for soap making, the manufacturer is usually
interested in the amount of free fatty acid contained therein, of
moisture, the titer, the percentage of unsaponifiable matter and to
previously determine the color of soap which will be obtained where
color is an object.


DETERMINATION OF FREE FATTY ACIDS.

Since the free fatty acid content of a fat or oil represents a loss of
glycerine, the greater the percentage of free fatty acid, the less
glycerine is contained in the fat or oil, it is advisable to purchase a
fat or oil with the lower free acid, other properties and the price
being the same.

While the mean molecular weight of the mixed free fatty acids varies
with the same and different oils or fats and should be determined for
any particular analysis for accuracy, the free fatty acid is usually
expressed as oleic acid, which has a molecular weight of 282.

To carry out the analysis 5 to 20 grams of the fat are weighed out into
an Erlenmeyer flask and 50 cubic centimeters of carefully neutralized
alcohol are added. In order to neutralize the alcohol add a few drops of
phenolphthalein solution to same and add a weak caustic soda solution
drop by drop until a very faint pink color is obtained upon shaking or
stirring the alcohol thoroughly. The mixture of fat and neutralized
alcohol is then heated to boiling and titrated with tenth normal alkali
solution, using phenolphthalein as an indicator. As only the free fatty
acids are readily soluble in the alcohol and the fat itself only
slightly mixes with it, the flask should be well agitated toward the end
of the titration. When a faint pink color remains after thoroughly
agitating the flask the end point is reached. In order to calculate the
percentage of free fatty acid as oleic acid, multiply the number of
cubic centimeters of tenth normal alkali used as read on the burette by
0.0282 and divide by the number of grams of fat taken for the
determination and multiply by 100.

When dark colored oils or fats are being titrated it is often difficult
to obtain a good end point with phenolphthalein. In such cases about 2
cubic centimeters of a 2 per cent. alcoholic solution of Alkali Blue 6 B
is recommended.

Another method of directly determining the free fatty acid content of
tallow or grease upon which this determination is most often made is to
weigh out into an Erlenmeyer flask exactly 5.645 grams of a sample of
tallow or grease. Add about 75 cubic centimeters of neutralized alcohol.
Heat until it boils, then titrate with tenth normal alkali and divide
the reading by 2, which gives the percentage of free fatty acid as
oleic. If a fifth normal caustic solution is used, the reading on the
burette gives the percentage of free fatty acid directly. This method,
while it eliminates the necessity of calculation, is troublesome in that
it is difficult to obtain the exact weight of fat.


MOISTURE.

To calculate the amount of moisture contained in a fat or oil 5 to 10
grams are weighed into a flat bottom dish, together with a known amount
of clean, dry sand, if it is so desired. The dish is then heated over a
water bath, or at a temperature of 100-110 degs. C., until it no longer
loses weight upon drying and reweighing the dish. One hour should elapse
between the time the dish is put on the water bath and the time it is
taken off to reweigh. The difference between the weight of the dish is
put on the water bath and the time it is taken off when it reaches a
constant weight is moisture. This difference divided by the original
weight of the fat or oil × 100 gives the percentage of moisture.

When highly unsaturated fats or oils are being analyzed for moisture, an
error may be introduced either by the absorption of oxygen, which is
accelerated at higher temperature, or by the formation of volatile fatty
acids. The former causes an increase in weight, the latter causes a
decrease. To obviate this, the above operation of drying should be
carried out in the presence of some inert gas like hydrogen, carbon
dioxide, or nitrogen.


TITER.

The titer of a fat or oil is really an indication of the amount of
stearic acid contained therein. The titer, expressed in degrees
Centigrade, is the solidification point of the fatty acids of an oil or
fat. In order to carry out the operation a Centigrade thermometer
graduated in one or two-tenths of a degree is necessary. A thermometer
graduated between 10 degs. centigrade to 60 degs. centigrade is best
adapted and the graduations should be clear cut and distinct.

To make the determination about 30 grams of fat are roughly weighed in a
metal dish and 30-40 cubic centimeters of a 30 per cent. (36 degs.
Baumé) solution of sodium hydroxide, together with 30-40 cubic
centimeters of alcohol, denatured alcohol will do, are added and the
mass heated until saponified. Heat over a low flame or over an asbestos
plate until the soap thus formed is dry, constantly stirring the
contents of the dish to prevent burning. The dried soap is then
dissolved in about 1000 cubic centimeters of water, being certain that
all the alcohol has been expelled by boiling the soap solution for about
half an hour. When the soap is in solution add sufficient sulphuric acid
to decompose the soap, approximately 100 cubic centimeters of 25 degs.
Baumé sulphuric acid, and boil until the fatty acids form a clear layer
on top of the liquid. A few pieces of pumice stone put into the mixture
will prevent the bumping caused by boiling. Siphon off the water from
the bottom of the dish and wash the fatty acids with boiling water until
free from sulphuric acid. Collect the fatty acids in a small casserole
or beaker and dry them over a steam bath or drying oven at 110 degs.
Centigrade. When the fatty acids are dry, cool them to about 10 degs.
above the titer expected and transfer them to a titer tube or short test
tube which is firmly supported by a cork in the opening of a salt mouth
bottle. Hang the thermometer by a cord from above the supported tube so
it reaches close to the bottom when in the titer tube containing the
fatty acids and so that it may be used as a stirrer. Stir the mass
rather slowly, closely noting the temperature. The temperature will
gradually fall during the stirring operation and finally remain
stationary for half a minute or so then rise from 0.1 to 0.5 degs. The
highest point to which the mercury rises after having been stationary is
taken as the reading of the titer.


DETERMINATION OF UNSAPONIFIABLE MATTER.

In order to determine the unsaponifiable matter in fats and oils they
are first saponified, then the unsaponifiable, which consists mainly of
hydrocarbons and the higher alcohols cholesterol or phytosterol, is
extracted with ether or petroleum ether, the ether evaporated and the
residue weighed as unsaponifiable.

To carry out the process first saponify about 5 grams of fat or oil with
an excess of alcoholic potassium hydrate, 20-30 cubic centimeters of a 1
to 10 solution of potassium hydroxide in alcohol until the alcohol is
evaporated over a steam bath. Wash the soap thus formed into a
separatory funnel of 200 cubic centimeters capacity with 80-100 cubic
centimeters water. Then add about 60 cubic centimeters of ether,
petroleum ether or 86 degs. gasoline and thoroughly shake the funnel to
extract the unsaponifiable. Should the two layers not separate readily,
add a few cubic centimeters of alcohol, which will readily cause them to
separate. Draw off the watery solution from beneath and wash the ether
with water containing a few drops of sodium hydrate and run to another
dish. Pour the watery solution into the funnel again and repeat the
extraction once or twice more or until the ether shows no discoloration.
Combine the ether extractions into the funnel and wash with water until
no alkaline reaction is obtained from the wash water. Run the ether
extract to a weighed dish, evaporate and dry rapidly in a drying oven.
As some of the hydrocarbons are readily volatile at 100 degs.
Centigrade, the drying should not be carried on any longer than
necessary. The residue is then weighed and the original weight of fat
taken divided into the weight of the residue × 100 gives the percentage
unsaponifiable.


TEST FOR COLOR OF SOAP.

It is often desirable to determine the color of the finished soap by a
rapid determination before it is made into soap. It often happens,
especially with the tallows, that a dark colored sample produces a light
colored soap, whereas a bleached light colored tallow produces a soap
off shade.

To rapidly determine whether the color easily washes out of the tallow
with lye, 100 cubic centimeters of tallow are saponified in an enameled
or iron dish with 100 cubic centimeters of 21 degs. Baumé soda lye and
100 cubic centimeters of denatured alcohol. Continue heating over a wire
gauze until all the alcohol is expelled and then add 50 cubic
centimeters of the 21 degs. Baumé lye to grain the soap. Allow the lyes
to settle and with an inverted pipette draw off the lyes into a test
tube or bottle. Close the soap with 100 cubic centimeters of hot water
and when closed again grain with 50 cubic centimeters of the lye by just
bringing to a boil over an open flame. Again allow the lyes to settle
and put aside a sample of the lye for comparison. Repeat the process of
closing, graining and settling and take a sample of lye. If the lye is
still discolored repeat the above operations again or until the lye is
colorless. Ordinarily all the color will come out with the third lye.
The soap thus obtained contains considerable water which makes it appear
white. The soap is, therefore, dried to about 15 per cent. moisture and
examined for color. The color thus obtained is a very good criterion as
to what may be expected in the soap kettle.

By making the above analyses of fats or oils the main properties as to
their adaptability for being made into soap are determined. In some
cases, especially where adulteration or mixtures of oils are suspected,
it is necessary to further analyze same. The methods of carrying out
these analyses are fully covered by various texts on fats and oils and
we will not go into details regarding the method of procedure in
carrying these out.


TESTING OF ALKALIS USED IN SOAP MAKING.

The alkalis entering into the manufacture of soap such as caustic soda
or sodium hydroxide, caustic potash or potassium hydrate, carbonate of
soda or sodium carbonate, carbonate of potash or potassium carbonate
usually contain impurities which do not enter into combination with the
fats or fatty acids to form soap. It is out of the question to use
chemically pure alkalis in soap making, hence it is often necessary to
determine the alkalinity of an alkali. It may again be pointed out that
in saponifying a neutral fat or oil only caustic soda or potash are
efficient and the carbonate contained in these only combines to a more
or less extent with any free fatty acids contained in the oils or fats.
Caustic soda or potash or lyes made from these alkalis upon exposure to
the air are gradually converted into sodium or potassium carbonate by
the action of the carbon dioxide contained in the air. While the amount
of carbonate thus formed is not very great and is greatest upon the
surface, all lyes as well as caustic alkalis contain some carbonate.
This carbonate introduces an error in the analysis of caustic alkalis
when accuracy is required and thus in the analysis of caustic soda or
potash it is necessary to remove the carbonate when the true alkalinity
as sodium hydroxide or potassium hydroxide is desired. This may be done
by titration in alcohol which has been neutralized.

In order to determine the alkalinity of any of the above mentioned
alkalis, it is first necessary to obtain a representative sample of the
substance to be analyzed. To do this take small samples from various
portions of the package and combine them into a composite sample.
Caustic potash and soda are hygroscopic and samples should be weighed at
once or kept in a well stoppered bottle. Sodium or potassium carbonate
can be weighed more easily as they do not rapidly absorb moisture from
the air.

To weigh the caustic soda or potash place about five grams on a watch
glass on a balance and weigh as rapidly as possible. Wash into a 500
cubic centimeter volumetric flask and bring to the mark with distilled
water. Pipette off 50 cubic centimeters into a 200 cubic centimeter
beaker, dilute slightly with distilled water, add a few drops of methyl
orange indicator and titrate with normal acid. For the carbonates about
1 gram may be weighed, washed into a 400 cubic centimeter beaker,
diluted with distilled water, methyl orange indicator added and titrated
with normal acid. It is advisable to use methyl orange indicator in
these titrations as phenolphthalein is affected by the carbon dioxide
generated when an acid reacts with a carbonate and does not give the
proper end point, unless the solution is boiled to expel the carbon
dioxide. Litmus may also be used as the indicator, but here again it is
necessary to boil as carbon dioxide also affects this substance. As an
aid to the action of these common indicators the following table may be
helpful:

                    _Color in     _Color in
  _Indicator._         Acid        Alkaline       _Action of
                    Solution._     Solution._        CO_{2}._

Methyl orange       Red             Yellow       Very slightly acid
Phenolphthalein     Colorless       Red          Acid
Litmus              Red             Blue         Acid

It may be further stated that methyl orange at the neutral point is
orange in color.

To calculate the percentage of effective alkali from the above
titrations, it must be first pointed out that in the case of caustic
potash or soda aliquot portions are taken. This is done to reduce the
error necessarily involved by weighing, as the absorption of water is
decided. Thus we had, say, exactly 5 grams which weighed 5.05 grams by
the time it was balanced. This was dissolved in 500 cubic centimeters of
water and 50 cubic centimeters or one tenth of the amount of the
solution was taken, or in each 50 cubic centimeters there were 0.505
grams of the sample. We thus reduced the error of weighing by one tenth
provided other conditions introduce no error. In the case of the
carbonates the weight is taken directly.

One cubic centimeter of a normal acid solution is the equivalent of:

                                           Grams.
    Sodium Carbonate, Na_{2}CO_{3}        0.05305
    Sodium Hydroxide, NaOH                0.04006
    Sodium Oxide, Na_{2}O                 0.02905
    Carbonate K_{2}CO_{3}                 0.06908
    Potassium Hydroxide, KOH              0.05616
    Potassium Oxide, K_{2}O               0.04715

Hence to arrive at the alkalinity we multiply the number of cubic
centimeters, read on the burette, by the factor opposite the terms in
which we desire to express the alkalinity, divide the weight in grams
thus obtained by the original weight taken, and multiply the result by
100, which gives the percentage of alkali in the proper terms. For
example, say, we took the 0.505 grams of caustic potash as explained
above and required 8.7 cubic centimeter normal acid to neutralize the
solution, then

    8.7 × .05616 = .4886 grams KOH in sample

    .4886
    ----- × 100 = 96.73% KOH in sample.
    .505

Caustic potash often contains some caustic soda, and while it is
possible to express the results in terms of KOH, regardless of any
trouble that may be caused by this mixture in soap making, an error is
introduced in the results, not all the alkali being caustic potash. In
such cases it is advisable to consult a book on analysis as the analysis
is far more complicated than those given we will not consider it. The
presence of carbonates, as already stated, also causes an error. To
overcome this the alkali is titrated in absolute alcohol, filtering off
the insoluble carbonate. The soluble portion is caustic hydrate and may
be titrated as such. The carbonate remaining on the filter paper is
dissolved in water and titrated as carbonate.


SOAP ANALYSIS.

To obtain a sample of a cake of soap for analysis is a rather difficult
matter as the moisture content of the outer and inner layer varies
considerably. To overcome this difficulty a borer or sampler may be run
right through the cake of soap, or slices may be cut from various parts
of the cake, or the cake may be cut and run through a meat chopper
several times and mixed. A sufficient amount of a homogeneous sample
obtained by any of these methods is preserved for the entire analysis by
keeping the soap in a securely stoppered bottle.

The more important determinations of soap are moisture, free alkali, or
fatty acid, combined alkali and total fatty matter. Besides these it is
often necessary to determine insoluble matter, glycerine, unsaponifiable
matter, rosin and sugar.


MOISTURE.

The analysis of soap for moisture, at its best, is most unsatisfactory,
for by heating it is impossible to drive off all the water, and on the
other hand volatile oils driven off by heat are a part of the loss
represented as moisture.

The usual method of determining moisture is to weigh 2 to 3 grams of
finely shaved soap on a watch glass and heat in an oven at 105 degrees
C. for 2 to 3 hours. The loss in weight is represented as water,
although it is really impossible to drive off all the water in this way.

To overcome the difficulties just mentioned either the Smith or Fahrion
method may be used. Allen recommends Smith's method which is said to be
truthful to within 0.25 per cent. Fahrion's method, according to the
author, gives reliable results to within 0.5 per cent. Both are more
rapid than the above manipulation. To carry out the method of Smith, 5
to 10 grams of finely ground soap are heated over a sand bath with a
small Bunsen flame beneath it, in a large porcelain crucible. The
heating takes 20 to 30 minutes, or until no further evidence is present
of water being driven off. This may be tested by the fogging of a cold
piece of glass held over the crucible immediately upon removing the
burner. When no fog appears the soap is considered dry. Any lumps of
soap may be broken up by a small glass rod, weighed with the crucible,
and with a roughened end to more easily separate the lumps. Should the
soap burn, this can readily be detected by the odor, which, of course,
renders the analysis useless. The loss in weight is moisture.

By Fahrion's method[13], 2 to 4 grams of soap are weighed in a platinum
crucible and about three times its weight of oleic acid, which has been
heated at 120 degrees C. until all the water is driven off and preserved
from moisture, is added and reweighed. The dish is then cautiously
heated with a small flame until all the water is driven off and all the
soap is dissolved. Care must be exercised not to heat too highly or the
oleic acid will decompose. The moment the water is all driven off a
clear solution is formed, provided no fillers are present in the soap.
The dish is then cooled in a dessicator and reweighed. The loss in
weight of acid plus soap is moisture and is calculated on the weight of
soap taken. This determination takes about fifteen minutes.


FREE ALKALI OR ACID.

(_a_) _Alcoholic Method._

Test a freshly cut surface of the soap with a few drops of an alcoholic
phenolphthalein solution. If it does not turn red it may be assumed free
fat is present; should a red color appear, free alkali is present. In
any case dissolve 2 to 5 grams of soap in 100 cubic centimeters of
neutralized alcohol and heat to boiling until in solution. Filter off
the undissolved portion containing carbonate, etc., and wash with
alcohol. Add phenolphthalein to the filtrate and titrate with N/10 acid
and calculate the per cent. of free alkali as sodium or potassium
hydroxide. Should the filtrate be acid instead of alkaline, titrate with
N/10 alkali and calculate the percentage of free fatty acid as oleic
acid.

The insoluble portion remaining on the filter paper is washed with water
until all the carbonate is dissolved. The washings are then titrated
with N/10 sulfuric acid and expressed as sodium or potassium carbonate.
Should borates or silicates be present it is possible to express in
terms of these. If borax is present the carbon dioxide is boiled off
after neutralizing exactly to methyl orange; cool, add mannite and
phenolphthalein and titrate the boric acid with standard alkali.

(_b_) _Bosshard and Huggenberg Method._[14]

In using the alcoholic method for the determination of the free alkali
or fat in soap there is a possibility of both free fat and free alkali
being present. Upon boiling in an alcoholic solution the fat will be
saponified, thus introducing an error in the analysis. The method of
Bosshard and Huggenberg overcomes this objection. Their method is
briefly as follows:

_Reagents._

1. N/10 hydrochloric acid to standardize N/10 alcoholic sodium
hydroxide.

2. Approximately N/10 alcoholic sodium hydroxide to fix and control the
N/40 stearic acid.

3. N/40 stearic acid. Preparation: About 7.1 grams of stearic acid are
dissolved in one liter of absolute alcohol, the solution filtered, the
strength determined by titration against N/10 NaOH and then protected in
a well stoppered bottle, or better still connected directly to the
burette.

4. A 10 per cent. solution of barium chloride. Preparation: 100 grams of
barium chloride are dissolved in one liter of distilled water and
filtered. The neutrality of the solution should be proven as it must be
neutral.

5. [Greek: alpha] naptholphthalein indicator according to Sorenson.
Preparation: 0.1 gram of [Greek: alpha] naphtholphthalein is dissolved in
150 cubic centimeters of alcohol and 100 cubic centimeters of water.
For every 10 cubic centimeters of liquid use at least 12 drops of
indicator.

6. Phenolphthalein solution 1 gram to 100 cubic centimeter 96 per cent.
alcohol.

7. Solvent, 50 per cent. alcohol neutralized.


MANIPULATION.

First--Determine the strength of the N/10 alcoholic sodium hydroxide in
terms of N/10 hydrochloric acid and calculate the factor, e. g.:

    10 c.c. N/10 alcoholic NaOH = 9.95 N/10 HCl}
    10 c.c. N/10 alcoholic NaOH = 9.96 N/10 HCl} 9.96

The alcoholic N/10 NaOH has a factor of 0.996.

Second--Control the N/40 stearic acid with the above alkali to obtain
its factor, e. g.:

    40 c.c. N/40 alcoholic stearic acid =
                              10.18 c.c. N/10 NaOH }
    40 c.c. N/40 alcoholic stearic acid =          } 10.2
                              10.22 c.c. N/10 NaOH }

    10.2 × F N/10 NaOH (0.996) = Factor N/40 stearic acid

        Therefore Factor N/40 stearic acid = 1.016.

Third--About 5 grams of soap are weighed and dissolved in 100 cubic
centimeters of 50 per cent. neutralized alcohol in a 250 cubic
centimeter Erlenmeyer flask over a water bath and connected with a
reflux condensor. When completely dissolved, which takes but a few
moments, it is cooled by allowing a stream of running water to run over
the outside of the flask.

Fourth--The soap is precipitated with 15 to 20 cubic centimeters of the
10 per cent. barium chloride solution.

Fifth--After the addition of 2 to 5 cubic centimeters of [Greek: alpha]
naphtholphthalein solution the solution is titrated with N/40 alcoholic
stearic acid. [Greek: alpha] naphtholphthalein is red with an excess of
stearic acid. To mark the color changes it is advisable to first run a
few blanks until the eye has become accustomed to the change in the
indicator in the same way. The change from green to red can then be
carefully observed.

Let us presume 5 grams of soap were taken for the analysis and 20 cubic
centimeters of N/40 stearic acid were required for the titration then to
calculate the amount of NaOH since the stearic factor is 1.016.

20 × 1.016 = 20.32 N/40 stearic acid really required.

1 cubic centimeter N/40 stearic acid = 0.02 per cent. NaOH for 5 grams
soap.

[Greek: Delta] 20.32 cubic centimeters N/40 stearic acid = 0.02 × 20.32
per cent. NaOH for 5 grams soap.

Hence the soap contains 0.4064 per cent. NaOH.

It is necessary, however, to make a correction by this method. When the
free alkali amounts to over 0.1 per cent. the correction is + 0.01, and
when the free alkali exceeds 0.4 per cent. the correction is + 0.04,
hence in the above case we multiply 0.004064 by 0.04, add this amount to
0.004064 and multiply by 100 to obtain the true percentage. Should the
alkalinity have been near 0.1 per cent. we would have multiplied by 0.01
and added this.

