Firſt occaſionally Written, among ſome other
Eſſays, to a Friend; and now ſuffer'd to
come abroad as
By the Honourable ROBERT BOYLE,
Fellow of the ROYAL SOCIETY.
Non fingendum, aut excogitandum, ſed inveniendum,
quid Natura faciat, aut ferat. Bacon.
Printed for Henry Herringman at the
Anchor on the Lower walk of the New
Exchange. MDCLXIV.
Aving in convenient places of the following Treatiſe,
mention'd the Motives, that induc'd me to write it, and the Scope I
propos'd to my ſelf in it; I think it ſuperfluous to entertain
the Reader now, with what he will meet with hereafter. And I ſhould
judge it needleſs, to trouble others, or my ſelf, with any
thing of Preface: were it not that I can ſcarce doubt, but this Book
will fall into the hands of ſome Readers, who being unacquainted
with the difficulty of attempts of this nature, will think itn
ſtrange that I ſhould publiſh any thing about Colours,
without a particular Theory of them. But I dare expect that Intelligent
and Equitable Readers will conſider on my behalf: That the
profeſſed Deſign of this Treatiſe is to deliver
things rather Hiſtorical than Dogmatical, and
conſequently if I have added divers new ſpeculative
Conſiderations and hints, which perhaps may afford no
deſpicable Aſſiſtance, towards the framing of a
ſolid and comprehenſive Hypotheſis, I have done at least
as much as I promis'd, or as the nature of my undertaking exacted. But
another thing there is, which if it ſhould be objected, I fear I
ſhould not be able ſo eaſily to anſwer it, and that
is; That in the following treatiſe (eſpecially in the Third
part of it) the Experiments might have been better Marſhall'd, and
ſome of them deliver'd in fewer words. For I muſt confeſs
that this Eſſay was written to a private Friend, and that too,
by ſnatches, at ſeveral times, and places, and (after my
manner) in looſe ſheets, of which I oftentimes had not all by
me that I had already written, when I was writing more, ſo that it
needs be no wonder if all the Experiments be not rang'd to the beſt
Advantage, and if ſome connections and conſecutions of them
might eaſily have been mended. Eſpecially ſince having
careleſſly laid by the looſe Papers, for ſeveral
years after they were written, when I came to put them together to
diſpatch them to the Preſs, I found ſome of thoſe I
reckon'd upon, to be very unſeaſonably wanting. And to make any
great change in the order of the reſt, was more than the Printers
importunity, and that, of my own avocations (and perhaps alſo
conſiderabler ſolicitations) would permit. But though ſome
few preambles of the particular Experiments might have (perchance) been
ſpar'd, or ſhorten'd, if I had had all my Papers under my View
at once; Yet in the moſt of thoſe Introductory
paſſages, the Reader will (I hope) find hints, or
Advertiſements, as well as Tranſitions. If I ſometimes
ſeem to inſiſt long upon the circumſtances of a
Tryall, I hope I ſhall be eaſily excuſed by thoſe
that both know, how nice divers experiments of Colours are, and
conſider that I was not barely to relate them, but ſo as
to teach a young Gentleman to make them. And if I was not
ſollicitous, to make a nicer diviſion of the whole
Treatiſe, than into three parts, whereof the One contains ſome
Conſiderations about Colours in general. The Other exhibits a
ſpecimen of an Account of particular Colours, Exemplifi'd in
Whiteneſs and Blackneſs. And the Third promiſcuous
Experiments about the remaining Colours (eſpecially Red) in order to
a Theory of them. If, I ſay, I contented my ſelf with this
eaſie Diviſion of my Diſcourſe, it was perhaps
becauſe I did not think it ſo neceſſary to be Curious
about the Method or Contrivance of a Treatiſe, wherein I do not
pretend to preſent my Reader with a compleat Fabrick, or ſo
much as Modell; but only to bring in Materials proper for the Building;
And if I did not well know how Ingenious the Curioſity and Civility
of Friends makes them, to perſwade Men by ſpecious allegations,
to gratifie their deſires; I ſhould have been made to believe
by perſons very well qualify'd to judge of matters of this nature,
that the following Experiments will not need the addition of accurate
Method and ſpeculative Notions to procure Acceptance for the
Treatiſe that contains them: For it hath been repreſented, That
in moſt of them, as the Novelty will make them ſurprizing, and
the Quickneſs of performance, keep them from being tedious; ſo
the ſenſible changes, that are effected by them, are ſo
manifest, ſo great, and ſo ſudden, that ſcarce any
will be diſpleaſed to ſee them, and thoſe that are
any thing Curious will ſcarce be able to ſee them, without
finding themſelves excited, to make Reflexions upon Them. But though
with me, who love to meaſure Phyſical things by their
uſe, not their ſtrangeneſs, or
prettineſs, the partiality of others prevails not to make me over
value theſe, or look upon them in themſelves as other than
Trifles: Yet I confeſs, that ever ſince I did divers years ago
ſhew ſome of them to a Learned Company of Virtuoſi:
ſo many perſons of differing Conditions, and ev'n Sexes,
have been Curious to ſee them, and pleas'd not to Diſlike them,
that I cannot Deſpair, but that by complying with thoſe that
urge the Publication of them, I may both gratifie and excite the Curious,
and lay perhaps a Foundation whereon either others or my ſelf may in
time ſuperſtruct a ſubſtantial theory of Colours. And
if Ariſtotle, after his Maſter Plato, have
rightly obſerv'd Admiration to be the Parent of Philoſophy,
the wonder, ſome of theſe Trifles have been wont to produce
in all ſorts of Beholders, and the acceſs they have
ſometimes gain'd ev'n to the Cloſets of Ladies, ſeem to
promiſe, that ſince the ſubject is ſo pleaſing,
that the Speculation appears as Delightful! as Difficult, ſuch
eaſie and recreative Experiments, which require but little time, or
charge, or trouble in the making, and when made are ſenſible
and ſurprizing enough, may contribute more than others, (far more
important but as much more difficult) to recommend thoſe parts of
Learning (Chymistry and Corpuſcular Philoſophy) by which they
have been produc'd, and to which they give Teſtimony ev'n to
ſuch kind of perſons, as value a pretty Trick more than a true
Notion, and would ſcarce admit Philoſophy, if it approach'd
them in another Dreſs: without the ſtrangeneſs or
endearments of pleaſantneſs to recommend it. I know that I do
but ill conſult my own Advantage in the conſenting to the
Publication of the following Treatiſe: For thoſe things, which,
whilſt men knew not how they were perform'd, appear'd ſo
ſtrange, will, when the way of making them, and the Grounds on which
I devis'd them, ſhall be Publick, quickly loſe all that their
being Rarityes, and their being thought Myſteries,
contributed to recommend them. But 'tis fitter for Mountebancks than
Naturalis to deſire to have their diſcoverys rather admir'd
than underſtood, and for my part I had much rather deſerve the
thanks of the Ingenious, than enjoy the Applauſe of the Ignorant.
And if I can ſo farr contribute to the diſcovery of the nature
of Colours, as to help the Curious to it, I ſhall have reach'd my
End, and ſav'd my ſelf ſome Labour which elſe I may
chance be tempted to undergo in proſecuting that ſubect, and
Adding to this Treatiſe, which I therefore call a History,
becauſe it chiefly contains matters of fact, and which
Hiſtory the Title declares me to look upon but as Begun:
Becauſe though that above a hundred, not to ſay a hundred
and fifty Experiments, (ſome looſe, and others interwoven
amongſt the diſcourſes themſelves) may ſuffice
to give a Beginning to a Hiſtory not hitherto, that I know,
begun, by any; yet the ſubject is ſo fruitfull, and ſo
worthy, that thoſe that are Curious of theſe Matters will be
farr more wanting to themſelves than I can ſuſpect, if
what I now publiſh prove any more than a Beginning. For, as I
hope my Endeavours may afford them ſome aſſistance towards
this work, ſo thoſe Endeavours are much too Vnfiniſh'd to
give them any diſcouragement, as if there were little left for
others to do towards the Hiſtory of Colours.
For (firſt) I have been willing to leave unmention'd the moſt part of thoſe Phænomena of Colours, that Nature preſents us of her own accord, (that is, without being guided or over-ruld by man) ſuch as the different Colours that ſeveral ſorts of Fruites paſs through before they are perfectly ripe, and thoſe that appear upon the fading of flowers and leaves, and the putrifaction (and its ſeveral degrees) of fruits, &c. together with a thouſand other obvious Instances of the changes of colours. Nor have I much medled with thoſe familiar Phænomena wherein man is not an Idle ſpectator; ſuch as the Greenneſs produc'd by ſalt in Beef much powder'd, and the Redneſs produc'd in the ſhells of Lobſters upon the boyling of thoſe fiſhes; For I was willing to leave the gathering of Obſervations to thoſe that have not the Opportunity to make Experiments. And for the ſame Reaſons, among others, I did purpoſly omit the Lucriferous practiſe of Trades-men about colours; as the ways of making Pigments, of Bleanching wax, of dying Scarlet, &c. though to divers of them I be not a stranger, and of ſome I have myſelf made Tryall.
Next; I did purpoſely paſs by divers Experiments of other Writers that I had made Tryall of (and that not without regiſtring ſome of their Events) unleſs I could ſome way or other improve them, becauſe I wanted leaſure to inſert them, and had thoughts of proſecuting the work once begun of laying together thoſe I had examin'd by themſelves in caſe of my not being prevented by others diligence. So that there remains not a little, among the things that are already publiſhed, to imploy thoſe that have a mind to exerciſe themſelves in repeating and examining them. And I will not undertake, that none of the things deliver'd, ev'n in this Treatiſe, though never ſo faithfully ſet down, may not prove to be thus farr of this Sort, as to afford the Curious ſomewhat to add about them. For I remember that I have ſomewhere in the Book it ſelf acknowledged, that having written it by ſnatches, partly in the Counntrey, and partly at unſeaſonable times of the year, when the want of fit Inſtruments, and of a competent variety of flowers, ſalts, Pigments, and other materials made me leave ſome of the following Experiments, (eſpecialy thoſe about Emphatical Colours) far more unfiniſh'd than they ſhould have been, if it had been as eaſie for me to ſupply what was wanting to compleat them, as to diſcern. Thirdly to avoyd diſcouraging the young Gentleman I call Pyrophilus, whom the leſs Familiar, and more Laborious operations of Chymistry would probably have frighted, I purpoſely declin'd in what I writ to him, the ſetting down any Number of ſuch Chymicall Experiments, as, by being very elaborate or tedious, would either require much skill, or exerciſe his patience. And yet that this ſort of Experiments is exceedingly Numerous, and might more than a little inrich the Hiſtory of Colours, thoſe that are vers'd in Chymical proceſſes, will, I preſume, eaſily allow me.
And (Laſtly) for as much as I have occaſion more than once in my ſeveral Writings to treat either porpoſely or incidentally of matters relating to Colours; I did not, perhaps, conceive my ſelf oblig'd, to deliver in one Treatiſe all that I would ſay concerning that ſubject.
But to conclude, by ſumming up what I would ſay concerning what I have and what I have not done, in the following Papers; I ſhall not (on the one ſide) deny, that conſidering that I pretended not to write an accurate Treatiſe of Colours, but an Occaſional Eſſay to acquaint a private friend with what then occurrd to me of the things I had thought or try'd concerning them; I might preſume I did enough for once, if I did clearly and faithfully ſet down, though not all the Experiments I could, yet at leaſt ſuch a variety of them, that an attentive Reader that ſhall conſider the Grounds on which they have been made, and the hints that are purpoſely (though diſperſedly) couched in them, may eaſily compound them, and otherwiſe vary them, ſo as very much to increaſe their Number. And yet (on the other ſide) I am ſo ſenſible both of how much I have, either out of neceſſity or choice, left undone, and of the fruitfullneſs of the ſubject I have begun to handle; that though I had performed far more then 'tis like many Readers will judge I have, I ſhould yet be very free to let them apply to my Attempts that of Seneca, where having ſpoken of the Study of Natures Myſteries, and Particularly of the Cauſe of Earth-Quakes, he ſubjoins.1 Nulla res conſummata eſt dum incipit. Nec in hac tantum re omnium maxima ac involutiſſimá, in quâ etiam cum multum actum erit, omnis ætas, quod agat inveniet; ſed in omni alio Negotio, longè ſemper à perfecto fuere Principia.
Friendly Reader,
Ere is preſented to thy view one of the
Abſtruſeſt as well as the Gentileſt Subjects of
Natural Philoſophy, the Experimentall Hiſtory of
Colours; which though the Noble Author be pleaſed to think but
Begun, yet I muſt take leave to ſay, that I think it
ſo well begun, that the work is more than half diſpatcht.
Concerning which I cannot but give this advertiſement to the Reader,
that I have heard the Author expreſs himſelf, that it would not
ſurpriſe him, if it ſhould happen to be objected, that
ſome of theſe Experiments have been already publiſhed,
partly by Chymiſts, and partly by two or three very freſh
Writers upon other Subjects. And though the number of theſe
Experiments be but very ſmall, and though they be none of the
conſiderableſt, yet it may on this occaſion be further
repreſented, that it is eaſie for our Author to name
ſeveral men, (of whoſe number I can truly name my ſelf)
who remember either their having ſeen him make, or their having
read, his Accounts of the Experiments delivered in the following Tract
ſeveral years ſince, and long before the publication of the
Books, wherein they are mentioned. Nay in divers paſſages
(where he could do it without any great inconvenience) he hath
ſtruck out Experiments, which he had tryed many years ago,
becauſe he ſince found them divulged by perſons from whom
he had not the leaſt hint of them; which yet is not touched, with
deſign to reflect upon any Ingenious Man, as if he were a Plagiary:
For, though our Generous Author were not reſerved enough in
ſhowing his Experiments to thoſe that expreſſed a
Curioſity to ſee them (amongſt whom a very Learned Man
hath been pleaſed publickly to acknowledge it ſeveral years
ago2; yet the
ſame thing may be well enough lighted on by perſons that know
nothing of one another. And eſpecially Chymical Laboratories may
many times afford the ſame Phænomenon about Colours to
ſeveral perſons at the ſame or differing times. And as for
the few Phænomena mentioned in the ſame Chymical writers, as
well as in the following Treatiſe, our Author hath given an account,
why he did not decline rejecting them, in the Anotations upon the
47th Experiment of the third part. Not here to mention, what
he elſewhere ſaith, to ſhew what uſe may be
Juſtifiably made of Experiments not of his own deviſing by a
writer of Natural Hiſtory, if, what he employes of others mens, be
well examined or verified by himſelf.
In the mean time, this Treatiſe is ſuch, that there needs no other invitation to peruſe it, but that tis compoſed by one of the Deepeſt & Moſt indefatigable ſearchers of Nature, which, I think the World, as far as I know it, affords. For mine own part, I feel a Secret Joy within me, to ſee ſuch beginings upon ſuch Themes, it being demonſtratively true, Mota facilius moveri, which cauſeth me to entertain ſtrong hopes, that this Illuſtrious Virtuoſo and Reſtleſs Inquirer into Nature's Secrets will not ſtop here, but go on and proſper in the Diſquiſition or the other principal Colours, Green, Red, and Yellow. The Reaſoning faculty ſet once afloat, will be carried on, and that with eaſe, eſpecially, when the productions thereof meet, as they do here, with ſo greedy an Entertainment at home and abroad. I am confident, that the ROYAL SOCIETY, lately conſtituted by his MOST EXCELLENT MAJESTY for improving Natural knowledge, will Judge it their intereſt to exhort our Author to the proſecution of this Argument, conſidering, how much it is their deſign and buſineſs to accumulate a good ſtock of ſuch accurate Obſervations and Experiments, as may afford them and their Offpring genuine Matter to raiſe a Maſculine Philoſophy upon, whereby the Mind of Man may be enobled with the Knowledge of ſolid Truths, and the Life of Man benefited with ampler accommodations, than it hath been hitherto.
Our Great Author, one of the Pillars of that Illuſtrious Corporation, is conſtantly furniſhing large Symbola's to this work, and is now falln, as you ſee, upon ſo comprehenſive and important a theme, as will, if inſiſted on and compleated, prove one of the conſiderableſt peeces of that ſtructure. To which, if he ſhall pleaſe to add his Treatiſe of Heat and Flame, as he is ready to publiſh his Experimental Accounts of Cold, I eſteem, the World will be obliged to Him for having ſhewed them both the Right and Left Hand of Nature, and the Operations thereof.
The conſidering Reader will by this very Treatiſe ſee abundant cauſe to ſollicit the Author for more; ſure I am, that of whatever of the Productions of his Ingeny comes into Forein parts (where I am happy in the acquaintance of many intelligent friends) is highly valued; And to my knowledge, there are thoſe among the French, that have lately begun to learn Engliſh, on purpoſe to enable themſelves to read his Books, being impatient of their Traduction into Latin. If I durſt ſay all, I know of the Elogies received by me from abroad concerning Him, I ſhould perhaps make this Preamble too prolix, and certainly offend the modeſty of our Author.
Wherefore I ſhall leave this, and conclude with deſiring the Reader, that if he meet with other faults beſides thoſe, that the Errata take notice of (as I believe he may) he will pleaſe to conſider both the weakneſs of the Authors eyes, for not reviewing, and the manifold Avocations of the Publiſher for not doing his part; who taketh his leave with inviting thoſe, that have alſo conſidered this Nice ſubject experimentally, to follow the Example of our Noble Author, and impart ſuch and the like performances to the now very inquiſitive world. Farewell.
The Author ſhews the Reaſon, first of his Writing on this Subject (1.) Next of his preſent manner of Handling it, and why he partly declines a Methodical way (2.) and why he has partly made uſe of it in the Hiſtory of Whiteneſs and Blackneſs. (3.)
Chap. 2. Some general Conſiderations are premis'd, firſt of the Inſignificancy of the Obſervaſion of Colours in many Bodies (4, 5.) and the Importance of it in others (5.) as particularly in the Tempering of Steel (6, 7, 8.) The reaſon why other particular Inſtances are in that place omitted (9) A neceſſary diſtinction about Colour premis'd (10, 11.) That Colour is not Inherent in the Object (11.) prov'd firſt by the Phantaſms of Colours to Dreaming men, and Lunaticks; Secondly by the ſenſation or apparition of Light upon a Blow given the Eye or the Diſtemper of the Brain from internal Vapours (12.) The Author recites a particular Instance in himſelf; another that hapn'd to an Excellent Perſon related to him (13.) and a third told him by an Ingenious Phyſician (14, 15.) Thirdly, from the change of Colours made by the Senſory Diſaffected (15, 16.) Some Inſtances of this are related by the Author, obſerv'd in himſelf (16, 17.) others told him by a Lady of known Veracity (18.) And others told him by a very Eminent Man (19.) But the ſtrange Inſtances afforded by ſuch as are Bit by the Tarantula are omitted, as more properly deliver'd in another place. (20.)
Chap. 3. That the Colour of Bodies depends chiefly on the diſpoſition of the Superficial parts, and partly upon the Variety of the Texture of the Object (21.) The former of theſe are confirm'd by ſeveral Perſons (22.) and two Inſtances, the firſt of the Steel mention'd before, the ſecond of melted Lead (23, 24.) of which laſt ſeveral Obſervables are noted (25.) A third Inſtance is added of the Porouſneſs of the appearing ſmooth Surface of Cork (26, 27.) And that the ſame kind of Porouſneſs may be alſo in the other Colour'd Bodies; And of what kind of Figures, the Superficial reflecting Particles of them may be (28.) and of what Bulks, and cloſeneſs of Poſition (29.) How much theſe may conduce to the Generation of Colour inſtanc'd in the Whiteneſs of Froth, and in the mixtures of Dry colour'd Powders (30.) A further explication of the Variety that may be in the Superficial parts of Colour'd Bodies, that may cauſe that Effect, by an example drawn from the Surface of the Earth (31.) An Apology for that groſs Compariſon (32.) That the appearances of the Superficial aſperities may be Varied from the poſition of the Eye, and ſeveral Inſtances given of ſuch appearances (33, 34, 35.) That the appearance of the Superficial particles may be Varied alſo by their Motion, confirm'd by an Inſtance of the ſmoaking Liquor (35.) eſpecially if the Superficial parts be of ſuch a Nature as to appear divers in ſeveral Poſtures, explain'd by the variety of Colours exhibited by the ſhaken Leaves of ſome Plants (36.) and by changeable Taffities (37, 38, 39.) The Authors wiſh that the Variety of Colours in Mother of Pearl were examin'd with a Microſcope (40.) And his Conjectures, that poſſibly good Microſcopes might diſcover thoſe Superficial inequalities to be Real, which we now only imagine with his reaſons drawn partly from the Diſcoveries of the Teleſcope, and Microſcope (41.) And partly alſo from the Prodigiouſly ſtrange example of a Blind man that could feel Colours (42.) whoſe Hiſtory is Related (43, 44, 45.) The Authors conjecture and thoughts of it (46, 47, 48, 49.) and ſeveral Concluſions and Corollaries drawn from it about the Nature of Blackneſs and Black Bodies (50, 51, 52.) and about the Aſperities of ſeveral other Colour'd Bodies (53.) And from theſe, and ſome premis'd Conſiderations, are propos'd ſome Conjectures; That the reaſon of the ſeveral Phænomena of Colours, afterwards to be met with, depends upon the Diſpoſition of the Seen parts of the Object (54.) That Liquors may alter the Colours of each other, and of other Bodies, first by their Inſinuating themſelves into the Pores, and filling them, whence the Aſperity of the Surface of a Body becomes alter'd, explicated with ſome Inſtances (55, 56.) Next by removing thoſe Bodies, which before hindred the appearance of the Genuine Colour, confirm'd by ſeveral examples (57) Thirdly, by making a Fiſſure or Separation either in the Contiguous or Continued Particles of a Body (58.) Fourthly, by a Union or Conjunction of the formerly ſeparated Particles; Illuſtrated with divers Inſtances of precipitated Bodies (59.) Fifthly, by Diſlocating the parts, and putting them both into other Orders and Poſtures, which is Illuſtrated with Inſtances (60, 61.) Sixthly, by Motion, which is explain'd (62.) And laſtly, and chiefly, by the Union of the Saline Bodies, with the Superficial parts of another Body, whereby both their Bigneſs and Shape muſt neceſſarily be alter'd (63, 64.) Explain'd by Experiments (65, 66.) That the Colour of Bodies may be Chang'd by the concurrence of two or more of theſe ways (67.) And beſides all theſe, Eight Reflective cauſes of Colours, there may be in Tranſparent Bodies ſeveral Refractive (68, 69) Why the Author thinks the Nature of Colours deſerves yet a further Inquiry (69.) Firſt for that the little Motes of Dust exhibited very lovely Colours in a darkned Room, whilſt in a convenient poſture to the Eye, which in other Poſtures and Lights they did not (70.) And that though the ſmaller Parts of ſome Colour'd Bodies are Tranſparent, yet of others they are not, ſo that the firſt Doubt's, whether the Superficial parts create thoſe Colours, and the ſecond, whether there be any Refraction at all in the later (71, 72, 73.) A famous Controverſie among Philoſophers, about the Nature of Colour decided. (74. 75.)