If carbonate is also present in the soap, another 5 grams of soap is
dissolved in 100 cubic centimeters of 50 per cent. alcohol and the
solution titrated directly after cooling with N/40 stearic acid, using
[Greek: alpha] naphtholphthalein or phenolphthalein as an indicator,
without the addition of barium chloride. From the difference of the two
titrations the alkali present as carbonate is determined.

If the decomposed soap solution is colorless with phenolphthalein, free
fatty acids are present, which may be quickly determined with alcoholic
N/10 sodium hydroxide.


INSOLUBLE MATTER.

The insoluble matter in soap may consist of organic or inorganic
substances. Among the organic substances which are usually present in
soap are oat meal, bran, sawdust, etc., while among the common inorganic
or mineral compounds are pumice, silex, clay, talc, zinc oxide,
infusorial earth, sand or other material used as fillers.

To determine insoluble matter, 5 grams of soap are dissolved in 75 cubic
centimeters of hot water. The solution is filtered through a weighed
gooch crucible or filter paper. The residue remaining on the filter is
washed with hot water until all the soap is removed, is then dried to
constant weight at 105 degrees C. and weighed. From the difference in
weight of the gooch or filter paper and the dried residue remaining
thereon after filtering and drying, the total percentage of insoluble
matter may easily be calculated. By igniting the residue and reweighing
the amount of insoluble mineral matter can be readily determined.


STARCH AND GELATINE.

Should starch or gelatine be present in soap it is necessary to extract
5 grams of the soap with 100 cubic centimeters of 95 per cent.
neutralized alcohol in a Soxhlet extractor until the residue on the
extraction thimble is in a powder form. If necessary the apparatus
should be disconnected and any lumps crushed, as these may contain soap.
The residue remaining on the thimble consists of all substances present
in soap, insoluble in alcohol. This is dried and weighed so that any
percentage of impurities not actually determined can be found by
difference. Starch and gelatine are separated from carbonate, sulfate
and borate by dissolving the latter out through a filter with cold
water. The starch and gelatine thus remaining can be determined by
known methods, starch by the method of direct hydrolysis[15] and
gelatine by Kjeldahling and calculating the corresponding amount of
gelatine from the percentage of nitrogen (17.9%) therein.[16]


TOTAL FATTY AND RESIN ACIDS.

To the filtrate from the insoluble matter add 40 cubic centimeters of
half normal sulfuric acid, all the acid being added at once. Boil, stir
thoroughly for some minutes and keep warm on a water bath until the
fatty acids have collected as a clear layer on the surface. Cool by
placing the beaker in ice and syphon off the acid water through a
filter. Should the fatty acids not readily congeal a weighed amount of
dried bleached bees-wax or stearic acid may be added to the hot mixture.
This fuses with the hot mass and forms a firm cake of fatty acids upon
cooling. Without removing the fatty acids from the beaker, add about 300
cubic centimeters of hot water, cool, syphon off the water through the
same filter used before and wash again. Repeat washing, cooling and
syphoning processes until the wash water is no longer acid. When this
stage is reached, dissolve any fatty acid which may have remained on the
filter with hot 95 per cent. alcohol into the beaker containing the
fatty acids. Evaporate the alcohol and dry the beaker to constant weight
over a water bath. The fatty acids thus obtained represent the combined
fatty acids, uncombined fat and hydrocarbons.


DETERMINATION OF ROSIN.

If resin acids are present, this may be determined by the
Liebermann-Storch reaction. To carry out this test shake 2 cubic
centimeters of the fatty acids with 5 cubic centimeters of acetic
anhydride; warm slightly; cool; draw off the anhydride and add 1:1
sulfuric acid. A violet color, which is not permanent, indicates the
presence of rosin in the soap. The cholesterol in linseed or fish oil,
which of course may be present in the soap, also give this reaction.

Should resin acids be present, these may be separated by the Twitchell
method, which depends upon the difference in the behavior of the fatty
and resin acids when converted into their ethyl esters through the
action of hydrochloric acid. This may be carried out as follows:

Three grams of the dried mixed acids are dissolved in 25 cubic
centimeters of absolute alcohol in a 100 cubic centimeter stoppered
flask; the flask placed in cold water and shaken. To this cooled
solution 25 cubic centimeters of absolute alcohol saturated with dry
hydrochloric acid is added. The flask is shaken occasionally and the
action allowed to continue for twenty minutes, then 10 grams of dry
granular zinc chloride are added, the flask shaken and again allowed to
stand for twenty minutes. The contents of the flask are then poured into
200 cubic centimeters of water in a 500 cubic centimeter beaker and the
flask rinsed out with alcohol. A small strip of zinc is placed in the
beaker and the alcohol evaporated. The beaker is then cooled and
transferred to a separatory funnel, washing out the beaker with 50 cubic
centimeters of gasoline (boiling below 80 degrees C.) and extracting by
shaking the funnel well. Draw off the acid solution after allowing to
separate and wash the gasoline with water until free from hydrochloric
acid. Draw off the gasoline solution and evaporate the gasoline.
Dissolve the residue in neutral alcohol and titrate with standard alkali
using phenolphthalein as an indicator. One cubic centimeter of normal
alkali equals 0.346 grams of rosin. The rosin may be gravimetrically
determined by washing the gasoline extract with water, it not being
necessary to wash absolutely free from acid, then adding 0.5 gram of
potassium hydroxide and 5 cubic centimeters of alcohol in 50 cubic
centimeters of water. Upon shaking the resin acids are rapidly
saponified and extracted by the dilute alkaline solution as rosin soaps,
while the ethyl esters remain in solution in the gasoline. Draw off the
soap solution, wash the gasoline solution again with dilute alkali and
unite the alkaline solutions. Decompose the alkaline soap solution with
an excess of hydrochloric acid and weigh the resin acids liberated as in
the determination of total fatty acids.

According to Lewkowitsch, the results obtained by the volumetric method
which assumes a combining weight of 346 for resin acids, are very likely
to be high. On the other hand those obtained by the gravimetric method
are too low.

Leiste and Stiepel[17] have devised a simpler method for the
determination of rosin. They make use of the fact that the resin acids
as sodium soaps are soluble in acetone and particularly acetone
containing two per cent. water, while the fatty acid soaps are soluble
in this solvent to the extent of only about 2 per cent. First of all it
is necessary to show that the sample to be analyzed contains a mixture
of resin and fatty acids. This may be done by the Liebermann-Storch
reaction already described. Glycerine interferes with the method. Two
grams of fatty acids or 3 grams of soap are weighed in a nickel crucible
and dissolved in 15-20 cubic centimeters of alcohol. The solution is
then neutralized with alcoholic sodium hydroxide, using phenolphthalein
as an indicator. The mass is concentrated by heat over an asbestos plate
until a slight film forms over it. Then about 10 grams of sharp,
granular, ignited sand are stirred in by means of a spatula, the alcohol
further evaporated, the mixture being constantly stirred and then
thoroughly dried in a drying oven. The solvent for the cooled mass is
acetone containing 2 per cent. water. It is obtained from acetone dried
by ignited sodium sulfate and adding 2 per cent. water by volume. One
hundred cubic centimeters of this solvent are sufficient for extracting
the above. The extraction of the rosin soap is conducted by adding 10
cubic centimeters of acetone eight times, rubbing the mass thoroughly
with a spatula and decanting. The decanted portions are combined in a
beaker and the suspended fatty soaps allowed to separate. The mixture is
then filtered into a previously weighed flask and washed several times
with the acetone remaining. The solution of rosin soap should show no
separation of solid matter after having evaporated to half the volume
and allowing to cool. If a separation should occur another filtration
and the slightest possible washing is necessary. To complete the
analysis, the acetone is completely evaporated and the mass dried to
constant weight in a drying oven. The weight found gives the weight of
the rosin soap. In conducting the determination, it is important to dry
the mixture of soap and sand thoroughly. In dealing with potash soaps it
is necessary to separate the fatty acids from these and use them as
acetone dissolves too great a quantity of a potash soap.


TOTAL ALKALI.

In the filtrate remaining after having washed the fatty acids in the
determination of total fatty and resin acids all the alkali present as
soap, as carbonate and as hydroxide remains in solution as sulfate. Upon
titrating this solution with half normal alkali the difference between
the half normal acid used in decomposing the soap and alkali used in
titrating the excess of acid gives the amount of total alkali in the
soap. By deducting the amount of free alkali present as carbonate or
hydroxide previously found the amount of combined alkali in the soap may
be calculated.

To quickly determine total alkali in soap a weighed portion of the soap
may be ignited to a white ash and the ash titrated for alkalinity using
methyl orange as an indicator.


UNSAPONIFIED MATTER.

Dissolve 5 grams of soap in 50 cubic centimeters of 50 per cent.
alcohol. Should any free fatty acids be present neutralize them with
standard alkali. Wash into a separatory funnel with 50 per cent. alcohol
and extract with 100 cubic centimeters of gasoline, boiling at 50
degrees to 60 degrees C. Wash the gasoline with water, draw off the
watery layer. Run the gasoline into a weighed dish, evaporate the
alcohol, dry and weigh the residue as unsaponified matter. The residue
contains any hydrocarbon oils or fats not converted into soap.


SILICA AND SILICATES.

The insoluble silicates, sand, etc., are present in the ignited residue
in the determination of insoluble matter. Sodium silicate, extensively
used as a filler, however, will only show itself in forming a pasty
liquid. Where it is desired to determine sodium silicate, 10 grams of
soap are ashed by ignition, hydrochloric acid added to the ash in excess
and evaporated to dryness. More hydrochloric acid is then added and the
mass is again evaporated until dry; then cooled; moistened with
hydrochloric acid; dissolved in water; filtered; washed; the filtrate
evaporated to dryness and again taken up with hydrochloric acid and
water; filtered and washed. The precipitates are then combined and
ignited. Silicon dioxide (SiO_{2}) is thus formed, which can be
calculated to sodium silicate (Na_{2}Si_{4}O_{9}). Should other metals
than alkali metals be suspected present the filtrate from the silica
determinations should be examined.


GLYCERINE IN SOAP.

To determine the amount of glycerine contained in soap dissolve 25 grams
in hot water, add a slight excess of sulfuric acid and keep hot until
the fatty acids form as a clear layer on top. Cool the mass and remove
the fatty acids. Filter the acid solution into a 25 cubic centimeter
graduated flask; bring to the mark with water and determine the
glycerine by the bichromate method as described under glycerine
analysis.

When sugar is present the bichromate would be reduced by the sugar,
hence this method is not applicable. In this case remove the fatty acids
as before, neutralize an aliquot portion with milk of lime, evaporate to
10 cubic centimeters, add 2 grams of sand and milk of lime containing
about 2 grams of calcium hydroxide and evaporate almost to dryness.
Treat the moist residue with 5 cubic centimeters of 96 per cent.
alcohol, rub the whole mass into a paste, then constantly stirring, heat
on a water bath and decant into a 250 cubic centimeter graduated flask.
Repeat the washing with 5 cubic centimeters of alcohol five or six
times, each time pouring the washings into the flask; cool the flask to
room temperature and fill to the mark with 96 per cent. alcohol, agitate
the flask until well mixed and filter through a dry filter paper. Take
200 cubic centimeters of the nitrate and evaporate to a syrupy
consistency over a safety water bath. Wash the liquor into a stoppered
flask with 20 cubic centimeters of absolute alcohol, add 30 cubic
centimeters of absolute ether 10 cubic centimeters at a time, shaking
well after each addition and let stand until clear. Pour off the
solution through a filter into a weighed dish and wash out the flask
with a mixture of three parts absolute ether and two parts absolute
alcohol. Evaporate to a syrup, dry for one hour at the temperature of
boiling water, weigh, ignite and weigh again. The loss is glycerine.
This multiplied by 5/4 gives the total loss for the aliquot portion
taken. The glycerine may also be determined by the acetin or bichromate
methods after driving off the alcohol and ether if so desired.


SUGAR IN SOAP.

To determine sugar in soap, usually present in transparent soaps,
decompose a soap solution of 5 grams of soap dissolved in 100 cubic
centimeters of hot water with an excess of hydrochloric acid and
separate the fatty acids as usual. Filter the acid solution into a
graduated flask and make up to the mark. Take an aliquot containing
approximately 1 per cent. of reducing sugar and determine the amount of
sugar by the Soxhlet method.[18]


GLYCERINE ANALYSIS.

The methods of analyzing glycerine varied so greatly due to the fact
that glycerine contained impurities which acted so much like glycerine
as to introduce serious errors in the determinations of crude glycerine.
This led to the appointment of committees in the United States and
Europe to investigate the methods of glycerine analysis. An
international committee met after their investigations and decided the
acetin method should control the buying and selling of glycerine, but
the more convenient bichromate method in a standardized form might be
used in factory control and other technical purposes. The following are
the methods of analysis and sampling as suggested by the international
committee:


SAMPLING.

The most satisfactory method available for sampling crude glycerine
liable to contain suspended matter, or which is liable to deposit salt
on settling, is to have the glycerine sampled by a mutually approved
sampler as soon as possible after it is filled into drums, but in any
case before any separation of salt has taken place. In such cases he
shall sample with a sectional sampler (see appendix) then seal the
drums, brand them with a number for identification, and keep a record of
the brand number. The presence of any visible salt or other suspended
matter is to be noted by the sampler, and a report of the same made in
his certificate, together with the temperature of the glycerine. Each
drum must be sampled. Glycerine which has deposited salt or other solid
matter cannot be accurately sampled from the drums, but an approximate
sample can be obtained by means of the sectional sampler, which will
allow a complete vertical section of the glycerine to be taken including
any deposit.


ANALYSIS.

1. _Determination of Free Caustic Alkali._--Put 20 grams of the sample
into a 100 cc. flask, dilute with approximately 50 cc. of freshly boiled
distilled water, add an excess of neutral barium chloride solution, 1
cc. of phenolphthalein solution, make up to the mark and mix. Allow the
precipitate to settle, draw off 50 cc. of the clear liquid and titrate
with normal acid (_N_/1). Calculate the percentage of Na_{2}O existing
as caustic alkali.

2. _Determination of Ash and Total Alkalinity._--Weigh 2 to 5 grams of
the sample in a platinum dish, burn off the glycerine over a luminous
Argand burner or other source of heat,[19] giving a low temperature, to
avoid volatilization and the formation of sulphides. When the mass is
charred to the point that water will not be colored by soluble organic
matter, lixiviate with hot distilled water, filter, wash and ignite the
residue in the platinum dish. Return the filtrate and washings to the
dish, evaporate the water, and carefully ignite without fusion. Weigh
the ash.

Dissolve the ash in distilled water and titrate total alkalinity, using
as indicator methyl orange cold or litmus boiling.

3. _Determination of Alkali Present as Carbonate._--Take 10 grams of the
sample, dilute with 50 cc. distilled water, add sufficient _N_/1 acid to
neutralize the total alkali found at (2), boil under a reflux condenser
for 15 to 20 minutes, wash down the condenser tube with distilled water,
free from carbon dioxide, and then titrate back with _N_/1 NaOH, using
phenolphthalein as indicator. Calculate the percentage of Na_{2}O.
Deduct the Na_{2}O found in (1). The difference is the percentage of
Na_{2}O existing as carbonate.

4. _Alkali Combined with Organic Acids._--The sum of the percentages of
Na_{2}O found at (1) and (3) deducted from the percentage found at (2)
is a measure of the Na_{2}O or other alkali combined with organic acids.

5. _Determination of Acidity._--Take 10 grams of the sample, dilute with
50 cc. distilled water free from carbon dioxide, and titrate with _N_/1
NaOH and phenolphthalein. Express in terms of Na_{2}O required to
neutralize 100 grams.

6. _Determination of Total Residue at 160° C._--For this determination
the crude glycerine should be slightly alkaline with Na_{2}CO_{3} not
exceeding 0.2 per cent. Na_{2}O, in order to prevent loss of organic
acids. To avoid the formation of polyglycerols this alkalinity must not
be exceeded.

Ten grams of the sample are put into a 100 cc. flask, diluted with water
and the calculated quantity of _N_/1 HCl or Na_{2}CO_{3} added to give
the required degree of alkalinity. The flask is filled to 100 cc., the
contents mixed, and 10 cc. measured into a weighed Petrie or similar
dish 2.5 in. in diameter and 0.5 in. deep, which should have a flat
bottom. In the case of crude glycerine abnormally high in organic
residue a smaller amount should be taken, so that the weight of the
organic residue does not materially exceed 30 to 40 milligrams.

The dish is placed on a water bath (the top of the 160° oven acts
equally well) until most of the water has evaporated. From this point
the evaporation is effected in the oven. Satisfactory results are
obtained in an oven[20] measuring 12 ins. cube, having an iron plate
0.75 in. thick lying on the bottom to distribute the heat. Strips of
asbestos millboard are placed on a shelf half way up the oven. On these
strips the dish containing the glycerine is placed.

If the temperature of the oven has been adjusted to 160° C. with the
door closed, a temperature of 130° to 140° can be readily maintained
with the door partially open, and the glycerine, or most of it, should
be evaporated off at this temperature. When only a slight vapor is seen
to come off, the dish is removed and allowed to cool.

An addition of 0.5 to 1.0 cc. of water is made, and by a rotary motion
the residue brought wholly or nearly into solution. The dish is then
allowed to remain on a water bath or top of the oven until the excess
water has evaporated and the residue is in such a condition that on
returning to the oven at 160° C. it will not spurt. The time taken up to
this point cannot be given definitely, nor is it important. Usually two
or three hours are required. From this point, however, the schedule of
time must be strictly adhered to. The dish is allowed to remain in the
oven, the temperature of which is carefully maintained at 160° C. for
one hour, when it is removed, cooled, the residue treated with water,
and the water evaporated as before. The residue is then subjected to a
second baking of one hour, after which the dish is allowed to cool in a
desiccator over sulphuric acid and weighed. The treatment with water,
etc., is repeated until a constant loss of 1 to 1.5 mg. per hour is
obtained.

In the case of acid glycerine a correction must be made for the alkali
added 1 cc. _N_/1 alkali represents an addition of 0.03 gram. In the
case of alkaline crudes a correction should be made for the acid added.
Deduct the increase in weight due to the conversion of the NaOH and
Na_{2}CO_{3} to NaCl. The corrected weight multiplied by 100 gives the
percentage of _total residue at 160° C._

This residue is taken for the determination of the non-volatile
acetylizable impurities (see acetin method).

7. _Organic residue._--Subtract the ash from the total residue at 160°
C. Report as organic residue at 160° C. (it should be noted that
alkaline salts of fatty acids are converted to carbonates on ignition
and that the CO_{3} thus derived is not included in the organic
residue).


ACETIN PROCESS FOR THE DETERMINATION OF GLYCEROL.

This process is the one agreed upon at a conference of delegates from
the British, French, German and American committees, and has been
confirmed by each of the above committees as giving results nearer to
the truth than the bichromate method on crudes in general. It is the
process to be used (if applicable) whenever only one method is employed.
On pure glycerines the results are identical with those obtained by the
bichromate process. For the application of this method the crude
glycerine should not contain over 60 per cent. water.


REAGENTS REQUIRED.

(_A_) _Best Acetic Anhydride._--This should be carefully selected. A
good sample must not require more than 0.1 cc. normal NaOH for
saponification of the impurities when a blank is run on 7.5 cc. Only a
slight color should develop during digestion of the blank.

The anhydride may be tested for strength by the following method: Into a
weighed stoppered vessel, containing 10 to 20 cc. of water, run about 2
cc. of the anhydride, replace the stopper and weigh. Let stand with
occasional shaking, for several hours, to permit the hydrolysis of all
the anhydride; then dilute to about 200 cc., add phenolphthalein and
titrate with _N_/1 NaOH. This gives the total acidity due to free acetic
acid and acid formed from the anhydride. It is worthy of note that in
the presence of much free anhydride a compound is formed with
phenolphthalein, soluble in alkali and acetic acid, but insoluble in
neutral solutions. If a turbidity is noticed toward the end of the
neutralization it is an indication that the anhydride is incompletely
hydrolyzed and inasmuch as the indicator is withdrawn from the solution,
results may be incorrect.

Into a stoppered weighing bottle containing a known weight of recently
distilled aniline (from 10 to 20 cc.) measure about 2 cc. of the sample,
stopper, mix, cool and weigh. Wash the contents into about 200 cc. of
cold water, and titrate the acidity as before. This yields the acidity
due to the original, preformed, acetic acid plus one-half the acid due
to anhydride (the other half having formed acetanilide); subtract the
second result from the first (both calculated to 100 grams) and double
the result, obtaining the cc. _N_/1 NaOH per 100 grams of the sample. 1
cc. _N_/NaOH equals 0.0510 anhydride.

(_B_) _Pure Fused Sodium Acetate._--The purchased salt is again
completely fused in a platinum, silica or nickel dish, avoiding
charring, powdered quickly and kept in a stoppered bottle or desiccator.
It is most important that the sodium acetate be anhydrous.

(_C_) _A Solution of Caustic Soda for Neutralizing, of about N_/1
_Strength, Free from Carbonate._--This can be readily made by dissolving
pure sodium hydroxide in its own weight of water (preferably water free
from carbon dioxide) and allowing to settle until clear, or filtering
through an asbestos or paper filter. The clear solution is diluted with
water free from carbon dioxide to the strength required.

(_D_) _N_/1 _Caustic Soda Free from Carbonate._--Prepared as above and
carefully standardized. Some caustic soda solutions show a marked
diminution in strength after being boiled; such solutions should be
rejected.

(_E_) _N_/1 _Acid._--Carefully standardized.

(_F_) _Phenolphthalein Solution._--0.5 per cent. phenolphthalein in
alcohol and neutralized.


THE METHOD.

In a narrow-mouthed flask (preferably round-bottomed), capacity about
120 cc., which has been thoroughly cleaned and dried, weigh accurately
and as rapidly as possible 1.25 to 1.5 grams of the glycerine. A Grethan
or Lunge pipette will be found convenient. Add about 3 grams of the
anhydrous sodium acetate, then 7.5 cc. of the acetic anhydride, and
connect the flask with an upright Liebig condenser. For convenience the
inner tube of this condenser should not be over 50 cm. long and 9 to 10
mm. inside diameter. The flask is connected to the condenser by either a
ground glass joint (preferably) or a rubber stopper. If a rubber stopper
is used it should have had a preliminary treatment with hot acetic
anhydride vapor.

Heat the contents and keep just boiling for one hour, taking precautions
to prevent the salts drying on the sides of the flask.

Allow the flask to cool somewhat, and through the condenser tube add 50
cc. of distilled water free from carbon dioxide at a temperature of
about 80° C., taking care that the flask is not loosened from the
condenser. The object of cooling is to avoid any sudden rush of vapors
from the flask on adding water, and to avoid breaking the flask. Time is
saved by adding the water before the contents of the flask solidify, but
the contents may be allowed to solidify and the test proceeded with the
next day without detriment, bearing in mind that the anhydride in excess
is much more effectively hydrolyzed in hot than in cold water. The
contents of the flask may be warmed to, but must not exceed, 80° C.,
until the solution is complete, except a few dark flocks representing
organic impurities in the crude. By giving the flask a rotary motion,
solution is more quickly effected.

Cool the flask and contents without loosening from the condenser. When
quite cold wash down the inside of the condenser tube, detach the flask,
wash off the stopper or ground glass connection into the flask, and
filter the contents through an acid-washed filter into a Jena glass
flask of about 1 litre capacity. Wash thoroughly with cold distilled
water free from carbon dioxide. Add 2 cc. of phenolphthalein solution
(_F_), then run in caustic soda solution (_C_) or (_D_) until a faint
pinkish yellow color appears throughout the solution. This
neutralization must be done most carefully; the alkali should be run
down the sides of the flask, the contents of which are kept rapidly
swirling with occasional agitation or change of motion until the
solution is nearly neutralized, as indicated by the slower disappearance
of the color developed locally by the alkali running into the mixture.
When this point is reached the sides of the flask are washed down with
carbon dioxide-free water and the alkali subsequently added drop by
drop, mixing after each drop until the desired tint is obtained.

Now run in from a burette 50 cc. or a calculated excess of _N_/1 NaOH
(_D_) and note carefully the exact amount. Boil gently for 15 minutes,
the flask being fitted with a glass tube acting as a partial condenser.
Cool as quickly as possible and titrate the excess of NaOH with _N_/1
acid (_E_) until the pinkish yellow or chosen end-point color just
remains.[21] A further addition of the indicator at this point will
cause an increase of the pink color; this must be neglected, and the
first end-point taken.

From the _N_/1 NaOH consumed calculate the percentage of glycerol
(including acetylizable impurities) after making the correction for the
blank test described below.

1 cc. _N_/1 NaOH = 0.03069 gram glycerol.

The coefficient of expansion for normal solutions is 0.00033 per cc.
for each degree centigrade. A correction should be made on this account
if necessary.

_Blank Test._--As the acetic anhydride and sodium acetate may contain
impurities which affect the result, it is necessary to make a blank
test, using the same quantities of acetic anhydride, sodium acetate and
water as in the analysis. It is not necessary to filter the solution of
the melt in this case, but sufficient time must be allowed for the
hydrolysis of the anhydride before proceeding with the neutralization.
After neutralization it is not necessary to add more than 10 cc. of the
_N_/1 alkali (_D_), as this represents the excess usually present after
the saponification of the average soap lye crude. In determining the
acid equivalent of the _N_/1 NaOH, however, the entire amount taken in
the analysis, 50 cc., should be titrated after dilution with 300 cc.
water free from carbon dioxide and without boiling.

_Determination of the Glycerol Value of the Acetylizable
Impurities._--The total residue at 160° C. is dissolved in 1 or 2 cc. of
water, washed into the acetylizing flask and evaporated to dryness. Then
add anhydrous sodium acetate and acetic anhydride in the usual amounts
and proceed as described in the regular analysis. After correcting for
the blank, calculate the result to glycerol.


WAYS OF CALCULATING ACTUAL GLYCEROL CONTENT.

(1) Determine the apparent percentage of glycerol in the sample by the
acetin process as described. The result will include acetylizable
impurities if any are present.

(2) Determine the total residue at 160° C.

(3) Determine the acetin value of the residue at (2) in terms of
glycerol.

(4) Deduct the result found at (3) from the percentage obtained at (1)
and report this corrected figure as glycerol. If volatile acetylizable
impurities are present these are included in this figure.

Trimethyleneglycol is more volatile than glycerine and can therefore be
concentrated by fractional distillation. An approximation to the
quantity can be obtained from the spread between the acetin and
bichromate results on such distillates. The spread multiplied by 1.736
will give the glycol.


BICHROMATE PROCESS FOR GLYCEROL DETERMINATION. REAGENTS REQUIRED.

(_A_) _Pure potassium bichromate_ powdered and dried in air free from
dust or organic vapors, at 110° to 120° C. This is taken as the
standard.

(_B_) _Dilute Bichromate Solution._--7.4564 grams of the above
bichromate are dissolved in distilled water and the solution made up to
one liter at 15.5° C.

(_C_) _Ferrous Ammonium Sulphate._--It is never safe to assume this salt
to be constant in composition and it must be standardized against the
bichromate as follows: dissolve 3.7282 grams of bichromate (_A_) in 50
cc. of water. Add 50 cc. of 50 per cent. sulphuric acid (by volume), and
to the cold undiluted solution add from a weighing bottle a moderate
excess of the ferrous ammonium sulphate, and titrate back with the
dilute bichromate (_B_). Calculate the value of the ferrous salt in
terms of bichromate.

(_D_) _Silver Carbonate._--This is prepared as required for each test
from 140 cc. of 0.5 per cent. silver sulphate solution by precipitation,
with about 4.9 cc. _N_/1 sodium carbonate solution (a little less than
the calculated quantity of _N_/1 sodium carbonate should be used as an
excess to prevent rapid settling). Settle, decant and wash one by
decantation.

(_E_) _Subacetate of Lead._--Boil a 10 per cent. solution of pure lead
acetate with an excess of litharge for one hour, keeping the volume
constant, and filter while hot. Disregard any precipitate which
subsequently forms. Preserve out of contact with carbon dioxide.

(_F_) _Potassium Ferricyanide._--A very dilute, freshly prepared
solution containing about 0.1 per cent.


THE METHOD.

Weigh 20 grams of the glycerine, dilute to 250 cc. and take 25 cc. Add
the silver carbonate, allow to stand, with occasional agitation, for
about 10 minutes, and add a slight excess (about 5 cc. in most cases) of
the basic lead acetate (_E_), allow to stand a few minutes, dilute with
distilled water to 100 cc., and then add 0.15 cc. to compensate for the
volume of the precipitate, mix thoroughly, filter through an air-dry
filter into a suitable narrow-mouthed vessel, rejecting the first 10
cc., and return the filtrate if not clear and bright. Test a portion of
the filtrate with a little basic lead acetate, which should produce no
further precipitate (in the great majority of cases 5 cc. are ample, but
occasionally a crude will be found requiring more, and in this case
another aliquot of 25 cc. of the dilute glycerine should be taken and
purified with 6 cc. of the basic acetate). Care must be taken to avoid a
marked excess of basic acetate.

Measure off 25 cc. of the clear filtrate into a flask or beaker
(previously cleaned with potassium bichromate and sulphuric acid). Add
12 drops of sulphuric acid (1: 4) to precipitate the small excess of
lead as sulphate. Add 3.7282 grams of the powdered potassium bichromate
(_A_). Rinse down the bichromate with 25 cc. of water and let stand with
occasional shaking until all the bichromate is dissolved (no reduction
will take place in the cold).

Now add 50 cc. of 50 per cent. sulphuric acid (by volume) and immerse
the vessel in boiling water for two hours and keep protected from dust
and organic vapors, such as alcohol, till the titration is completed.
Add from a weighing bottle a slight excess of the ferrous ammonium
sulphate (_C_), making spot tests on a porcelain plate with the
potassium ferricyanide (_F_). Titrate back with the dilute bichromate.
From the amount of bichromate reduced calculate the percentage of
glycerol.

1 gram glycerol = 7.4564 grams bichromate.

1 gram bichromate = 0.13411 gram glycerol.

The percentage of glycerol obtained above includes any oxidizable
impurities present after the purification. A correction for the
non-volatile impurities may be made by running a bichromate test on the
residue at 160° C.


NOTES.

(1) It is important that the concentration of acid in the oxidation
mixture and the time of oxidation should be strictly adhered to.

(2) Before the bichromate is added to the glycerine solution it is
essential that the slight excess of lead be precipitated with sulphuric
acid, as stipulated.

(3) For crudes practically free from chlorides the quantity of silver
carbonate may be reduced to one-fifth and the basic lead acetate to 0.5
cc.

(4) It is sometimes advisable to add a little potassium sulphate to
insure a clear filtrate.


SAMPLING CRUDE GLYCERINE.

The usual method of sampling crude glycerine hitherto has been by means
of a glass tube, which is slowly lowered into the drum with the object
of taking as nearly as possible a vertical section of the glycerine
contained in the drum. This method has been found unsatisfactory, owing
to the fact that in cold climates glycerine runs into the tube very
slowly, so that, owing to the time occupied, it is impossible to take a
complete section of the crude. Another objection to the glass tube is
that it fails to take anything approaching a correct proportion of any
settled salt contained in the drum.

The sampler which is illustrated herewith has been devised with the
object of overcoming the objections to the glass tube as far as
possible. It consists of two brass tubes, one fitting closely inside the
other. A number of ports are cut out in each tube in such a way that
when the ports are opened a continuous slot is formed which enables a
complete section to be taken throughout the entire length of the drum.
By this arrangement the glycerine fills into the sampler almost
instantaneously. There are a number of ports cut at the bottom of the
sampler which render it possible to take a proportion of the salt at the
bottom of the drum. The instrument is so constructed that all the ports,
including the bottom ones, can be closed simultaneously by the simple
action of turning the handle at the top; a pointer is arranged which
indicates on a dial when the sampler is open or closed. In samplers of
larger section (1 in.) it is possible to arrange a third motion whereby
the bottom ports only are open for emptying, but in samplers of smaller
dimensions (5/8 in.) this third motion must be dispensed with, otherwise
the dimensions of the ports have to be so small that the sampler would
not be efficient.

In using the sampler it is introduced into the drum with the ports
closed, and when it has touched the bottom, the ports are opened for a
second or two, then closed and withdrawn, and the sample discharged into
the receiving vessel by opening the ports. When the drum contains salt
which has deposited, the ports must be opened before the sampler is
pushed through the salt, thus enabling a portion to be included in the
sample. It is, however, almost impossible to obtain a correct proportion
of salt after it has settled in the drum and it is therefore recommended
that the drum be sampled before any salt has deposited. A sampler 1 in.
in diameter withdraws approximately 10 oz. from a 110-gal. drum. A
sampler 5/8 in. in diameter will withdraw about 5 oz.

FOOTNOTES:

[13] Zeit. Angew. Chem. 19, 385 (1906).

[14] Zeit. Angew. Chem. 27, 11-20 (1914).

[15] Bull. 107, Bur. Chem. U. S. Dept. Agriculture.

[16] Richards and Gies, Am. J. Physiol. (1902) 7, 129.

[17] Seifensieder Ztg. (1913) No. 46.

[18] Bull 107, Bur. Chem. U. S. Dept. Agriculture.

[19] Carbon is readily burned off completely, without loss of chlorides,
in a gas-heated muffle furnace adjusted to a dull red heat.

[20] An electric oven suitable for this work, which is readily adjusted
to 160 degs. C., has been made for Mr. Low and the chairman, by the
Apparatus and Specialty Company, Lansing, Mich. Its size is 9-1/2 × 10 ×
16 inches, and capacity 8 Petrie dishes. It gives a strong draft at
constant temperature.

[21] A precipitate at this point is an indication of the presence of
iron or alumina, and high results will be obtained unless a correction
is made as described below.




CHAPTER VII

Standard Methods for the Sampling and Analysis of Commercial Fats and
Oils[22]


The following report of the _Committee on Analysis of Commercial Fats
and Oils_ of the _Division of Industrial Chemists and Chemical
Engineers_ of the American Chemical Society was adopted April 14, 1919,
by unanimous vote:

W. D. RICHARDSON, _Chairman_,
Swift and Co., Chicago, Ill.

R. W. BAILEY,
Stillwell and Gladding, New York City.

W. J. GASCOYNE,
W. J. Gascoyne and Co., Baltimore, Md.

I. KATZ,[A]
Wilson and Co., Chicago, Ill.

A. LOWENSTEIN,[A]
Morris and Co., Chicago, Ill.

H. J. MORRISON,
Proctor and Gamble Co.,
Ivorydale, Ohio.

J. R. POWELL,
Armour Soap Works, Chicago, Ill.

R. J. QUINN,[A]
Midland Chemical Co., Argo, Ill.

PAUL RUDNICK,
Armour and Co., Chicago, Ill.

L. M. TOLMAN,
Wilson and Co., Chicago, Ill.

E. TWITCHELL,[A]
Emery Candle Co., Cincinnati, Ohio.

J. J. VOLLERTSEN,
Morris and Co., Chicago, Ill.

[Note A: Resigned.]


Scope, Applicability and Limitations of the Methods.


SCOPE.

These methods are intended to aid in determining the commercial
valuation of fats and fatty oils in their purchase and sale, based on
the fundamental assumption commonly recognized in the trade, namely,
that the product is true to name and is not adulterated. For methods for
determining the identity of oils and fats, the absence of adulterants
therein and for specific tests used in particular industries, the
chemist is referred to standard works on the analysis of fats and oils.


APPLICABILITY.

The methods are applicable in commercial transactions involving fats and
fatty oils used in the soap, candle and tanning industries, to edible
fats and oils and to fats and fatty oils intended for lubricating and
burning purposes. The methods are applicable to the raw oils used in the
varnish and paint industry with the exceptions noted under limitations,
but special methods have not been included.


LIMITATIONS.

The methods have not been developed with special reference to waxes
(beeswax, carnauba wax, wool wax, etc.) although some of them may be
found applicable to these substances. The Committee considers the Wijs
method superior to the Hanus method for the determination of iodine
number of linseed oil as well as other oils, although the Hanus method
has been considered standard for this work for some time and has been
adopted by the American Society for Testing Materials and in various
specifications. It has been customary to use the Hübl method for the
determination of iodine value of tung oil (China wood oil) but the
Committee's work indicates that the Wijs method is satisfactory for this
determination.


Sampling.


TANK CARS.

1. SAMPLING WHILE LOADING--Sample shall be taken at discharge of pipe
where it enters tank car dome. The total sample taken shall be not less
than 50 lbs. and shall be a composite of small samples of about 1 pound
each, taken at regular intervals during the entire period of loading.

The sample thus obtained is thoroughly mixed and uniform 3-lb. portions
placed in air-tight 3-lb. metal containers. At least three such samples
shall be put up, one for the buyer, one for the seller, and the third to
be sent to a referee chemist in case of dispute. All samples are to be
promptly and correctly labeled and sealed.

2. SAMPLING FROM CAR ON TRACK[23]--(_a_) _When contents are solid._[24]
In this case the sample is taken by means of a large tryer measuring
about 2 in. across and about 1-1/2 times the depth of the car in length.
Several tryerfuls are taken vertically and obliquely toward the ends of
the car until 50 lbs. are accumulated, when the sample is softened,
mixed and handled as under (1). In case the contents of the tank car
have assumed a very hard condition, as in Winter weather, so that it is
impossible to insert the tryer, and it becomes necessary to soften the
contents of the car by means of the closed steam coil (in nearly all
tank cars the closed steam coil leaks) or by means of open steam in
order to draw a proper sample, suitable arrangements must be made
between buyer and seller for the sampling of the car after it is
sufficiently softened, due consideration being given to the possible
presence of water in the material in the car as received and also to the
possible addition of water during the steaming. The Committee knows of
no direct method for sampling a hard-frozen tank car of tallow in a
satisfactory manner.

(_b_) _When contents are liquid._ The sample taken is to be a 50-lb.
composite made up of numerous small samples taken from the top, bottom
and intermediate points by means of a bottle or metal container with
removable stopper or top. This device attached to a suitable pole is
lowered to the various desired depths, when the stopper or top is
removed and the container allowed to fill. The 50-lb. sample thus
obtained is handled as under (1).

In place of the device described above, any sampler capable of taking a
sample from the top, bottom, and center, or from a section through car,
may be used.

(_c_) _When contents are in semi-solid condition, or when stearine has
separated from liquid portions._ In this case, a combination of (_a_)
and (_b_) may be used or by agreement of the parties the whole may be
melted and procedure (_b_) followed.


BARRELS, TIERCES, CASKS, DRUMS, AND OTHER PACKAGES.

All packages shall be sampled, unless by special agreement the parties
arrange to sample a lesser number; but in any case not less than 10 per
cent of the total number shall be sampled. The total sample taken shall
be at least 20 lbs. in weight for each 100 barrels, or equivalent.

1. BARRELS, TIERCES AND CASKS--(_a_) _When contents are solid._ The
small samples shall be taken by a tryer through the bunghole or through
a special hole bored in the head or side for the purpose, with a 1-in.
or larger auger. Care should be taken to avoid and eliminate all borings
and chips from the sample. The tryer is inserted in such a way as to
reach the head of the barrel, tierce, or cask. The large sample is
softened, mixed and handled according to TANK CARS (1).

(_b_) _When contents are liquid._ In this case use is made of a glass
tube with constricted lower end. This is inserted slowly and allowed to
fill with the liquid, when the upper end is closed and the tube
withdrawn, the contents being allowed to drain into the sample
container. After the entire sample is taken it is thoroughly mixed and
handled according to TANK CARS (1).

(_c_) _When contents are semi-solid._ In this case the tryer or a glass
tube with larger outlet is used, depending on the degree of fluidity.

(_d_) _Very hard materials, such as natural and artificial stearines._
By preference the barrels are stripped and samples obtained by breaking
up contents of at least 10 per cent of the packages. This procedure is
to be followed also in the case of cakes shipped in sacks. When shipped
in the form of small pieces in sacks they can be sampled by grab
sampling and quartering. In all cases the final procedure is as outlined
under TANK CARS (1).

2. DRUMS--Samples are to be taken as under (1), use being made of the
bunghole. The tryer or tube should be sufficiently long to reach to the
ends of the drum.

3. OTHER PACKAGES--Tubs, pails and other small packages not mentioned
above are to be sampled by tryer or tube (depending on fluidity) as
outlined above, the tryer or tube being inserted diagonally whenever
possible.

4. MIXED LOTS AND PACKAGES--When lots of tallow or other fats are
received in packages of various shapes and sizes, and especially wherein
the fat itself is of variable composition, such must be left to the
judgment of the sampler. If variable, the contents of each package
should be mixed as thoroughly as possible and the amount of the
individual samples taken made proportional to the sizes of the packages.


Analysis.


SAMPLE.

The sample must be representative and at least three pounds in weight
and taken in accordance with the STANDARD METHODS FOR THE SAMPLING OF
COMMERCIAL FATS AND OILS. It must be kept in an air-tight container, in
a dark, cool place.

Soften the sample if necessary by means of a gentle heat, taking care
not to melt it. When sufficiently softened, mix the sample thoroughly by
means of a mechanical egg beater or other equally effective mechanical
mixer.


MOISTURE AND VOLATILE MATTER.

APPARATUS: _Vacuum Oven_--The Committee Standard Oven.

DESCRIPTION--The Standard F. A. C. Vacuum Oven has been designed with
the idea of affording a simple and compact vacuum oven which will give
as uniform temperatures as possible on the shelf. As the figure shows,
it consists of an iron casting of rectangular sections with hinged front
door made tight by means of a gasket and which can be lowered on opening
the oven so as to form a shelf on which samples may be rested. The oven
contains but one shelf which is heated from above as well as below by
means of resistance coils. Several thermometer holes are provided in
order to ascertain definitely the temperature at different points on the
shelf. In a vacuum oven where the heating is done almost entirely by
radiation it is difficult to maintain uniform temperatures at all
points, but the F. A. C. oven accomplishes this rather better than most
vacuum ovens. Larger ovens containing more than one shelf have been
tried by the Committee, but have been found to be lacking in temperature
uniformity and means of control. The entire oven is supported by means
of a 4-in. standard pipe which screws into the base of the oven and
which in turn is supported by being screwed into a blind flange of
suitable diameter which rests on the floor or work table.

_Moisture Dish_--A shallow, glass dish, lipped, beaker form,
approximately 6 to 7 cm. diameter and 4 cm. deep, shall be standard.

DETERMINATION--Weigh out 5 grams (= 0.2 g. of the prepared sample) into
a moisture dish. Dry to constant weight in _vacuo_ at a uniform
temperature, not less than 15° C. nor more than 20° C. above the boiling
point of water at the working pressure, which must not exceed 100 mm. of
mercury.[25] Constant weight is attained when successive dryings for
1-hr. periods show an additional loss of not more that 0.05 per cent.
Report loss in weight as MOISTURE AND VOLATILE MATTER.[26]

[Illustration: STANDARD VACUUM OVEN]

The vacuum-oven method cannot be considered accurate in the case of fats
of the coconut oil group containing free acid and the Committee
recommends that it be used only for oils of this group when they contain
less than 1 per cent free acid. In the case of oils of this group
containing more than 1 per cent free acid, recourse should be had
temporarily to the routine control method for moisture and volatile
matter[27] until the Committee develops a more satisfactory method.