Chap. 4. The controverſie ſtated about Real and Emphatical Colours (75, 76.) That the great Diſparity between them ſeems to be, partly their Duration in the ſame ſtate, and partly, that Genuine Colours are produc'd in Opacous Bodies by Reflection, and Emphatical in Tranſparent by Refraction (78.) but that this is not to be taken in too large a Senſe, the Cautionary inſtance of Froth is alleged and inſiſted on (78, 79.) That the Duration is not a ſufficient Characteristick, exemplify'd by the duration of Froth, and other Emphatical Colours, and the ſuddain fading of Flowers, and other Bodies of Real ones (80.) That the poſition of the Eye is not neceſſary to the diſcerning Emphatical Colours, ſhew'd by the ſeeing white Froth, or an Iris caſt on the Wall by a Priſm, in what place of the Room ſoever the Eye be (81.) which proceeds from the ſpecular Reflection of the Wall (82.) that Emphatical Colours may be Compounded, and that the preſent Diſcourſe is not much concern'd, whether there be, or be not made a diſtinction between Real and Emphatical Colours. (83.)
Chap. 5. Six Hypotheſes about Colour recited (84, 85) Why the Author cannot more fully Speak of any of theſe (86.) nor Acquieſce in them (87, 88.) What Pyrophilus is to expect in this Treatiſe (88, 89.) What Hypotheſis of Light and Colour the Author most inclines too (90.) Why he thinks neither that nor any other ſufficient; and what his Difficulties are, that make him decline all Hypotheſes, and to think it very difficult to ſtick to any. (91, 92.)
Of the Nature of Whiteneſs and Blackneſs.
The reaſon why the Author choſe the Explication of Whiteneſs and Blackneſs (93.) Wherein Democritus thought amiſs of theſe (94.) Gaſſendus his Opinion about them (95.) What the Author approves, and a more full Explication of White, makinig it a Multiplicity of Light or Reflections (96, 97.) Confirm'd first by the Whiteneſs of the Meridian Sun, obſerv'd in Water (98.) and of a piece of Iron glowing Hot (99.) Secondly, by the Offenſiveneſs of Snow to the Travellers eyes, confirm'd by an example of a Perſon that has Travell'd much in Ruſſia (100.) and by an Obſervation out of Olaus Magnus (100.) and that the Snow does inlighten and clear the Air in the Night, confirm'd by the Moſco Phyſician, and Captain James (101.) But that Snow has no inherent Light, prov'd by Experience (102.) Thirdly, by the great ſtore of Reflections, from white Bodies obſerv'd in a darkned Room, and by their unaptneſs to be Kindled by a Burning-glaſs (103.) Fourthly, the Specularneſs of White Bodies is confirm'd by the Reflections in a dark Room from other Bodies (104.) and by the appearance of a River, which both to the Eye and in a darkned Room appear'd White (105, 106.) Fifthly, by the Whiteneſs of diſtill'd Mercury, and that of the Galaxie (107, 108.) and by the Whiteneſs of Froth, rais'd from whites of Eggs beaten; that this Whiteneſs comes not from the Air, ſhew'd by Experiments (109, 110.) where occaſionally the Whiteneſs of Diſtill'd Oyls, Hot water, &c. are ſhew'd (111.) That it ſeems not neceſſary the Reflecting Surfaces ſhould be Sphærical, confirm'd by Experiments (112, 113.) Sixthly, by the Whiteneſs of the Powders of tranſparent Bodies (114.) Seventhly, by the Experiment of Whitening and Burniſhing Silver. (115, 116.)
Chap. 2. A Recital of ſome Opinions about Blackneſs, and which the Author inclines to (117.) which he further inſists on and explicates (118, 119.) and ſhews for what reaſons he imbrac'd that Hypotheſis (120.) Firſt, from the contrary Nature of Whiteneſs and Blackneſs, White reflecting moſt Beams outwards, Black ſhould reflect moſt inward (120.) Next, from the Black appearance of all Bodies, when Shadow'd; And the manner how this paucity of Reflection outwards is caus'd, is further explicated, by ſhewing that the Superficial parts may be Conical and Pyramical (121.) This and other Conſiderations formerly deliver'd, Illuſtrated by Experiments with black and white Marble (122, 123.) Thirdly, from the Black appearance of Holes in white Linnen, and from the appearance of Velvet ſtroak'd ſeveral ways, and from an Obſervation of Carrots (124, 125.) Fourthly, from the ſmall Reflection from Black in a darkned Room (125, 126.) Fifthly, from the Experiment of a Checker'd Tile expos'd to the Sun-beams (127.) which is to be preferr'd before a Similar Experiment try'd in Italy, with black and white Marble (128.) Some other congruous Obſervations (129.) Sixthly, from the Roaſting black'd Eggs in the Sun (130.) Seventhly, by the Obſervation of the Blind man lately mention'd, and of another mention'd by Bartholine (130.) That notwithſtanding all theſe Reaſons, the Author is not abſolutely Poſitive, but remains yet a Seeker after the true Nature of Whiteneſs and Blackneſs. (131, 132.)
Experiments in Conſort, touching Whiteneſs and Blackneſs.
The firſt Experiment, with a Solution of Sublimate, made White with Spirit of Urine, &c. (133, 134.)
The ſecond Experiment, with an Infuſion of Galls, made Black with Vitriol, &c. (135, 136.) further Diſcours'd of (137.)
The third Experiment, of the Blacking of Hartſhorn, and Ivory, and Tartar, and by a further Calcination making them White (138, 139.)
The fourth Experiment, limiting the Chymiſt's principle, Aduſta nigra ſed peruſta alba, by ſeveral Inſtances of Calcin'd Alabaſter, Lead, Antimony, Vitriol, and by the Teſtimony of Bellonius, about the white Charcoles of Oxy-cædar, and by that of Camphire. (140, 141, 142.) That which follows about Inks was miſplac'd by an Errour of the Printer, for it belongs to what has been formerly ſaid of Galls (142, 143.)
The fifth Experiment, of the black Smoak of Camphire (144.)
The ſixth Experiment, of a black Caput Mortuum, of Oyl of Vitriol, with Oyl of Worm-word, and alſo with Oyl of Winter-Savory (145.)
The ſeventh Experiment, of whitening Wax (146.)
The eighth Experiment, with Tin-glaſs, and Sublimate (147, 148.)
The ninth Experiment, of a Black powder of Gold in the bottom of Aqua-fortis, and of the Blacking of Refin'd Gold and Silver (148, 149.)
The tenth Experiment, of the ſtaining Hair, Skin, Ivory, &c. Black, with Cryſtals of Silver (150, 151.)
The eleventh Experiment, about the Blackneſs of the Skin, and Hair of Negroes, and Inhabitants of Hot Climates. Several Objections are made, and the whole Matter more fully diſcours'd and ſtated from ſeveral notable Hiſtories and Obſervations (from the 151 to the 167.)
The twelfth Experiment, of the white Powders, afforded by Precipitating ſeveral Bodies, as Crabs Eyes, Minium, Coral, Silver, Lead, Tin, Quick-ſilver, Tin-glaſs, Antimony, Benzoin, and Reſinous Gumms out of Spirit of Wine, &c. but this is not Univerſal, ſince other Bodies, as Gold, Antimony, Quick-ſilver, &c. may be Precipitated of other Colours (168, 169, 170.)
The thirteenth Experiment, of Changing the Blackneſs of ſome Bodies into other Colours (171, 172.) and of Whitening what would be Minium, and Copper, with Tin, and of Copper with Arſnick, which with Coppilling again Vaniſhes; of covering the Colour of that of 1/3 of Gold with 2/3 of Silver melted in a Maſs together (173, 174)
The fourteenth Experiment, of turning the black Body of Horn into a White immediately with Scraping, without changing the Subſtantial form, or without the Intervention of Salt, Sulphur, or Mercury (176.)
The fifteenth Experiment, contains ſeveral Inſtances againſt the Opinion of the Chymiſts that Sulphur Aduſt is the cauſe of Blackneſs, and the whole Matter is fully diſcuſs'd and ſtated (from 176 to 184)
Concerning Promiſcuous Experiments about Colours.
IN confirmation of a former Conjecture about the Generation of Colours from diverſity of Reflections are ſet down ſeveral Obſervations made in a Darkned room (186, 187.)
Experiment the ſecond, That white Linnen ſeem'd Ting'd with the Red of Silk plac'd near it in a light Room (188,189.)
Experiment the third, Of the Trajection of Light through Colour'd Papers (189, 190.)
Experiment the fourth, Obſervations of a Priſm in a dark Room (191, 192.)
Experiment the fifth, Of the Refracting and Reflecting Priſmatical Colours in a light Room (193.)
Experiment the ſixth, On the Vaniſhing of the Iris of the Priſm, upon the acceſs of a greater adventitious Light (194.)
Experiment the ſeventh, Of the appearances of the ſame Colour'd Papers by Candle-light (195, 196).
Experiment the eighth, Of the Yellowneſs of the Flame of a Candle (197).
Experiment the ninth, Of the Greeniſh Blew tranſparency of Leaf Gold (198).
Experiment the tenth, Of the curious Tinctures afforded by Lignum Nephriticum (from 199 to 203). Several trials for the Inveſtigation of the Nature of it (from 204 to 206.) Kircher's relation of this Wood ſet down, and examin'd (from 206 to 212). A Corollary on this tenth Experiment, ſhewing how it may be applicable for the Diſcovering, whether any Salt be of an Acid, or a Sulphureous, and Alcalizate Nature (from 213 to 216).
The eleventh Experiment, Of certain pieces of Glaſs that afforded this Variety of Colours; And of the way of ſo Tinging any Plate of Glaſs with Silver (from 216 to 219).
The twelfth Experiment, Of the Mixing and Tempering of Painters Pigments (219, 220, 221).
The thirteenth Experiment, Of compounding ſeveral Colours by Trajecting the Sun-beams through Ting'd Glaſſes (from 221 to 224).
The fourteenth Experiment, Of the Compounding of Real and Phantaſtical Colours, and the Reſults (224, 225, 226.) as alſo the ſame of Phantaſtical Colours (226, 227.)
The fifteenth Experiment, Of Varying the Trajected Iris by a Colour'd Priſm (228, 229.)
The ſixteenth Experiment, Of the Red fumes of Spirit of Nitre, and, the reſembling Redneſs of the Horizontal Sun-beams (230, 231.)
The ſeventeenth Experiment, Of making a Green by nine Kinds of Compoſitions (from 231 to 236.) And ſome Deductions from them againſt the neceſſity of recurring to Subſtantial forms and Hypoſtatical principles for the production of Colours (from 237 to 240.)
The eighteenth Experiment, Of ſeveral Compoſitions of Blew and Yellow which produce not a Green, and of the production of a Green by other Colours (241, 242.)
The nineteenth Experiment, contains ſeveral inſtances of producing Colours, without the alteration of any Hypoſtatical principle, by the Priſm, Bubbles, and Feathers ( from 242 to 245.)
The twentieth Experiment Of turning the Blew of Violets into a Red by Acid Salts, and to a Green by Alcalizate (245, 246.) and the uſe of it for Inveſtigating the Nature of Salts (247, 248.)
The one and twentieth Experiment, of the ſame Changes effected by the ſame means on the Blew Tinctures of Corn-flowers (249, 250.) And ſome Reſtrictions to ſhew it not to be ſo general a propriety as one might imagine (251.)
The twenty ſecond Experiment, of turning a Solution of Verdigreaſe into a Blew, with Alcalizate and Urinous Salts (252, 253, 254.)
The twenty third Experiment, of taking away the Colour of Roſes with the Steams of Sulphur, and heightning them with the Steams Condens'd into Oyl of Sulphur per Campanam (254, 255.)
The twenty fourth Experiment, of Tinging a great quantity of Liquor with a very little Ting'd Subſtance, Inſtanced in Cochineel (from 255 to 257.)
The twenty fifth Experiment, of the more general uſe of Alcalizate and Sulphureous Salts in the Tinctures of Vegetables, further Inſtanced in the Tincture of Privet Berries, and of the Flowers of Meſereon and Peaſe (from 257 to 259.) An Annotation, ſhewing that of the three Hypoſtatical principles, Salt according to Paracelſus is the moſt active about Colours (from 259 to 261.) Some things Precurſory premis'd to three ſeveral Inſtances next following, againſt the fore-mention'd Operations of Salts (261, 262.)
The twenty ſixth Experiment, containing Trials with Acid and Sulphureous Salts on the Red Tinctures of Clove-july-flowers, Buckthorn Berries, Red-Roſes, Braſil, &c. (262, 263.)
The twenty ſeventh Experiment, of the changes of the Colour of Jaſmin flowers, and Snow drops, by Alcalizate and Sulphureous Salts (263, 264.)
The twenty eighth Experiment, of other differing Effects on Mary-golds, Prim-roſes, and freſh Madder (265.) with an Admonition, that theſe Salts may have differing Effects in the changing of the tinctures of divers other Vegetables (266, 267.)
The twenty ninth Experiment, of the differing Effects of theſe Salts on Ripe and Unripe Juices, inſtanced in Black-berries, and the Juices of Roſes (from 267 to 270.) Two reaſons, why the Author added this twenty ninth Experiment, the laſt of which is confirm'd by an Inſtance of Mr. Parkinſon, conſonant to the Confeſſion of the Makers of ſuch Colours (272.)
The thirtieth Experiment, of ſeveral changes in Colours
by Digeſtion, exemplify'd by an Amalgam of 
and 
and by Spirit of Harts-horn. And (to
ſuch as believe it) by the changes of the Elixir.
The thirty firſt Experiment, ſhewing that moſt Tinctures drawn by Digeſtion Incline to a Red, inſtanc'd in Jalap, Guaicum, Amber, Benzoin, Sulphur, Antimony, &c. (276, 277.)
The thirty ſecond Experiment, That ſome Reds with Diluting turn Yellow, others not, exemplify'd by the Tincture of Cochineel, and by Balſam of Sulphur, Tinctures of Amber, &c. (277, 278, 279.)
The thirty third Experiment, of a Red Tincture of
Saccarum 
and Oyl of Turpentine made by
Digeſtion (279.)
The thirty fourth Experiment, of drawing a Volatile red Tincture of Mercury, whoſe Steams were white, but it would Tinge the Skin black (279, 280.)
The thirty fifth Experiment, of a ſuddain way of making a Blood red Colour with Oyl of Vitriol, and Oyl of Anniſeeds, two tranſparent Liquors (280, 281.)
The thirty ſixth Experiment, of the Degenerating of ſeveral Colours exemplify'd in the laſt mention'd Blood red, and by Mr. Parkinſons relation of Turnſol, by ſome Trials with the Juice of Buck-thorn Berries, and other Vegetables, to which ſeveral notable Conſiderations and Advertiſements back'd with Experiments are adjoyn'd (from 281 to 288.)
The thirty ſeventh Experiment, Of Varying the Colour of the Tinctures of Cochineel, Red-cherries, and Braſil, with Acid and Sulphureous Salts, and divers Conſiderations thereon (from 288 to 290.)
The thirty eighth Experiment, About the Red fumes of ſome, and White of other diſtill'd Bodies, and of their Coalition for the most part into a tranſparent Liquor (290, 291.) And of the various Colours of dry Sublimations, exemplify'd with ſeveral Experiments (292, 293, 294.)
The thirty ninth Experiment, Of Varying the Decoction of Balauſtiums with Acid and Urinous Salts (294, 295.) Some Annotations wherein two Experiments of Gaſſendus are Related, Examined, and Improv'd (from 295 to 302.)
The fortieth Experiment, Of the no leſs Strange than Pleaſant changes made with a Solution of Sublimate (from 301 to 306.) The difference between a Chymical axd Philoſophical Solution of a Phænomenon (307, 308.) The Authors Chymical Explication of the Phænomena, confirm d by ſeveral Experiments made on Mercury, with ſeveral Saline Liquors (from 308 to 310.) An Improvement of the fortieth Experiment, by a freſh Decoction of Antimony in a Lixivium (311, 312, 313.) Reflections on the tenth, twentieth, and fortieth Experiments, compar'd together, ſhewing a way with this Tincture of Sublimate to diſtinguiſh whether any Saline Body to be examin'd be of a Urinous or Alcalizate Nature (from 314 to 317.) The Examination of Spirit of Sal-armoniack, and Spirit of Oak by theſe Principles (from 316 to 319.) That the Author knows ways of making highly Operative Saline bodies, that produce none of the before mention'd effects (319, 320.) Some notable Experiments about Solutions and Precipitations of Gold and Silver (320, 321.)
The one and fortieth Experiment, Of Depriving a deep Blew Solution of Copper of its Colour (322.) to which is adjoyn'd the Diſcolouring or making Tranſparent a Solution of Verdigreaſe, &c. and another of Reſtoring or Increaſing it (322, 323.)
The forty ſecond Experiment, Of changing a Milk white Precipitate of Mercury into a Yellow, by Affuſion of fair Water, with ſeveral Conſiderations thereon (from 323 to 326.)
The forty third Experiment, Of Extracting a Green Solution with fair Water out of imperfectly Calcin'd Vitriol (327.)
The forty fourth Experiment, Of the Deepning and Diluting of ſeveral Tinctures, by the Affuſions of Liquors, and by Conical Glaſſes that contain'd them, Exemplify'd in the Tinctures of Cochineel, Braſil, Verdigreaſe, Glaſs, Litmus, of which laſt on this occaſion ſeveral pleaſant Phænomena are related (from 328 to 335.) To which are adjoyn'd certain Cautional Corollaries (335, 336.) The Waterdrinker and ſome of his Legerdemain tricks related.(337.)
The forty fifth Experiment, Of the turning Rheniſh and White Wine into a lovely Green, with a preparation of Steel (338, 339.) Some further Trial made about theſe Tinctures, and a Similar Experiment of Olaus Wormius (340.)
The forty ſixth Experiment, Of the Internal Colour of Metalls exhibited by Calcination (341, 342, 343.) Annotation the first, That ſeveral degrees of Fire may diſcloſe a differing Colour (343.) Annotation the ſecond, That the Glaſſes of Metalls may exhibit alſo other Kinds of Colours (344.) Annotation the third, That Minerals by ſeveral degrees of Fire may diſcloſe ſeveral Colours(345).
Experiment the forty ſeventh, Of the Internal Colours of Metalls diſclos'd by their Diſſolutions in ſeveral Menſtruums (from 345 to 350.) Annotation the firſt, The Authors Apology for Recording ſome already known Experiments, without mentioning their Authors (from 350 to 352.) Annotation the ſecond, That ſome Minerals alſo by Diſſolutions in Menſtruums may exhibit divers Colours. Annotation the third, That Metalls diſcloſe other Colours by Precipitations, inſtanc'd in Mercury (from 353 to 355.)
The forty eighth Experiment, Of Tinging Glaſs Blew with Leaf Silver, and with Calcin'd Copper, and White with Putty (from 355 to 358.) Annotation the firſt, That this white Glaſs is the Baſis of Ammels (358.) Annotion the ſecond, That Colour'd Glaſſes may be Compounded like Colour'd Liquors in Dying Fats (359.) Annotation the third, Of Tinging Glaſs with Minerel Subſtances, and of trying what Metalls they contain by this means (from 360 to 362.) Annotation the fourth, That Metalls may be Ting'd by Mineralls (362, 363.) Annotation the fifth, Of making ſeveral Kinds of Amauſes or Counterfeit Stones (from 363 to 365.) Annotation the ſixth, Of the Scarlet Dye, of the Stains of diſſolv'd Gold and Silver (366, 367) Of the Greenneſs of Salt Beef, and Redneſs of Neats Tongues from Salts; of Gilding Silver with Bathe Water (368, 369.) And Tinging the Nails and Skin with Alcanna (369)
The forty ninth Experiment, Of making Lakes (369.) A particular example in Turmerick (370, 371.) Annotation the first, That in Precipitations wherein Allum is a Coefficient, a great part of them may conſiſt of the Stony particles of that Compound Body (from 372 to 375.) Annotation the ſecond, That Lakes may be made of other Subſtances, as Madder, Rue, &c. but that Alcalizate Salts do not Always Extract the ſame Colour of which the Vegetable appears (from 376 to 378.) Annotation the third, That the Experiments related may Hint divers others (378) Annotation the fourth, That Alum is uſefull for the preparing other than Vegetable Pigments (379.)
The fiftieth Experiment, Of the Similar effects of
Saccarum and Alkalies, of Precipitating with
Oyl of Vitriol out of Aqua-fortis, and Spirit of
Vinegar; and of divers Varyings of the Colours, with theſe
Compounded (from 380 to 384.) Another very pretty Experiment, with
a Solution of Minium (384, 385.) That theſe Experiments
Skilfully digeſted may hint divers matters about Colours (386.) The Authors Apologetick concluſion, in
which is Curſorily hinted the Bow or Scarlet Dye (387.) The Authors Letter to Sir Robert Moray,
concerning his Obſervations on the Shining Diamond (391. &c.) And the Obſervations
themſelves.
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have ſeen you ſo paſſionately addicted, Pyrophilus to the delightful Art of Limning and Painting, that I cannot but think my ſelf obliged to acquaint you with ſome of thoſe things that have occurred to mee concerning the changes of Colours. And I may expect that I ſhall as well ſerve the Virtuoſi in general, as gratifie you in particular, by furniſhing a perſon, who, I hope, will both improve my Communications, and communicate his Improvements, with ſuch Experiments and Obſervations as may both invite you to enquire ſeriouſly into the Nature of Colours, and aſſiſt you in the Inveſtigation of it. This being the principal ſcope of the following Tract, I ſhould do that which might prevent my own deſign, [pg 2] if I ſhould here attempt to deliver you an accurate and particular Theory of Colours; for that were to preſent you with what I deſire to receive from you; and, as farr as in mee lay, to make that ſtudy needleſs, to which I would engage you.