The air-oven method cannot be considered even approximately accurate in
the case of the drying and semi-drying oils and those of the coconut oil
group. Therefore, in the case of such oils as cottonseed oil, maize oil
(corn oil), soy bean oil, linseed oil, coconut oil, palm kernel oil,
etc., the vacuum-oven method should always be used, except in the case
of fats of the coconut group containing more than 1 per cent free acid,
as noted above.


INSOLUBLE IMPURITIES.

Dissolve the residue from the moisture and volatile matter determination
by heating it on a steam bath with 50 cc. of kerosene. Filter the
solution through a Gooch crucible properly prepared with asbestos,[28]
wash the insoluble matter five times with 10-cc. portions of hot
kerosene, and finally wash the residual kerosene out thoroughly with
petroleum ether. Dry the crucible and contents to constant weight, as in
the determination of moisture and volatile matter and report results as
INSOLUBLE IMPURITIES.


SOLUBLE MINERAL MATTER.

Place the combined kerosene filtrate and kerosene washings from the
insoluble impurities determination in a platinum dish. Place in this an
ashless filter paper folded in the form of a cone, apex up. Light the
apex of the cone, whereupon the bulk of the kerosene burns quietly. Ash
the residue in a muffle, to constant weight, taking care that the
decomposition of alkaline earth carbonates is complete, and report the
result as SOLUBLE MINERAL MATTER.[29] When the percentage of soluble
mineral matter amounts to more than 0.1 per cent, multiply the
percentage by 10 and add this amount to the percentage of free fatty
acids as determined.[30]


FREE FATTY ACIDS.

The ALCOHOL[31] used shall be approximately 95 per cent ethyl alcohol,
freshly distilled from sodium hydroxide, which with phenolphthalein
gives a definite and distinct end-point.

DETERMINATION--Weigh 1 to 15 g. of the prepared sample into an
Erlenmeyer flask, using the smaller quantity in the case of
dark-colored, high acid fats. Add 50 to 100 cc. hot, neutral alcohol,
and titrate with _N_/2, _N_/4 or _N_/10 sodium hydroxide depending on
the fatty acid content, using phenolphthalein as indicator. Calculate to
oleic acid, except that in the case of palm oil the results may also be
expressed in terms of palmitic acid, clearly indicating the two methods
of calculation in the report. In the case of coconut and palm kernel
oils, calculate to and report in terms of lauric acid in addition to
oleic acid, clearly indicating the two methods of calculation in the
report. In the case of fats or greases containing more than 0.1 per cent
of soluble mineral matter, add to the percentages of free fatty acids as
determined 10 times the percentage of bases in the soluble mineral
matter as determined.[30] This addition gives the equivalent of fatty
acids combined with the soluble mineral matter.


TITER.

STANDARD THERMOMETER--The thermometer is graduated at zero and in tenth
degrees from 10° C. to 65° C., with one auxiliary reservoir at the upper
end and another between the zero mark and the 10° mark. The cavity in
the capillary tube between the zero mark and the 10° mark is at least 1
cm. below the 10° mark, the 10° mark is about 3 or 4 cm. above the bulb,
the length of the thermometer being about 37 cm. over all. The
thermometer has been annealed for 75 hrs. at 450° C. and the bulb is of
Jena normal 16''' glass, or its equivalent, moderately thin, so that the
thermometer will be quick-acting. The bulb is about 3 cm. long and 6 mm.
in diameter. The stem of the thermometer is 6 mm. in diameter and made
of the best thermometer tubing, with scale etched on the stem, the
graduation is clear-cut and distinct, but quite fine. The thermometer
must be certified by the U. S. Bureau of Standards.

GLYCEROL CAUSTIC SOLUTION--Dissolve 250 g. potassium hydroxide in 1900
cc. dynamite glycerin with the aid of heat.

DETERMINATION--Heat 75 cc. of the glycerol-caustic solution to 150° C.
and add 50 g. of the melted fat. Stir the mixture well and continue
heating until the melt is homogeneous, at no time allowing the
temperature to exceed 150° C. Allow to cool somewhat and carefully add
50 cc. 30 per cent sulfuric acid. Now add hot water and heat until the
fatty acids separate out perfectly clear. Draw off the acid water and
wash the fatty acids with hot water until free from mineral acid, then
filter and heat to 130° C. as rapidly as possible while stirring.
Transfer the fatty acids, when cooled somewhat, to a 1-in. by 4-in.
titer tube, placed in a 16-oz. salt-mouth bottle of clear glass, fitted
with a cork that is perforated so as to hold the tube rigidly when in
position. Suspend the titer thermometer so that it can be used as a
stirrer and stir the fatty acids slowly (about 100 revolutions per
minute) until the mercury remains stationary for 30 seconds. Allow the
thermometer to hang quietly with the bulb in the center of the tube and
report the highest point to which the mercury rises as the titer of the
fatty acids. The titer should be made at about 20° C. for all fats
having a titer above 30° C. and at 10° C. below the titer for all other
fats. Any convenient means may be used for obtaining a temperature of
10° below the titer of the various fats. The committee recommends first
of all a chill room for this purpose; second, an artificially chilled
small chamber with glass window; third, immersion of the salt-mouth
bottle in water or other liquid of the desired temperature.


UNSAPONIFIABLE MATTER.

EXTRACTION CYLINDER--The cylinder shall be glass-stoppered, graduated at
40 cc., 80 cc. and 130 cc., and of the following dimensions: diameter
about 1-3/8 in., height about 12 in.

PETROLEUM ETHER--Redistilled petroleum ether, boiling under 75° C.,
shall be used. A blank must be made by evaporating 250 cc. with about
0.25 g. of stearine or other hard fat (previously brought to constant
weight by heating) and drying as in the actual determination. The blank
must not exceed a few milligrams.

DETERMINATION--Weigh 5 g. (±0.20 g.) of the prepared sample into a
200-cc. Erlenmeyer flask, add 30 cc. of redistilled 95 per cent
(approximately) ethyl alcohol and 5 cc. of 50 per cent aqueous potassium
hydroxide, and boil the mixture for one hour under a reflux condenser.
Transfer to the extraction cylinder and wash to the 40-cc. mark with
redistilled 95 per cent ethyl alcohol. Complete the transfer, first with
warm, then with cold water, till the total volume amounts to 80 cc. Cool
the cylinder and contents to room temperature and add 50 cc. of
petroleum ether. Shake _vigorously_ for one minute and allow to settle
until both layers are clear, when the volume of the upper layer should
be about 40 cc. Draw off the petroleum ether layer as closely as
possible by means of a slender glass siphon into a separatory funnel of
500 cc. capacity. Repeat extraction at least four more times, using 50
cc. of petroleum ether each time. More extractions than five are
necessary where the unsaponifiable matter runs high, say over 5 per
cent, and also in some cases where it is lower than 5 per cent, but is
extracted with difficulty. Wash the combined extracts in a separatory
funnel three times with 25-cc. portions of 10 per cent alcohol, shaking
vigorously each time. Transfer the petroleum ether extract to a
wide-mouth tared flask or beaker, and evaporate the petroleum ether on a
steam bath in an air current. Dry as in the method for MOISTURE AND
VOLATILE MATTER. Any blank must be deducted from the weight before
calculating unsaponifiable matter. Test the final residue for solubility
in 50 cc. petroleum ether at room temperature. Filter and wash free from
the insoluble residue, if any, evaporate and dry in the same manner as
before. The Committee wishes to emphasize the necessity of thorough and
vigorous shaking in order to secure accurate results. The two phases
must be brought into the most intimate contact possible, otherwise low
and disagreeing results may be obtained.


IODINE NUMBER--WIJS METHOD.

PREPARATION OF REAGENTS--_Wijs Iodine Solution_--Dissolve 13.0 g. of
resublimed iodine in one liter of C. P. glacial acetic acid and pass in
washed and dried chlorine gas until the original thiosulfate titration
of the solution is not quite doubled. The solution is then preserved in
amber glass-stoppered bottles, sealed with paraffin until ready for use.

Mark the date on which the solution is prepared on the bottle or
bottles and do not use Wijs solution which is more than 30 days old.

There should be no more than a slight excess of iodine, and no excess of
chlorine. When the solution is made from iodine and chlorine, this point
can be ascertained by not quite doubling the titration.[32]

The glacial acetic acid used for preparation of the Wijs solution should
be of 99.0 to 99.5 per cent strength. In case of glacial acetic acids of
somewhat lower strength, the Committee recommends freezing and
centrifuging or draining as a means of purification.

_N_/10 _Sodium Thiosulfate Solution_--Dissolve 24.8 g. of C. P. sodium
thiosulfate in recently boiled distilled water and dilute with the same
to one liter at the temperature at which the titrations are to be made.

_Starch Paste_--Boil 1 g. of starch in 200 cc. of distilled water for 10
min. and cool to room temperature.

An improved starch solution may be prepared by autoclaving 2 g. of
starch and 6 g. of boric acid dissolved in 200 cc. water at 15 lbs.
pressure for 15 min. This solution has good keeping qualities.

_Potassium Iodide Solution_--Dissolve 150 g. of potassium iodide in
water and make up to one liter.

_N_/10 _Potassium Bichromate_--Dissolve 4.903 g. of C. P. potassium
bichromate in water and make the volume up to one liter at the
temperature at which titrations are to be made.

The Committee calls attention to the fact that occasionally potassium
bichromate is found containing sodium bichromate, although this is of
rare occurrence. If the analyst suspects that he is dealing with an
impure potassium bichromate, the purity can be ascertained by titration
against re-sublimed iodine. However, this is unnecessary in the great
majority of cases.

_Standardization of the Sodium Thiosulfate Solution_--Place 40 cc. of
the potassium bichromate solution, to which has been added 10 cc. of the
solution of potassium iodide, in a glass-stoppered flask. Add to this 5
cc. of strong hydro-chloric acid. Dilute with 100 cc. of water, and
allow the _N_/10 sodium thiosulfate to flow slowly into the flask until
the yellow color of the liquid has almost disappeared. Add a few drops
of the starch paste, and with constant shaking continue to add the
_N_/10 sodium thiosulfate solution until the blue color just disappears.

DETERMINATION--Weigh accurately from 0.10 to 0.50 g. (depending on the
iodine number) of the melted and filtered sample into a clean, dry,
16-oz. glass-stoppered bottle containing 15-20 cc. of carbon
tetrachloride or chloroform. Add 25 cc. of iodine solution from a
pipette, allowing to drain for a definite time. The excess of iodine
should be from 50 per cent to 60 per cent of the amount added, that is,
from 100 per cent to 150 per cent of the amount absorbed. Moisten the
stopper with a 15 per cent potassium iodide solution to prevent loss of
iodine or chlorine but guard against an amount sufficient to run down
inside the bottle. Let the bottle stand in a dark place for 1/2 hr. at
a uniform temperature. At the end of that time add 20 cc. of 15 per cent
potassium iodide solution and 100 cc. of distilled water. Titrate the
iodine with _N_/10 sodium thiosulfate solution which is added gradually,
with constant shaking, until the yellow color of the solution has almost
disappeared. Add a few drops of starch paste and continue titration
until the blue color has entirely disappeared. Toward the end of the
reaction stopper the bottle and shake violently so that any iodine
remaining in solution in the tetrachloride or chloroform may be taken up
by the potassium iodide solution. Conduct two determinations on blanks
which must be run in the same manner as the sample except that no fat is
used in the blanks. Slight variations in temperature quite appreciably
affect the titer of the iodine solution, as acetic acid has a high
coefficient of expansion. It is, therefore, essential that the blanks
and determinations on the sample be made at the same time. The number of
cc. of standard thiosulfate solution required by the blank, less the
amount used in the determination, gives the thiosulfate equivalent of
the iodine absorbed by the amount of sample used in the determination.
Calculate to centigrams of iodine absorbed by 1 g. of sample (= per cent
iodine absorbed).

DETERMINATION, TUNG OIL--Tung oil shows an erratic behavior with most
iodine reagents and this is particularly noticeable in the case of the
Hanus reagent which is entirely unsuitable for determining the iodine
number of this oil since extremely high and irregular results are
obtained. The Hübl solution shows a progressive absorption up to 24 hrs.
and probably for a longer time but the period required is entirely too
long for a chemical determination. The Wijs solution gives good results
if the following precautions are observed:

Weigh out 0.15 ± 0.05 g., use an excess of 55 ± 3 per cent Wijs
solution. Conduct the absorption at a temperature of 20-25° C. for 1 hr.
In other respects follow the instructions detailed above.


SAPONIFICATION NUMBER (KOETTSTORFER NUMBER).

PREPARATION OF REAGENTS. _N/2 Hydrochloric Acid_--Carefully
standardized.

_Alcoholic Potassium Hydroxide Solution_--Dissolve 40 g. of pure
potassium hydroxide in one liter of 95 per cent redistilled alcohol (by
volume). The alcohol should be redistilled from potassium hydroxide over
which it has been standing for some time, or with which it has been
boiled for some time, using a reflux condenser. The solution must be
clear and the potassium hydroxide free from carbonates.

DETERMINATION--Weigh accurate about 5 g. of the filtered sample into a
250 to 300 cc. Erlenmeyer flask. Pipette 50 cc. of the alcoholic
potassium hydroxide solution into the flask, allowing the pipette to
drain for a definite time. Connect the flask with an air condenser and
boil until the fat is completely saponified (about 30 minutes). Cool and
titrate with the _N_/2 hydrochloric acid, using phenolphthalein as an
indicator. Calculate the Koettstorfer number (mg. of potassium hydroxide
required to saponify 1 g. of fat). Conduct 2 or 3 blank determinations,
using the same pipette and draining for the same length of time as
above.


MELTING POINT.

APPARATUS--_Capillary tubes_ made from 5 mm. inside diameter thin-walled
glass tubing drawn out to 1 mm. inside diameter. Length of capillary
part of tubes to be about 5 cm. Length of tube over all 8 cm.

_Standard thermometer_ graduated in tenths of a degree.

_600 cc. beaker._

DETERMINATION--The sample should be clear when melted and entirely free
from moisture, or incorrect results will be obtained.

Melt and thoroughly mix the sample. Dip three of the capillary tubes
above described in the oil so that the fat in the tube stands about 1
cm. in height. Now fuse the capillary end carefully by means of a small
blast flame and allow to cool. These tubes are placed in a refrigerator
over night at a temperature of from 40 to 50° F. They are then fastened
by means of a rubber band or other suitable means to the bulb of a
thermometer graduated in tenths of a degree. The thermometer is
suspended in a beaker of water (which is agitated by air or other
suitable means) so that the bottom of the bulb of the thermometer is
immersed to a depth of about 3 cm. The temperature of the water is
increased gradually at the rate of about 1° per minute.

The point at which the sample becomes opalescent is first noted and the
heating continued until the contents of the tube becomes uniformly
transparent. The latter temperature is reported as the melting point.

Before finally melting to a perfectly clear fluid, the sample becomes
opalescent and usually appears clear at the top, bottom, and sides
before becoming clear at the center. The heating is continued until the
contents of the tube become uniformly clear and transparent. This
temperature is reported as the melting point.[33] It is usually only a
fraction of a degree above the opalescent point noted. The thermometer
should be read to the nearest 1/2° C., and in addition this temperature
may be reported to the nearest degree Fahrenheit if desired.


CLOUD TEST.

PRECAUTIONS--(1) The oil must be perfectly dry, because the presence of
moisture will produce a turbidity before the clouding point is reached.

(2) The oil must be heated to 150° C. over a free flame, immediately
before making the test.

(3) There must not be too much discrepancy between the temperature of
the bath and the clouding point of the oil. An oil that will cloud at
the temperature of hydrant water should be tested in a bath of that
temperature. An oil that will cloud in a mixture of ice and water should
be tested in such a bath. An oil that will not cloud in a bath of ice
and water must be tested in a bath of salt, ice, and water.

DETERMINATION--The oil is heated in a porcelain casserole over a free
flame to 150° C., stirring with the thermometer. As soon as it can be
done with safety, the oil is transferred to a 4 oz. oil bottle, which
must be perfectly dry. One and one-half ounces of the oil are sufficient
for the test. A dry centigrade thermometer is placed in the oil, and the
bottle is then cooled by immersion in a suitable bath. The oil is
constantly stirred with the thermometer, taking care not to remove the
thermometer from the oil at any time during the test, so as to avoid
stirring air bubbles into the oil. The bottle is frequently removed from
the bath for a few moments. The oil must not be allowed to chill on the
sides and bottom of the bottle. This is effected by constant and
vigorous stirring with the thermometer. As soon as the first permanent
cloud shows in the body of the oil, the temperature at which this cloud
occurs is noted.

With care, results concordant to within 1/2° C. can be obtained by this
method. A Fahrenheit thermometer is sometimes used because it has become
customary to report results in degrees Fahrenheit.

The oil must be tested within a short time after heating to 150° C. and
a re-test must always be preceded by reheating to that temperature. The
cloud point should be approached as quickly as possible, yet not so
fast that the oil is frozen on the sides or bottom of the bottle before
the cloud test is reached.


Notes on the Above Methods.


SAMPLING.

The standard size of sample adopted by the committee is at least 3 lbs.
in weight. The committee realizes that this amount is larger than any
samples usually furnished even when representing shipments of from
20,000 to 60,000 lbs. but it believes that the requirement of a larger
sample is desirable and will work toward uniform and more concordant
results in analysis. It will probably continue to be the custom of the
trade to submit smaller buyers' samples than required by the committee,
but these are to be considered only as samples for inspection and not
for analysis. The standard analytical sample must consist of 3 lbs. or
more.

The reasons for keeping samples in a dark, cool place are obvious. This
is to prevent any increase in rancidity and any undue increase in free
fatty acids. In the case of many fats the committee has found in its
co-operative analytical work that free acid tends to increase very
rapidly. This tendency is minimized by low temperatures.


MOISTURE AND VOLATILE MATTER.

After careful consideration the committee has decided that moisture is
best determined in a vacuum oven of the design which accompanies the
above report. Numerous results on check samples have confirmed the
committee's conclusions. The oven recommended by the committee is
constructed on the basis of well-known principles and it is hoped that
this type will be adopted generally by chemists who are called upon to
analyze fats and oils. The experiments of the committee indicate that it
is a most difficult matter to design a vacuum oven which will produce
uniform temperatures throughout; and one of the principal ideas in the
design adopted is uniformity of temperature over the entire single
shelf. This idea has not quite been realized in practice but,
nevertheless, the present design approaches much closer to the ideal
than other vacuum ovens commonly used. In the drawing the essential
dimensions are those between the heating units and the shelf and the
length and breadth of the outer casting. The standard Fat Analysis
Committee Oven (F. A. C. Oven) can be furnished by Messrs. E. H. Sargent
& Company, 125 West Lake street, Chicago.

The committee realizes that for routine work a quicker method is
desirable and has added one such method and has also stated the
conditions under which comparable results can be obtained by means of
the ordinary well-ventilated air oven held at 105 to 110° C. However, in
accordance with a fundamental principle adopted by the committee at its
first meeting, only one standard method is adopted and declared official
for each determination.

The committee realizes that in the case of all methods for determining
moisture by means of loss on heating there may be a loss due to volatile
matter (especially fatty acids) other than water. The title of the
determination MOISTURE AND VOLATILE MATTER indicates this idea, but any
considerable error from this source may occur only in the case of high
acid fats and oils and particularly those containing lower fatty acids
such as coconut and palm kernel oil. In the case of extracted greases
which have not been properly purified, some of the solvent may also be
included in the moisture and volatile matter determination, but inasmuch
as the solvent, usually a petroleum product, can only be considered as
foreign matter, for commercial purposes, it is entirely proper to
include it with the moisture.

The committee has also considered the various distillation methods for
the determination of moisture in fats and oils, but since according to
the fundamental principles which it was endeavoring to follow it could
only standardize one method, it was decided that the most desirable one
on the whole was the vacuum-oven method as given. There are cases
wherein a chemist may find it desirable to check a moisture
determination or investigate the moisture content of a fat or oil
further by means of one of the distillation methods.

However, in co-operative work the distillation method in various types
of apparatus has not yielded satisfactory results. The difficulties
appear to be connected with a proper choice of solvent and particularly
with the tendency of drops of water to adhere to various parts of the
glass apparatus instead of passing on to the measuring device. When
working on coconut oil containing a high percentage of free fatty acids,
concordant results could not be obtained by the various members of the
committee when working with identical samples, solvents and apparatus.

On the other hand, the committee found by individual work, co-operative
work and collaborative work by several members of the committee in one
laboratory, that the old, well-known direct heating method (which the
committee has designated the hot plate method) yielded very satisfactory
results on all sorts of fats and oils including emulsions such as butter
and oleomargarine and even on coconut oil samples containing 15 to 20
per cent free fatty acids and 5 to 6 per cent of moisture.
Unfortunately, this method depends altogether on the operator's skill
and while the method may be taught to any person whether a chemist or
not so that he can obtain excellent results with it, it is difficult to
give a sufficiently, complete description of it so that any chemist
anywhere after reading the description could follow it successfully. The
method is undoubtedly worthy of much confidence in careful hands. It is
quick, accurate and reliable. It is probably the best single method for
the determination of moisture in all sorts of samples for routine
laboratory work. On account of this fact the committee desires to
announce its willingness to instruct any person in the proper use of the
method who desires to become acquainted with it and who will visit any
committee member's laboratory.


INSOLUBLE IMPURITIES.

This determination, the title for which was adopted after careful
consideration, determines the impurities which have generally been known
as dirt, suspended matter, suspended solids, foreign solids, foreign
matter, etc., in the past. The first solvent recommended by the
committee is hot kerosene to be followed by petroleum ether kept at
ordinary room temperature. Petroleum ether, cold or only slightly warm,
is not a good fat and metallic soap solvent, whereas hot kerosene
dissolves these substances readily, and for this reason the committee
has recommended the double solvent method so as to exclude metallic
soaps which are determined below as soluble mineral matter.


SOLUBLE MINERAL MATTER.

Soluble mineral matter represents mineral matter combined with fatty
acids in the form of soaps in solution in the fat or oil. Formerly, this
mineral matter was often determined in combination by weighing the
separated metallic soap or by weighing it in conjunction with the
insoluble impurities. Since the soaps present consist mostly of lime
soap, it has been customary to calculate the lime present therein by
taking 0.1 the weight of the total metallic soaps. The standard method
as given above is direct and involves no calculation. The routine method
given in the note has been placed among the methods for the reason that
it is used in some laboratories, but has not been adopted as a standard
method in view of the fact that the committee has made it a rule to
adopt only one standard method. It should be pointed out, however, that
the method cannot be considered accurate for the reason that insoluble
impurities may vary from sample to sample to a considerable extent and
the error due to the presence of large particles of insoluble impurities
is thus transferred to the soluble mineral matter. The committee has
found one type of grease (naphtha bone grease) which shows most unusual
characteristics. The type sample contains 4.3 per cent soluble mineral
matter by the committee method which would be equivalent to 43.0 per
cent free fatty acid. The kerosene and gasoline filtrate was
particularly clear, nevertheless the ash was found to contain 36.43 per
cent P_{2}O_{5} equivalent to 79.60 per cent of Ca_{3}(PO_{4})_{2} and
9.63 per cent of Fe_{2}O_{3}. The method, therefore, determines the
soluble mineral matter in this case satisfactorily but the factor 10 is
not applicable for calculating the fatty acids combined therewith. It is
necessary, therefore, in order to determine the fatty acids combined
with soluble mineral matter in the original sample to determine the
actual bases in the soluble mineral matter as obtained by ashing the
kerosene and gasoline filtrate. To the bases so determined the factor 10
can then be applied.


FREE FATTY ACID.

The fatty acid method adopted is sufficiently accurate for commercial
purposes. In many routine laboratories the fat or oil is measured and
not weighed, but the committee recommends weighing the sample in all
cases. For scientific purposes the result is often expressed as "acid
number," meaning the number of milligrams of KOH required to neutralize
the free acids in one gram of fat, but the commercial practice has been,
and is, to express the fatty acids as oleic acid or in the case of palm
oil, as palmitic acid, in some instances. The committee sees no
objection to the continuation of this custom so long as the analytical
report clearly indicates how the free acid is expressed. For a more
exact expression of the free acid in a given fat, the committee
recommends that the ratio of acid number to saponification number be
used. This method of expressing results is subject to error when
unsaponifiable fatty matter is present, since the result expresses the
ratio of free fatty acid to total saponifiable fatty matter present.


TITER.

At the present time the prices of glycerol and caustic potash are
abnormally high, but the committee has considered that the methods
adopted are for normal times and normal prices. For routine work during
the period of high prices the following method may be used for preparing
the fatty acids and is recommended by the committee:

Fifty grams of fat are saponified with 60 cc. of a solution of 2 parts
of methyl alcohol to 1 of 50 per cent NaOH. The soap is dried,
pulverized and dissolved in 1000 cc. of water in a porcelain dish and
then decomposed with 25 cc. of 75 per cent sulphuric acid. The fatty
acids are boiled until clear oil is formed and then collected and
settled in a 150-cc. beaker and filtered into a 50-cc. beaker. They are
then heated to 130° C. as rapidly as possible with stirring, and
transferred, after they have cooled somewhat, to the usual 1-in. by
4-in. titer tube.

The method of taking the titer, including handling the thermometer, to
be followed is the same as that described in the standard method. Even
at present high prices many laboratories are using the glycerol-caustic
potash method for preparing the fatty acids, figuring that the saving of
time more than compensates for the extra cost of the reagents. Caustic
soda cannot be substituted for caustic potash in the glycerol method.

UNSAPONIFIABLE MATTER.

The committee has considered unsaponifiable matter to include those
substances frequently found dissolved in fats and oils which are not
saponified by the caustic alkalies and which at the same time are
soluble in the ordinary fat solvents. The term includes such substances
as the higher alcohols, such as cholesterol which is found in animal
fats, phytosterol found in some vegetable fats, paraffin and petroleum
oils, etc. UNSAPONIFIABLE MATTER should not be confused in the lay mind
with INSOLUBLE IMPURITIES OR SOLUBLE MINERAL MATTER.

The method adopted by the committee has been selected only after the
most careful consideration of other methods, such as the dry extraction
method and the wet method making use of the separatory funnel. At first
consideration the dry extraction process would seem to offer the best
basis for an unsaponifiable matter method, but in practice it has been
found absolutely impossible for different analysts to obtain agreeing
results when using any of the dry extraction methods proposed.
Therefore, this method had to be abandoned after numerous trials,
although several members of the committee strongly favored it in the
beginning.

IODINE NUMBER--The iodine number adopted by the committee is that
determined by the well-known Wijs method. This method was adopted after
careful comparison with the Hanus and Hübl methods. The Hübl method was
eliminated from consideration almost at the beginning of the committee's
work for the reason that the time required for complete absorption of
the iodine is unnecessarily long and, in fact, even after absorption has
gone on over night, it is apparently not complete. In the case of the
Hanus and Wijs methods complete absorption takes place in from 15
minutes to an hour, depending on conditions. Formerly, many chemists
thought the Hanus solution rather easier to prepare than the Wijs
solution, but the experience of the committee was that the Wijs solution
was no more difficult to prepare than the Hanus. Furthermore, absorption
of iodine from the Wijs solution appeared to take place with greater
promptness and certainty than from the Hanus and was complete in a
shorter time. Results by the Wijs method were also in better agreement
in the case of oils showing high iodine absorption than with the Hanus
solution and showed a slightly higher iodine absorption for the same
length of time. However, the difference was not great. The committee
investigated the question of substitution since it has been suggested
that in case of the Wijs solution substitution of iodine in the organic
molecule might occur, and found no evidence of this in the time required
for the determination, namely, 1/2 hr., or even for a somewhat longer
period. One member of the committee felt that it was not desirable to
introduce the Wijs method into these standard methods since the Hanus
method was already standardized by the Association of Official
Agricultural Chemists, but the committee felt that it must follow the
principle established at the commencement of its work, namely, that of
adopting the method which appeared to be the best from all standpoints,
taking into consideration accuracy, convenience, simplicity, time,
expense, etc., without allowing precedent to have the deciding vote.

IODINE NUMBER, TUNG OIL--The committee has made an extensive study of
the application of the Wijs method to the determination of iodine value
in the case of tung oil with the result that it recommends the method
for this oil but has thought it desirable to limit the conditions under
which the determination is conducted rather narrowly, although
reasonably good results are obtained by the committee method without
making use of the special limitations.

The co-operative work of the committee and the special investigations
conducted by individual members bring out the following points:

_Influence of Temperature_--From 16° C. to 30° C. there is a moderate
increase in the absorption, but above 30° the increase is rather rapid
so that it was thought best to limit the temperature in the case of tung
oil to 20° to 25° C.

_Influence of Time_--The absorption increases with the time but
apparently complete absorption, so far as unsaturated bonds are
concerned, occurs well within one hour's time. Consequently, one hour
was set as the practical limit.

_Influence of Excess_--The excess of iodine solution also tends to
increase the iodine number, hence the Committee thought it necessary to
limit the excess rather rigidly to 55 ± 3 per cent, although with
greater latitude results were reasonably good.

_Influence of Age of Solution_--Old solutions tend to give low results
although up to 2 mo. no great differences were observed. Nevertheless,
it was thought best to limit the age of the solution to 30 days--long
enough for all practical purposes.

_Amount of Sample_--As a practical amount of sample to be weighed out
the Committee decided on 0.15 g. with a tolerance of 0.05 g. in either
direction according to preference. In other words, the amount of sample
to be taken for the determination to be from 0.1 to 0.2 g. in the
discretion of the analyst.

The Committee's study of the Hübl method which has been adopted by the
Society for Testing Materials in the case of tung oil indicates that
this method when applied to tung oil is subject to the same influences
as the Wijs method and it has the additional very serious disadvantage
of requiring a long period of time for absorption which cannot be
considered reasonable for a modern analytical method. When using the
Hübl solution, the absorption is not complete in the case of tung oil
at 3, 7, 18 or even 24 hrs.

The Hanus method in the case of tung oil gives very high and erratic
results, as high as 180 to 240 in ordinary cases for an oil whose true
iodine number is about 165.


MELTING POINT.

A melting point is the temperature at which a solid substance assumes
the liquid condition. If the solid is a pure substance in the
crystalline condition the melting point is sharp and well defined for
any given pressure. With increased pressure the melting point is lowered
or raised, depending on whether the substance contracts or expands in
melting. The lowering or raising of the melting point with pressure is
very slight and ordinarily is not taken into consideration.
Melting-point determinations are commonly carried out under ordinary
atmospheric pressures without correction. The general effect of soluble
impurities is to lower the melting point, and this holds true whether
the impurity has a higher or lower melting point than the pure substance
(solvent). Thus if a small amount of stearic acid be added to liquid
palmitic acid and the solution frozen, the melting point of this solid
will be lower than that of palmitic acid. Likewise the melting point of
stearic acid is lowered by the addition of a small amount of palmitic
acid. A eutectic mixture results when two components solidify
simultaneously at a definite temperature. Such a mixture has a constant
melting point and because of this and also because both solid and liquid
phases have the same composition, eutectic mixtures were formerly looked
upon as compounds. The phenomenon of double melting points has been
observed in the case of a number of glycerides. Such a glyceride when
placed in the usual capillary tube and subjected to increasing
temperature quickly resolidifies only to melt again and remain melted
at a still higher temperature. This phenomenon has not yet been
sufficiently investigated to afford a satisfactory explanation.

Non-crystalline substances such as glass, sealing wax and various other
waxes and wax mixtures, and most colloidal substances do not exhibit a
sharp melting point, but under the application of heat first soften very
gradually and at a considerably higher temperature melt sufficiently to
flow. This phenomenon of melting through a long range of temperature may
be due to the amorphous nature of the substance or to the fact that it
consists of a very large number of components of many different melting
points.

The fats and oils of natural origin, that is, the animal and vegetable
fats and oils, consist of mixtures of glycerides and, generally
speaking, of a considerable number of such components. These components
are crystalline and when separated in the pure state have definite
melting points, although some exhibit the phenomenon of double melting
point. For the most part the naturally occurring glycerides are mixed
glycerides. In the natural fats and oils there are present also certain
higher alcohols, of which cholesterol is characteristic of the animal
fats and oils and phytosterol of many of the vegetable fats and oils. In
addition to the crystalline glycerides and the higher alcohols present
in neutral fats, there are in fats of lower grade, fatty acids, which
are crystalline, and also various non-crystalline impurities of an
unsaponifiable nature, and the presence of these impurities tends to
lower the melting point. They also tend to induce undercooling and when
the liquid fat or oil is being chilled for purposes of solidification or
in determination of titer.

The presence of water, especially when this is thoroughly mixed or
emulsified with a fat or oil, also influences the melting point to a
marked extent, causing the mixture to melt through a longer range of
temperatures than would be the case if the water were absent. This is
particularly true of emulsified fats and oils, such as butter and
oleomargarine, both of which contain, besides water, the solids
naturally present in milk or cream and including casein, milk sugar, and
salts. The melting-point method recommended by the Committee is not
applicable to such emulsions or other watery mixtures and the Committee
has found it impossible to devise an accurate method for making
softening-point or melting-point determinations on products of this
nature. Not only the amount of water present but also the fineness of
its particles, that is, its state of subdivision and distribution, in a
fat or oil influences the softening point or melting point and causes it
to vary widely in different samples.

As a consequence of the foregoing facts, natural fats and oils do not
exhibit a definite melting point, composed as they are of mixtures of
various crystalline glycerides, higher alcohols, fatty acids, and
non-crystalline substances. Therefore, the term melting point when
applied to them requires further definition. They exhibit first a lower
melting point (the melting point of the lowest melting component) or
what might be called the softening point and following this the fat
softens through a shorter or longer range of temperature to the final
melting point at which temperature the fat is entirely liquid. This is
the melting point determined by the Committee's melting-point method.
The range between the softening point and the final melting point varies
greatly with the different fats and oils depending on their chemical
components, the water associated with them, emulsification, etc. In the
case of coconut oil the range between softening point and final melting
point is rather short; in the case of butter, long. Various methods have
been devised to determine the so-called melting point of fats and oils.
Most of these methods, however, determine, not the melting point, but
the softening point or the flow point of the fat and the great
difficulty has been in the past to devise a method which would determine
even this point with reasonable accuracy and so that results could be
easily duplicated. It has been the aim of the Committee to devise a
simple method for the determination of the melting point of fats and
oils, but it should be understood that the term melting point in the
scientific sense is not applicable to natural fats and oils.

FOOTNOTES:

[22] Approved by the Supervisory Committee on Standard Methods of
Analysis of the American Chemical Society.

[23] Live steam must not be turned into tank cars or coils before
samples are drawn, since there is no certain way of telling when coils
are free from leaks.

[24] If there is water present under the solid material this must be
noted and estimated separately.

[25] Boiling point of water at reduced pressures.

 Pressure    Boiling Point   Boiling Point   Boiling Point
  Mm. Hg.      to 1° C.        +15° C.           +20° C.
   100           52° C.         67° C.            72° C.
    90           50             65                70
    80           47             62                67
    70           45             60                65
    60           42             57                62
    50           38             53                58
    40           34             49                54

[26] Results comparable to those of the Standard Method may be obtained
on most fats and oils by drying 5-g. portions of the sample, prepared
and weighed as above, to constant weight in a well-constructed and
well-ventilated air oven held uniformly at a temperature of 105° to 110°
C. The thermometer bulb should be close to the sample. The definition of
constant weight is the same as for the Standard Method.

[27] The following method is suggested by the Committee for routine
control work: Weigh out 5- to 25-g. portions of prepared sample into a
glass or aluminum (_Caution_: Aluminum soap may be formed) beaker or
casserole and heat on a heavy asbestos board over burner or hot plate,
taking care that the temperature of the sample does not go above 130° C.
at any time. During the heating rotate the vessel gently on the board by
hand to avoid sputtering or too rapid evolution of moisture. The proper
length of time of heating is judged by absence of rising bubbles of
steam, by the absence of foam or by other signs known to the operator.
Avoid overheating of sample as indicated by smoking or darkening. Cool
in desiccator and weigh.

By co-operative work in several laboratories, the Committee has
demonstrated that this method can be used and satisfactory results
obtained on coconut oil even when a considerable percentage of free
fatty acids is present, and the method is recommended for this purpose.
Unfortunately on account of the very great personal factor involved, the
Committee cannot establish this method as a preferred method.
Nevertheless, after an operator has learned the technique of the method,
it gives perfectly satisfactory results for ordinary oils and fats,
butter, oleomargarine and coconut oil, and deserves more recognition
than it has heretofore received.

[28] For routine control work, filter paper is sometimes more convenient
than the prepared Gooch crucible, but must be very carefully washed,
especially around the rim, to remove the last traces of fat.

[29] For routine work, an ash may be run on the original fat, and the
soluble mineral matter obtained by deducting the ash on the insoluble
impurities from this. In this case the Gooch crucible should be prepared
with an ignited asbestos mat so that the impurities may be ashed
directly after being weighed. In all cases ignition should be to
constant weight so as to insure complete decomposition of carbonates.

[30] See note on Soluble Mineral Matter following these methods. When
the ash contains phosphates the factor 10 cannot be applied, but the
bases consisting of calcium oxide, etc., must be determined, and the
factor 10 applied to them.

[31] For routine work methyl or denatured ethyl alcohol of approximately
95 per cent strength may be used. With these reagents the end-point is
not sharp.

[32] P. C. McIlhiney, _J. Am. Chem. Soc._, 29 (1917), 1222, gives the
following details for the preparation of the iodine monochloride
solution:

The preparation of the iodine monochloride solution presents no great
difficulty, but it must be done with care and accuracy in order to
obtain satisfactory results. There must be in the solution no sensible
excess either of iodine or more particularly of chlorine, over that
required to form the monochloride. This condition is most satisfactorily
attained by dissolving in the whole of the acetic acid to be used the
requisite quantity of iodine, using a gentle heat to assist the
solution, if it is found necessary, setting aside a small portion of
this solution, while pure and dry chlorine is passed into the remainder
until the halogen content of the whole solution is doubled. Ordinarily
it will be found that by passing the chlorine into the main part of the
solution until the characteristic color of free iodine has just been
discharged there will be a slight excess of chlorine which is corrected
by the addition of the requisite amount of the unchlorinated portion
until all free chlorine has been destroyed. A slight excess of iodine
does little or no harm, but excess of chlorine must be avoided.

[33] The melting point of oils may be determined in general according to
the above procedure, taking into consideration the lower temperature
required.




PLANT AND MACHINERY

Illustrations of machinery and layouts of the plant of a modern
soap-making establishment.

[Illustration: HOIST, LYE TANK, ETC.]

[Illustration: MELTING-OUT TROUGH]

[Illustration: LAUNDRY SOAP PLANT]

[Illustration: DRYING RACK]

[Illustration: SOAP KETTLE]

[Illustration: REMELTER]

[Illustration: CRUTCHER (Cross Section)]

[Illustration: HORIZONTAL CRUTCHER]

[Illustration: CRUTCHER]

[Illustration: WRAPPING MACHINE (LAUNDRY SOAP)]

[Illustration: SLABBER]

[Illustration: CUTTING TABLE]

[Illustration: AUTOMATIC POWER CUTTING TABLE]

[Illustration: AUTOMATIC PRESS (LAUNDRY)]

[Illustration: CUTTING TABLE (HAND)]

[Illustration: CARTON WRAPPING MACHINE]

[Illustration: DRYING RACKS]

[Illustration: SOAP POWDER BOX]

[Illustration: SCOURING SOAP PRESS]

[Illustration: FRAME]

[Illustration: SOAP POWDER EQUIPMENT]

[Illustration: FLUFFY SOAP POWDER EQUIPMENT]

[Illustration: SOAP POWDER MIXER]

[Illustration: SOAP POWDER MILL]

[Illustration: TOILET SOAP EQUIPMENT]

[Illustration: TOILET SOAP DRYER]

[Illustration: MILLING BOX]

[Illustration: AMALGAMATOR]

[Illustration: TOILET SOAP MILL]

[Illustration: TOILET SOAP MILL]

[Illustration: CHIPPER]

[Illustration: PLODDER]

[Illustration: HORIZONTAL CHIPPER]

[Illustration: AMALGAMATOR (IMPROVED)]

[Illustration: PRESS (LETTERING ON 4 SIDES OF CAKE)]

[Illustration: Press (Foot)]

[Illustration: Press (Foot)]

[Illustration: PLODDER]

[Illustration: AUTOMATIC PRESS (TOILET)]

[Illustration: MULTIPLE CAKE CUTTER]

[Illustration: CAKE CUTTER]

[Illustration: CHIPPER]

[Illustration: GLYCERINE DISTILLING PLANT]

[Illustration: CRUDE GLYCERINE PLANT]

[Illustration: H-A FATTY ACID DISTILLING PLANT]




Appendix

Tables marked * are taken from the German Year Book for Soap Industry.


(U. S. BUREAU OF STANDARDS)

THE METRIC SYSTEM.

The fundamental unit of the metric system is the meter (the unit of
length). From this the units of mass (gram) and capacity (liter) are
derived. All other units are the decimal sub-divisions or multiples of
these. These three units are simply related, so that for all practical
purposes the volume of one kilogram of water (one liter) is equal to one
cubic decimeter.


============================================================
                                        |
Prefixes.       Meaning.                |     Units.
________________________________________|___________________
                                        |
Milli- = one thousandth 1-1000     .001 |
Centi- = one hundredth 1-100       .01  | Meter for length.
Deci- = one tenth 1-10             .1   |
Unit = one                        1.    | Gram for mass.
Deka- = ten 10-1                 10.    |
Hecto- = one hundred 100-1      100.    | Liter for capacity.
Kilo- = one thousand 1000-1    1000.    |
============================================================

The metric terms are formed by combining the words "Meter," "Gram" and
"Liter" with the six numerical prefixes.


LENGTH

10 milli-meters mm = 1 centi-meter                  c m

10 centi-meters    = 1 deci-meter                   d m

10 deci-meters     = 1 meter (about 40 inches)        m

10 meters          = 1 deka-meter                 d k m

10 deka-meters     = 1 hecto-meter                  h m

10 hecto-meters    = 1 kilo-meter (about 5/8 mile)  k m


MASS.

10 milli-grams. m g = 1 centi-gram                   c g
10 centi-grams      = 1 deci-gram                    d g
10 deci-grams       = 1 gram (about 15 grains)         g
10 grams            = 1 deka-gram                  d k g
10 Deka-grams       = 1 hecto-gram                   h g
10 hecto-grams      = 1 kilo-gram (about 2 pounds)   k g


CAPACITY.

10 milli-liters. m l = 1 centi-liter                    c l
10 centi-liters      = 1 deci-liter                     d l
10 deci-liters       = 1 liter (about 1 quart)            l
10 liters            = 1 deka-liter                   d k l
10 deka-liters       = 1 hecto-liter (about a barrel)   h l
10 hecto-liters      = 1 kilo-liter                     k l

The square and cubic units are the squares and cubes of the linear
units.