2 Wherefore my preſent work ſhall be but to divert and recreate, as well as excite you by the delivery of matters of fact, ſuch as you may for the moſt part try with much eaſe, and poſſibly not without ſome delight: And leſt you ſhould expect any thing of Elaborate or Methodical in what you will meet with here, I muſt confeſs to you before-hand, that the ſeaſons I was wont to chuſe to deviſe and try Experiments about Colours, were thoſe daies, wherein having taken Phyſick, and finding my ſelf as unfit to ſpeculate, as unwilling to be altogether idle, I choſe this diverſion, as a kind of Mean betwixt the one and the other. And I have the leſs ſcrupled to ſet down the following Experiments, as ſome of them came to my mind, and as the Notes wherein I had ſet down the reſt, occurr'd to my hands, that by declining a Methodical way of delivering them, I might leave you and my ſelf the greater liberty and convenience to add to them, and tranſpoſe them as ſhall appear expedient. [pg 3]
3 Yea, that you may not think mee too reſerv'd, or look upon an Enquiry made up of meer Narratives, as ſomewhat jejune, am content to premiſe a few conſiderations, that now offer themſelves to my thoughts, which relate in a more general way, either to the Nature of Colours, or to the ſtudy of it. And I ſhall inſert an Eſſay, as well Speculative as Hiſtorical, of the Nature of Whiteneſs and Blackneſs, that you may have a Specimen of the Hiſtory of Colours, I have ſometimes had thoughts of; and if you diſlike not the Method I have made uſe of, I hope, you, and ſome of the Virtuoſi, your friends, may be thereby invited to go thorow with Red, Blew, Yellow, and the reſt of the particular Colours, as I have done with White and Black, but with farr more ſagacity and ſucceſs. And if I can invite Ingenious men to undertake ſuch Tasks, I doubt not but the Curious will quickly obtain a better Account of Colours, than as yet we have, ſince in our Method the Theorical part of the Enquiry being attended, and as it were interwoven with the Hiſtorical, whatever becomes of the diſputable Conjectures, the Philoſophy of Colours will be promoted by the indiſputable Experiments.
[pg 4]1 To come then in the firſt place to our more general Conſiderations, I ſhall begin with ſaying ſomething as to the Importance of examining the Colours of Bodies. For there are ſome, eſpecially Chymiſts, who think, that a conſiderable diverſity of Colours does conſtantly argue an equal diverſity of Nature, in the Bodies wherein it is conſpicuous; but I confeſs I am not altogether of their mind; for not to mention changeable Taffaties, the blew and golden necks of Pidgeons, and divers Water-fowl, Rainbows Natural and Artificial, and other Bodies, whoſe Colours the Philoſophers have been pleaſed to call not Real, but Apparent and Phantaſtical; not to inſiſt on theſe, I ſay, (for fear of needleſly engaging in a Controverſie) we ſee in Parrots, Goldfinches, and divers other Birds, not only that the contiguous feathers which are probably as near in properties as place, are ſome of them Red, and others White, ſome of them Blew, & others Yellow, &c. but that in the ſeveral parts of the ſelf-ſame feather there may often be ſeen the greateſt diſparity of Colours; and ſo in the leaves of Tulips, July-flowers, and ſome other Vegetables [pg 5] the ſeveral leaves, and even the ſeveral parts of the ſame leaf, although no difference have been obſerved in their other properties, are frequently found painted with very different Colours. And ſuch a variety we have much more admired in that lovely plant which is commonly, and not unjuſtly call'd the Marvayl of Peru; for of divers ſcores of fine Flowers, which in its ſeaſon that gaudy Plant does almoſt daily produce, I have ſcarce taken notice of any two that were dyed perfectly alike. But though Pyro: ſuch things as theſe, among others, keep mee from daring to affirm, that the Diverſity and change of Colours does alwaies argue any great difference or alteration, betwixt, or in, the Bodies, wherein it is to be diſcerned, yet that oftentimes the Alteration of Colours does ſignifie conſiderable Alterations in the diſpoſition of parts of Bodies, may appear in the Extraction of Tinctures, and divers other Chymical Operations, wherein the change of Colours is the chief, and ſometimes the only thing, by which the Artiſt regulates his proceeding, and is taught to know when 'tis ſeaſonable for him to leave off. Inſtances of this ſort are more obvious in divers ſorts of fruits, as Cherries, Plums, &c. wherein, according as the Vegetable ſap is ſweetned, or otherwiſe [pg 6] ripened, by paſſing from one degree to another of Maturation, the external part of the fruit paſſes likewiſe from one to another Colour. But one of the nobleſt Inſtances I have met with of this kind, is not ſo obvious; and that is the way of tempering Steel to make Gravers, Drills, Springs, and other Mechanical Inſtruments, which we have divers times both made Artificers practiſe in our preſence, and tryed our ſelves, after the following manner, Firſt, the ſlender Steel to be tempered is to be hardened by heating as much of it as is requiſite among glowing Coals, till it be glowing hot, but it muſt not be quenched aſſoon as it is taken from the fire (for that would make it too brittle, and ſpoil it) but muſt be held over a baſon of water, till it deſcend from a White heat to a Red one, which aſſoon as ever you perceive, you muſt immediately quench as much as you deſire to harden in the cold water. The Steel thus hardened, will, if it be good, look ſomewhat White and muſt be made bright at the end, that its change of Colours may be there conſpicuous; and then holding it ſo in the flame of a Candle, that the bright end may be, for about half an inch, or more, out of the flame, that the ſmoak do not ſtain or ſully the brightneſs of it, you ſhall after a [pg 7] while ſee that clean end, which is almoſt contiguous to the flame, paſs very nimbly from one Colour to another, as from a brighter Yellow, to a deeper and reddiſh Yellow, which Artificers call a ſanguine, and from that to a fainter firſt, and then a a deeper Blew. And to bring home this Experiment to our preſent purpoſe, it is found by daily Experience, that each of theſe ſucceeding Colours argue ſuch a change made in the texture of the Steel, that if it be taken from the flame, and immediately quenched in the tallow (whereby it is ſetled in whatever temper it had before) when it is Yellow, it is of ſuch a hardneſs as makes it fit for Gravers Drills, and ſuch like tools; but if it be kept a few minutes longer in the flame till it grow Blew, it becomes much ſofter, and unfit to make Gravers for Metalls, but fit to make Springs for Watches, and ſuch like Inſtruments, which are therefore commonly of that Colour; and if the Steel be kept in the flame, after that this deep Blew hath diſcloſed it ſelf, it will grow ſo ſoft, as to need to be new hardened again, before it can be brought to a temper, fit for Drills or Penknives. And I confeſs Pyro. I have taken much pleaſure to ſee the Colours run along from the parts of the Steel contiguous to the flame, to the end of the Inſtrument, [pg 8] and ſucceed one another ſo faſt, that if a man be not vigilant, to thruſt the Steel into the tallow at the very nick of time, at which it has attain'd its due Colour, he ſhall miſs of giving his tool the right temper. But becauſe the flame of a Candle is offenſive to my weak eyes, and becauſe it is apt to either black or ſully the contiguous part of the Steel which is held in it, and thereby hinder the change of Colours from being ſo long and clearly diſcern'd, I have ſometimes made this Experiment by laying the Steel to be tempered upon a heated bar of Iron, which we finde alſo to be employ'd by ſome Artificers in the tempering of ſuch great Inſtruments, as are too big to be ſoon heated ſufficiently by the flame of a Candle. And you may eaſily ſatisfie your ſelf Pyro: of the differing hardneſs and toughneſs, which is aſcribed to Steel temper'd at different Colours, if you break but ſome ſlender wires of Steel ſo temper'd, and obſerve how they differ in brittleneſs, and if with a file you alſo make tryal of their various degrees of hardneſs.
2 But Pyrophilus, I muſt not at preſent any further proſecute the Conſideration of the importance of Experiments about Colours, not only becauſe you will in the following papers finde ſome inſtances, that would here [pg 9] be preſented you out of their due place, of the uſe that may be made of ſuch Experiments, in diſcovering in divers bodies, what kind the ſalt is, that is predominant in them; but alſo becauſe a ſpeculative Naturaliſt might juſtly enough allege, that as Light is ſo pleaſing an object, as to be well worth our looking on, though it diſcover'd to us nothing but its ſelf; ſo modifi'd Light called Colour, were worth our contemplation, though by underſtanding its Nature we ſhould be taught nothing elſe. And however, I need not make either you or my ſelf excuſes for entertaining you on the ſubject I am now about to treat of, ſince the pleaſure Pyro: takes in mixing and laying on of Colours, will I preſume keep him, and will (I am ſure) keep mee from thinking it troubleſome to ſet down, eſpecially after the tedious proceſſes (about other matters) wherewith I fear I may have tyr'd him, ſome eaſie, and not unpleaſant Experiments relating to that ſubject.
3 But, before we deſcend to the more particular conſiderations, we are to preſent you concerning Colours, I preſume it will be ſeaſonable to propoſe at the very entrance a Diſtinction; the ignorance or neglect of which, ſeems to mee to have frequently enough occaſioned either miſtakes or confuſion [pg 10] in the Writings of divers Modern Philoſophers; for Colour may be conſidered, either as it is a quality reſiding in the body that is ſaid to be coloured, or to modifie the light after ſuch or ſuch a manner; or elſe as the Light it ſelf, which ſo modifi'd, ſtrikes upon the organ of ſight, and ſo cauſes that Senſation which we call Colour; and that this latter may be look'd upon as the more proper, though not the uſual acception of the word Colour, will be made probable by divers paſſages in the inſuing part of our diſcourſe; and indeed it is the Light it ſelf, which after a certain manner, either mingled with ſhades, or ſome other waies troubled, ſtrikes our eyes, that does more immediately produce that motion in the organ, upon whoſe account men ſay they ſee ſuch or ſuch a Colour in the object; yet, becauſe there is in the body that is ſaid to be coloured, a certain diſpoſition of the ſuperficial particles, whereby it ſends the Light reflected, or refracted, to our eyes thus and thus alter'd, and not otherwiſe, it may alſo in ſome ſenſe be ſaid, that Colour depends upon the viſible body; and therefore we ſhall not be againſt that way of ſpeaking of Colours that is moſt uſed among the Modern Naturaliſts, provided we be allowed to have recourſe when occaſion ſhall [pg 11] require to the premis'd diſtinction, and to take the more immediate cauſe of Colour to be the modifi'd Light it ſelf, as it affects the Senſory; though the diſpoſition alſo of the colour'd body, as that modifies the Light, may be call'd by that name Metonimically (to borrow a School term) or Efficiently, that is in regard of its turning the Light, that rebounds from it, or paſſes thorow it, into this or that particular Colour.
4 I know not whether I may not on this occaſion add, that Colour is ſo far from being an Inherent quality of the object in the ſenſe that is wont to be declar'd by the Schools, or even in the ſenſe of ſome Modern Atomiſts, that, if we conſider the matter more attentively, we ſhall ſee cauſe to ſuſpect, if not to conclude, that though Light do more immediately affect the organ of ſight, than do the bodies that ſend it thither, yet Light it ſelf produces the ſenſation of a Colour, but as it produces ſuch a determinate kind of local motion in ſome part of the brain; which, though it happen moſt commonly from the motion whereinto the ſlender ſtrings of the Retina are put, by the appulſe of Light, yet if the like motion happen to be produc'd by any other cauſe, wherein the Light concurrs not at [pg 12] all, a man ſhall think he ſees the ſame Colour. For proof of this, I might put you in mind, that 'tis uſual for dreaming men to think they ſee the Images that appear to them in their ſleep, adorn'd ſome with this, and ſome with that lively Colour, whilſt yet, both the curtains of their bed, and thoſe of their eyes are cloſe drawn. And I might add the confidence with which diſtracted perſons do oftentimes, when they are awake, think, they ſee black fiends in places, where there is no black object in ſight without them. But I will rather obſerve, that not only when a man receives a great ſtroak upon his eye, or a very great one upon ſome other part of his head, he is wont to ſee, as it were, flaſhes of lightning, and little vivid, but vaniſhing flames, though perhaps his eyes be ſhut: But the like apparitions may happen, when the motion proceeds not from ſomething without, but from ſomething within the body, provided the unwonted fumes that wander up and down in the head, or the propagated concuſſion of any internal part in the body, do cauſe about the inward extremities of the Optick Nerve, ſuch a motion as is wont to be there produc'd, when the ſtroak of the Light upon the Retina makes us conclude, that we ſee either Light, or ſuch and ſuch a [pg 13] Colour: This the moſt ingenious Des Cartes hath very well obſerv'd, but becauſe he ſeems not to have exemplifi'd it by any unobvious or peculiar obſervation, I ſhall indeavour to illuſtrate this doctrine by a few Inſtances.
5 And firſt, I remember, that having, through Gods goodneſs, been free for ſeveral years, from troubleſome Coughs, being afterwards, by an accident, ſuddenly caſt into a violent one, I did often, when I was awaked in the night by my diſtempers, obſerve, that upon coughing ſtrongly, it would ſeem to mee, that I ſaw very vivid, but immediately diſappearing flames, which I took particular notice of, becauſe of the conjecture I am now mentioning.
6 An excellent and very diſcreet perſon, very near ally'd both to you and mee, was relating to mee, that ſome time ſince, whilſt ſhe was talking with ſome other Ladies, upon a ſudden, all the objects, ſhe looked upon, appeared to her dyed with unuſual Colours, ſome of one kind, and ſome of another, but all ſo bright and vivid, that ſhe ſhould have been as much delighted, as ſurpriz'd with them, but that finding the apparition to continue, ſhe fear'd it portended ſome very great alteration as to her health: As indeed the day after ſhe was aſſaulted [pg 14] with ſuch violence by Hyſterical and Hypocondrical Diſtempers, as both made her rave for ſome daies, and gave her, during that time, a Baſtard Palſey.
7 Being a while ſince in a Town, where the Plague had made great havock, and inquiring of an ingenious man, that was ſo bold, as without much ſcruple to viſit thoſe that were ſick of it, about the odd ſymptomes of a Diſeaſe that had ſwept away ſo many there; he told mee, among other things, that he was able to tell divers Patients, to whom he was called, before they took their beds, or had any evident ſymptomes of the Plague, that they were indeed infected upon peculiar obſervations, that being asked, they would tell him that the neighbouring objects, and particularly his cloths, appear'd to them beautifi'd with moſt glorious Colours, like thoſe of the Rainbow, oftentimes ſucceeding one another; and this he affirm'd to be one of the moſt uſual, as well as the moſt early ſymptomes, by which this odd Peſtilence diſclos'd it ſelf: And when I asked how long the Patients were wont to be thus affected, he anſwered, that it was moſt commonly for about a day; and when I further inquired whether or no Vomits, which in that Peſtilence were uſually given, did not remove this ſymptome [pg 15] (For ſome uſed the taking of a Vomit, when they came aſhore, to cure themſelves of the obſtinate and troubleſome giddineſs caus'd by the motion of the ſhip) reply'd, that generally, upon the evacuation made by the Vomit, that ſtrange apparition of Colours ceaſed, though the other ſymptomes were not ſo ſoon abated, yet he added (to take notice of that upon the by, becauſe the obſervation may perchance do good) that an excellent Phyſician, in whoſe company he was wont to viſit the ſick, did give to almoſt all thoſe to whom he was called, in the beginning before Nature was much weakened, a pretty odd Vomit conſiſting of eight or ten dramms of Infuſion of Crocus Metallorum, and about half a dramm, or much more, of White Vitriol, with ſuch ſucceſs, that ſcarce one of ten to whom it was ſeaſonably adminiſtred, miſcarried.
8 But to return to the conſideration of Colours: As an apparition of them may be produced by motions from within, without the aſſiſtance of an outward object, ſo I have obſerved, that 'tis ſometimes poſſible that the Colour that would otherwiſe be produced by an outward object, may be chang'd by ſome motion, or new texture already produced in the Senſory, as long as that unuſual motion, or new diſpoſition [pg 16] laſts; for I have divers times try'd, that after I have through a Teleſcope look'd upon the Sun, though thorow a thick, red, or blew glaſs, to make its ſplendor ſupportable to the eye, the impreſſion upon the Retina, would be not only ſo vivid, but ſo permanent, that if afterwards I turned my eye towards a flame, it would appear to mee of a Colour very differing from its uſual one. And if I did divers times ſucceſſively ſhut and open the ſame eye, I ſhould ſee the adventitious Colour, (if I may ſo call it) changed or impair'd by degrees, till at length (for this unuſual motion of the eye would not preſently ceaſe) the flame would appear to mee, of the ſame hew that it did to other beholders; a not unlike effect I found by looking upon the Moon, when ſhe was near full, thorow an excellent Teleſcope, without colour'd Glaſs to ſcreen my eye with; But that which I deſire may be taken notice of, becauſe we may elſewhere have occaſion to reflect upon it, and becauſe it ſeems not agreeable to what Anatomiſts and Optical Writers deliver, touching the relation of the two eyes to each other, is this circumſtance, that though my Right eye, with which I looked thorow the Teleſcope, were thus affected by the over-ſtrong impreſſion of the light, yet when the flame [pg 17] of a Candle, or ſome other bright object appear'd to me of a very unuſual Colour, whilſt look'd upon with the Diſcompos'd Eye, or (though not ſo notably) with both eyes at once; yet if I ſhut that Eye, and looked upon the ſame object with the other, it would appear with no other than its uſual Colour, though if I again opened, and made uſe of the Dazled eye, the vivid adventitious Colour would again appear. And on this occaſion I muſt not pretermit an Obſervation which may perſwade us, that an over-vehement ſtroak upon the Senſory, eſpecially if it be naturally of a weak conſtitution, may make a more laſting impreſſion than one would imagine, which impreſſion may in ſome caſes, as it were, mingle with, and vitiate the action of vivid objects for a long time after.
For I know a Lady of unqueſtionable Veracity, who having lately, by a deſperate fall, receiv'd ſeveral hurts, and particularly a conſiderable one upon a part of her face near her Eye, had her ſight ſo troubl'd and diſorder'd, that, as ſhe hath more than once related to me, not only when the next morning one of her ſervants came to her bed ſide, to ask how ſhe did, his cloaths appear'd adorn'd with ſuch variety of dazling Colours, that ſhe was fain preſently to [pg 18] command him to withdraw, but the Images in her Hangings, did, for many daies after, appear to her, if the Room were not extraordinarily darken'd, embelliſh'd with ſeveral offenſively vivid Colours, which no body elſe could ſee in them; And when I enquir'd whether or no White Objects did not appear to her adorn'd with more luminous Colours than others, and whether ſhe ſaw not ſome which ſhe could not now well deſcribe to any, whoſe eyes had never been diſtemper'd, ſhe anſwer'd mee, that ſometimes ſhe thought ſhe ſaw Colours ſo new and glorious, that they were of a peculiar kind, and ſuch as ſhe could not deſcribe by their likeneſs to any ſhe had beheld either before or ſince, and that White Objects did ſo much diſorder her ſight, that if ſeveral daies after her fall, ſhe look'd upon the inſide of a Book, ſhe fanci'd ſhe ſaw there Colours like thoſe of the Rain-bow, and even when ſhe thought her ſelf pretty well recover'd, and made bold to leave her Chamber, the coming into a place where the Walls and Ceeling were whited over, made thoſe Objects appear to her cloath'd with ſuch glorious and dazling Colours, as much offended her ſight, and made her repent her venturouſneſs, and ſhe added, that this Diſtemper of her Eyes laſted no leſs [pg 19] than five or ſix weeks, though, ſince that, ſhe hath been able to read and write much without finding the leaſt Inconvenience in doing ſo. I would gladly have known, whether if ſhe had ſhut the Injur'd Eye, the Phænomena would have been the ſame, when ſhe employ'd only the other, but I heard not of this accident early enough to ſatisfie that Enquiry.
9 Wherefore, I ſhall now add, that ſome years before, a perſon exceedingly eminent for his profound Skil in almoſt all kinds of Philological Learning, coming to adviſe with mee about a Diſtemper in his Eyes, told me, among other Circumſtances of it, that, having upon a time looked too fixedly upon the Sun, thorow a Teleſcope, without any coloured Glaſs, to take off from the dazling ſplendour of the Object, the exceſs of Light did ſo ſtrongly affect his Eye, that ever ſince, when he turns it towards a Window, or any White Object, he fancies, he ſeeth a Globe of Light, of about the bigneſs the Sun then appeared of to him, to paſs before his Eyes: And having Inquir'd of him, how long he had been troubled with this Indiſpoſition, he reply'd, that it was already nine or ten years, ſince the Accident, that occaſioned it, firſt befel him.
[pg 20]I could here ſubjoyn, Pyrophilus, ſome memorable Relations that I have met with in the Account given us by the experienc'd Epiphanius Ferdinandus, of the Symptomes he obſerv'd to be incident to thoſe that are bitten with the Tarantula, by which (Relations) I could probably ſhew, that without any change in the Object, a change in the Inſtruments of Viſion may for a great while make ſome Colours appear Charming, and make others Provoking, and both to a high degree, though neither of them produc'd any ſuch Effects before. Theſe things, I ſay, I could here ſubjoyn in confirmation of what I have been ſaying, to ſhew, that the Diſpoſition of the Organ is of great Importance in the Dijudications we make of Colours, were it not that theſe ſtrange Stories belonging more properly to another Diſcourſe, I had rather, (contenting my ſelf to have given you an Intimation of them here) that you ſhould meet with them fully deliver'd there.
But, Pyrophilus, I would not by all that I have hitherto diſcours'd, be thought to have forgotten the Diſtinction [pg 21] (of Colour) that I mentioned to you about the beginning of the third Section of the former Chapter; and therefore, after all I have ſaid of Colour, as it is modifi'd Light, and immediately affects the Senſory, I ſhall now re-mind you, that I did not deny, but that Colour might in ſome ſenſe be conſider'd as a Quality reſiding in the body that is ſaid to be Colour'd, and indeed the greateſt part of the following Experiments referr to Colour principally under that Notion, for there is in the bodyes we call Colour'd, and chiefly in their Superficial parts, a certain diſpoſition, whereby they do ſo trouble the Light that comes from them to our Eye, as that it there makes that diſtinct Impreſſion, upon whoſe Account we ſay, that the Seen body is either White or Black, or Red or Yellow, or of any one determinate Colour. But becauſe we ſhall (God permiting) by the Experiments that are to follow ſome Pages hence, more fully and particularly ſhew, that the Changes, and conſequently in divers places the Production and the appearance of Colours depends upon the continuing or alter'd Texture of the Object, we ſhall in this place intimate (and that too but as by the way) two or three things about this Matter.
2. And firſt it is not without ſome Reaſon, [pg 22] that I aſcribe Colour (in the ſenſe formerly explan'd) chiefly to the Superficial parts of Bodies, for not to queſtion how much Opacous Corpuſcles may abound even in thoſe Bodies we call Diaphanous, it ſeems plain that of Opacous bodies we do indeed ſee little elſe than the Superficies, for if we found the beams of Light that rebound from the Object to the Eye, to peirce deep into the Colour'd body, we ſhould not judge it Opacous, but either Tranſlucid, or at leaſt Semi-diaphanous, and though the Schools ſeem to teach us that Colour is a Penetrative Quality, that reaches to the Innermoſt parts of the Object, as if a piece of Sealing-wax be broken into never ſo many pieces, the Internal fragments will be as Red as the External ſurface did appear, yet that is but a Particular Example that will not overthrow the Reaſon lately offer'd, eſpecially ſince I can alleage other Examples of a contrary Import, and two or three Negative Inſtances are ſufficient to overthrow the Generality of a Poſitive Rule, eſpecially if that be built but upon One or a Few Examples. Not (then) to mention Cherries, Plums, and I know not how many other Bodies, wherein the skin is of one Colour, and what it hides of another, I ſhall name a couple of Inſtances drawn from the Colours [pg 23] of Durable bodies that are thought far more Homogeneous, and have not parts that are either Organical, or of a Nature approaching thereunto.