The ordinary unit of land area is the Hectare (about 2-1/2 acres).


U.S. BUREAU OF STANDARDS TABLE OF METRIC EQUIVALENTS


Meter = 39.37 inches.

Legal Equivalent Adopted by Act of Congress July 28, 1866.


LENGTH.

Centimeter              = 0.3937 inch
Meter                   = 3.28 feet
Meter                   = 1.094 yards
Kilometer               = 0.621 statute mile
Kilometer               = 0.5396 nautical mile
Inch                    = 2.540 centimeters
Foot                    = 0.305 meter
Yard                    = 0.914 meter
Statute mile            = 1.61 kilometers
Nautical mile           = 1.853 kilometers


AREA.

Sq. centimeter          = 0.155 sq. inch
Sq. meter               = 10.76 sq. feet
Sq. meter               = 1.196 sq. yards
Hectare                 = 2.47 acres
Sq. kilometer           = 0.386 sq. mile
Sq. inch                = 6.45 sq. centimeters
Sq. foot                = 0.0929 sq. meter
Sq. yard                = 0.836 sq. meter
Acre                    = 0.405 hectare
Sq. mile                = 2.59 sq. kilometers


WEIGHT.

Gram                    = 15.43 grains
Gram                    =  0.772 U. S. apoth. scruple
Gram                    =  0.2572 U. S. apoth. dram
Gram                    =  0.0353 avoir. ounce
Gram                    =  0.03215 troy ounce
Kilogram                =  2.205 avoir. pounds
Kilogram                =  2.679 troy pounds
Metric ton              =  0.984 gross or long ton
Metric ton              =  1.102 short or net tons
Grain                   =  0.064 gram
U. S. apoth. scruple    =  1.296 grams
U. S. apoth. dram       =  3.89 grams
Avoir. ounce            = 28.35 grams
Troy ounce              = 31.10 grams
Avoir. pound            =  0.4536 kilogram
Troy pound              =  0.373 kilogram
Gross or long ton       =  1.016 metric tons
Short or net ton        =  0.907 metric ton


VOLUME.

Cu. centimeter          =  0.0610 cu. inch
Cu. meter               = 35.3 cu. feet
Cu. meter               =  1.308 cu. yards
Cu. inch                = 16.39 cu. centimeters
Cu. foot                =  0.283 cu. meter
Cu. yard                =  0.765 cu. meter


CAPACITY.

Millimeter             =  0.0338 U. S. liq. ounce
Millimeter             =  0.2705 U. S. apoth. dram
Liter                  =  1.057  U. S. liq. quarts
Liter                  =  0.2642 U. S. liq. gallon
Liter                  =  0.908  U. S. dry quart
Dekaliter              =  1.135  U. S. pecks
Hectoliter             =  2.838  U. S. bushels
U. S. liq. ounce       = 29.57   millimeters
U. S. apoth. dram      =  3.70   millimeters
U. S. liq. quarts      =  0.946  liter
U. S. dry quarts       =  1.101  liters
U. S. liq. gallon      =  3.785  liters
U. S. peck             =  0.881  dekaliter
U. S. bushel           =  0.3524 hectoliter


AVOIRDUPOIS WEIGHT.

1 pound = 16 ounces = 256 drams
           1 ounce  =  16   "


TROY (APOTHECARIES') WEIGHT (U. S.)

1 pound = 12 ounces = 96 drams = 288 scruples = 5,760 grains
          1 ounce  =  8 drams =  24 scruples =   480 grains
                       1 dram =   3 scruples =    60 grains
                                  1 scruple  =    20 grains


WINE (APOTHECARIES) LIQUID MEASURE (U. S.)

1 gallon = 8 pints = 128 fl. ozs. = 1,024 fl. drams = 61,440 minims
           1 pint  =  16 fl. ozs. =   128 fl. drams =  7,689 minims
                       1 fl. oz.  =     8 fl. drams =    480 minims
                                        1 fl. dram  =     60 minims

_To find diameter of a circle_ multiply circumference by .31831.

_To find circumference of a circle_, multiply diameter by 3.1416.

_To find area of a circle_, multiply square of diameter by .7854.

_To find surface of a ball_, multiply square of diameter by 3.1416.

_To find side of an equal square_, multiply diameter by .8862.

_To find cubic inches in a ball_, multiply cube of diameter by .5236.

_Doubling the diameter of a pipe_, increases its capacity four times.

_One cubic foot of anthracite coal_ weighs about 53 lbs.

_One cubic foot of bituminous coal_ weighs from 47 to 50 pounds.

_A gallon of water_ (U. S. standard) weighs 8-1/3 pounds and contains
231 cubic inches.

_A cubic foot of water_ contains 7-1/2 gallons, 1728 cubic inches and
weighs 62-1/2 pounds.

_To find the number of pounds of water a cylindrical_ tank contains,
square the diameter, multiply by .785 and then by the height in feet.
This gives the number of cubic feet which multiplied by 62-1/2 gives the
capacity in pounds of water. Divide by 7-1/2 and this gives the capacity
in gallons.

_A horse-power_ is equivalent to raising 33,000 pounds 1 foot per
minute, or 550 pounds 1 foot per second.

_The friction of water in pipes_ is as the square of velocity. The
capacity of pipes is as the square of their diameters; thus, doubling
the diameter of a pipe increases its capacity four times.

_To find the diameter of a pump cylinder_ to move a given quantity of
water per minute (100 feet of piston being the standard of speed),
divide the number of gallons by 4, then extract the square root, and the
product will be the diameter in inches of the pump cylinder.

_To find the horse-power necessary to elevate water_ to a given height,
multiply the weight of the water elevated per minute in pounds by the
height in feet, and divide the product by 33,000 (an allowance should be
added for water friction, and a further allowance for loss in steam
cylinder, say from 20 to 30 per cent).

_To compute the capacity of pumping engines_, multiply the area of water
piston, in inches, by the distance it travels, in inches, in a given
time. Deduct 3 per cent for slip and rod displacement. The product
divided by 231 gives the number of gallons in time named.

_To find the velocity in feet per minute_ necessary to discharge a given
volume of water in a given time, multiply the number of cubic feet of
water by 144 and divide the product by the area of the pipe in inches.

_To find the area of a required pipe_, the volume and velocity of water
being given, multiply the number of cubic feet of water by 144 and
divide the product by the velocity in feet per minute. The area being
found, the diameter can be learned by using any table giving the "area
of circles" and finding the nearest area, opposite to which will be
found the diameter to correspond.


Physical and Chemical Constants of Fixed Oils and Fats.

(FROM LEWKOWITSCH AND OTHER AUTHORITIES.)

______________________________________________________________________________
                       |            |          |             |               |
                       |  Specific  |Specific  |   Melting-  |Solidifying-   |
                       |  gravity   | gravity  |    point.   |    point.     |
                       |  at 15°C.  | at 100°C.|      C.     |       C.      |
_______________________|____________|__________|_____________|_______________|
                       |            |          |             |               |
Linseed oil            | 0.931-0.938|  0.880   | -16° to -26°|      -16°     |
Hemp-seed oil          | 0.925-0.931|          |             |      -27°     |
Walnut oil             | 0.925-0.926|  0.871   |             |      -27°     |
Poppy-seed oil         | 0.924-0.927|  0.873   |             |      -18°     |
Sunflower oil          | 0.924-0.926|  0.919   |             |      -17°     |
Fir-seed oil           | 0.925-0.928|          |             |  -27° to -30° |
Maize oil              | 0.921-0.926|          |             |  -10° to -15° |
Cotton-seed oil        | 0.922-0.930|  0.867   |             |      12°      |
Sesame oil             | 0.923-0.924|  0.871   |             |      -5°      |
Rape-seed oil          | 0.914-0.917|  0.863   |             |  -2° to -10°  |
Black mustard oil      | 0.916-0.920|          |             |     -17.5°    |
Croton oil             | 0.942-0.955|          |             |      -16°     |
Castor oil             | 0.960-0.966|  0.910   |             |  -12° to -18° |
Apricot-kernel oil     | 0.915-0.919|          |             |      -14°     |
Almond oil |           | 0.915-0.920|          |             |  -10° to -20° |
Peanut (arachis) oil   | 0.916-0.920|  0.867   |             |   -3° to -7°  |
Olive oil              | 0.914-0.917|  0.862   |             |       2°      |
Menhaden oil           | 0.927-0.933|          |             |      -4°      |
Cod-liver oil          | 0.922-0.927|  0.874   |             |   0° to -10°  |
Seal oil               | 0.924-0.929|  0.873   |             |       3°      |
Whale oil              | 0.920-0.930|  0.872   |             |      -2°      |
Dolphin oil            | 0.917-0.918|          |             |   5° to -3°   |
Porpoise oil           |    0.926   |  0.871   |             |      -16°     |
Neat's-foot oil        | 0.914-0.916|  0.861   |             |   0° to 1.5°  |
Cotton-seed stearine   | 0.919-0.923|  0.867   |      40°    |  31° to 32.5° |
Palm oil               | 0.921-0.925|  0.856   |  27° to 42° |               |
Cacao butter           | 0.950-0.952|  0.858   |  30° to 33° |   25° to 26°  |
Cocoa-nut oil          | 0.925-0.926|  0.873   |  20° to 26° |   16° to 20°  |
Myrtle wax             |    0.995   |  0.875   |  40° to 44° |   39° to 43°  |
Japan wax              | 0.970-0.980|  0.875   | 51° to 54.5°|      46°      |
Lard                   | 0.931-0.938|  0.861   |  41° to 46° |      29°      |
Bone fat               | 0.914-0.916|          |  21° to 22° |   15° to 17°  |
Tallow                 | 0.943-0.952|  0.860   |  42° to 46° |   35° to 37°  |
Butter fat             | 0.927-0.936|  0.866   | 29.5° to 33°|   19° to 20°  |
Oleomargarine          | 0.924-0.930|  0.859   |             |               |
Sperm oil              | 0.875-0.884|  0.833   |             |      -25°     |
Bottle-nose oil        | 0.879-0.880|  0.827   |             |               |
Carnauba wax           | 0.990-0.999|  0.842   |  84° to 85° |   80° to 81°  |
Wool-fat               |    0.973   |  0.901   |  39° to 42° |  30° to 30.2° |
Beeswax                | 0.958-0.969|  0.822   |  62° to 64° |  60.5° to 62° |
Spermaceti             |    0.960   |  0.812   | 43.5° to 49°| 43.4° to 44.2°|
Chinese wax            |    0.970   |  0.810   | 80.5° to 81°|  80.5° to 81° |
Tung (Chinese wood oil)| 0.936-0.942|          |             |   below -17°  |
Soya-bean oil          | 0.924-0.927|          |             |    8° to 15°  |
_______________________|____________|__________|_____________|_______________|


Physical and Chemical Constants of Fixed Oils and Fats.

(FROM LEWKOWITSCH AND OTHER AUTHORITIES.)

Column Headings:
A: Saponification value.
B: Maumené test.
C: Iodine value.
D: Hehner value.
E: Reichert value.

______________________________________________________________________________
                   |             |             |            |         |      |
                   |     [A]     |     [B]     |     [C]    |   [D]   | [E]  |
___________________|_____________|_____________|____________|_________|______|
                   |             |             |            |         |      |
Linseed oil        |   190-195   |  104°-111°  |   175-190  |         |      |
Hemp-seed oil      |   190-193   |   95°-96°   |     148    |         |      |
Walnut oil         |     195     |   96°-101°  |   144-147  |         |      |
Poppy-seed oil     |     195     |   86°-88°   |   134-141  |  95.38  |      |
Sunflower oil      |   193-194   |   72°-75°   |   120-129  |    95   |      |
Fir-seed oil       |    191.3    |   98°-99°   | 118.9-120  |         |      |
Maize oil          |   188-193   |  56°-60.5°  |  117-125   | 89-95.7 | 2.5  |
Cotton-seed oil    |   191-195   |   68°-77°   |  104-110   |  96-17  |      |
Sesame oil         |   189-193   |   64°-68°   |  105-109   |  95.8   | 0.35 |
Rape-seed oil      |   170-178   |   51°-60°   |   95-105   |    95   |      |
Black mustard oil  |  174-174.6  |   43°-44°   |   96-110   |  95.05  |      |
Croton oil         | 210.3-215   |             | 101.7-104  |    89   | 13.5 |
Castor oil         |   178-186   |   46°-47°   |  83.4-85.9 |         | 1.4  |
Apricot-kernel oil | 192.2-193.1 |  42.5°-46°  |   100-107  |         |      |
Almond oil         | 190.5-195.4 |   51°-54°   |    93-97   |  96.2   |      |
Peanut (arachis)   |             |             |            |         |      |
  oil              |   190-197   |   45°-49°   |    85-98   |  95.86  |      |
Olive oil          |   191-196   | 41.5°-45.5° |  80.6-84.5 |  95.43  | 0.3  |
Menhaden oil       | 189.3-192   |  123°-128°  |   140-170  |         | 1.2  |
Cod-liver oil      |   182-187   |  102°-103°  |   154-180  |  95.3   |      |
Seal oil           |   190-196   |     92°     |   127-140  |  94.2   | 0.22 |
Whale-oil          |   188-193   |   91°-92°   |   110-136  |  93.5   | 2.04 |
Dolphin  {Body oil |    197.3    |             |    99.5    |  93.07  | 5.6  |
  oil    {Jaw oil  |     200     |             |    32.8    |  66.28  |65.92 |
Porpoise {Body oil |   216-218.8 |     50°     |   119.4    |         |23.45 |
  oil    {Jaw oil  |    253.7    |             |    49.6    |  68.41  |65.8  |
Neat's-foot oil    |    194.3    |  47°-48.5°  |  69.3-70.4 |         |      |
Cotton-seed        |             |             |            |         |      |
  stearine.        | 194.6-195.1 |     48°     |  88.7-92.8 |  96.3   |      |
Palm oil           | 196.3-202   |             |    53-57   |  95.6   | 0.5  |
Cacao butter       | 192.2-193.5 |             |    32-41   |  94.59  | 1.6  |
Cocoa-nut oil      |   250-253   |             |   8.5-9.3  |  88.6   | 3.7  |
Myrtle wax         | 205.7-211.7 |             |     2.9    |         |      |
Japan wax          |   220-222.4 |             |   4.2-8.5  |  90.6   |      |
Lard               | 195.3-196.6 |   27°-32°   |    57-70   |   96    |      |
Bone fat           |    190.9    |             |  46.3-49.6 |         |      |
Tallow             |   195-198   |             |    36-47   |  95.6   | 0.25 |
Butter fat         | 221.5-227   |             |    26-35   |  87.5   |28.78 |
Oleomargarine      |   194-203.7 |             |   55.3-60  |  95-96  | 2.6  |
Sperm oil          | 132.5-147   |   47°-51°   |     84     |         | 1.3  |
Bottle-nose oil    |   126-134   |   41°-47°   |   77.4-82  |         | 1.4  |
Carnauba wax       |    80-84    |             |    13.5    |         |      |
Wool-fat           |  98.2-102.4 |             |    25-28   |         |      |
Beeswax            |    91-96    |             |   8.3-11   |         |      |
Spermaceti         |     128     |             |            |         |      |
Chinese wax        |     63      |             |            |         |      |
Tung (Chinese      |             |             |            |         |      |
  wood oil)        |     193     |             |   150-165  |         |      |
Soya-bean oil      | 190.6-192.9 |   59°-61°   | 121.3-124  |  95.5   |      |
___________________|_____________|_____________|____________|_________|______|


*Temperature Correction Table for Hehner's Concentrated Bichromate
Solution for Glycerine Analysis

__________________________________________
            |                  |
     A      |         f        |
Temperature | Corrected Volume | Logarithm
            |       1 c.c.     |
____________|__________________|__________
            |                  |
   11° C    |    0.9980 ccm    |   99913
   12° "    |    0.9985 "      |   99935
   13° "    |    0.9990 "      |   99956
   14° "    |    0.9995 "      |   99978
   15° "    |    1.0000 "      |   00000
   16° "    |    1.0005 "      |   00022
   17° "    |    1.0010 "      |   00043
   18° "    |    1.0015 "      |   00065
   19° "    |    1.0020 "      |   00087
   20° "    |    1.0025 "      |   00108
   21° "    |    1.0030 "      |   00130
   22° "    |    1.0035 "      |   00152
   23° "    |    1.0040 "      |   00173
____________|__________________|__________


*Table of Important Fatty Acids

_______________________________________________________________________________
           |                   |      |                      |       |
           |                   |      |     Boiling Point    |       |
           |                   |      |______________________|       |Neutral-
           |                   | Mol. |          |           | Melt- |ization
   Name    |      Formula      | Wt.  | Ordinary |  100 mm   |  ing  |value
           |                   |      | Pressure | Pressure  |   Pt. | Mg. KOH
___________|___________________|______|__________|___________|_______|__________
           |                   |      |          |           |       |
Butyric    | C_{4}H_{8}O_{2}   |  88  |  162.3   |           |       |637.5
Caproic    | C_{6}H_{12}O_{2}  | 116  |  199.7   |           |       |483.6
Caprylic   | C_{8}H_{16}O_{2}  | 144  | 236-237  |           | 16.5  |389.6
Capric     | C_{10}H_{20}O_{2} | 172  | 268-270  | 199.5-200 | 31.3  |326.2
Lauric     | C_{12}H_{24}O_{2} | 200  |          |    225    | 43.6  |280.5
Myristic   | C_{14}H_{28}O_{2} | 228  |          |   250.5   | 53.8  |246.1
Palmitic   | C_{16}H_{32}O_{2} | 256  |          |   268.5   |  62   |219.1
Stearic    | C_{18}H_{36}O_{2} | 284  |          |    291    |  69.2 |197.5
Arachidic  | C_{20}H_{40}O_{2} | 302  |          |           |  75   |185.8
Behenic    | C_{22}H_{44}O_{2} | 330  |          |           | 77-78 |170.0
Cerotic    | C_{27}H_{54}O_{2} | 400  |          |           |  78   |140.25
Melissic   | C_{30}H_{60}O_{2} | 442  |          |           |  90   |126.5
Oleic      | C_{18}H_{34}O_{2} | 282  |          | 185.5-286 |  14   |198.9
Erucic     | C_{22}H_{42}O_{2} | 338  |          |           | 33-34 |165.9
Linolic    | C_{18}H_{32}O_{2} | 280  |          |           |       |200.4
Linolenic  | C_{18}H_{30}O_{2} | 278  |          |           |       |201.5
Ricinoleic | C_{18}H_{34}O_{3} | 298  |          |           |       |181.6
___________|___________________|______|__________|___________|_______|__________


*Comparison of Thermometer Scales

n Degree Celsius = 4/5n Degree Reaumur = 32 + 9/5n Degree Fahrenheit

n Degree Reaumur = 5/4n Degree Celsius = 32 + 9/4n Degree Fahrenheit

n Degree Fahrenheit = 5/9 (n - 32) Degree Celsius = 4/9 (n - 32) Deg. R

=============================================================================
 C.   R.     F.     |  C.  R.    F.    | C.  R.    F.     |  C.   R.     F.
--------------------|------------------|------------------|------------------
-20  -16     -4     | 20  16     68    | 60  48    140    | 100   80    212
-19  -15.2   -2.2   | 21  16.8   69.8  | 61  48.8  141.8  | 101   80.8 213.8
-18  -14.4   -0.4   | 22  17.6   71.6  | 62  49.6  143.6  | 102   81.6 215.6
-17  -13.6    1.4   | 23  18.4   73.4  | 63  50.4  145.4  | 103   82.4 217.4
-16  -12.8    3.2   | 24  19.2   75.2  | 64  51.2  147.2  | 104   83.2 219.2|
                    |                  |                  |
-15  -12      5     | 25  20     77    | 65  52    149    | 105   84    221
-14  -11.2    6.8   | 26  20.8   78.8  | 66  52.8  150.8  | 106   84.8 222.8
-13  -10.4    8.6   | 27  21.6   80.6  | 67  53.6  152.6  | 107   85.6 224.6
-12   -9.6   10.4   | 28  22.4   82.4  | 68  54.4  154.4  | 108   86.4 226.4
-11   -8.8   12.2   | 29  23.2   84.2  | 69  55.2  156.2  | 109   87.2 228.2
                    |                  |                  |
-10   -8     14     | 30  24     86    | 70  56    158    | 110   88    230
 -9   -7.2   15.8   | 31  24.8   87.8  | 71  56.8  159.8  | 111   88.8 231.8
 -8   -6.4   17.6   | 32  25.6   89.6  | 72  57.6  161.6  | 112   89.6 233.6
 -7   -5.6   19.4   | 33  26.4   91.4  | 73  58.4  163.4  | 113   90.4 235.4
 -6   -4.8   21.2   | 34  27.2   93.2  | 74  59.2  165.2  | 114   91.2 237.2
                    |                  |                  |
 -5   -4     23     | 35  28     95    | 75  60    167    | 115   92    239
 -4   -3.2   24.8   | 36  28.8   96.8  | 76  60.8  168.8  | 116   92.8 240.8
 -3   -2.4   26.6   | 37  29.6   98.6  | 77  61.6  170.6  | 117   93.6 242.6
 -2   -1.6   28.4   | 38  30.4  100.4  | 78  62.4  172.4  | 118   94.4 244.4
 -1   -0.8   30.2   | 39  31.2  102.2  | 79  63.2  174.2  | 119   95.2 246.2
                    |                  |                  |
  0    0     32     | 40  32    104    | 80  64    176    | 120   96    248
  1    0.8   33.8   | 41  32.8  105.8  | 81  64.8  177.8  | 121   96.8 249.8
  2    1.6   35.6   | 42  33.6  107.6  | 82  65.6  179.6  | 122   97.6 252.6
  3    2.4   37.4   | 43  34.4  109.4  | 83  66.4  181.4  | 123   98.4 253.4
  4    3.2   39.2   | 44  35.2  111.2  | 84  67.2  183.2  | 124   99.2 255.2
                    |                  |                  |
  5    4     41     | 45  36    113    | 85  68    185    | 125  100    257
  6    4.8   42.8   | 46  36.8  114.8  | 86  68.8  186.8  | 126  100.8 258.8
  7    5.6   44.6   | 47  37.6  116.6  | 87  69.6  188.6  | 127  101.6 260.6
  8    6.4   46.4   | 48  38.4  118.4  | 88  70.4  190.4  | 128  102.4 262.4
  9    7.2   48.2   | 49  39.2  120.2  | 89  71.2  192.2  | 129  103.2 264.2
                    |                  |                  |
 10    8     50     | 50  40    122    | 90  72    194    | 130  104    266
 11    8.8   51.8   | 51  40.8  123.8  | 91  72.8  195.8  | 131  104.8 267.8
 12    9.6   53.6   | 52  41.6  125.6  | 92  73.6  197.6  | 132  105.6 269.6
 13   10.4   55.4   | 53  42.4  127.4  | 93  74.4  199.4  | 133  106.4 271.4
 14   11.2   57.2   | 54  43.2  129.2  | 94  75.2  201.2  | 134  107.2 273.2
                    |                  |                  |
 15   12     59     | 55  44    131    | 95  76    203    | 135  108    275
 16   12.8   60.8   | 56  44.8  132.8  | 96  76.8  204.8  | 136  108.8 276.8
 17   13.6   62.6   | 57  45.6  134.6  | 97  77.6  206.6  | 137  109.6 278.6
 18   14.4   64.4   | 58  46.4  136.4  | 98  78.4  208.4  | 138  110.4 280.4
 19   15.2   66.2   | 59  47.2  138.2  | 99  79.2  210.2  | 139  111.2 282.2
===============================================================================