3 To give you the firſt Inſtance, I ſhall need but to remind you of what I told you a little after the beginning of this Eſſay, touching the Blew and Red and Yellow, that may be produc'd upon a piece of temper'd Steel, for theſe Colours though they be very Vivid, yet if you break the Steel they adorn, they will appear to be but Superficial; not only the innermoſt parts of the Metall, but thoſe that are within a hairs breadth of the Superficies, having not any of theſe Colours, but retaining that of the Steel it ſelf. Beſides that, we may as well confirm this Obſervation, as ſome other particulars we elſewhere deliver concerning Colours, by the following Experiment which we purpoſely made.
4 We took a good quantity of clean Lead, and melted it with a ſtrong Fire, and then immediately pouring it out into a clean Veſſel of a convenient ſhape and matter, (we us'd one of Iron, that the great and ſudden Heat might not injure it) and then carefully and nimbly taking off the Scum that floated on the top, we perceiv'd, as we expected, the ſmooth and [pg 24] gloſſie Surface of the melted matter, to be adorn'd with a very glorious Colour, which being as Tranſitory as Delightfull, did almoſt immediately give place to another vivid Colour, and that was as quickly ſucceeded by a third, and this as it were chas'd away by a fourth, and ſo theſe wonderfully vivid Colours ſucceſſively appear'd and vaniſh'd, (yet the ſame now and then appearing the ſecond time) till the Metall ceaſing to be hot enough to afford any longer this pleaſing Spectacle, the Colours that chanc'd to adorn the Surface, when the Lead thus began to cool, remain'd upon it; but were ſo Superficial, that how little ſoever we ſcrap'd off the Surface of the Lead, we did in ſuch places ſcrape off all the Colour, and diſcover only that which is natural to the Metall it ſelf, which receiving its adventitious Colours, only when the heat was very Intenſe, and in that part which was expos'd to the comparatively very cold Air, (which by other Experiments ſeems to abound with ſubtil Saline parts, perhaps not uncapable of working upon Lead ſo diſpos'd:) Theſe things I ſay, together with my obſerving that whatever parts of the ſo ſtrongly melted Lead were expos'd a while to the Air, turn'd into a kind of Scum or Litharge, [pg 25] how bright and clean ſoever they appear'd before, ſuggeſted to me ſome Thoughts or Ravings, which I have not now time to acquaint You with. One that did not know me, Pyrophilus, would perchance think I endeavour'd to impoſe upon You by relating this Experiment, which I have ſeveral times try'd, but the Reaſon why the Phænomena mention'd have not been taken notice of, may be, that unleſs Lead be brought to a much higher degree of Fuſion or Fluidity than is uſual, or than is indeed requiſite to make it melt, the Phænomena I mention'd will ſcarce at all diſcloſe themſelves; And we have alſo obſerv'd that this ſucceſſive appearing and vaniſhing of vivid Colours, was wont to be impair'd or determin'd whilſt the Metal expos'd to the Air remain'd yet hotter than one would readily ſuſpect. And one thing I muſt further Note, of which I leave You to ſearch after the Reaſon, namely, that the ſame Colours did not always and regularly ſucceed one another, as is uſually in Steel, but in the diverſify'd Order mention'd in this following Note, which I was ſcarce able to write down, the ſucceſſion of the Colours was ſo very quick, whether that proceeded from the differing degrees of Heat in the Lead expos'd to the cool Air, or from ſome [pg 26] other Reaſon, I leave you to examine.
[Blew, Yellow, Purple, Blew; Green, Purple, Blew, Yellow, Red; Purple, Blew, Yellow and Blew, Yellow, Blew, Purple, Green mixt, Yellow, Red, Blew, Green, Yellow, Red, Purple, Green.]
5. The Atomiſts of Old, and ſome Learned men of late, have attempted to explicate the variety of Colours in Opacous bodies from the various Figures of their Superficial parts; the attempt is Ingenious, and the Doctrine ſeems partly True, but I confeſs I think there are divers other things that muſt be taken in as concurrent to produce thoſe differing forms of Aſperity, whereon the Colours of Opacous bodies ſeem to depend. To declare this a little, we muſt aſſume, that the Surfaces of all ſuch Bodies how Smooth or polite ſoever they may appear to our Dull Sight and Touch, are exactly ſmooth only in a popular, or at moſt in a Phyſical ſenſe, but not in a ſtrict and rigid ſenſe.
6. This, excellent Microſcopes ſhew us in many Bodies, that ſeem Smooth to our naked Eyes; and this not only as to the little Hillocks or Protuberancies that ſwell [pg 27] above that which may be conceiv'd to be the Plain or Level of the conſider'd Surface, for it is obvious enough to thoſe that are any thing converſant with ſuch Glaſſes, but as to numerous Depreſſions beneath that Level, of which ſort of Cavities by the help of a Microſcope, which the greateſt Artificer that makes them, judges to be the greateſt Magnifying Glaſs in Europe, except one that equals it, we have on the Surface of a thin piece of Cork that appear'd ſmooth to the Eye, obſerv'd about ſixty in a Row, within the length of leſs then an 31 and 32 part of an Inch, (for the Glaſs takes in no longer a ſpace at one view) and theſe Cavities (which made that little piece of Cork look almoſt like an empty Honey-comb) were not only very diſtinct, and figur'd like one another, but of a conſiderable bigneſs, and a ſcarce credible depth; inſomuch that their diſtinct ſhadows as well as ſides were plainly diſcern'd and eaſiy to be reckon'd, and might have been well diſtinguiſh'd, though they had been ten times leſſer than they were; which I thought it not amiſs to mention to you Pyrophilus upon the by, that you may thence make ſome Eſtimate, what a ſtrange Inequality, and what a multitude of little Shades, there may really be, in a [pg 28] ſcarce ſenſible part of the Phyſical ſuperficies, though the naked Eye ſees no ſuch matter. And as Excellent Microſcopes ſhew us this Ruggedneſs in many Bodies that paſs for Smooth, ſo there are divers Experiments, though we muſt not now ſtay to urge them, which ſeem to perſwade us of the ſame thing as to the reſt of ſuch Bodies as we are now treating off; So, that there is no ſenſible part of an Opacous body, that may not be conceiv'd to be made up of a multitude of ſingly inſenſible Corpuſcles, but in the giving theſe ſurfaces that diſpoſition, which makes them alter the Light that reflects thence to the Eye after the manner requiſite to make the Object appear Green, Blew, &c. the Figures of theſe Particles have a great, but not the only ſtroak. 'Tis true indeed that the protuberant Particles may be of very great variety of Figures, Sphærical, Elliptical, Conical, Cylindrical, Polyedrical, and ſome very irregular, and that according to the Nature of theſe, and the ſituation of the Lucid body, the Light muſt be variouſly affected, after one manner from Surfaces (I now ſpeak of Phyſical Surfaces) conſiſting of Sphaerical, and in another from thoſe that are made up of Conical or Cylindrical Corpuſcles; ſome [pg 29] being fitted to reflect more of the incident Beams of Light, others leſs, and ſome towards one part, others towards another. But beſides this difference of Shape, there may be divers other things that may eminently concurr to vary the forms of Aſperity that Colours ſo much depend on. For, willingly allowing the Figure of the Particles in the firſt place, I conſider ſecondly, that the ſuperficial Corpuſcles, if I may ſo call them, may be bigger in one Body, and leſs in another, and conſequently fitted to allay the Light falling on them with greater ſhades. Next, the protuberant Particles may be ſet more or leſs cloſe together, that is, there may be a greater or a ſmaller number of them within the compaſs of one, than within the compaſs of another ſmall part of the Surface of the ſame Extent, and how much theſe Qualities may ſerve to produce Colour may be ſomewhat gueſs'd at, by that which happens in the Agitation of Water; for if the Bubbles that are thereby made be Great, and but Few, the Water will ſcarce acquire a ſenſible Colour, but if it be reduc'd to a Froth, conſiſting of Bubbles, which being very Minute and Contiguous to each other, are a multitude of them crowded into a narrow Room, the Water (turned to [pg 30] Froth) does then exhibit a very manifeſt White Colour,3 (to which theſe laſt nam'd Conditions of the Bubbles do as well as their Convex figure contribute) and that for Reaſons to be mention'd anon. Beſides, it is not neceſſary that the Superficial particles that exhibit one Colour, ſhould be all of them Round, or all Conical, or all of any one Shape, but Corpuſcles of differing Figures may be mingled on the Surface of the Opacous Body, as when the Corpuſcles that make a Blew colour, and thoſe that make a Yellow, come to be Accurately and Skilfully mix'd, they make up a Green, which though it ſeem one ſimple Colour, yet in this caſe appears to be made by Corpuſcles of very differing Kinds, duely commix'd. Moreover the Figure and Bigneſs of the little Depreſſions, Cavities, Furrows or Pores intercepted betwixt theſe protuberant Corpuſcles, are as well to be conſider'd as the Sizes and Shapes of the Corpuſcles themſelves: For we may conceive the Phyſical ſuperficies of a Body, where (as we ſaid) its Colour does as it were reſide, to be cut Tranſverſly by a Mathematical plain, which you know is conceiv'd to be without any Depth or Thickneſs at all, and then as [pg 31] ſome parts of the Phyſical Superficies will be Protuberant; or ſwell above this laſt plain, ſo others may be depreſs'd beneath it; as (to explane my ſelf by a groſs Compariſon) in divers places of the Surface of the Earth, there are not only Neighbouring Hills, Trees, &c. that are rais'd above the Horizontal Level of the Valley, but Rivers, Wells, Pits and other Cavities that are depreſs'd beneath it, and that ſuch Protuberant and Concave parts of a Surface may remit the Light ſo differingly, as much to vary a Colour, ſome examples and other things, that we ſhall hereafter have occaſion to take notice off in this Tract, will ſufficiently declare, till when, it may ſuffice to put you in mind, that of two Flat-ſides of the ſame piece of, for example, red Marble, the one being diligently Poliſhed, and the other left to its former Roughneſs, the differing degrees or ſorts of Aſperity, for the ſide that is ſmooth to the Touch wants not its Roughneſs, will ſo diverſifie the Light reflected from the ſeveral Plains to the Eye, that a Painter would employ two differing Colours to repreſent them.
7. And I hope, Pyrophilus, you will not think it ſtrange or impertinent, that I employ in divers paſſages of theſe Papers, [pg 32] examples drawn from Bodies and Shadows far more Groſs, than thoſe minute Protuberances and ſhady Pores on which in moſt caſes the Colour of a Body as 'tis an Inherent Quality or Diſpoſition of its Surface, ſeems to depend. For ſometimes I employ ſuch Examples, rather to declare my Meaning, than prove my Conjecture; things, whom their Smallneſs makes Inſenſible, being better repreſented to the Imagination by ſuch familiar Objects, as being like them enough in other reſpects, are of a Viſible bulk. And next, though the Beams of Light are ſuch ſubtil Bodies, that in reſpect of them, even Surfaces that are ſenſibly Smooth, are not exactly ſo, but have their own degree of Roughneſs, conſiſting of little Protuberances and Depreſſions; and though conſequently ſuch Inequalities may ſuffice to give Bodies differing Colours, as we ſee in Marble that appears White or Black, or Red or Blew, even when the moſt carefully Poliſh'd, yet 'tis plain by the late Inſtance of Red Marble, and many others, that even bigger Protuberances and greater Shades may likewiſe ſo Diverſifie the Roughneſs of a Bodies Superficies, as manifeſtly to concurr to the varying of its Colour, whereby ſuch Examples appear to be proper enough [pg 33] to be employ'd in ſuch a Subject as we have now in hand. And having hinted thus much on this Occaſion, I now proceed.
8. The Situation alſo of the Superficial particles is conſiderable, which I diſtinguiſh into the Poſture of the ſingle Corpuſcles, in reſpect of the Light, and of the Eye, and the Order of them in reference alſo to one another; for a Body may otherwiſe reflect the Light, when its Superficial particles are more erected upon the Plain that may be conceiv'd to paſs along their Baſis, and when the Points or Extremes of ſuch Particles are Obverted to the Eye, than when thoſe Particles are ſo Inclin'd, that their Sides are in great part Diſcernable, as the Colour of Pluſh or Velvet will appear Vary'd to you, if you carefully ſtroak part of it one way, and part of it another, the poſture of the particular Thrids, in reference to the Light, or the Eye, becoming thereby different. And you may obſerve in a Field of ripe Corn blown upon by the Wind, that there will appear as it were Waves of a Colour (at leaſt Gradually) differing from that of the reſt of the Field, the Wind by Depreſſing ſome of the Ears, and not at the ſame time others, making the one Reflect more from [pg 34] the Lateral and Strawy parts, than do the reſt. And ſo, when Doggs are ſo angry, as to Erect the Hairs upon their Necks, and upon ſome other parts of their Bodies, thoſe Parts ſeem to acquire a Colour vary'd from that which the ſame Hairs made, when in their uſual Poſture they did farr more ſtoop. And that the Order wherein the Superficial Corpuſcles are Rang'd is not to be neglected, we may gueſs by turning of Water into Froth, the beating of Glaſs, and the ſcraping of Horns, in which caſes the Corpuſcles that were before ſo marſhall'd as to be Perſpicuous, do by the troubling of that Order become Diſpos'd to terminate and reflect more Light, and thereby to appear Whitiſh. And there are other ways in which the Order of the Protuberant parts, in reference to the Eye, may much contribute to the appearing of a particular Colour, for I have often obſerv'd, that when Peaſe are Planted, or Set in Parallel Lines, and are Shot up about half a Foot above the Surface of the Ground, by looking on the Field or Plot of Ground from that part towards which the Parallel Lines tended, the greater part of the Ground by farr would appear of its own dirty Colour, but if I look'd upon it Tranſverſly, the Plot [pg 35] would appear very Green, the upper parts of the Peaſe hindering the intercepted parts of the Ground, which as I ſaid retain'd their wonted Colour, from being diſcover'd by the Eye. And I know not, Pyrophilus, whether I might not add, that even the Motion of the Small Parts of a Viſible Object may in ſome caſes contribute, though it be not ſo eaſie to ſay how, to the Producing or the Varying of a Colour; for I have ſeveral times made a Liquor, which when it has well ſettled in a cloſe Vial, is Tranſparent and Colourleſs, but as ſoon as the Glaſs is unſtopp'd, begins to fly away very plentifully in a White and Opacous fume; and there are other Bodies, whoſe Fumes, when they fill a Receiver, would make one ſuſpect it contains Milk, and yet when theſe Fumes ſettle into a Liquor, that Liquor is not White, but Tranſparent; And ſuch White Fumes I have ſeen afforded by unſtopping a Liquor I know, which yet is it ſelf Diaphanous and Red; Nor are theſe the only Inſtances of this Kind, that our Tryals can ſupply us with. And if the Superficial Corpuſcles be of the Groſſer ſort, and be ſo Framed, that their differing Sides or Faces may exhibit differing Colours, then the Motion or Reſt of thoſe Corpuſcles may be [pg 36] conſiderable, as to the Colour of the Superficies they compoſe, upon this account, that ſometimes more, ſometimes fewer of the Sides diſpos'd to exhibit ſuch a Colour may by this means become or continue more Obverted to the Eye than the reſt, and compoſe a Phyſical Surface, that will be more or leſs ſenſibly interrupted; As, to explane my meaning, by propoſing a groſs Example, I remember, that in ſome ſorts of Leavy Plants thick ſet by one another, the two ſides of whoſe Leaves were of ſomewhat differing Colours, there would be a notable Diſparity as to Colour, if you look'd upon them both when the Leaves being at Reſt had their upper and commonly expos'd ſides Obverted to the Eye, and when a breath of Wind paſſing thorow them, made great Numbers of the uſually Hidden ſides of the Leaves become conſpicuous. And though the Little Bodies, we were lately ſpeaking of, may Singly and Apart ſeem almoſt Colourleſs, yet when Many of them are plac'd by one another, ſo near, that the Eye does not eaſily diſcern an Interruption, within a ſenſible ſpace, they may exhibit a Colour; as we ſee, that though a Slendereſt Thrid of Dy'd Silk do's, whilſt look'd on Single, ſeem almoſt quite Devoyd of Redneſs, (for inſtance) [pg 37] yet when numbers of theſe Thrids are brought together into one Skein, their Colour becomes notorious.
9. But the ſame Occaſion that invited me to ſay what I have mention'd concerning the Leaves of Trees, invites me alſo to give you ſome account of what happens in Changeable Taffities, where we ſee differing Colours, as it were, Emerge and Vaniſh upon the Ruffling of the ſame piece of Silk: As I have divers times with Pleaſure obſerv'd, by the help of ſuch a Microſcope, as, though it do not very much Magnifie the Object, has in recompence this great Conveniency, that you may eaſily, as faſt as you pleaſe, remove it from one part to another of a Large Object, of which the Glaſs taking a great part at once, you may thereby preſently Survey the Whole. Now by the help of ſuch a Microſcope I could eaſily (as I began to ſay) diſcern, that in a piece of Changeable Taffity, (that appear'd, for Inſtance, ſometimes Red, and ſometimes Green) the Stuff was compos'd of Red thrids and Green, paſſing under and over each other, and croſſing one another in almoſt innumerable points; and if I look'd through the Glaſs upon any conſiderable portion of the Stuff, that (for example ſake) to the [pg 38] naked Eye appear'd to be Red, I could plainly ſee, that in that Poſition, the Red thrids were Conſpicuous, and reflected a vivid Light; and though I could alſo perceive, that there were Green ones, yet by reaſon of their diſadvantagious Poſition in the Phyſical Surface of the Taffity, they were in part hid by the more Protuberant Thrids of the other Colour; and for the ſame cauſe, the Reflection from as much of the Green as was diſcover'd, was comparatively but Dim and Faint. And if, on the contrary, I look'd through the Microſcope upon any part that appear'd Green, I could plainly ſee that the Red thrids were leſs fully expos'd to the Eye, and obſcur'd by the Green ones, which therefore made up the Predominant Colour. And by obſerving the Texture of the Silken Stuff, I could eaſiſy ſo expoſe the Thrids either of the one Colour or of the other to my Eye, as at pleaſure to exhibit an apparition of Red or Green, or make thoſe Colours ſucceed one another: So that, when I obſerv'd their Succeſſion by the help of the Glaſs, I could mark how the Predominant Colour did as it were ſtart out, when the Thrids that exhibited it came to be advanagiouſly plac'd; And by making little Folds in the Stuff after a certain manner, [pg 39] the Sides that met and terminated in thoſe Folds, would appear to the naked Eye, one of them Red, and the other Green. When Thrids of more than two differing Colours chance to be Interwoven, the reſulting changeableneſs of the Taffity may be alſo ſomewhat different. But I chooſe to give an Inſtance in the Stuff I have been ſpeaking off, becauſe the mixture being more Simple, the way whereby the Changeableneſs is produc'd, may be the more eaſily apprehended: and though Reaſon alone might readily enough lead a conſidering Man to gueſs at the Explication, in caſe he knew how Changeable Taffities are made: yet I thought it not impertinent to mention it, becauſe both Scholars and Gentlemen are wont to look upon the Inquiry into Manufactures, as a Mechanick imployment, and conſequently below Them; and becauſe alſo with ſuch a Microſcope as I have been mentioning, the diſcovery is as well Pleaſant as Satisfactory, and may afford Hints of the Solution of other Phænomena of Colours. And it were not amiſs, that ſome diligent Inquiry were made, whether the Microſcope would give us an account of the Variableneſs of Colour, that is ſo Conſpicuous and ſo Delightfull in Mother of Pearl, in Opalls, and ſome [pg 40] other reſembling Bodies: For though I remember I did formerly attempt ſomething of that Kind (fruitleſly enough) upon Mother of Pearl, yet not having then the advantage of my beſt Microſcope, nor ſome Conveniences that might have been wiſh'd, I leave it to you, who have better Eyes, to try what you can do further; ſince 'twill be Some diſcovery to find, that, in this caſe, the beſt Eyes and Microſcopes themſelves can make None.
10. I confeſs, Pyrophilus, that a great part of what I have deliver'd, (or propos'd rather) concerning the differing forms of Aſperity in Bodies, by which Differences the incident Light either comes to be Reflected with more or leſs of Shade, and with that Shade more or leſs Interrupted, or elſe happens to be alſo otherwiſe Modify'd or Troubl'd, is but Conjectural. But I am not ſure, that if it were not for the Dullneſs of our Senſes, either theſe or ſome other Notions of Kin to them, might be better Countenanc'd; for I am apt to ſuſpect, that if we were Sharp ſighted enough, or had ſuch perfect Microſcopes, as I fear are more to be wiſh'd than hop'd for, our promoted Senſe might diſcern in the Phyſical Surfaces of Bodies, both a great many latent Ruggidneſſes, and the particular [pg 41] Sizes, Shapes, and Situations of the extremely little Bodies that cauſe them, and perhaps might perceive among other Varieties that we now can but imagine, how thoſe little Protuberances and Cavities do Interrupt and Dilate the Light, by mingling with it a multitude of little and ſingly undiſcernable Shades, though ſome of them more, and ſome of them leſs Minute, ſome leſs, and ſome more Numerous; according to the Nature and Degree of the particular Colour we attribute to the Viſible Object; as we ſee, that in the Moon we can with Excellent Teleſcopes diſcern many Hills and Vallies, and as it were Pits and other Parts, whereof ſome are more, and ſome leſs Vividly illuſtrated, and others have a fainter, others a deeper Shade, though the naked Eye can diſcern no ſuch matter in that Planet. And with an Excellent Microſcope, where the Naked Eye did ſee but a Green powder, the Aſſisted Eye as we noted above, could diſcern particular Granules, ſome of them of a Blew, and ſome of them of a Yellow colour, which Corpuſcles we had beforehand caus'd to be exquiſitly mix'd to compound the Green.
11. And, Pyrophilus, that you may not think me altogether extravagant in what I [pg 42] have ſaid of the Poſſibility, (for I ſpeak of no more) of diſcerning the differing forms of Aſperity in the Surfaces of Bodies of ſeveral Colours, I'l here ſet down a Memorable particular that chanc'd to come to my Knowledge, ſince I writ a good part of this Eſſay; and it is this. Meeting caſually the other Day with the deſervedly Famous4 Dr. J. Finch, Extraordinary Anatomiſt to that Great Patron of the Virtuoſi, the now Great Duke of Toſcany, and enquiring of this Ingenious Perſon, what might be the chief Rarity he had ſeen in his late return out of Italy into England, he told me, it was a Man at Maeſtricht in the Low-Countrys, who at certain times can diſcern and diſtinguiſh Colours by the Touch with his Fingers. You'l eaſily Conclude, that this is farr more ſtrange, than what I propos'd but as not Impoſſible; ſince the Senſe of the Retina ſeeming to be much more Tender and quick than that of thoſe Groſſer Filaments, Nerves or Membranes of our Fingers, wherewith we uſe to handle Groſs and Hard Bodies, it ſeems ſcarce credible, that any Accuſtomance, or Diet, or peculiarity of Conſtitution, ſhould enable a Man to diſtinguiſh [pg 43] with ſuch Groſs and Unſuitable Organs, ſuch Nice and Subtile Differences as thoſe of the forms of Aſperity, that belong to differing Colours, to receive whoſe Languid and Delicate Impreſſions by the Intervention of Light, Nature ſeems to have appointed and contexed into the Retina the tender and delicate Pith of the Optick Nerve. Wherefore I confeſs, I propos'd divers Scruples, and particularly whether the Doctor had taken care to bind a Napkin or Hankerchief over his Eyes ſo carefully, as to be ſure he could make no uſe of his Sight, though he had but Counterfeited the want of it, to which I added divers other Queſtions, to ſatisfie my Self, whether there were any Likelihood of Colluſion or other Tricks. But I found that the Judicious Doctor having gone farr out of his way, purpoſely to ſatisfie Himſelf and his Learned Prince about this Wonder, had been very Watchfull and Circumſpect to keep Himſelf from being Impos'd upon. And that he might not through any miſtake in point of Memory mis-inform Me, he did me the Favour at my Requeſt, to look out the Notes he had Written for his Own and his Princes Information, the ſumm of which Memorials, as far as we ſhall mention them here, was this, That the Doctor [pg 44] having been inform'd at Utrecht, that there Lived one at ſome Miles diſtance from Maestricht, who could diſtinguiſh Colours by the Touch, when he came to the laſt nam'd Town, he ſent a Meſſenger for him, and having Examin'd him, was told upon Enquiry theſe Particulars:
That the Man's name was John Vermaaſen, at that time about 33 Years of Age; that when he was but two years Old, he had the Small Pox, which rendred him abſolutely Blind: That at this preſent he is an Organiſt, and ſerves that Office in a publick Quire.
That the Doctor diſcourſing with him over Night, the Blind man affirm'd, that he could diſtinguiſh Colours by the Touch, but that he could not do it, unleſs he were Faſting; Any quantity of Drink taking from him that Exquiſitneſs of Touch, which is requiſite to ſo Nice a Senſation.
That hereupon the Doctor provided againſt the next Morning ſeven pieces of Ribbon, of theſe ſeven Colours, Black, White, Red, Blew, Green, Yellow, and Gray, but as for mingled Colours, this Vermaaſen would not undertake to diſcern them, though if offer'd, he would tell that they were Mix'd.
That to diſcern the Colour of the Ribbon, [pg 45] he places it betwixt the Thumb and the Fore-finger, but his moſt exquiſite perception was in his Thumb, and much better in the right Thumb than in the left.
That after the Blind man had four or five times told the Doctor the ſeveral Colours, (though Blinded with a Napkin for fear he might have ſome Sight) the Doctor found he was twice miſtaken, for he call'd the White Black, and the Red Blew, but ſtill, he, before his Errour, would lay them by in Pairs, ſaying, that though he could eaſily diſtinguiſh them from all others, yet thoſe two Pairs were not eaſily diſtinguiſh'd amongſt themſelves, whereupon the Doctor deſir'd to be told by him what kind of Diſcrimination he had of Colours by his Touch, to which he gave a reply, for whoſe ſake chiefly I inſert all this Narrative in this place, namely, That all the difference was more or leſs Aſperity, for ſays he, (I give you the Doctor's own words) Black feels as if you were feeling Needles points, or ſome harſh Sand, and Red feels very Smooth.
That the Doctor having deſir'd him to tell in Order the difference of Colours to his Touch, he did as follows;
Black and White are the moſt aſperous [pg 46] or unequal of all Colours, and ſo like, that 'tis very hard to diſtinguiſh them, but Black is the moſt Rough of the two, Green is next in Aſperity, Gray next to Green in Aſperity, Yellow is the fifth in degree of Aſperity, Red and Blew are ſo like, that they are as hard to diſtinguiſh as Black and White, but Red is ſomewhat more Aſperous than Blew, ſo that Red has the ſixth place, and Blew the ſeventh in Aſperity.
12. To theſe Informations the Obliging Doctor was pleas'd to add the welcome preſent of three of thoſe very pieces of Ribbon, whoſe Colours in his preſence the Blind man had diſtinguiſhed, pronouncing the one Gray, the other Red, and the third Green, which I keep by me as Rarities, and the rather, becauſe he fear'd the reſt were miſcarry'd.
13. Before I ſaw the Notes that afforded me the precedent Narrative, I confeſs I ſuſpected this man might have thus diſcriminated Colours, rather by the Smell than by the Touch; for ſome of the Ingredients imployed by Dyers to Colour things, have Sents, that are not ſo Languid, nor ſo near of Kin, but that I thought it not impoſſible that a very Critical Noſe might diſtinguiſh them, and this I the rather ſuſpected, becauſe he requir'd, that the Ribbons, [pg 47] whoſe Colours he was to Name, ſhould be offer'd him Faſting in the morning; for I have obſerv'd in Setting Doggs, that the feeding of them (especially with ſome ſorts of Aliments) does very much impair the exquiſite ſent of their Noſes. And though ſome of the foregoing particulars would have prevented that Conjecture, yet I confeſs to you (Pyrophilus) that I would gladly have had the Opportunity of Examining this Man my ſelf, and of Queſtioning him about divers particulars which I do not find to have been yet thought upon. And though it be not incredible to me, that ſince the Liquors that Dyers imploy to tinge, are qualifi'd to do ſo by multitudes of little Corpuſcles of the Pigment or Dying ſtuff, which are diſſolved and extracted by the Liquor, and ſwim to and fro in it, thoſe Corpuſcles of Colour (as the Atomiſts call them) inſinuating themſelves into, and filling all the Pores of the Body to be Dyed, may Aſperate its Superficies more or leſs according to the Bigneſs and Texture of the Corpuſcles of the Pigment; yet I can ſcarce believe, that our Blind man could diſtinguiſh all the Colours he did, meerly by the Ribbons having more or leſs of Aſperity, ſo that I cannot but think, notwithſtanding this Hiſtory, that the Blind man [pg 48] diſtinguiſh'd Colours not only by the Degrees of Aſperity in the Bodies offer'd to him, but by Forms of it, though this (latter) would perhaps have been very difficult for him to make an Intelligible mention of, becauſe thoſe Minute diſparities having not been taken notice of by men for want of touch as Exquiſite as our Blind Mans, are things he could not have Intelligibly expreſs'd, which will eaſily ſeem Probable, if you conſider, that under the name of Sharp, and Sweet, and Sour, there are abundance of, as it were, immediate peculiar Reliſhes or Taſts in differing ſorts of Wine, which though Critical and Experienc'd Palats can eaſily diſcern themſelves cannot make them be underſtood by others, ſuch Minute differences not having hitherto any Diſtinct names aſſign'd them. And it ſeems that there was ſomthing in the Forms of Aſperity that was requiſite to the Diſtinction of Colours, beſides the Degree of it, ſince he found it ſo difficult to diſtinguſh Black and White from one another, though not from other Colours. For I might urge, that he ſeems not conſonant to himſelf about the Red, which as you have ſeen in one place, he repreſents as ſomewhat more Aſperous than the Blew; and in another, very Smooth: But becauſe he ſpeaks of this Smoothneſs in that place, [pg 49] where he mentions the Roughneſs of Black, we may favourably preſume that he might mean but a comparative Smoothneſs; and therefore I ſhall not Inſiſt on this, but rather Countenance my Conjecture by this, that he found it ſo Difficult, not only, to Diſcriminate Red and Blew, (though the firſt of our promiſcuous Experiments will inform you, that the Red reflects by great Odds more Light than the other) but alſo to diſtinguiſh Black and White from one another, though not from other Colours. And indeed, though in the Ribbonds that were offer'd him, they might be almoſt equally Rough, yet in ſuch ſlender Corpuſcles as thoſe of Colour, there may eaſily enough be Conceiv'd, not only a greater Cloſeneſs of Parts, or elſe Paucity of Protuberant Corpuſcles, and the little extant Particles may be otherwiſe Figur'd, and Rang'd in the White than in the Black, but the Cavities may be much Deeper in the one than the other.
14. And perhaps, (Pyrophilus) it may prove ſome Illuſtration of what I mean, and help you to conceive how this may be, if I Repreſent, that where the Particles are ſo exceeding Slender, we may allow the Parts expos'd to the Sight and Touch to be a little Convex in compariſon of the Erected [pg 50] Particle of Black Bodies, as if there were Wyres I know not how many times Slenderer than a Hair: whether you ſuppoſe them to be Figur'd like Needles, or Cylindrically, like the Hairs of a Bruſh, with Hemiſphærical (or at leaſt Convex) Tops, they will be ſo very Slender, and conſequently the Points both of the one ſort and the other ſo very Sharp, that even an exquiſite Touch will be able to diſtinguiſh no greater Difference between them, than that which our Blind man allow'd, when comparing Black and White Bodies, he ſaid, that the latter was the leſs Rough of the two. Nor is every Kind of Roughneſs, though Senſible enough, Inconſiſtent with Whiteneſs, there being Caſes, wherein the Phyſical Superficies of a Body is made by the ſame Operation both Rough and white, as when the Level Surface of clear Water being by agitation Aſperated with a multitude of Unequal Bubbles, do's thereby acquire a Whiteneſs; and as a Smooth piece of Glaſs, by being Scratch'd with a Diamond, do's in the Aſperated part of its Surface diſcloſe the ſame Colour. But more (perchance) of this elſewhere.
15. And therefore, we ſhall here paſs by the Queſtion, whether any thing might [pg 51] be conſider'd about the Opacity of the Corpuſcles of Black Pigments, and the Comparative Diaphaneity of thoſe of many White Bodies, apply'd to our preſent Caſe; and proceed, to repreſent, That the newly mention'd Exiguity and Shape of the extant Particles being ſuppos'd, it will then be conſiderable what we lately but Hinted, (and therefore muſt now ſomewhat Explane) That the Depth of the little Cavities, intercepted between the extant Particles, without being ſo much greater in Black Bodies than in White ones, as to be perceptibly ſo to the Groſs Organs of Touch, may be very much greater in reference to their Diſpoſition of Reflecting the imaginary ſubtile Beams of Light. For in Black Bodies, thoſe Little intercepted Cavities, and other Depreſſions, may be ſo Figur'd, ſo Narrow and ſo Deep, that the incident Beams of Light, which the more extant Parts of the Phyſical Superficies are diſpos'd to Reflect inwards, may be Detain'd there, and prove unable to Emerge; whilſt in a White Body, the Slender Particles may not only by their Figure be fitted to Reflect the Light copiouſly outwards, but the intercepted Cavities being not Deep, nor perhaps very Narrow, the Bottoms of them may be ſo Conſtituted, as to [pg 52] be fit to Reflect outwards much of the Light that falls even upon Them; as you may poſſibly better apprehend, when we ſhall come to treat of Whiteneſs and Blackneſs. In the mean time it may ſuffice, that you take Notice with me, that the Blind mans Relations import no neceſſity of Concluding, that, though, becauſe, according to the Judgment of his Touch, Black was the Rougheſt, as it is the Darkeſt of Colours, therefore White, which (according to us) is the Lighteſt, ſhould be alſo the Smootheſt: ſince I obſerve, that he makes Yellow to be two Degrees more Aſperous than Blew, and as much leſs Aſperous than Green; whereas indeed, Yellow do's not only appear to the Eye a Lighter Colour than Blew, but (by our firſt Experiment hereafter to be mention'd) it will appear, that Yellow reflected much more Light than Blew, and manifeſtly more than Green, (which we need not much wonder at, ſince in this Colour and the two others (Blew and Yellow) 'tis not only the Reflected Light that is to be conſidered, ſince to produce both theſe, Refraction ſeems to Intervene, which by its Varieties may much alter the Caſe:) which both ſeems to ſtrengthen the Conjecture I was formerly propoſing, that there was ſomething elſe [pg 53] in the Kinds of Aſperity, as well as in the Degrees of it, which enabled our Blind man to Diſcriminate Colours, and do's at leaſt ſhow, that we cannot in all Caſes from the bare Difference in the Degrees of Aſperity betwixt Colours, ſafely conclude, that the Rougher of any two always Reflects the leaſt Light.
16. But this notwithſtanding, (Pyrophilus) and what ever Curioſity I may have had to move ſome Queſtions to our Sagacious Blind man, yet thus much I think you will admit us to have gain'd by his Teſtimony, that ſince many Colours may be felt with the Circumſtances above related, the Surfaces of ſuch Coloured Bodies muſt certainly have differing Degrees, and in all probability have differing Forms or Kinds of Aſperity belonging to them, which is all the Uſe that my preſent attempt obliges me to make of the Hiſtory above deliver'd, that being ſufficient to prove, that Colour do's much depend upon the Diſpoſition of the Superficial parts of Bodies, and to ſhew in general, wherein 'tis probable that ſuch a Diſpoſition do's (principally at leaſt) conſiſt.
17. But to return to what I was ſaying before I began to make mention of our Blind Organiſt, what we have deliver'd [pg 54] touching the cauſes of the ſeveral Forms or Aſperity that may Diverſifie the Surfaces of Colour'd Bodies, may perchance ſomewhat aſſiſt us to make ſome Conjectures in the general, at ſeveral of the ways whereby 'tis poſſible for the Experiments hereafter to be mention'd, to produce the ſuddain changes of Colours that are wont to be Conſequent upon them; for moſt of theſe Phænomena being produc'd by the Intervention of Liquors, and theſe for the moſt part abounding with very Minute, Active, and Variouſly Figur'd Saline Corpuſcles, Liquors ſo Qualify'd may well enough very Nimbly after the Texture of the Body they are imploy'd to Work upon, and ſo may change the form of Aſperity, and thereby make them Remit to the Eye the Light that falls on them, after another manner than they did before, and by that means Vary the Colour, ſo farr forth as it depends upon the Texture or Diſpoſition of the Seen Parts of the Object, which I ſay, Pyrophilus, that you may not think I would abſolutely exclude all other ways of Modifying the Beams of Light between their Parting from the Lucid Body, and their Reception into the common Senſory.
18. Now there ſeem to me divers ways, [pg 55] by which we may conceive that Liquors may Nimbly alter the Colour of one another, and of other Bodies, upon which they Act, but my preſent haſte will allow me to mention but ſome of them, without Inſiſting ſo much as upon thoſe I ſhall name.
19. And firſt, the Minute Corpuſcles that compoſe a Liquor may early inſinuate themſelves into thoſe Pores of Bodies, whereto their Size and Figure makes them Congruous, and theſe Pores they may either exactly Fill, or but Inadequately, and in this latter Caſe they will for the moſt part alter the Number and Figure, and always the Bigneſs of the former Pores. And in what capacity ſoever theſe Corpuſcles of a Liquor come to be Lodg'd or Harbour'd in the Pores that admit them, the Surface of the Body will for the moſt part have its Aſperity alter'd, and the Incident Light that meets with a Groſſer Liquor in the little Cavities that before contain'd nothing but Air, or ſome yet Subtiler Fluid, will have its Beams either Refracted, or Imbib'd, or elſe Reflected more or leſs Interruptedly, than they would be, if the Body had been Unmoiſtned, as we ſee, that even fair Water falling on white Paper, or Linnen, and divers other Bodies [pg 56] apt to ſoak it in, will for ſome ſuch Reaſons as thoſe newly mention'd, immediately alter the Colour of them, and for the moſt part make it Sadder than that of the Unwetted Parts of the ſame Bodies. And ſo you may ſee, that when in the Summer the High-ways are Dry and Duſty, if there falls ſtore of Rain, they will quickly appear of a much Darker Colour than they did before, and if a Drop of Oyl be let fall upon a Sheet of White Paper, that part of it, which by the Imbibition of the Liquor acquires a greater Continuity, and ſome Tranſparency, will appear much Darker than the reſt, many of the Incident Beams of Light being now Tranſmitted, that otherwiſe would be Reflected towards the Beholders Eyes.
20. Secondly, A Liquor may alter the Colour of a Body by freeing it from thoſe things that hindred it from appearing in its Genuine Colour; and though this may be ſaid to be rather a Reſtauration of a Body to its own Colour, or a Retection of its native Colour, than a Change, yet ſtill there Intervenes in it a change of the Colour which the Body appear'd to be of before this Operation. And ſuch a change a Liquor may work, either by Diſſolving, or Corroding, or by ſome ſuch way of [pg 57] carrying off that Matter, which either Veil'd or Diſguis'd the Colour that afterwards appears. Thus we reſtore Old pieces of Dirty Gold to a clean and nitid Yellow, by putting them into the Fire, and into Aqua-fortis, which take off the adventitious Filth that made that pure Metall look of a Dirty Colour. And there is alſo an eaſie way to reſtore Silver Coyns to their due Luſtre, by fetching off that which Diſcolour'd them. And I know a Chymical Liquor, which I employ'd to reſtore pieces of Cloath ſpotted with Greaſe to their proper Colour, by Imbibing the Spotted part with this Liquor, which Incorporating with the Greaſe, and yet being of a very Volatile Nature, does eaſily carry it away with it Self. And I have ſometimes try'd, that by Rubbing upon a good Touch-ſtone a certain Metalline mixture ſo Compounded, that the Impreſſion it left upon the Stone appear'd of a very differing Colour from that of Gold, yet a little of Aqua-fortis would in a Trice make the Golden Colour diſcloſe it ſelf, by Diſſolving the other Metalline Corpuſcles that conceal'd thoſe of the Gold, which you know that Menstruum will leave Untouch'd.
21. Thirdly, A Liquor may alter the [pg 58] Colour of a Body by making a Comminution of its Parts, and that principally two ways, the firſt by Diſjoyning and Diſſipating thoſe Cluſters of Particles, if I may ſo call them, which ſtuck more Looſely together, being faſtned only by ſome more eaſily Diſſoluble Ciment, which ſeems to be the Caſe of ſome of the following Experiments, where you'l find the Colour of many Corpuſcles brought to cohere by having been Precipitated together, Deſtroy'd by the Affuſion of very peircing and inciſive Liquors. The other of the two ways I was ſpeaking of, is, by Dividing the Groſſer and more Solid Particles into Minute ones, which will be always Leſſer, and for the moſt part otherwiſe Shap'd than the Entire Corpuſcle ſo Divided, as it will happen in a piece of Wood reduc'd into Splinters or Chips, or as when a piece of Chryſtal heated red Hot and quench'd in Cold water is crack'd into a multitude of little Fragments, which though they fall not aſunder, alter the Diſpoſition of the Body of the Chryſtal, as to its manner of Reflecting the Light, as we ſhall have Occaſion to ſhew hereafter.
22. There is a fourth way contrary to the third, whereby a Liquor may change the Colour of another Body, eſpecially of [pg 59] another Fluid, and that is, by procuring the Coalition of ſeveral Particles that before lay too Scatter'd and Diſpers'd to exhibit the Colour that afterwards appears. Thus ſometimes when I have had a Solution of Gold ſo Dilated, that I doubted whether the Liquor had really Imbib'd any true Gold or no, by pouring in a little Mercury, I have been quickly able to ſatisfie my Self, that the Liquor contain'd Gold, that Mettall after a little while Cloathing the Surface of the Quick-ſilver, with a Thin Film of its own Livery. And chiefly, though not only by this way of bringing the Minute parts of Bodies together in ſuch Numbers as to make them become Notorious to the Eye, many of theſe Colours ſeem to be Generated which are produc'd by Precipitations, eſpecially by ſuch as are wont to be made with fair Water, as when Reſinous Gumms diſſolv'd in Spirit of Wine, are let fall again, if the Spirit be Copiouſly diluted with that weakning Liquor. And ſo out of the Rectify'd and Tranſparent Butter of Antimony, by the bare Mixture of fair Water, there will be plentifully Precipitated that Milk-white Subſtance, which by having its Looſer Salts well waſh'd off, is turn'd into that Medicine, which Vulgar Chymiſts are pleas'd to call Mercurius Vitæ.
[pg 60]23. A fifth way, by which a Liquor may change the Colour of a Body, is, by Diſlocating the Parts, and putting them out of their former Order into another, and perhaps alſo altering the Poſture of the ſingle Corpuſcles as well as their Order or Situation in reſpect of one another. What certain Kinds of Commotion or Diſlocation of the Parts of a Body may do towards the Changing its Colour, is not only evident in the Mutations of Colour obſervable in Quick-ſilver, and ſome other Concretes long kept by Chymiſts in a Convenient Heat, though in cloſe Veſſels, but in the Obvious Degenerations of Colour, which every Body may take notice of in Bruis'd Cherries, and other Fruit, by comparing after a while the Colour of the Injur'd with that of the Sound part of the ſame Fruit. And that alſo ſuch Liquors, as we have been ſpeaking of, may greatly Diſcompoſe the Textures of many Bodies, and thereby alter the Diſpoſition of their Superficial parts, the great Commotion made in Metalls, and ſeveral other Bodies by Aqua-fortis, Oyl of Vitriol, and other Saline Menſtruums, may eaſily perſwade us, and what ſuch Vary'd Situations of Parts may do towards the Diverſifying of the manner of their Reflecting the Light, may [pg 61] be Gueſs'd in ſome Meaſure by the Beating of Tranſparent Glaſs into a White Powder, but farr better by the Experiments lately Pointed at, and hereafter Deliver'd, as the Producing and Deſtroying Colours by the means of ſubtil Saline Liquors, by whoſe Affuſion the Parts of other Liquors are manifeſtly both Agitated, and likewiſe Diſpos'd after another manner than they were before ſuch Affuſion. And in ſome Chymical Oyls, as particularly that of Lemmon Pills, by barely Shaking the Glaſs, that holds it, into Bubbles, that Tranſpoſition of the Parts which is conſequent to the Shaking, will ſhew you on the Surfaces of the Bubbles exceeding Orient and Lively Colours, which when the Bubbles relapſe into the reſt of the Oyl, do immediately Vaniſh.