*Quantities of Alkali Required for Saponification of Fats of Average
Molecular Weight 670

(Cocoanut Oil, Palmkernel Oil)

_________________________________________________
      |                     |                   |
      |    Liters Alkali    |   Liters Alkali   |
      |      Solution       |     Solution      |
Kilos |     Sp. Gr. 1.1     |    Sp. Gr. 1.2    |
______|_____________________|___________________|
      |          |          |         |         |
      |   NaOH   |    KOH   |   NaOH  |   KOH   |
______|__________|__________|_________|_________|
      |          |          |         |         |
 1000 |  1875.83 |  1902.99 |  844.67 |  930.35 |
 2000 |  3751.66 |  3805.97 | 1689.35 | 1860.70 |
 3000 |  5627.50 |  5708.96 | 2534.02 | 2791.04 |
 4000 |  7508.33 | 7611.94  | 3378.69 | 3721.39 |
 5000 |  9379.16 |  9514.93 | 4223.37 | 4651.74 |
 6000 | 11254.99 | 11417.91 | 5068.04 | 5582.09 |
 7000 | 13130.82 | 13320.90 | 5912.71 | 6512.44 |
 8000 | 15006.66 | 15223.88 | 6757.38 | 7442.78 |
 9000 | 16882.49 | 17126.87 | 7602.06 | 8373.13 |
10000 | 18758.32 | 19029.85 | 8446.73 | 9303.48 |
______|__________|__________|_________|_________|

______________________________________________
      |                   |
      |   Liters Alkali   |  Liters Alkali
      |     Solution      |    Solution
Kilos |    Sp. Gr. 1.3    |  Sp. Gr. 1.355
______|___________________|___________________
      |         |         |         |
      |   NaOH  |   KOH   |   NaOH  |   KOH
______|_________|_________|_________|_________
      |         |         |         |
 1000 |  510.27 |  622.71 |  409.61 |  517.97
 2000 | 1020.54 | 1245.41 |  819.21 | 1035.95
 3000 | 1530.81 | 1868.12 | 1228.82 | 1553.92
 4000 | 2041.01 | 2490.83 | 1638.43 | 2071.90
 5000 | 2551.35 | 3113.54 | 2048.04 | 2589.87
 6000 | 3061.61 | 3736.24 | 2457.65 | 3107.84
 7000 | 3571.88 | 4358.95 | 2867.26 | 3625.82
 8000 | 4082.15 | 4981.66 | 3276.86 | 4143.79
 9000 | 4592.42 | 5604.36 | 3886.47 | 4661.77
10000 | 5102.69 | 6227.02 | 4096.08 | 5179.74
______|_________|_________|_________|_________


*Quantities of Alkali Required for Saponification of Fats of Average
Molecular Weight 860

(Tallow, Cottonseed Oil, Olive Oil, Etc.)

_________________________________________________
      |                     |                   |
      |    Liters Alkali    |   Liters Alkali   |
      |      Solution       |     Solution      |
Kilos |     Sp. Gr. 1.1     |    Sp. Gr. 1.2    |
______|_____________________|___________________|
      |          |          |         |         |
      |   NaOH   |    KOH   |   NaOH  |   KOH   |
______|__________|__________|_________|_________|
      |          |          |         |         |
 1000 |  1461.40 |  1482.56 |  658.05 |  724.81 |
 2000 |  2922.81 |  2965.12 | 1316.12 | 1449.61 |
 3000 |  4384.21 |  4447.67 | 1974.18 | 2174.42 |
 4000 |  5845.62 |  5930.23 | 2632.24 | 2899.22 |
 5000 |  7307.02 |  7412.79 | 3290.80 | 3624.03 |
 6000 |  8768.42 |  8895.85 | 3948.35 | 4348.84 |
 7000 | 10229.83 | 10377.91 | 4606.41 | 5073.64 |
 8000 | 11691.23 | 11860.45 | 5264.47 | 5798.45 |
 9000 | 13152.64 | 13343.02 | 5922.53 | 6523.25 |
10000 | 14614.04 | 14825.58 | 6580.59 | 7248.06 |
______|__________|__________|_________|_________|
______________________________________________
      |                   |
      |   Liters Alkali   |  Liters Alkali
      |     Solution      |    Solution
Kilos |    Sp. Gr. 1.3    |  Sp. Gr. 1.355
______|___________________|___________________
      |         |         |         |
      |   NaOH  |   KOH   |   NaOH  |   KOH
______|_________|_________|_________|_________
      |         |         |         |
 1000 |  397.54 |  485.13 |  319.11 |  403.54
 2000 |  795.07 |  970.27 |  638.23 |  807.08
 3000 | 1192.61 | 1455.40 |  957.34 | 1210.61
 4000 | 1590.14 | 1940.53 | 1276.45 | 1614.15
 5000 | 1987.68 | 2425.67 | 1595.57 | 2017.69
 6000 | 2385.21 | 2910.80 | 1914.68 | 2421.23
 7000 | 2782.75 | 3395.93 | 2233.79 | 2824.77
 8000 | 3180.28 | 3881.06 | 2552.90 | 3228.30
 9000 | 3577.82 | 4366.20 | 2872.02 | 3631.84
10000 | 3975.35 | 4851.33 | 3191.13 | 4035.38
______|_________|_________|_________|_________


DENSITY AND STRENGTH OF SULPHURIC ACID (SIDERSKY).

Column Headings:
A: Degrees Twaddell
B: Sp. Gr. at 15° C.
C: % of pure acid (H_{2}SO_{4}).
D: Equivalent (in cc.) of a kilo of pure acid.
E: Equivalent (in cc.) of a liter of pure acid.


=========================================

 [A]    [B]     [C]      [D]        [E]
_________________________________________

1     1.007     1.9     52.620     96.930
3     1.014     2.8     35.710     66.450
4     1.022     3.8     25.650     47.230
6     1.029     4.8     20.410     37.582
8     1.037     5.8     16.670     30.690
9     1.045     6.8     14.085     25.938
10    1.052     7.8     12.198     22.460
12    1.062     8.8     10.755     19.803
13    1.067     9.8      9.524     17.540
15    1.075    10.9      8.547     15.740
17    1.083    11.9      7.752     14.278
18    1.091    13.0      7.042     12.969
20    1.100    14.1      6.452     11.882
22    1.108    15.2      5.953     10.962
23    1.116    16.2      5.526     10.177
25    1.125    17.3      5.405      9.954
27    1.134    18.5      4.76       8.770
29    1.142    19.6      4.465      8.223
30    1.152    20.8      4.184      7.723
32    1.162    22.2      3.876      7.138
34    1.171    23.3      3.663      6.745
36    1.180    24.5      3.541      6.521
38    1.190    25.8      3.258      5.999
40    1.200    27.1      3.077      5.666
42    1.210    28.4      2.907      5.353
44    1.220    29.6      2.770      5.102
46    1.231    31.0      2.618      4.865
48    1.241    32.2      2.500      4.604
50    1.252    33.4      2.392      4.406
53    1.263    34.7      2.283      4.205
55    1.274    36.0      2.179      4.012
57    1.285    37.4      2.079      3.829
60    1.297    38.8      1.988      3.661
62    1.308    40.2      1.905      3.508
64    1.320    41.6      1.821      3.354
66    1.332    43.0      1.745      3.214
69    1.345    44.4      1.665      3.085
71    1.357    45.5      1.621      2.985
74    1.370    46.9      1.558      2.869
77    1.383    48.3      1.497      2.757
80    1.397    49.8      1.436      2.646
82    1.410    51.2      1.386      2.551
85    1.424    52.6      1.335      2.459
88    1.438    54.0      1.287      2.370
91    1.453    55.4      1.237      2.270
94    1.468    56.9      1.195      2.200
97    1.483    58.3      1.156      2.130
100   1.498    59.6      1.116      2.050
103   1.514    61.0      1.080      1.980
106   1.530    62.5      1.045      1.930
108   1.540    64.0      1.010      1.860
113   1.563    65.5      0.975      1.800
116   1.580    67.0      0.950      1.740
120   1.597    68.6      0.917      1.690
123   1.615    70.0      0.888      1.630
127   1.634    71.6      0.855      1.570
130   1.652    73.2      0.845      1.520
134   1.671    74.7      0.800      1.470
138   1.691    76.4      0.774      1.430
142   1.711    78.1      0.749      1.390
146   1.732    79.9      0.722      1.320
151   1.753    81.7      0.705      1.280
155   1.774    84.1      0.672      1.235
160   1.798    86.5      0.639      1.190
164   1.819    89.7      0.609      1.120
168   1.842   100.0      0.544      1.000


*Densities of Potassium Carbonate Solutions at 15 C (Gerlach)

=======================
        |             |
        |  Per cent   |
Sp. Gr. |   of pure   |
        | K_{2}CO_{3} |
________|_____________|
        |             |
1.00914 |    1        |
1.01829 |    2        |
1.02743 |    3        |
1.03658 |    4        |
1.04572 |    5        |
1.05513 |    6        |
1.06454 |    7        |
1.07396 |    8        |
1.08337 |    9        |
1.09278 |   10        |
1.10258 |   11        |
1.11238 |   12        |
1.12219 |   13        |
1.13199 |   14        |
1.14179 |   15        |
1.15200 |   16        |
1.16222 |   17        |
1.17243 |   18        |
1.18265 |   19        |
1.19286 |   20        |
1.20344 |   21        |
1.21402 |   22        |
1.22459 |   23        |
1.23517 |   24        |
1.24575 |   25        |
1.25681 |   26        |
1.26787 |   27        |
1.27893 |   28        |
1.28999 |   29        |
1.30105 |   30        |
1.31261 |   31        |
1.32417 |   32        |
1.33573 |   33        |
1.34729 |   34        |
1.35885 |   35        |
1.37082 |   36        |
1.38279 |   37        |
1.39476 |   38        |
1.40673 |   39        |
1.41870 |   40        |
1.43104 |   41        |
1.44338 |   42        |
1.45573 |   43        |
1.46807 |   44        |
1.48041 |   45        |
1.49314 |   46        |
1.50588 |   47        |
1.51861 |   48        |
1.53135 |   49        |
1.54408 |   50        |
1.55728 |   51        |
1.57048 |   52        |
1.57079 |   53.024    |
________|_____________|


*Constants of Certain Fatty Acids and Triglycerides

=========================================================
              |          |            |
              |          |            |  Per cent Yield
Triglycerides | Mol. Wt. | Mol. Wt.   |__________________
      of      | of Fatty | of Tri-    |       |
              | of Fatty | glycerides | Fatty | Glycerine
              |          |            | Acid  |
______________|__________|____________|_______|___________
              |          |            |       |
Stearic Acid  |    284   |     890    | 95.73 |  10.34
Oleic Acid    |    282   |     884    | 95.70 |  10.41
Margaric Acid |    270   |     848    | 95.52 |  10.85
Palmitic Acid |    256   |     806    | 95.28 |  11.42
Myristic Acid |    228   |     722    | 94.47 |  12.74
Lauric Acid   |    200   |     638    | 94.04 |  14.42
Capric Acid   |    172   |     594    | 93.14 |  15.48
Caproic Acid  |    116   |     386    | 90.16 |  23.83
Butyric Acid  |     88   |     302    | 87.41 |  30.46
______________|__________|____________|_______|___________


PERCENTAGES OF SOLID CAUSTIC SODA AND CAUSTIC POTASH IN CAUSTIC LYES
ACCORDING TO BAUME SCALE.

Degrees    %     %
 Baumé.  NaOH   KOH

 1       0.61   0.90
 2       0.93   1.70
 3       2.00   2.60
 4       2.71   3.50
 5       3.35   4.50
 6       4.00   5.60
 7       4.556  6.286
 8       5.29   7.40
 9       5.87   8.20
10       6.55   9.20
11       7.31  10.10
12       8.00  10.90
13       8.68  12.00
14       9.42  12.90
15      10.06  13.80
16      10.97  14.80
17      11.84  15.70
18      12.64  16.50
19      13.55  17.60
20      14.37  18.60
21      15.13  19.50
22      15.91  20.50
23      16.77  21.40
24      17.67  22.50
25      18.58  23.30
26      19.58  24.20
27      20.59  25.10
28      21.42  26.10
29      22.64  27.00
30      23.67  28.00
31      24.81  28.90
32      25.80  29.80
33      26.83  30.70
34      27.80  31.80
35      28.83  32.70
36      29.93  33.70
37      31.22  34.90
38      32.47  35.90
39      33.69  36.90
40      34.96  37.80
41      36.25  38.90
42      37.53  39.90
43      38.80  40.90
44      39.99  42.10
45      41.41  43.40
46      42.83  44.60
47      44.38  45.80
48      46.15  47.10
49      47.58  48.25
50      49.02  49.40


GLYCERINE CONTENT OF MORE COMMON OILS AND FATS USED IN SOAP MAKING.

   Kind.          Theoretical     Average Free     % Pure        Yield
                 Yield of Pure   Fatty Acid in    Glycerine     Soap Lye
                 Glycerine of      Commercial   in Commercial   80% Crude
                  Neutral Oil        Oil.            Oil.       Glycerine.
                    or Fat.

Beef Tallow           10.7             5           10.2         12.75
Bone Grease           10.5            20-50         5.2- 8.4     6.5-10.5
Castor Oil             9.8           0.5-10         8.8- 9.8    11.0-12.45
Cocoanut Oil          13.9             3-5         13.2-13.5    16.5-16.9
Cocoanut Oil Off                      15-40         8.3-11.8    10.37-14.75
Corn Oil              10.4             1-10         9.3-10.3    11.62-12.9
Cottonseed Oil        10.6            Trace        10.6         13.25
Hog Grease            10.6           0.5-1         10.5-10.6    13.12-13.25
Horse Grease          10.6             1-3         10.5-10.6    13.12-13.25
Olive Oil             10.3             2-25         7.7-10.2     9.62-12.75
Olive Foots                           30-60           4-7           5-8.75
Palm Oil              11.0            10-50         5.5-10       6.87-12.5
Palmkernel Oil        13.3             4-8         12.2-12.8    15.25-16
Peanut Oil            10.4             5-20         8.3-9.9     10.37-12.37
Soya Bean Oil         10.4             2           10.2         12.75
Train Oil             10.0             2-20           8-9.8     10.0-12.25
Vegetable Tallow      10.9             1-3         10.5-10.8    13.12-13.5


*Table of Specific Gravities of Pure Commercial Glycerine with
Corresponding Percentage of Water. Temperature 15 C.

------------------+------------------
 Sp. Gr.  % Water | Sp. Gr.  % Water
  1.262      0    |  1.160      38
  1.261      1    |  1.157      39
  1.258      2    |  1.155      40
  1.255      3    |  1.152      41
  1.2515     4    |  1.149      42
  1.250      5    |  1.1464     43
  1.2467     6    |  1.1437     44
  1.2450     7    |  1.141      45
  1.243      8    |  1.1377     46
  1.241      9    |  1.1353     47
  1.237     10    |  1.1326     48
  1.235     11    |  1.1304     49
  1.2324    12    |  1.127      50
  1.229     13    |  1.125      51
  1.2265    14    |  1.1224     52
  1.2245    15    |  1.1204     53
  1.2225    16    |  1.117      54
  1.2185    17    |  1.114      55
  1.2174    18    |  1.112      56
  1.2142    19    |  1.109      57
  1.211     20    |  1.106      58
  1.207     21    |  1.103      59
  1.203     22    |  1.1006     60
  1.2004    23    |  1.088      65
  1.198     24    |  1.075      70
  1.195     25    |  1.0623     75
  1.1923    26    |  1.049      80
  1.189     27    |  1.0365     85
  1.188     28    |  1.0243     90
  1.1846    29    |  1.0218     91
  1.182     30    |  1.0192     92
  1.179     31    |  1.0168     93
  1.176     32    |  1.0147     94
  1.1734   33     |  1.0125     95
  1.171    34     |  1.01       96
  1.168    35     |  1.0074     97
  1.165    36     |  1.0053     98
  1.163    37     |  1.0026     99
------------------+------------------


Table of Percentage, Specific Gravity and Beaume Degree of Pure
Glycerine Solutions

=========+===========+===========++=========+===========+===========
Per cent |Sp. Gr.    |Degree     ||Per cent |Sp. Gr.    |Degree
Water    |Champion   |Beaume     ||Water    |Champion   |Beaume
         |and Pellet |(Berthelot)||         |and Pellet |(Berthelot)
=========+===========+===========++=========+===========+===========
     0   |    1.2640 |      31.2 ||    11.0 |    1.2350 |      28.6
     0.5 |    1.2625 |      31.0 ||    11.5 |    1.2335 |      28.4
     1.0 |    1.2612 |      30.9 ||    12.0 |    1.2322 |      28.3
     1.5 |    1.2600 |      30.8 ||    12.5 |    1.2307 |      28.2
     2.0 |    1.2585 |      30.7 ||    13.0 |    1.2295 |      28.0
     2.5 |    1.2575 |      30.6 ||    13.5 |    1.2280 |      27.8
     3.0 |    1.2560 |      30.4 ||    14.0 |    1.2270 |      27.7
     3.5 |    1.2545 |      30.3 ||    14.5 |    1.2255 |      27.6
     4.0 |    1.2532 |      30.2 ||    15.0 |    1.2242 |      27.4
     4.5 |    1.2520 |      30.1 ||    15.5 |    1.2230 |      27.3
     5.0 |    1.2505 |      30.0 ||    16.0 |    1.2217 |      27.2
     5.5 |    1.2490 |      29.9 ||    16.5 |    1.2202 |      27.0
     6.0 |    1.2480 |      29.8 ||    17.0 |    1.2190 |      26.9
     6.5 |    1.2465 |      29.7 ||    17.5 |    1.2177 |      26.8
     7.0 |    1.2455 |      29.6 ||    18.0 |    1.2165 |      26.7
     7.5 |    1.2440 |      29.5 ||    18.5 |    1.2150 |      26.5
     8.0 |    1.2427 |      29.3 ||    19.0 |    1.2137 |      26.4
     8.5 |    1.2412 |      29.2 ||    19.5 |    1.2125 |      26.3
     9.0 |    1.2400 |      29.0 ||    20.0 |    1.2112 |      26.2
     9.5 |    1.2390 |      28.9 ||    20.5 |    1.2100 |      26.0
    10.0 |    1.2375 |      28.8 ||    21.0 |    1.2085 |      25.0
    10.5 |    1.2362 |      28.7 ||         |           |
=========+===========+===========++=========+===========+===========


*Table of Specific Gravities of Pure Glycerine Solutions with
Corresponding Beaume Degree and Percent Water

--------+--------+-------+---------+--------+--------
Per cent| Sp. Gr.| Degree| Percent | Sp. Gr.| Degree
Water   |        | Beaume|  Water  |        | Beaume
--------+--------+-------+---------+--------+--------
        |        |       |         |        |
  0.0   | 1.2640 |  31.2 |    1.0  | 1.2612 |  30.9
  0.5   | 1.2625 |  31.0 |    1.5  | 1.2600 |  30.8
  2.0   | 1.2585 |  30.7 |   12.0  | 1.2322 |  28.3
  2.5   | 1.2575 |  30.6 |   12.5  | 1.2307 |  28.2
  3.0   | 1.2560 |  30.4 |   13.0  | 1.2295 |  28.0
  3.5   | 1.2545 |  30.3 |   13.5  | 1.2280 |  27.8
  4.0   | 1.2532 |  30.2 |   14.0  | 1.2270 |  27.7
  4.5   | 1.2520 |  30.1 |   14.5  | 1.2255 |  27.6
  5.0   | 1.2505 |  30.0 |   15.0  | 1.2242 |  27.4
  5.5   | 1.2490 |  29.9 |   15.5  | 1.2230 |  27.3
  6.0   | 1.2480 |  29.8 |   16.0  | 1.2217 |  27.2
  6.5   | 1.2465 |  29.7 |   16.5  | 1.2202 |  27.0
  7.0   | 1.2455 |  29.6 |   17.0  | 1.2190 |  26.9
  7.5   | 1.2440 |  29.5 |   17.5  | 1.2177 |  26.8
  8.0   | 1.2427 |  29.3 |   18.0  | 1.2165 |  26.7
  8.5   | 1.2412 |  29.2 |   18.5  | 1.2150 |  26.5
  9.0   | 1.2400 |  29.0 |   19.0  | 1.2137 |  26.4
  9.5   | 1.2390 |  28.9 |   19.5  | 1.2125 |  26.3
 10.0   | 1.2375 |  28.8 |   20.0  | 1.2112 |  26.2
 10.5   | 1.2362 |  28.7 |   20.5  | 1.2100 |  26.0
 11.0   | 1.2350 |  28.6 |   21.0  | 1.2085 |  25.9
 11.5   | 1.2335 |  28.4 |         |        |
--------+--------+-------+---------+--------+--------




INDEX


A

Acetin process for the determination of glycerol, 155.