24. I know not, Pyrophilus, whether I ſhould mention as a Diſtinct way, becauſe it is of a ſomewhat more General Nature, that Power, whereby a Liquor may alter the Colour of another Body, by putting the Parts of it into Motion; For though poſſibly the Motion ſo produc'd, does, as ſuch, ſeldome ſuddenly change the Colour of the Body whoſe Parts are Agitated, yet this ſeems to be one of the moſt General, however not Immediate cauſes of [pg 62] the Quick change of Colours in Bodies. For the Parts being put into Motion by the adventitious Liquor, divers of them that were before United, may become thereby Diſjoyn'd, and when that Motion ceaſes or decays others of them may ſtick together, and that in a new Order, by which means the Motion may ſometimes produce Permanent changes of Colours, as in the Experiment you will meet with hereafter, of preſently turning a Snowy White Body into a Yellow, by the bare Affuſion of fair Water, which probably ſo Diſſolves the Saline Corpuſcles that remain'd in the Calx, and ſets them at Liberty to Act upon one another, and the Metall, far more Powerfully than the Water without the Aſſiſtance of ſuch Saline Corpuſcles could do. And though you rubb Blew Vitriol, how Venereal and Unſophiſticated ſoever it be, upon the Whetted Blade of a Knife, it will not impart to the Iron its Latent Colour, but if you moiſten the Vitriol with your Spittle, or common Water, the Particles of the Liquor diſjoyning thoſe of the Vitriol, and thereby giving them the Various Agitation requiſite to Fluid Bodies, the Metalline Corpuſcles of the thus Diſſolv'd Vitriol will Lodge themſelves in Throngs in the Small and Congruous [pg 63] Pores of the Iron they are Rubb'd on, and ſo give the Surface of it the Genuine Colour of the Copper.
25. There remains yet a way, Pyrophilus to be mention'd, by which a Liquor may alter the Colour of another Body, and this ſeems the moſt Important of all, becauſe though it be nam'd but as One, yet it may indeed comprehend Many, and that is, by Aſſociating the Saline Corpuſcles, or any other Sort of the more Rigid ones of the Liquor, with the Particles of the Body that it is employ'd to Work upon. For theſe Adventitious Corpuſcles Aſſociating themſelves with the Protuberant Particles of the Surface of a Colour'd Body, muſt neceſſarily alter their Bigneſs, and will moſt commonly alter their Shape. And how much the Colours of Bodies depend upon the Bulk and Figure of their Superficial Particles, you may Gueſs by this, that eminent antient Philoſophers and divers Moderns, have thought that all Colours might in a general way be made out by theſe two; whoſe being Diverſify'd, will in our Caſe be attended with theſe two Circumſtances, the One, that the Protuberant Particles being Increas'd in Bulk, they will oftentimes be Vary'd as to the Cloſneſs or Laxity of [pg 64] their Order, fewer of them being contain'd within the ſame Senſible (though Minute) ſpace than before; or elſe by approaching to one another, they muſt Straighten the Pores, and it may be too, they will by their manner of Aſſociating themſelves with the Protuberant Particles, intercept new Pores. And this invites me to conſider farther, that the Adventitious Corpuſcles, I have been ſpeaking of, may likewiſe produce a great Change as well in the Little Cavities or Pores as in the Protuberances of a Colour'd Body; for beſides what we have juſt now taken notice of, they may by Lodging themſelves in thoſe little Cavities, fill them up, and it may well happen, that they may not only fill the Pores they Inſinuate themſelves into, but likewiſe have their Upper Parts extant above them; and partly by theſe new Protuberances, partly by Increaſing the Bulk of the former, theſe Extraneous Corpuſcles may much alter the Number and Bigneſs of the Surfaces Pores, changing the Old and Intercepting new ones. And then 'tis Odds, but the Order of the Little Extancies, and conſequently that of the Little Depreſſions in point of Situation will be alter'd likewiſe: as if you diſſolve Quick-ſilver in ſome kind of Aqua-fortis, [pg 65] the Saline Particles of the Menstruum Aſſociating themſelves with the Mercurial Corpuſcles, will make a Green Solution, which afterwards eaſily enough Degenerates. And Red Lead or Minium being Diſſolv'd in Spirit of Vinegar, yields not a Red, but a Clear Solution, the Redneſs of the Lead being by the Liquor Deſtroy'd. But a better Inſtance may be taken from Copper, for I have try'd, that if upon a Copper-plate you let ſome Drops of weak Aqua-fortis reſt for a while, the Corpuſcles of the Menſtruum, joyning with thoſe of the Metall, will produce a very ſenſible Aſperity upon the Surface of the Plate, and will Concoagulate that way into very minute Grains of a Pale Blew Vitriol; whereas if upon another part of the ſame Plate you ſuffer a little ſtrong Spirit of Urine to reſt a competent time, you ſhall find the Aſperated Surface adorn'd with a Deeper and Richer Blew. And the ſame Aqua-fortis, that will quickly change the Redneſs of Red Lead into a Darker Colour, will, being put upon Crude Lead, produce a Whitiſh Subſtance, as with Copper it did a Blewiſh. And as with Iron it will produce a Reddiſh, and on White Quills a Yellowiſh, ſo much may the Coalition of the Parts of the ſame [pg 66] Liquor, with the differingly Figur'd Particles of Stable Bodies, divers ways Aſperate the differingly Diſpos'd Surfaces, and to Diverſifie the Colour of thoſe Bodies. And you'l eaſily believe, that in many changes of Colour, that happen upon the Diſſolutions of Metalls, and Precipitations made with Oyl of Tartar, and the like Fix'd Salts, there may Intervene a Coalition of Saline Corpuſcles with the Particles of the Body Diſſolv'd or Precipitated, if you examine how much the Vitriol of a Metall may be Heavier than the Metalline part of it alone, upon the Score of the Saline parts Concoagulated therewith, and, that in Several Precipitations the weight of the Calx does for the ſame Reaſon much exceed that of the Metall, when it was firſt put in to be Diſſolv'd.
26. But, Pyrophilus, to conſider theſe Matters more particularly would be to forget that I declar'd againſt Adventuring, at leaſt for this time, at particular Theories of Colours, and that accordingly you may juſtly expect from me rather Experiments than Speculations, and therefore I ſhall Diſmiſs this Subject of the Forms of Superficial Aſperity in Colour'd Bodies, as ſoon as I ſhall but have nam'd to you by way of Supplement to what we have [pg 67] hitherto Diſcours'd in this Section, a Couple of Particulars, (which you'l eaſily grant me) The one, That there are divers other ways for the ſpeedy Production even of True and Permanent Colours in Bodies, beſides thoſe Practicable by the help of Liquors; for proof of which Advertiſement, though ſeveral Examples might be alleged, yet I ſhall need but Re-mind you of what I mention'd to you above, touching the change of Colours ſuddenly made on Temper'd Steel, and on Lead, by the Operation of Heat, without the Intervention of a Liquor. But the other particular I am to obſerve to you is of more Importance to our preſent Subject and it is, That though Nature and Art may in ſome caſes ſo change the Aſperity of the Superficial parts of a Body, as to change its Colour by either of the ways I have propos'd Single or Unaſſiſted, yet for the moſt part 'tis by two or three, or perhaps by more of the fore-mention'd ways Aſſociated together, that the Effect is produc'd, and if you conſider how Variouſly thoſe ſeveral ways and ſome others Ally'd unto them, which I have left unmention'd, may be Compounded and Apply'd, you will not much wonder that ſuch fruitfull, whether Principles (or Manners of Diverſification) [pg 68] ſhould be fitted to Change or Generate no ſmall ſtore of Differing Colours.
27. Hitherto, Pyrophilus, we have in diſcourſing of the Aſperity of Bodies conſider'd the little Protuberances of other Superficial particles which make up that Roughneſs, as if we took it for granted, that they muſt be perfectly Opacous and Impenetrable by the Beams of Light, and ſo, muſt contribute to the Variety of Colours as they terminate more or leſs Light, and reflect it to the Eye mix'd with more or leſs of thus or thus mingl'd Shades. But to deal Ingenuouſly with you, Pyrophilus, before I proceed any further, I muſt not conceal from you, that I have often thought it worth a Serious Enquiry, whether or no Particles of Matter, each of them ſing'y Inſenſible, and therefore ſmall enough to be capable of being ſuch Minute Particles as the Atomiſts both of old and of late have (not abſurdly) called Corpuſcula Coloris, may not yet conſiſt each of them of divers yet Minuter Particles, betwixt which we may conceive little Commiſſures where they Adhere to one another, and, however, may not be Porous enough to be, at leaſt in ſome degree, Pervious to the unimaginably ſubtile Corpuſcles that make up the Beams of [pg 69] Light, and conſequently to be in ſuch a degree Diaphanous. For, Pyrophilus, that the propoſed Enquiry may be of moment to him that ſearches after the Nature of Colour, you'l eaſily grant, if you conſider, that whereas Perfectly Opacous bodies can but reflect the incident Beams of Light, thoſe that are Diaphanous are qualified to refract them too, and that Refraction has ſuch a ſtroak in the Production of Colours, as you cannot but have taken notice of, and perhaps admir'd in the Colours generated by the Trajection of Light through Drops of Water that exhibit a Rain-bow, through Priſmatical glaſſes, and through divers other Tranſparent bodies. But 'tis like, Pyrophilus, you'l more eaſily allow that about this matter 'tis rather Important to have a Certainty, than that 'tis Rational to entertain a Doubt; wherefore I muſt mention to you ſome of the Reaſons that make me think it may need a further Enquiry, for I find that in a Darkned Room, where the Light is permitted to enter but at One hole, the little wandering Particles of Duſt, that are commonly called Motes, and, unleſs in the Sunbeams, are not taken notice of by the unaſſiſted Sight, I have, I ſay, often obſerv'd, that theſe roving Corpuſcles being look'd on by an Eye plac'd on one ſide of the [pg 70] Beams that enter'd the Little hole, and by the Darkneſs having its Pupill much Enlarg'd, I could diſcern that theſe Motes as ſoon as they came within the compaſs of the Luminous, whether Cylinder or Inverted Cone, if I may ſo call it, that was made up by the Unclouded Beams of the Sun, did in certain poſitions appear adorn'd with very vivid Colours, like thoſe of the Rain-bow, or rather like thoſe of very Minute, but Sparkling fragments of Diamonds; and as ſoon as the Continuance of their Motion had brought them to an Inconvenient poſition in reference to the Light and the Eye, they were only viſible without Darting any lively Colours as before, which ſeems to argue that theſe little Motes, or minute Fragments, of ſeveral ſorts of bodies reputed Opacous, and only crumbled as to their Exteriour and Looſer parts into Duſt, did not barely Reflect the Beams that fell upon them, but remit them to the Eye Refracted too. We may alſo obſerve, that ſeveral Bodies, (as well ſome of a Vegetable, as others of an Animal nature) which are wont to paſs for Opacous, appear in great part Tranſparent, when they are reduc'd into Thin parts, and held againſt a powerful Light. This I have not only taken notice of in pieces of Ivory reduc'd but into Thick leaves, as alſo in divers conſiderable [pg 71] Thick ſhells of Fiſhes, and in ſhaving of Wood, but I have alſo found that a piece of Deal, far thicker than one would eaſily imagine, being purpoſly interpoſed betwixt my Eye plac'd in a Room, and the clear Daylight, was not only ſomewhat Tranſparent, but (perhaps by reaſon of its Gummous nature) appear'd quite through of a lovely Red. And in the Darkned Room above mention'd, Bodies held againſt the hole at which the Light enter'd, appear'd far leſs Opacous then they would elſewhere have done, inſomuch that I could eaſily and plainly ſee through the whole Thickneſs of my Hand, the Motions of a Body plac'd (at a very near diſtance indeed, but yet) beyond it. And even in Minerals, the Opacity is not always ſo great as many think, if the Body be made Thin, for White Marble though of a pretty Thickneſs, being within a Due diſtance plac'd betwixt the Eye and a Convenient Light, will Suffer the Motions of ones Finger to be well diſcern'd through it, and ſo will pieces, Thick enough, of many common Flints. But above all, that Inſtance is remarkable, that is afforded us by Muſcovie glaſs, (which ſome call Selenites, others Lapis Specularis) for though plates of this Mineral, though but of a moderate Thickneſs, do often appear Opacous, yet if [pg 72] one of theſe be Dextrouſly ſplit into the thinneſt Leaves 'tis made up of, it will yield ſuch a number of them, as ſcarce any thing but Experience could have perſwaded me, and theſe Leaves will afford the moſt Tranſparent ſort of conſiſtent Bodies, that, for ought I have obſerv'd, are yet known; and a ſingle Leaf or Plate will be ſo far from being Opacous, that 'twill ſcarce be ſo much as Viſible. And multitudes of Bodies there are, whoſe Fragments ſeem Opacous to the naked Eye, which yet, when I have included them in good Microſcopes, appear'd Tranſparent; but, Pyrophilus, on the other ſide I am not yet ſure that there are no Bodies, whoſe Minute Particles even in ſuch a Microſcope as that of mine, which I was lately mentioning, will not appear Diaphanous. For having conſider'd Mercury Precipitated per ſe, the little Granules that made up the powder, look'd like little fragments of Coral beheld by the naked Eye at a Diſtance (for very Near at hand Coral will ſometimes, eſpecially if it be Good, ſhew ſome Tranſparency.) Filings likewiſe of Steel and Copper, though in an excellent Microſcope, and a fair Day, they ſhow'd like pretty Big Fragments of thoſe Metalls, and had conſiderable Brightneſs on ſome of their Surfaces, yet I was not ſatisfi'd, that I perceiv'd [pg 73] any Reflection from the Inner parts of any of the Filings. Nay, having look'd in my beſt Microſcope upon the Red Calx of Lead, (commonly call'd Minium) neither I, nor any I ſhew'd it to, could diſcern it to be other than Opacous, though the Day were Clear, and the Object ſtrongly Enlightned. And the deeply Red Colour of Vitriol appear'd in the ſame Microſcope (notwithſtanding the great Comminution effected by the Fire) but like Groſſy beaten Brick. So that, Pyrophilus, I ſhall willingly reſign you the care of making ſome further Enquiries into the Subject we have now been conſidering; for I confeſs, as I told you before, that I think that the Matter may need a further Scrutiny, nor would I be forward to Determine how far or in what caſes the Tranſparency or Semi-diaphaniety of the Superficial Corpuſcles of Bigger Bodies, may have an Intereſt in the Production of their Colours, eſpecially becauſe that even in divers White bodies, as Beaten Glaſs, Snow and Froth, where it ſeems manifeſt that the Superficial parts are ſingly Diaphanous, (being either Water, or Air, or Glaſs) we ſee not that ſuch Variety of Colours are produc'd as uſually are by the Refraction of Light, even in thoſe Bodies, when by their Bigneſs, Shape, &c. they are conveniently [pg 74] qualify'd to exhibit ſuch Various and Lively Colours as thoſe of the Rain-bow, and of Priſmatical Glaſſes.
28. By what has been hitherto diſcours'd, Pyrophilus, we may be aſſiſted to judge of that famous Controverſie which was of Old diſputed betwixt the Epicureans and other Atomiſts on the one ſide, and moſt other Philoſophers on the other ſide. The former Denying Bodies to be Colour'd in the Dark, and the Latter making Colour to be an Inherent quality, as well as Figure, Hardneſs; Weight, or the like. For though this Controverſie be Reviv'd, and hotly Agitated among the Moderns, yet I doubt whether it be not in great part a Nominal diſpute, and therefore let us, according to the Doctrine formerly deliver'd, Diſtinguiſh the Acceptions of the word Colour, and ſay, that if it be taken in the Stricter Senſe, the Epicureans ſeem to be in the Right, for if Colour be indeed, though not according to them, but Light Modify'd, how can we conceive that it can Subſiſt in the Dark, that is, where it muſt be ſuppos'd there is no Light; but on the other ſide, if Colour be conſider'd as a certain Conſtant Diſpoſition of the Superficial parts of the Object to Trouble the Light they Reflect after ſuch and ſuch a Determinate manner, [pg 75] this Conſtant, and, if I may ſo ſpeak, Modifying diſpoſition perſevering in the Object, whether it be Shin'd upon or no, there ſeems no juſt reaſon to deny, but that in this Senſe, Bodies retain their Colour as well in the Night as Day; or, to Speak a little otherwiſe, it may be ſaid, that Bodies are Potentially Colour'd in the Dark, and Actually in the Light. But of this Matter diſcourſing more fully elſewhere, as 'tis a difficulty that concerns Qualities in general, I ſhall forbear to inſiſt on it here.
1. Of greater Moment in the Inveſtigation of the Nature of Colours is the Controverſie, Whether thoſe of the Rain-bow, and thoſe that are often ſeen in Clouds, before the Riſing, or after the Setting of the Sun; and in a word, Whether thoſe other Colours, that are wont to be call'd Emphatical, ought or ought not to be accounted True Colours. I need not tell you that the Negative is the Common Opinion, eſpecially in the Schools, as may appear by that Vulgar diſtinction of Colours, whereby theſe under Conſideration are term'd Apparent, by way of Oppoſition [pg 76] to thoſe that in the other Member of the Diſtinction are call'd True or Genuine. This queſtion I ſay ſeems to me of Importance, upon this Account, that it being commonly Granted, (or however, eaſie enough to be Prov'd) that Emphatical Colours are Light it ſelf Modify'd by Refractions chiefly, with a concurrence ſometimes of Reflections, and perhaps ſome other Accidents depending on theſe two; if theſe Emphatical Colours be reſolv'd to be Genuine, it will ſeem conſequent, that Colours, or at leaſt divers of them, are but Diverſify'd Light, and not ſuch Real and Inherent qualities as they are commonly thought to be.
2. Now ſince we are wont to eſteem the Echoes and other Sounds of Bodies, to be True Sounds, all their Odours to be True Odours, and (to be ſhort) ſince we judge other Senſible Qualities to be True ones, becauſe they are the proper Objects of ſome or other of our Senſes, I ſee not why Emphatical Colours, being the proper and peculiar Objects of the Organ of Sight, and capable to Affect it as Truly and as Powerfully as other Colours, ſhould be reputed but Imaginary ones.
And if we have (which perchance you'l allow) formerly evinc'd Colour, (when [pg 77] the word is taken in its more Proper ſenſe) to be but Modify'd Light, there will be ſmall Reaſon to deny theſe to be true Colours, which more manifeſtly than others diſcloſe themſelves to be produc'd by Diverſifications of the Light.
3. There is indeed taken notice of a Difference betwixt theſe Apparent colours, and thoſe that are wont to be eſteem'd Genuine, as to the Duration, which has induc'd ſome Learned Men to call the former rather Evanid than Fantaſtical. But as the Ingenious Gaſſendus does ſomewhere Judiciouſly obſerve, if this way of Arguing were Good, the Greeneſs of a Leaf ought to paſs for Apparent, becauſe, ſoon Fading into a Yellow, it Scarce laſts at all, in compariſon of the Greeneſs of an Emerauld. I ſhall add, that if the Sun-beams be in a convenient manner trajected through a Glaſs-priſm, and thrown upon ſome well-ſhaded Object within a Room, the Rain-bow thereby Painted on the Surface of the Body that Terminates the Beams, may oftentimes laſt longer than Some Colours I have produc'd in certain Bodies, which would juſtly, and without ſcruple be accounted Genuine Colours, and yet ſuddenly Degenerate, and loſe their Nature.
4. A greater Diſparity betwixt Emphatical [pg 78] Colours, and others, may perhaps be taken from this, that Genuine Colours ſeem to be produc'd in Opacous Bodies by Reflection, but Apparent ones in Diaphanous Bodies, and principally by Refraction, I ſay Principally rather than Solely, becauſe in ſome caſes Reflection alſo may concurr, but ſtill this ſeems not to conclude theſe Latter Colours not to be True ones. Nor muſt what has been newly ſaid of the Differences of True and Apparent Colours, be interpreted in too Unlimited a Senſe, and therefore it may perhaps ſomewhat Aſſiſt you, both to Reflect upon the two fore-going Objections, and to judge of ſome other Paſſages which you'l meet with in this Tract, if I take this Occaſion to obſerve to you, that if Water be Agitated into Froth, it exhibits you know a White colour, which ſoon after it Loſes upon the Reſolution of the Bubbles into Air and Water, now in this caſe either the Whiteneſs of the Froth is a True Colour or not, if it be, then True Colours, ſuppoſing the Water pure and free from Mixtures of any thing Tenacious, may be as Short-liv'd as thoſe of the Rain-bow; alſo the Matter, wherein the Whiteneſs did Reſide, may in a few moments perfectly Loſe all foot-ſteps or remains of it. And [pg 79] beſides, even Diaphanous Bodies may be capable of exhibiting True Colours by Reflection, for that Whiteneſs is ſo produc'd, we ſhall anon make it probable. But if on the other ſide it be ſaid, that the Whiteneſs of Froth is an Emphatical Colour, then it muſt no longer be ſaid, that Fantaſtical Colours require a certain Poſition of the Luminary and the Eye, and muſt be Vary'd or Deſtroy'd by the Change thereof, ſince Froth appears White, whether the Sun be Riſing or Setting, or in the Meridian, or any where between it and the Horizon, and from what (Neighbouring) place ſoever the Beholders Eye looks upon it. And ſince by making a Liquor Tenacious enough, yet without Deſtroying its Tranſparency, or Staining it with any Colour, you may give the Little Films, whereof the Bubbles conſiſt, ſuch a Texture, as may make the Froth laſt very many Hours, if not ſome Days, or even Weeks, it will render it ſomewhat Improper to aſſign Duration for the Diſtinguiſhing Character to Diſcriminate Genuine from Fantaſtical Colours. For ſuch Froth may much outlaſt the Undoubtedly true Colours of ſome of Nature's Productions, as in that Gaudy Plant not undeſervedly call'd the Mervail of Peru, the Flowers do often Fade, the [pg 80] ſame Day they are Blown; And I have often ſeen a Virginian Flower, which uſually Withers within the compaſs of a Day; and I am credibly Inform'd, that not far from hence a curious Herboriſt has a Plant, whoſe Flowers periſh in about an Hour. But if the Whiteneſs of Water turn'd into Froth muſt therefore be reputed Emphatical, becauſe it appears not that the Nature of the Body is Alter'd, but only that the Diſpoſition of its Parts in reference to the Incident Light is Chang'd, why may not the Whiteneſs be accounted Emphatical too, which I ſhall ſhew anon to be Producible, barely by ſuch another change in Black Horn? and yet this ſo eaſily acquir'd Whiteneſs ſeems to be as truly its Colour as the Blackneſs was before, and at leaſt is more Permanent than the Greenneſs of Leaves, the Redneſs of Roſes, and, in ſhort, than the Genuine Colours of the moſt part of Nature's Productions. It may indeed be further Objected, that according as the Sun or other Luminous Body changes place, theſe Emphatical Colours alter or vaniſh. But not to repeat what I have juſt now ſaid, I ſhall add, that if a piece of Cloath in a Drapers Shop (in ſuch the Light being ſeldome Primary) be variouſly Folded, it will appear of differing [pg 81] Colours, as the Parts happen to be more Illuminated or more Shaded, and if you ſtretch it Flat, it will commonly exhibit ſome one Uniform Colour, and yet theſe are not wont to be reputed Emphatical, ſo that the Difference ſeems to be chiefly this, that in the Caſe of the Rain-bow, and the like, the Poſition of the Luminary Varies the Colour, and in the Cloath I have been mentioning, the Poſition of the Object does it. Nor am I forward to allow that in all Caſes the Apparition of Emphatical Colours requires a Determinate poſition of the Eye, for if Men will have the Whiteneſs of Froth Emphatical, you know what we have already Inferr'd from thence. Beſides, the Sun-beams trajected through a Triangular Glaſs, after the manner lately mention'd, will, upon the Body that Terminates them, Paint a Rain-bow, that may be ſeen whether the Eye be plac'd on the Right Hand of it or the Left, or Above or Beneath it, or Before or Behind it; and though there may appear ſome Little Variation in the Colours of the Rain-bow, beheld from Differing parts of the Room, yet ſuch a Diverſity may be alſo obſerv'd by an Attentive Eye in Real Colours, look'd upon under the like Circumſtances, Nor will it follow, [pg 82] that becauſe there remains no Footſteps of the Colour upon the Object, when the Priſm is Remov'd, that therefore the Colour was not Real, ſince the Light was truly Modify'd by the Refraction and Reflection it Suffer'd in its Trajection through the Priſm; and the Object in our caſe ſerv'd for a Specular Body, to Reflect that Colour to the Eye. And that you may not be Startled, Pyrophilus, that I ſhould Venture to ſay, that a Rough and Coiour'd Object may ſerve for a Speculum to Reflect the Artificial Rain-bow I have been mentioning, conſider what uſually happens in Darkned Rooms, where a Wall, or other Body conveniently Situated within, may ſo Reflect the Colours of Bodies, without the Room, that they may very clearly be Diſcern'd and Diſtinguiſh'd, and yet 'tis taken for granted, that the Colours ſeen in a Darkned Room, though they leave no Traces of themſelves upon the Wall or Body that Receives them, are the True Colours of the External Objects, together with which the Colours of the Images are Mov'd or do Reſt. And the Errour is not in the Eye, whoſe Office is only to perceive the Appearances of things, and which does Truly ſo, but in the Judging or Eſtimative faculty, which Miſtakingly [pg 83] concludes that Colour to belong to the Wall, which does indeed belong to the Object, becauſe the Wall is that from whence the Beams of Light that carry the Viſible Species, do come in Straight Lines directly to the Eye, as for the ſame Reaſon we are wont at a certain Diſtance from Concave Sphærical Glaſſes, to perſwade our Selves that we ſee the Image come forth to Meet us, and Hang in the Air betwixt the Glaſs and Us, becauſe the Reflected Beams that Compoſe the image croſs in that place, where the Image ſeems to be, and thence, and not from the Glaſs, do in Direct Lines take their Courſe to the Eye, and upon the like Cauſe it is, that divers Deceptions in Sounds and other Senſible Objects do depend, as we elſewhere declare.
5. I know not, whether I need add, that I have purpoſely Try'd, (as you'l find ſome Pages hence, and will perhaps think ſomewhat ſtrange) that Colours that are call'd Emphatical, becauſe not Inherent in, the Bodies in which they Appear, may be Compounded with one another, as thoſe that are confeſſedly Genuine may. But when all this is ſaid, Pyrophilus, I muſt Advertiſe you, that it is but Problematically Spoken, and that though I think the Opinion [pg 84] I have endeavour'd to fortifie Probable, yet a great part of our Diſcourſe concerning Colours may be True, whether that Opinion be ſo or not.
1. There are you know, Pyrophilus, beſides thoſe Obſolete Opinions about Colours which have been long ſince Rejected, very Various Theories that have each of them, even at this day, Eminent Men for its Abetters; for the Peripatetick Schools, though they diſpute amongſt themſelves divers particulars concerning Colours, yet in this they ſeem Unanimouſly enough to Agree, that Colours are Inherent and Real Qualities, which the Light doth but Diſcloſe, and not concurr to Produce. Beſides there are Moderns, who with a ſlight Variation adopt the Opinion of Plato, and as he would have Colour to be nothing but a Kind of Flame conſiſting of Minute Corpuſcles as it were Darted by the Object againſt the Eye, to whoſe Pores their Littleneſs and Figure made them congruous, ſo theſe would have Colour to be an Internal Light of the more Lucid parts of the Object, Darkned and conſequently Alter'd by the Various Mixtures of the leſs Luminous [pg 85] parts. There are alſo others, who in imitation of ſome of the Ancient Atomiſts, make Colour not to be Lucid ſteam, but yet a Corporeal Effluvium iſſuing out of the Colour'd Body, but the Knowingſt of theſe have of late Reform'd their Hypotheſis, by acknowledging and adding that ſome External Light is neceſſary to Excite, and as they ſpeak, Sollicit theſe Corpuſcles of Colour as they call them, and Bring them to the Eye. Another and more principal Opinion of the Modern Philoſophers, to which this laſt nam'd may by a Favourable explication be reconcil'd, is that which derives Colours from the Mixture of Light and Darkneſs, or rather Light and Shadows. And as for the Chymiſts 'tis known, that the generality of them aſcribes the Origine of Colours to the Sulphureous Principle in Bodies, though I find, as I elſewhere largely ſhew, that ſome of the Chiefeſt of them derive Colours rather from Salt than Sulphur, and others, from the third Hypoſtatical Principle, Mercury. And as for the Carteſians I need not tell you, that they, ſuppoſing the Senſation of Light to bee produc'd by the Impulſe made upon the Organs of Sight, by certain extremely Minute and Solid Globules, to which the Pores of the Air and other Diaphanous [pg 86] bodies are pervious, endeavour to derive the Varieties of Colours from the Various Proportion of the Direct Progreſs or Motion of theſe Globules to their Circumvolution or Motion about their own Centre, by which Varying Proportion they are by this Hypotheſis ſuppos'd qualify'd to ſtrike the Optick Nerve after ſeveral Diſtinct manners, ſo to produce the perception of Differing Colours.
2. Beſides theſe ſix principal Hypotheſes, Pyrophilus, there may be ſome others, which though Leſs known, may perhaps as well as theſc deſerve to be taken into conſideration by you; but that I ſhould copiouſly debate any of them at preſent, I preſume you will not expect, if you conſider the Scope of theſe Papers, and the Brevity I have deſign'd in them, and therefore I ſhall at this time only take notice to you in the general of two or three things that do more peculiarly concern the Treatiſe you have now in your hands.
3. And firſt, though the Embracers of the Several Hypotheſes I have been naming to you, by undertaking each Sect of them to explicate Colours indefinitely, by the particular Hypotheſes they maintain, ſeem to hold it forth as the only Needful Theory about that Subject, yet for my part I doubt [pg 87] whether any one of all theſe Hypotheſes have a right to be admitted Excluſively to all others, for I think it Probable, that Whiteneſs and Blackneſs may be explicated by Reflection alone without Refraction, as you'l find endeavour'd in the Diſcourſe you'l meet with e're long Of the Origine of Whiteneſs and Blackneſs, and on the other ſide, ſince I have not found that by any Mixture of White and True Black, (for there is a Blewiſh Black which many miſtake for a Genuine) there can be a Blew, a Yellow, or a Red, to name no other Colours, produced, and ſince we do find that theſe Colours may be produc'd in the Glaſs-priſm and other Tranſparent bodies, by the help of Refractions, it ſeems that Refraction is to be taken in into the Explication of ſome Colours, to whoſe Generation they ſeem to concurr, either by making a further or other Commixture of Shades with the Refracted Light, or by ſome other way not now to be diſcours'd. And as it ſeems not improbable, that in caſe the Pores of the Air, and other Diaphanous bodies be every where almoſt fill'd with ſuch Globuli as the Carteſians ſuppoſe, the Various kind of Motion of theſe Globuli, may in many caſes have no ſmall ſtroak in Varying our Perception of Colour, ſo [pg 88] without the Suppoſition of theſe Globuli, which 'tis not ſo eaſie to evince, I think we may probably enough conceive in general, that the Eye may be Variouſly affected, not only by the Entire Beams of Light that fall upon it as they are ſuch, but by the Order, and by the Degree of Swiftneſs, and in a word by the Manner according to which the Particles that compoſe each Particular Beam arrive at the Senſory, ſo that whatever be the Figure of the Little Corpuſcles, of which the Beams of Light conſiſt, not only the Celerity or Slowneſs of their Revolution or Rotation in reference to their Progreſſive Motion, but their more Abſolute Celerity, their Direct or Undulating Motion, and other Accidents, which may attend their Appulſe to the Eye, may fit them to make Differing Impreſſions on it.
4. Secondly, For theſe and the like Conſiderations, Pyrophilus, I muſt deſire that you would look upon this little Treatiſe, not as a Diſcourſe written Principally to maintain any of the fore-mention'd Theories, Excluſively to all others, or ſubſtitute a New one of my Own, but as the beginning of a Hiſtory of Colours, upon which, when you and your Ingenious friends ſhall have Enrich'd it, a Solid Theory may be [pg 89] ſafely built. But yet becauſe this Hiſtory is not meant barely for a Regiſter of the things recorded in it, but for an Apparatus to a ſound and comprehenſitive Hypotheſis, I thought fit, ſo to temper the whole Diſcourſe, as to make it as conducible, as conveniently I can to that End, and therefore I have not ſcrupled to let you ſee that I was willing, as to ſave you the labour of Cultivating ſome Theories that I thought would never enable you to reach the Ends you aim at, ſo to contract your Enquiries into a Narrow compaſs, for both which purpoſes I thought it requiſite to do theſe two things, the One, to ſet down ſome Experiments which by the help of the Reflections and Inſinuations that attend them, may aſſiſt you to diſcover the Infirmneſs and Inſufficiency both of the common Peripatetick Doctrine, and of the now more applauded Theory of the Chymists about Colour, becauſe thoſe two Doctrines having Poſſeſs'd themſelves, the one of the moſt part of the Schools, and the other of the Eſteem of the Generality ef Phyſicians and other Learned Men, whoſe Profeſſions and Ways of Study do not exact that they ſhould Scrupulouſly examine the very Firſt and Simpleſt Principles of Nature, I fear'd it would be to [pg 90] little purpoſe, without doing ſomething to diſcover the Inſufficiency of theſe Hypotheſes, that I ſhould, (which was the Other thing I thought requiſite for me to do) ſet down among my other Experiments thoſe in the greateſt Number, that may let you ſee, that, till I ſhall be Better Inform'd, I encline to take Colour to be a Modification of Light, and would invite you chiefly to Cultivate that Hypotheſis, and Improve it to the making out of the Generation of Particular Colours, as I have Endeavour'd to apply it to the Explication of Whiteneſs and Blackneſs.
5. Thirdly. But, Pyrophilus, though this be at preſent the Hypotheſis I preferr, yet I propoſe it but in a General Senſe, teaching only that the Beams of Light, Modify'd by the Bodies whence they are ſent (Reflected or Refracted) to the Eye, produce there that Kind of Senſation, Men commonly call Colour; But whether I think this Modification of the Light to be perform'd by Mixing it with Shades, or by Varying the Proportion of the Progreſs and Rotation of the Carteſian Globuli Cæleſtes, or by ſome other way which I am not now to mention, I pretend not here to Declare. Much leſs do I pretend to Determine, or ſcarce ſo much as to Hope to [pg 91] know all that were requiſite to be Known, to give You, or even my Self, a perfect account of the Theory of Viſion and Colours, for in Order to ſuch an undertaking I would firſt Know what Light is, and if it be a Body (as a Body or the Motion of a Body it ſeems to be) what Kind of Corpuſcles for Size and Shape it conſiſts of, with what Swiftneſs they move Forwards, and Whirl about their own Centres. Then I would Know the Nature of Refraction, which I take to be one of the Abſtruſeſt things (not to explicate Plauſibly, but to explicate Satisfactorily) that I have met with in Phyſicks; I would further Know what Kind and what Degree of Commixture of Darkneſs or Shades is made by Refractions or Reflections, or both, in the Superficial particles of thoſe Bodies, that being Shin'd upon, conſtantly exhibit the one, for Inſtance, a Blew, the other a Yellow, the third a Red Colour; I would further Know why this Contemperation of Light and Shade, that is made, for Example, by the Skin of a Ripe Cherry, ſhould exhibit a Red, and not a Green, and the Leaf of the ſame Tree ſhould exhibit a Green rather than a Red; and indeed, Laſtly, why ſince the Light that is Modify'd into theſe Colours conſiſts but of Corpuſcles [pg 92] moved againſt the Retina or Pith of the Optick Nerve, it ſhould there not barely give a Stroak, but produce a Colour, whereas a Needle wounding likewiſe the Eye, would not produce Colour but Pain. Theſe, and perhaps other things I ſhould think requiſite to be Known, before I ſhould judge my Self to have fully Comprehended the True and Whole Nature of Colours; and therefore, though by making the Experiments and Reflections deliver'd in this Paper, I have endeavour'd ſomewhat to Leſſen my Ignorance in this Matter, and think it far more Deſireable to diſcover a Little, than to diſcover Nothing, yet I pretend but to make it Probable by the Experiments I mention, that ſome Colours may be Plauſibly enough Explicated in the General by the Doctrine here propos'd; For whenſoever I would Deſcend to the Minute and Accurate Explication of Particulars, I find my Self very Senſible of the great Obſcurity of things, without excepting thoſe which we never ſee but when they are Enlightned, and confeſs with Scaliger5, Latet natura hæc, (ſays he, Speaking of that of Colour) & ſicut aliarum rerum ſpecies in profundiſſima caligine inſcitiæ humanæ.
[pg 93]
Of the Nature of Whiteneſs and Blackneſs.
| 1. |  |
Hough after what I have acknowledged, Pyrophilus, of the Abſtruſe Nature of Colours in particular, you will eaſily believe, that I pretend not to give you a Satisfactory account of Whiteneſs and Blackneſs; Yet not wholly to fruſtrate your Expectation of my offering ſomething by way of Specimen towards the Explication of ſome Colours in particular, [pg 94] I ſhall make choice of Theſe as the moſt Simple Ones, (and by reaſon of their mutual Oppoſition the Leaſt hardly explicable) about which to preſent you my Thoughts, upon condition you will take them at moſt to be my Conjectures, not my Opinions.
2. When I apply'd my Self to conſider, how the cauſe of Whiteneſs might be explan'd by Intelligible and Mechanical Principles, I remembred not to have met with any thing among the Antient Corpuſcularian Philoſophers, touching the Quality we call Whiteneſs, ſave that Democritus is by Ariſtotle ſaid to have aſcrib'd the Whiteneſs of Bodies to their Smoothneſs, and on the contrary their Blackneſs to their Aſperity.6 But though about the Latter of thoſe Qualities his Opinion be allowable, as we ſhall ſee anon, yet that he heeds a Favourable Interpretation in what is Deliver'd concerning the Firſt, (at leaſt if his Doctrine be not Mis-repreſented in this point, as it has been in many others) we ſhall quickly have Occaſion to manifeſt. But amongſt the Moderns, the moſt Learned Gaſſendus in his Ingenious Epiſtle publiſh'd in the Year 1642. De apparente [pg 95] Magnitudine ſolis humilis & ſublimis, reviving the Atomical Philoſophy, has, though but Incidentally, deliver'd ſomething towards the Explication of Whiteneſs upon Mechanical Principles: And becauſe no Man that I know of, has done ſo before him, I ſhall, to be ſure to do him Right, give you his Senſe in his own Words:7 Cogites velim (ſays he) lucem quidem in Diaphano nullius coloris videri, ſed in Opaco tamen terminante Candicare, ac tantò magis, quantò denſior ſeu collectior fuerit. Deinde aquam non eſſe quidem coloris ex ſe candidi & radium tamen ex eâ reflexum verſus oculum candicare. Rurſus cum plana aquæ Superficies non niſi ex una parte eam reflexionem faciat: ſi contigerit tamen illam in aliquot bullas intumeſcere, bullam unamquamque reflectionem facere, & candoris ſpeciem creare certa Superficiei parte. Ad hæc Spumam ex aqua pura non alia ratione videri candeſcere & albeſcerere quam quod ſit congeries confertiſſima minutiſſimarum bullarum, quarum unaquæque ſuum radium reflectit, unde continens candor alborve apparet. Denique Nivem nihil aliud videri quam ſpeciem puriſſimæ ſpumæ ex bullulis quam minutiſſimis & confertiſſimis cohærentis. Sed ridiculam me exhibeam, ſi tales meas nugas uberius proponem.
[pg 96]3. But though in this paſſage, that very Ingenous Perſon has Anticipated part of what I ſhould ſay; Yet I preſume you will for all that expect, that I ſhould give you a fuller Account of that Notion of Whiteneſs, which I have the leaſt Exceptions to, and of the Particulars whence I deduce it, which to do, I muſt mention to you the following Experiments and Obſervations.
Whiteneſs then conſider'd as a Quality in the Object, ſeems chiefly to depend upon this, That the Superficies of the Body that is call'd White, is Aſperated by almoſt innumerable Small Surfaces, which being of an almoſt Specular Nature, are alſo ſo Plac'd, that ſome Looking this way, and ſome that way, they yet Reflect the Rays of Light that fall on them, not towards one another, but outwards towards the Spectators Eye. In this Rude and General account of Whiteneſs, it ſeems that beſides thoſe Qualities, which are common to Bodies of other Colours, as for inſtance the Minuteneſs and Number of the Superficial parts, the two chief things attributed to Bodies as White are made to be, Firſt, that its Little Protuberances and Superficial parts be of ſomewhat a Specular Nature, that they may as little Looking-glaſſes each of them Reflect the Beams it [pg 97] receives, (or the little Picture of the Sun made on it) without otherwiſe conſiderably Altering them; whereas in moſt other Colours, they are wont to be much Chang'd, by being alſo Refracted, or by being Return'd to the Eye, mixt with Shades or otherwiſe. And next, that its Superficial parts be ſo Situated, that they Retain not the Incident Rays of Light by Reflecting them Inwards, but Send them almoſt all Back, ſo that the Outermoſt Corpuſcles of a White Body, having their Various Little Surfaces of a Specular Nature, a Man can from no place Behold the Body, but that there will be among thoſe Innumerable Superficieculæ, that Look ſome one way, and ſome another, enough of them Obverted to his Eye, to afford like a broken Looking-glaſs, a confuſed Idæa, or Repreſentation of Light, and make ſuch an Impreſſion on the Organ, as that for which Men are wont to call a Body White. But this Notion will perhaps be beſt Explan'd by the ſame Experiments and Obſervations, on which it is Built, And therefore I ſhall now advance to Them.
4. And in the firſt place I conſider, that the Sun and other Powerfully Lucid Bodies, are not only wont to Offend, which we call to Dazle our Eyes, but that if any [pg 98] Colour be to be Aſcrib'd to them as they are Lucid, it ſeems it ſhould be Whiteneſs: For the Sun at Noon-day, and in Clear weather, and when his Face is leſs Troubled, and as it were Stained by the Steams of Sublunary Bodies, and when his Beams have much leſs of the Atmoſphere to Traject in their Paſſage to our Eyes, appears of a Colour more approaching to White, than when nearer the Horizon, the Interpoſition of certain Sorts of Fumes and Vapours make him oftentimes appear either Red, or at leaſt more Yellow. And when the Sun Shines upon that Natural Looking-glaſs, a Smooth water, that part of it, which appears to this or that particular Beholder, the moſt Shin'd on, does to his Eye ſeem far Whiter than the reſt. And here I ſhall add, that I have ſometimes had the Opportunity to obſerve a thing, that may make to my preſent purpoſe, namely, that when the Sun was Veil'd over as it were, with a Thin White Cloud, and yet was too Bright to be Look'd upon Directly without Dazling, by caſting my Eyes upon a Smooth water, as we ſometimes do to obſerve Eclipſes without prejudice to our Eyes, the Sun then not far from the Meridian, appear'd to me not Red, but ſo White, that 'twas [pg 99] not without ſome Wonder, that I made the Obſervation. Beſides, though we in Engliſh are wont to ſay, a thing is Red hot, as an Expreſſion of its being Superlatively Ignitum, (if I may ſo Speak for want of a proper Engliſh word) yet in the Forges of Smiths, and the Furnaces of other Artificers, by that which they call a White heat, they mean a further Degree of Ignition, than by that which both they and we call a Red heat.
5. Secondly, I conſider, that common Experience informs us, that as much Light Over-powers the Eye, ſo when the Ground is covered with Snow, (a Body extremely White) thoſe that have Weak Eyes are wont to complain of too much Light: And even thoſe that have not, are generally Senſible of an Extraordinary meaſure of Light in the Air; and if they are fain to Look very long upon the Snow, find their Sight Offended by it. On which occaſion we may call to mind what Xenophon relates, that his Cyrus marching his Army for divers days through Mountains covered with Snow, the Dazling ſplendor of its Whiteneſs prejudic'd the Sight of very many of his Souldiers, and Blinded ſome of them; and other Stories of that Nature be met with in Writers of good [pg 100] Note. And the like has been affirm'd to me by credible Perſons of my own Acquaintance, and eſpecially by one who though Skill'd in Phyſick and not Ancient confeſs'd to me when I purpoſely ask'd him, that not only during his ſtay in Muſcovy, he found his Eyes much Impair'd, by being reduc'd frequently to Travel in the Snow, but that the Weakneſs of his Eyes did not Leave him when he left that Country, but has follow'd him into theſe Parts, and yet continues to Trouble him. And to this doth agree what I as well as others have obſerv'd, namely, that when I Travell'd by Night, when the Ground was all cover'd with Snow, though the Night otherwiſe would not have been Lightſome, yet I could very well ſee to Chooſe my way. But much more Remarkable to my preſent purpoſe is that, which I have met with in Olaus Magnus,8 concerning the way of Travelling in Winter in the Northern Regions, where the Days of that Seaſon are ſo very Short; for after other things not needfull to be here Tranſcribed: Iter, ſays he, Diurnum duo ſcilicet montana milliaria (quæ 12 Italica ſunt) conſiciunt. Nocte verò ſub ſplendiſſima luna, duplatum iter conſumunt aut triplatum. Neque id incommodè fit, [pg 101] cum nivium reverberatione lunaris ſplendoris ſublimes & declives campos illuſtret, ac etiam montium præcipitia ac noxias feras à lorgè proſpiciant evitandas. Which Teſtimony I the leſs Scruple to allege, becauſe that it agrees very well with what has been Affirm'd to me by a Phyſician of Moſco, whom the Notion I have been Treating of concerning Whiteneſs invited me to ask whether he could not See much farther when he Travell'd by Night in Ruſſia than he could do in England, or elſewhere, when there was no Snow upon the Ground; For this Ingenious Perſon inform'd me, that he could See Things at a farr greater Diſtance, and with more Clearneſs, when he Travell'd by Night on the Ruſſian Snow, though without the Aſſiſtance of Moon-ſhine, than we in theſe Parts would eaſily be perſwaded. Though it ſeems not unlikely to me, that the Intenſeneſs of the Cold may contribute ſomething to the conſiderableneſs of the Effect, by much Clearing the Air of Darkiſh Steams, which in theſe more Temperate Climates are wont to Thicken it in Snowy weather: For having purpoſely inquir'd of this Doctor, and conſulted that Ingenious Navigator Captain James's Voyage hereafter to be further mention'd, I find both their Relations [pg 102] agree in this, that in Dark Froſty Nights they could Diſcover more Stars, and See the reſt Clearer than we in England are wont to do.