Acid, Clupanodonic, 20.

Acid, Hydrochloric, 111.

Acid, Lauric, 2.

Acid, Myristic, 2.

Acid, Napthenic, 24.

Acid, Oleic, 15, 19.

Acid, Palmitic, 2.

Acid, Pinic, 22.

Acid, Resin, 144.

Acid, Stearic, 15, 19.

Acid, Sulfuric, 112.

Acid, Sylvic, 22.

Acid saponification, 120.

Air bleaching of palm oil, 12.

Albuminous matter, Removal from tallow, 6.

Alcohol, Denatured, 82.

Alcoholic method for free alkali in soap, 139.

Alkali Blue 6 B, indicator, 129.

Alkali, Total, determination of in soap, 147.

Alkalis, 25.

Alkalis used in soap making,
  Testing of, 134.

Amalgamator, 33.

Analysis, Glycerine, International, 150.

Analysis, Soap, 137.

Analysis, Standard methods for fats and oils, 165-196.

Aqueous saponification, 121.

Arachis oil, 79.

Autoclave saponification, 118.

Automobile soaps, 41.


B

Barrels, sampling, 168.

Baumé scale, 25.

Bayberry wax, Use in shaving soap, 89.

Bichromate Process for glycerol determination, 160.

Bleaching, Fullers' earth process for tallow, 4.

Bleaching palm oil by bichromate method, 9.

Bleaching palm oil by air, 12.

Bosshard & Huggenberg method for determination of free alkali, 140.

Bunching of soap, 52.


C

Candelite, 96.

Candle tar, 125.

Carbolic soap, 77.

Carbon Dioxide, Formation of in carbonate saponification, 45.

Carbonate, potassium, 29.

Carbonate, saponification, 35, 45.

Carbonate, sodium, 28.

Castile soap, 79.

Castor oil ferment, 121.

Castor oil, Use of in transparent soaps, 83.

Caustic potash, 26.

Caustic potash, Electrolytic, 27.

Caustic soda, 26.

Changes in soap-making, 36.

Chemist, Importance of, 127.

Chipper, Soap, 32.

Chip soap, 54.

Chip soap, Cold made, 55.

Chip soap, Unfilled, 56.

Chrome bleaching of palm oil, 9.

Cloud test for oil, Standard method, 182-183.

Clupanodonic acid, 20.

Cocoanut oil, 6.

Cold cream soap, 78.

Cold made chip soaps, 55.

Cold made toilet soaps, 72.

Cold made transparent soaps, 84.

Cold process, 35, 43.

Colophony, 22.

Coloring soap, 75.

Copra, 7.

Corn oil, 14.

Corrosive sublimate, 78.

Cotton goods. Soaps used for, 103.

Cottonseed oil, 14.

Cream, Shaving, 90.

Crude glycerine, 113.

Crutcher, 32.

Curd soap, 71.

Cutting table, 32.


D

Determination of free fatty acid, 128.

Determination of unsaponifiable matter, 132.

Distillation of fatty acids, 125.

Drying machine, 32.


E

Enzymes, 17.

Eschweger soap, 81.

Examination of fats and oils, 128.


F

Fahrion's method for moisture, 138.

Fats and oils, Examination of, 128.

Fats and oils used in soap manufacture, 3.

Fatty acids, 14.

Fatty acids, Distillation of, 125.

Ferments, Splitting fats with, 121.

Fillers for laundry soaps, 53.

Fillers for soap powders, 58.

Finishing change, 36.

Fish oils, 20.

Floating soap, 62.

Formaldehyde soap, 78.

Frames, 31.

Free alkali in soap, Determination of, 139.

Free fatty acid, Determination of, 128.

Free fatty acids, Extraction from tallow, 6.

Free fatty acid, Standard method of dilu., 174.
  Note on method, 188-189.

Full boiled soaps, 35.

Fullers' earth bleaching of tallow, 4.


G

Glycerides, 2.

Glycerine, 2.

Glycerine analysis, 150.

Glycerine change, 36.

Glycerine, Crude, 113.

Glycerine in spent lyes, Recovery of, 106.

Glycerine in soap, Determination of, 149.

Glycerine, Sampling crude, 162.

Glycerine soaps, 83.

Glycerol content, Ways of calculating actual, 159.

Glycerol determination, Acetin process, 155.

Glycerol determination, Bichromate process for, 160.

Graining soap, 30.

Grease, 21.

Grease, Bleaching, 21.

Grinding soap, 34.


H

Hand Paste, 93.

Hard water, 29.

Hardened oils in toilet soap, Use of, 96.

Hydrocarbon oils, 2.

Hydrogenating oils, 19.

Hydrolysis of fats and oils, 17.

Hydrolytic dissociation of soap, 1.

Hydrometers, 25.


I

Indicators, Action, 135-6.

Insoluble impurities in fatty oils, Determination of (standard method), 172.
  Note on method, 187.

Insoluble matter in soap, determination of, 143.

International committee on glycerine analysis, 150.

Iodine manufacturing oil, 191.

Iodine member Wijs method, Standard, 177-181.
  Note on method, 191.

Iodine soap, 78.


J

Joslin, ref., 113.


K

"Killing" change, 36.

Koettstorfer number (Standard method), 181-182.

Kontakt reagent, 117.

Krebitz Process, 123.

Krutolin, 96.


L

Leiste & Stiepel method for rosin in soap, 146.

Liebermann, Storch reaction, 144.

Light powders, 60.

Laundry soap, 48.

LeBlanc Process, 28.

Lewkowitsch, ref., 17, 146.

Lime saponification, 118.

Lime, Use in Krebitz Process, 123.

Lime, Use in treatment of glycerine water, 116.

Liquid medicinal soaps, 79.

Liquid soaps, 94.

Lyes, Spent, 37.


M

Magnesia, Use in  autoclave saponification, 120.

Manganese sulfate, Use of as catalyzer in fermentative cleavage of fats, 122.

Marine soaps, 39.

Medicinal soaps, 76.

Medicinal soaps, Less important, 78.

Medicinal soaps, Therapeutic value of, 76.

Melting point of fat or oil, Standard method, 193.

Mercury soaps, 78.

Metallic soaps, 1.

Methyl orange, indicator, 136.

Meyerheim, ref., 21.

Mill soap, 32.

Moisture in soap, Determination of, 138, 130.

Moisture and volatile matter in fats and oils, Standard method for
  detm. of, 170.
    Note on method, 184-185.

Mottle in soap, 81.

Mug shaving soap, 90.


N

Naphtha, Incorporation in soap, 49.

Naphthenic acids, 24.

Nigre, 36.

Normal acids, Equivalent in alkalis, 136.


O

Oils and fats, 1.

Oils and fats, Chemical constants, 18.

Oils and fats, Distinction, 1.

Oils and fats, Preserving, 18.

Oils and fat, Nature of used in soap manufacture, 2.

Oils and fats, Rancidity of, 16.

Oil hardening, 19.

Oleic acid, 15, 19.

Olein, 2, 19.

Olive oil, 14.

Olive oil foots, 14.

Organoleptic methods, 127.


P

Palmatin, 2.

Palm kernel oil, 8.

Palmitic acid, 2.

Palm oil, 8.

Palm oil, air bleaching, 12.

Palm oil, Chrome bleaching of, 9.

Palm oil soap, 66.

Pearl ash, 29.

Perfuming and coloring toilet soaps, 73.

Peroxide soap, 78.

Petroff reagent, 117.

Pfeilring reagent, 117.

Phenol, 77.

Phenolphthalein, indicator, 38.

Phenolphthalein, Using as indicator, 51.

Phenols, Soaps containing, 77.

Pinic acid, 22.

Plodder, 33.

Potash from wood ash, 27.

Potassium carbonate, 29.

Powders, Light, 60.

Powders, Scouring, 61.

Powders, Shaving, 90.

Powders, Soap, 56.

Precipitation test for treated spent lyes, 110.

Prevention of rancidity, 18.

Pumice or sand soaps, 93.

Purple shade in soap, 75.


R

Rancidity of oils and fats, 16.

Rancidity, Prevention, 18.

Recovery of glycerine from spent lye, 106.

Red oil, 15.

Red oil, Saponified, 15.

Resin acids, Total fatty and, Determination of in soap, 144.

Ribot, ref., 20.

Rosin, 22.

Rosin, Determination of in soap, 144.

Rosin saponification, 23.

Run and glued up soaps, 69.

Run soaps, 39.


S

Sal soda, 29.

Salt, 30.

Salting out, 30.

Salt "pickle," 37.

Sampling crude glycerine, 162.

Sampling for standard method, 166.
  Note on, 184.

Sampling oils and fats, 128.

Sampling soap, 137.

Saponification by ferments, 121.

Saponification, Acid, 120.

Saponification, Aqueous, 121.

Saponification, Autoclave, 118.

Saponification, Carbonate, 45.

Saponification defined, 2, 105.

Saponification, Lime, 118.

Saponification number, 181-182.

Saponification, Rosin, 23.

Saponification, Various methods, 105.

Scouring and fulling soaps for wool, 98.

Scouring powders, 61.

Scouring soap, 61.

Semi-boiled laundry soaps, 49.

Semi-boiled process, 44.

Shaving cream, 90.

Shaving powder, 90.

Shaving soaps, 87.

Silica and silicates, Determination of in soap, 148.

Silk dyeing, 102.

Silk industry, Soaps used in, 101.

Slabber, 32.

Smith method for moisture in soap, 138.

Soap analysis, 137.

Soap, Automobile, 41.

Soap, Carbolic, 71.

Soap, Castile, 79.

Soap, Chip, 54.

Soap Chip, cold made, 55.

Soap, Chip, unfilled, 56.

Soap, Cold cream, 78.

Soap, Coloring, 75.

Soap containing phenols, 77.

Soap, Curd, 71.

Soap, Defined, 1.

Soap, Determination insoluble matter, 143.

Soap, Determining glycerine in, 149.

Soap, Eschweger, 81.

Soap, Floating, 62.

Soap, Formaldehyde, 78.

Soap for wool, Scouring and fulling, 98.

Soap, Full boiled, 35.

Soap, Iodine, 78.

Soap kettle, 31.

Soap, Laundry, 48.

Soap, Liquid, 94.

Soap lye crude glycerine, 113.

Soap, Marine, 39.

Soap, Medicinal, 76.

Soap, Medicinal, less important, 78.

Soap, Mercury, 78.

Soap, Metallic, 1.

Soap, Peroxide, 78.

Soap powders, 56.

Soap, Pumice or sand, 93.

Soap, Rosin settled, 50.

Soap, Run and glued up, 69.

Soap, Scouring, 61.

Soap, Semi-boiled laundry, 49.

Soap, Shaving, 87.

Soap, Sulphur, 77.

Soap, Tannin, 78.

Soap, Tar, 77.

Soap, Test for color of, 133.

Soap, Textile, 98.

Soap, Toilet, 65.

Soap, Toilet cheaper, 68.

Soap, Toilet, cold made, 72.

Soap, Toilet perfuming and coloring, 73.

Soap, Transparent, 82.

Soap, Transparent, cold made, 84.

Soap used for cotton goods, 103.

Soap used in the silk industry, 101.

Soap, Witch hazel, 78.

Soap, Wool thrower's, 100.

Soap, Worsted finishing, 101.

Soda ash, 28.

Sodium carbonate, 28.

Sodium perborate, Use of in soap powders, 57.

Soft soaps, 40.

Soluble mineral matter detm. of in fats and oils, 173.
  Note on method, 187-188.

Solvay process, 28.

Soya bean oil, 14.

Spent lye, Recovery of glycerine from, 106.

Spent lyes, 37.

Spent lyes, Treatment of for glycerine recovery, 107.

Splitting fats with ferments, 121.

Standard methods of analysis for fats and oils, 165-196.

Starch and gelatine, Determination in soap, 143.

Stearic acid, 15, 19.

Stearin, 2, 19.

Strengthening change, 36.

Strengthening lyes, 38.

Strunz crutcher, 63.

Sugar in soap, Determination of, 150.

Sugar, Use in transparent soap, 83.

Sulfate of alumina, Use of in spent lyes, 108.

Sulphonated oils, 104.

Sulphur soaps, 77.

Sweating of soap, 62.

Sweet water, 119.

Sylvic acid, 22.


T

Talgol, 96.

Tallow, 4.

Tallow, Fullers' earth bleaching of, 4.

Tallow, Improving color by extraction of free fatty acid, 6.

Tannin soap, 78.

Tar soap, 77.

Test for color of soap, 133.

Testing of alkalis used in soap making, 134.

Textile soaps, 98.

Titer, 130.

Tank cars, Sampling, 166.

Tierces, Sampling, 168.

Titer, Standard method, 175.

Titer, Note on, 189.

Tung oil, Note one iodine, number of, 180.

Toilet soap, 65.

Toilet soaps, Cheaper, 68.

Toilet soap, Use of hardened oils in, 96.

Total alkali, Determination of in soap, 147.

Total fatty and resin acids, Determination of in soap, 144.

Train oils, 20.

Transparent soap, 82.

Transparent soap, Cold made, 84.

Troweling soap, 52.

Tsujimoto, ref., 20.

Tubes for transparent soap, 85.

Turkey red oil, 104.

Twaddle scale, 25.

Twitchell method for rosin, 145.

Twitchell process, 113.

Twitchell process, Advantages, 113.


U

Unsaponifiable matter, Determination of in oils and fats, 132.

Unsaponifiable matter, Determination of in soap, 148.

Unsaponifiable matter, determination of by standard method, 176.


V

Vacuum Oven, Standard, 176.

Vegetable oils, 6.


W

Water, 29.

Water, Hard, 29.

Witch hazel soap, 78.

Wool thrower's soap, 100.

Worsted finishing soaps, 101.


Z

Zinc oxide, Use of in autoclave saponification, 120.

Zinc oxide, Use of in soap, 33.




LITERATURE OF THE CHEMICAL INDUSTRIES


On our shelves is the most complete stock of technical, industrial,
engineering and scientific books in the United States. The technical
literature of every trade is well represented, as is also the literature
relating to the various sciences, both the books useful for reference as
well as those fitted for students' use as textbooks.

A large number of these we publish and for an ever increasing number we
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The Soap-Maker's Book Shelf

A list of standard books relating to soapmaking and allied industries.

Published and For Sale by

D. VAN NOSTRAND COMPANY

_Publishers and Booksellers_

8 WARREN STREET          NEW YORK


~Askinson, George W.~ Perfumes and Cosmetics. Their preparation and
manufacture. Fourth Edition, translated from the German, and revised
with additions by W. L. Dudley. 32 illustrations. 6-1/4 × 9-1/2. Cloth.
354 pp. New York, 1915. ~$5.00~

~Chalmers, T. W.~ The Production and Treatment of Vegetable Oils.
Including chapters on the refining of oils, the hydrogenation of oils,
the generation of hydrogen, soap making, the recovery and refining of
glycerine, and the splitting of oils. 95 illustrations, 9 folding
plates. 8 × 11-1/2. Cloth. 163 pp. London, 1919. ~$7.50~

~Deite, C.~ Manual of Toilet Soap-Making. Comprising toilet soaps,
medicated soaps, and other specialties. Second Revised Edition. 85
illustrations. 6-1/2 × 10. Cloth. 356 pp. London, 1920. ~$7.50~

~Ellis, Carleton G.~ The Hydrogenation of Oils, Catalyzers and Catalysis
and the Generation of Hydrogen and Oxygen. Second Edition, thoroughly
revised and enlarged. 240 illustrations. 6-1/4 × 9-1/2. Cloth. 767 pp.
N. Y., 1919. ~$7.50~

~Fischer, M. H.~ Soaps and Proteins, Their Colloid Chemistry in Theory and
Practice. With the collaboration of G. D. McLaughlin and M. O. Hooker.
114 illustrations. 6 × 9-1/4. Cloth. 281 pp. New York, 1921. ~$4.00~

~Holde, D.~ The Examination of Hydrocarbon Oils, and of the Saponifiable
Fats and Waxes. Translated from the Fourth German Edition by Edward
Mueller. 115 illustrations. 6-1/4 × 9-1/4. Cloth. 499 pp. N. Y., 1915.
~Net, $5.00~

~Hurst, G. H~. Soaps. A practical manual of the manufacture of domestic,
toilet and other soaps. Second Edition. 66 illustrations. 6 × 8-3/4.
Cloth. 385 pp. London, 1907. ~$6.00~

~Hurst, George H., and Simmons, W. H.~ Textile Soaps and Oils. A handbook
on the preparation, properties, and analysis of the soaps and oils and
in textile manufacturing, dyeing and printing. Third Edition, revised.
12 illustrations. 5-1/2 × 8-3/4. Cloth. 212 pp. London, 1921. ~$4.00~

~Koller, T. Cosmetics.~ A handbook of the manufacture, employment, and
testing of all cosmetic materials and cosmetic specialties, with
numerous recipes. Translated from the German. Third Edition. 5 × 7-1/2.
Cloth. 264 pp. London, 1920. ~$3.50~

~Koppe, S. W. Glycerine.~ Its introduction, Uses and Examination. For
chemists, perfumers, soapmakers, pharmacists, and explosives
technologists. 7 illustrations. 5-1/4 × 7-1/2. Cloth. 260 pp. New York,
1915. ~$3.50~

~Lamborn, L. L.~ Modern Soaps, Candles, and Glycerin. A practical manual
of modern methods of utilization of fats and oils in the manufacture of
soaps and candles, and the recovery of glycerin. 228 illustrations.
6-1/2 × 9-1/4. Cloth. 708 pp. N. Y., 1906. ~$10.00~

~Murray, B. L.~ Standards and Tests for Reagent Chemicals. 6 × 9. Cloth.
400 pp. New York, 1920. ~$3.00~

~Parry, Ernest J.~ The Chemistry of Essential Oils and Artificial
Perfumes. Vol. I, Monographs on Essential Oils. Fourth Edition, revised
and enlarged. 51 illustrations. 6-1/4 × 10. Cloth. 557 pp. London, 1921.
~$9.00~

Vol. II. Constituents of Essential Oils, Synthetic Perfumes and Isolated
Aromatics, and the Analysis of Essential Oils. Third Edition, revised
and enlarged. Illustrated. 351 pp. London, 1919. ~$7.00~

~Partington, J. R.~ The Alkali Industry. 63 illustrations. 5-1/2 × 8-1/2.
Cloth. 318 pp. London, 1918. ~$3.00~

~Rogers, Allen.~ Industrial Chemistry. A manual for the student and
manufacturer. Third Edition, thoroughly revised and enlarged. 377
illustrations. 6-1/2 × 9-3/4. Flexible fabrikoid. 1255 pp. New York,
1920. ~$7.50~

~Scott, Wilfred W.~ (Editor). Standard Methods of Chemical Analysis. A
manual of analytical methods and general reference for the analytical
chemist and for the advanced student. Second Edition, revised, with
additional tables. 142 illustrations, 3 color plates. 7 × 9-1/4. Cloth.
900 pp. N. Y., 1917. ~$7.50~

~Simmons, W. H.~ Fats, Waxes and Essential Oils. ~In Press.~

~Simmons, William H.~ Soap. Its composition, manufacture and properties.
11 illustrations. 4-3/4 × 7-1/4. Cloth. 133 pp. London, 1916. ~$1.00~

~Simmons, W. H., and Appleton, H. A.~ The Handbook of Soap Manufacture. 27
illustrations. 6 × 9. Cloth. 166 pp. London, 1908. ~$4.00~

~Van Nostrand's Chemical Annual.~ Edited by John C. Olsen. A handbook of
useful data for analytical manufacturing and investigating chemists and
chemical students. Fourth Issue, enlarged. 5 × 7-1/2. Flexible
fabrikoid. 785 pp. New York, 1918. ~$3.00~

~Watt, A.~ Art of Soapmaking. A practical handbook of the manufacture of
hard and soft soaps, toilet soaps, etc. Seventh Edition, revised and
enlarged. 43 illustrations. 5-1/4 × 7-1/2. Cloth. 323 pp. London, 1918.
~$4.00~

~Wright, C. R. A.~ Animal and Vegetable Fixed Oils, Fats, Butters, and
Waxes: Their Preparation and Properties, and the Manufacture Therefrom
of Candles, Soaps, and Other Products. Third Edition, revised and
greatly enlarged by C. Ainsworth Mitchell. 185 illustrations, 3 plates.
6 × 9. Cloth. 953 pp. London, 1921. ~$16.50~