6. I know indeed that divers Learned Men think, that Snow ſo ſtrongly Affects our Eye, not by a Borrow'd, but a Native Light; But I venture to give it as a Proof, that White Bodies reflect more Light than Others, becauſe having once purpoſely plac'd a parcel of Snow in a Room carefully Darkned, that no Celeſtial Light might come to fall upon it; neither I, nor an ingenous Perſon, (Skill'd in Opticks) whom I deſir'd for a Witneſs, could find, that it had any other Light than what it receiv'd. And however, 'tis uſual among thoſe that Travel in Dark Nights, that the Guides wear ſomething of White to be Diſcern'd by, there being ſcarce any Night ſo Dark, but that in the Free Air there remains ſome Light, though Broken and Debilitated perhaps by a thouſand Reflections from the Opacous Corpuſcles that Swim in the Air, and lend it to one another before it comes to arrive at the Eye.
7. Thirdly, And the better to ſhew that White Bodies reflect ſtore of Light, in comparſon of thoſe that are otherwiſe Colour'd, I did in the Darkn'd Room, [pg 103] formerly mention'd, hold not far from the Hole, at which the Light was admitted, a Sheet only of White Paper, from whence caſting the Sun-beams upon a White Wall, whereunto it was Obverted, it manifeſtly appear'd both to Me, and to the Perſon I took for a Witneſs of the Experiment, that it Reflected a far greater Light, than any of the other Colours formerly mention'd, the Light ſo thrown upon one Wall notably Enlightning it, and by it a good part of the Room. And yet further to ſhow you, that White Bodies Reflect the Beams From them, and not Towards themſelves, Let me add, that Ordinary Burning-glaſſes, ſuch as are wont to be employ'd to light Tobacco, will not in a great while Burn, or ſo much as Diſcolour a Sheet of White Paper. Inſomuch that even when I was a Boy, and Lov'd to make Tryals with Burning-glaſſes, I could not but wonder at this Odd Phænomenon, which ſet me very Early upon Gueſſing at the Nature of Whiteneſs, eſpecially becauſe I took notice, that the Image of the Sun upon a White Paper was not ſo well Defin'd (the Light ſeeming too Diffus'd) as upon Black, and becauſe I try'd, that Blacking over the Paper with Ink, not only the Ink would be quickly Dry'd up, but the [pg 104] Paper that I could not Burn before, would be quickly ſet on Fire. I have alſo try'd, that by expoſing my Hand with a Thin Black Glove over it to the Warm Sun, it was thereby very quickly and conſiderably more Heated, than if I took off the Glove, and held my Hand Naked, or put on it another Glove of Thin but White Leather. And having thus ſhewn you, Pyrophilus, that White Bodies reflect the moſt Light of any, let us now proceed, to conſider what is further to be taken notice of in them, in order to our preſent Enquiry.
8. And Fourthly, whereas among the Diſpoſitions we attributed to White Bodies, we alſo intimated this, That ſuch Bodies are apt, like Speculums, though but Imperfect ones, to Reflect the Light that falls on them Untroubled or Unſtain'd, we ſhall beſides other particulars to be met with in theſe Papers, offer you this in favour of the Conjecture; That in the Darkned Room ſeveral times mention'd in this Treatſe, we try'd that the Sun-beams being caſt from a Coloured Body upon a neighbouring White Wall, the Determinate Colour of the Body was from the Wall reflected to the Eye; whereas we could in divers caſes manifeſtly Alter the Colour arriving at the Eye, by Subſtituting [pg 105] at a convenient Diſtance, a (conveniently) Colour'd (and Gloſſy) Body inſtead of the White Wall. As by throwing the Beams from a Yellow Body upon a Blew, there would be Exhibited a kind of Green, as in the Experiments about Colours is more fully Declar'd.
9. I know not whether I ſhould on this Occaſion take notice, that when, as when looking upon the Calm and Smooth Surface of a River betwixt my Eye and the Sun, it appear'd to be a natural Speculum, wherein that Part which Reflected to my Eye the Entire and defin'd Image of the Sun, and the Beams leſs remote from thoſe which exhibited That Image, appear'd indeed of a great and Whitiſh Brightneſs, but the reſt Comparatively Dark enough: if afterwards the Superficies chanc'd to be a little, but not much troubled, by a gentle Breath of Wind, and thereby reduc'd into a Multitude of Small and Smooth Speculums, the Surface of the River would ſuitably to the Doctrine lately deliver'd, at a Diſtance appear very much of Kin to White, though it would loſe that Brightneſs or Whiteneſs upon the Return of the Surface to Calmneſs and an Uniform Level. And I have ſometimes for Tryals ſake brought in by a Lenticular Glaſs, the Image of a River, Shin'd upon [pg 106] by the Sun, into an Upper Room Darkn'd, and Diſtant about a Quarter of a Mile from the River, by which means the Numerous Declining Surfaces of the Water appear'd ſo Contracted, that upon the Body that receiv'd the Images, the whole River appear'd a very White Object at two or three paces diſtance. But if we drew Near it, this Whiteneſs appear'd to proceed from an Innumerable company of Lucid Reflections, from the ſeveral Gently wav'd Superficies of the Water, which look'd Near at hand like a Multitude of very Little, but Shining Scales of Fiſh, of which many did every moment Diſappear, and as many were by the Sun, Wind and River generated anew. But though this Obſervation ſeem'd Sufficiently to diſcover, how the Appearing Whiteneſs in that caſe was Produc'd, yet in ſome other caſes Water may have the Same, though not ſo Vivid a Colour upon other Accounts; for oftentimes it happens that the Smooth Surface of the Water does appear Bright or Whitiſh, by reaſon of the Reflection not immediatly of the Images of the Sun, but of the Brightneſs of the Sky; and in ſuch caſes a Convenient Wind may where it paſſes along make the Surface look Black, by cauſing many ſuch Furrows and Cavities, as may make the Inflected Superficies [pg 107] of the Water reflect the Brightneſs of the Sky rather Inward than Outward. And again if the Wind increaſe into a Storm, the Water may appear White, eſpecially near the Shore and the Ship, namely becauſe the Rude Agitation Breaks it into Fome or Froth. So much do Whiteneſs and Blackneſs depend upon the Diſpoſition of the Superficial parts of a Body to Reflect the Beams of Light Inward or Outward. But that as White Bodies reflect the moſt Light of any, ſo there Superficial Particles are, in the Senſe newly Deliver'd, of a Specular Nature, I ſhall now further endeavour to ſhew both by the making of Specular bodies White, and the making of a White body Specular.
10. In the Fifth place then, I will inform You, that (not to repeat what Gaſſendus obſerves concerning Water) I have for Curioſity ſake Diſtill'd Quickſilver in a Cucurbit, fitted with a Capacious Glaſs-head, and obſerv'd that when the Operation was perform'd by the Degrees of Fire requiſite for my purpoſe, there would ſtick to the Inſide of the Alembick a multitude of Little round drops of Mercury. And as you know that Mercury is a Specular Body, ſo each of theſe Little drops was a ſmall round Looking-glaſs, [pg 108] and a Multitude of them lying Thick and Near one another, they did both in my Judgment, and that of thoſe I Invited to ſee it, make the Glaſs they were faſtened to, appear manifeſtly a White Body. And yet as I ſaid, this Whiteneſs depended upon the Minuteneſs and Nearneſs of the Little Mercurial Globuli, the Convexity of whoſe Surfaces fitted them to repreſent in a Narrow compaſs a Multitude of Little Lucid Images to differingly ſituated Beholders. And here let me obſerve a thing that ſeems much to countenance the Notion I have been recommending: namely, that whereas divers parts of the Sky, and eſpecially the Milky-way, do to the naked Eye appear White, (as the name it ſelf imports) yet the Galaxie look'd upon through the Teleſcope, does not ſhew White, but appears to be made up of a Vaſt multitude of Little Starrs; ſo that a Multitude of Lucid Bodies, if they be ſo Small that they cannot Singly or apart be diſcern'd by the Eye, and if they be ſufficiently Thick ſet by one another, may by their confus'd beams appear to the Eye One White Body. And why it is not poſſible, that the like may be done, when a Multitude of Bright and Little Corpuſcles being crowded together, are made to ſend together Vivid beams to the Eye, [pg 109] though they Shine but as the Planets by a Borrow'd Light?
11. But to return to our Experiments. We may take notice, That the White of an Egg, though in part Tranſparent, yet by its power of Reflecting ſome Incident Rays of Light, is in ſome meaſure a Natural Speculum, being long agitated with a Whisk or Spoon, loſes its Tranſparency, and becomes very White, by being turn'd into Froth, that is into an Aggregate of Numerous ſmall Bubbles, whoſe Convex Superficies fits them to Reflect the Light every way Outwards. And 'tis worth Noting, that when Water, for inſtance, is Agitated into Froth, if the Bubbles be Great and Few, the Whiteneſs will be but Faint, becauſe the number of Specula within a Narrow compaſs is but Small, and they are not Thick ſet enough to Reflect ſo Many Little Images or Beams of the Lucid Body, as are requiſite to produce a Vigorous ſenſation of Whiteneſs: And partly leaſt it ſhould be ſaid, that the Whiteneſs of ſuch Globulous Particles proceeds from the Air Included in the Froth; (which to make good, it ſhould be prov'd that the Air it ſelf is White) and partly to illuſtrate the better the Notion we have propos'd of Whiteneſs, I ſhall add, that I purpoſely made this Experiment, I took a quantity [pg 110] Fair water, & put to it in a clear Glaſs phial, a convenient quantity of Oyl or Spirit of Turpentine, becauſe that Liquor will not incorporate with Water, and yet is almoſt as Clear and Colourleſs as it; theſe being Gently Shaken together, the Agitation breaks the Oyl (which as I ſaid, is Indiſpos'd to Mix like Wine or Milk per minima with the Water) into a Multitude of Little Globes, which each of them Reflecting Outwards a Lucid Image, make the Imperfect Mixture of the two Liquors appear Whitiſh; but if by Vehemently Shaking the Glaſs for a competent time you make a further Comminution of the Oyl into far more Numerous and Smaller Globuli, and thereby confound it alſo better with the Water, the Mixture will appear of a Much greater Whiteneſs, and almoſt like Milk; whereas if the Glaſs be a while let alone, the Colour will by degrees Impair, as the Oyly globes grow Fewer and Bigger, and at length will quite Vaniſh, leaving both the Liquors Diſtinct and Diaphanous as before. And ſuch a Tryal hath not ill ſucceeded, when inſteed of the Colourleſs Oyl of Turpentine I took a Yellow Mixture made of a good Proportion of Crude Turpentine diſſolv'd in that Liquor; and (if I mis-remember not) it alſo Succeeded better than one would [pg 111] expect, when I employ'd an Oyl brought by Filings of Copper infuſed in it, to a deep Green. And this (by the way) may be the Reaſon, why often times when the Oyls of ſome Spices and of Anniſeeds &c. are Diſtilled in a Limbec with Water, the Water (as I have ſeveral times obſerv'd) comes over Whitiſh, and will perhaps continue ſo for a good while, becauſe if the Fire be made too Strong, the ſubtile Chymical Oyl is thereby much Agitated and Broken, and Blended with the Water in ſuch Numerous and Minute Globules, as cannot eaſily in a ſhort time Emerge to the Top of the Water, and whilſt they Remain in it, make it, for the Reaſon newly intimated, look Whitiſh; and perhaps upon the ſame Ground a cauſe may be rendred, why Hot water is obſerv'd to be uſually more Opacous and Whitiſh, than the ſame Water Cold, the Agitation turning the more Spirituous or otherwiſe Conveniently Diſpos'd Particles of the Water into Vapours, thereby Producing in the Body of the Liquor a Multitude of Small Bubbles, which interrupt the Free paſſage, that the Beams of Light would elſe have Every way, and from the Innermoſt parts of the Water Reflect many of them Outwards. Theſe and the like Examples, Pyrophilus, [pg 112] have induc'd me to Suſpect, that the Superficial Particles of White bodies, may for the Moſt part be as well Convex as Smooth; I content my ſelf to ſay Suſpect and for the moſt part, becauſe it ſeems not Eaſie to prove, that when Diaphanous bodies, as we ſhall ſee by and by, are reduc'd into White Powders, each Corpuſcle muſt needs be of a Convex Superficies, ſince perhaps it may Suffice that Specular Surfaces look ſeverally ways. For (as we have ſeen) when a Diaphanous Body comes to be reduc'd to very Minute parts, it thereby requires a Multitude of Little Surfaces within a Narrow compaſs. And though each of theſe ſhould not be of a Figure Convenient to Reflect a Round Image of the Sun, yet even from ſuch an Inconveniently Figur'd body, there may be Reflected ſome (either Streight or Crooked) Phyſical Line of Light, which Line I call Phyſical, becauſe it has ſome Breadth in it, and in which Line in many caſes ſome Refraction of the Light falling upon the Body it depends on, may contribute to the Brightneſs, as if a Slender Wire, or Solid Cylinder of Glaſs be expos'd to the Light, you ſhall ſee in ſome part of it a vivid Line of Light, and if we were able to draw out and lay together a Multitude of theſe Little [pg 113] Wires or Thrids of Glaſs, ſo Slender, that the Eye could not diſcern a Diſtance betwixt the Luminous Lines, there is little doubt (as far as I can gueſs by a Tryal purpoſely made with very Slender, but far leſs Slender Thrids of Glaſs, whoſe Aggregate was Look'd upon one way White) but the whole Phyſical Superficies compos'd of them, would to the Eye appear White, and if ſo, it will not be always neceſſary that the Figure of thoſe Corpuſcles, that make a Body appear White, ſhould be Globulous. And as for Snow it ſelf, though the Learned Gaſſendus (as we have ſeen above) makes it to ſeem nothing elſe but a pure Frozen Froth, conſiſting of exceedingly Minute and Thickſet Bubbles; yet I ſee no neceſſity of Admitting that, ſince not only by the Variouſly and Curiouſly Figur'd Snow, that I have divers times had the Opportunity with Pleaſure to obſerve, but alſo by the Common Snow, it rather doth appear both to the Naked Eye, and in a Microſcope, often, if not moſt commonly, to conſiſt principally of Little Slender Icicles of ſeveral Shapes, which afford ſuch Numerous Lines of Light, as we have been newly Speaking of.
12. Sixthly, If you take a Diaphanous Body, as for inſtance a Piece of Glaſs, and [pg 114] reduce it to Powder, the ſame Body, which when it was Entire, freely Tranſmitted the Beams of Light, acquiring by Contuſion a multitude of Minute Surfaces, each of which is as it were a Little, but Imperfect Speculum, is qualify'd to Reflect in a Confus'd manner, ſo many either Beams, or Little and Singly Unobſervable Images of the Lucid Body, that from a Diaphanous it Degenerates into a White Body. And I remember, I have for Trials ſake taken Lumps of Rock Cryſtal, and Heating them Red hot in a Crucible, I found according to my Expectation, that being Quench'd in Fair water, even thoſe that remain'd in ſeemingly entire Lumps exchang'd their Tranſlucency for Whiteneſs, the Ignition and Extinction having as it were Crack'd each Lump into a multitude of Minute Bodies, and thereby given it a great multitude of new Surfaces. And ev'n with Diaphanous Bodies, that are Colour'd, there may be this way a Greater Degree of Whiteneſs produced, than one would lightly think; as I remember, I have by Contuſion obtain'd Whitiſh Powders of Granates, Glaſs of Antimony, and Emeralds finely Beaten, and you may more eaſily make the Experiment, by taking Good Venereal Vitriol of a Deep Blew, [pg 115] and comparing with ſome of the Entire Cryſtalls purpoſely reſerv'd, ſome of the Subtile Powder of the ſame Salt, which will Comparatively exhibit a very conſiderable degree of Whitiſhneſs.
13. Seventhly, And as by a Change of Poſition in the Parts, a Body that is not White, may be made White, ſo by a Slight change of the Texture of its Surface, a White Body may be Depriv'd of its Whiteneſs. For if, (as I have try'd in Gold-ſmiths Shops) you take a piece of Silver that has been freſhly Boyl'd, as the Artificers call it, (which is done by, firſt Bruſhing, and then Decocting it with Salt and Tartar, and perhaps ſome other Ingredients) you ſhall find it to be of a Lovely White. But if you take a piece of Smooth Steel, and therewith Burniſh a part of it, which may be preſently done, you ſhall find that Part will Loſe its Whiteneſs, and turn a Speculum, looking almoſt every where Dark, as other Looking-glaſſes do, which may not a little confirm our Doctrine. For by this we may gueſs, what it is chiefly that made the Body White before, by conſidering that all that was done to deprive it of that Whiteneſs, was only to Depreſs the Little Protuberances that were before on the Surface of the Silver [pg 116] into one Continu'd Superficies, and thereby effect this, that now the Image of the Lucid Body, and conſequently a Kind of Whiteneſs ſhall appear to your Eye, but in ſome place of the greater Silver Looking-glaſs (whence the Beams reflected at an Angle Equal to that wherewith they fall on it, may reach your Eye) whilſt the Aſperity remain'd Undeſtroy'd, the Light falling on innumerable Little Specula Obverted ſome one way, and ſome another, did from all Senſibly Diſtinguiſhable parts of the Superficies reflect confus'd Beams or Repreſentations of Light to the Beholders Eye, from whence ſoever he chance to Look upon it. And among the Experiments annex'd to this Diſcourſe, you will find One, wherein by the Change of Texture in Bodies, Whiteneſs is in a Trice both Generated and Deſtroy'd.
1. What we have Diſcours'd of Whiteneſs, may ſomewhat Aſſiſt us to form a Notion of Blackneſs, thoſe two Qualities being Contrary enough to Illuſtrate each other. Yet among the Antient Philoſophers I find leſs Aſſiſtance [pg 117] to form a Notion of Blackneſs than of Whiteneſs, only Democritus in the paſſage above Recited out of Aristotle has given a General Hint of the Cauſe of this Colour, by referring the Blackneſs of Bodies to their Aſperity. But this I call but a General Hint, becauſe thoſe Bodies that are Green, and Purple, and Blew, ſeem to be ſo as well as Black ones, upon the Account of their Superficial Aſperity. But among the Moderns, the formerly mention'd Gaſſendus, perhaps invited by this Hint of Democritus, has Incidentally in another Epiſtle given us, though a very Short, yet a ſomewhat Clearer account of the Nature of Blackneſs in theſe words: Existimare par est corpora ſuâpte Naturâ nigra constare ex particulis, quarum Superficieculæ ſcabræ ſint, nec facilè lucem extrorſum reflectant. I wiſh this Ingenious Man had enlarg'd himſelf upon this Subject; For indeed it ſeems, that as that which makes a Body White, is chiefly ſuch a Diſpoſition of its Parts, that it Reflects (I mean without much Interruption) more of the Light that falls on it, than Bodies of any other Colour do, ſo that which makes a Body Black is principally a Peculiar kind of Texture, chiefly of its Superficial Particle, whereby it does as it were Dead the Light [pg 118] that falls on it, ſo that very little is Reflected Outwards to the Eye.
2. And this Texture may be Explicated two, and perhaps more than two ſeveral ways, whereof the firſt is by Suppoſing in the Superficies of the Black Body a Particular kind of Aſperity, whereby the Superficial Particles reflect but Few of the Incident Beams Outwards, and the reſt Inwards towards the Body it ſelf. As if for Inſtance, we ſhould conceive the Surface of a Black Body to be Aſperated by an almoſt Numberleſs throng of Little Cylinders, Pyramids, Cones, and other ſuch Corpuſcles, which by their being Thick Set and Erected, reflect the Beams of Light from one to another Inwards, and ſend them too and fro ſo often, that at length they are Loſt before they can come to Rebound out again to the Eye. And this is the firſt of the two mention'd ways of Explicating Blackneſs. The other way is by Suppoſing the Texture of Black Bodies to be ſuch, that either by their Yielding to the Beams of Light, or upon ſome other Account, they do as it were Dead the Beams of Light, and keep them from being Reflected in any Plenty, or with any Conſiderable Vigour of Motion, Outwards. According to this Notion it may be ſaid, that [pg 119] the Corpuſcles that make up the Beams of Light, whether they be Solary Effluviums, or Minute Particles of ſome Ætherial Subſtance, Thruſting on one another from the Lucid Body, do, falling on Black Bodies, meet with ſuch a Texture, that ſuch Bodies receive Into themſelves, and Retain almoſt all the Motion communicated to them by the Corpuſcles that make up the Beams of Light, and conſequently Reflect but Few of them, or thoſe but Languidly, towards the Eye, it happening here almoſt in like manner as to a ball, which thrown againſt a Stone or Floor, would Rebound a great way Upwards, but Rebounds very Little or not at all, when it is thrown againſt Water, or Mud, or a Looſe Net, becauſe the Parts yield, and receive into themſelves the Motion, on whoſe Account the Ball ſhould be Reflected Outwards. But this Laſt way of Explicating Blackneſs, I ſhall content my Self to have Propos'd, without either Adopting it, or abſolutely Rejecting it. For the Hardneſs of Touchſtones, Black Marble and other Bodies, that being Black are Solid, ſeem to make it ſomewhat Improbable, that ſuch Bodies ſhould be of ſo Yielding a Texture, unleſs we ſhould ſay, that ſome Bodies may be more Diſpos'd to Yield to the Impulſes of [pg 120] the Corpuſcles of Light by reaſon of a Peculiar Texture, than other Bodies, that in other Tryals appear to be Softer than they. But though the Former of theſe two Explications of Blackneſs be that, by which we ſhall Endeavour to give an Account of it, yet as we ſaid, we ſhall not Abſolutely Reject this Latter, partly becauſe they both Agree in this, that Black Bodies Reflect but Little of the Light that falls on them, and partly becauſe it is not Impoſſible, that in ſome Caſes both the Diſpoſition of the Superficial particles, as to Figure and Poſition, and the Yielding of the Body, or ſome of its Parts, may joyntly, though not in an Equal meaſure concurr to the rendring of a Body Black. The Conſiderations that induc'd me to propoſe this Notion of Blackneſs, as I Explan'd it, are principally theſe:
3. Firſt, That as I lately ſaid, Whiteneſs and Blackneſs being generally reputed to be Contrary Qualities, Whiteneſs depending as I ſaid upon the Diſpoſition of the Parts of a Body to Reflect much Light, it ſeems likely, that Blackneſs may depend upon a Contrary Diſpoſition of the Black Bodies Surface; But upon this I ſhall not Inſiſt.
4. Next then we ſee, that if a Body of [pg 121] One and the ſame Colour be plac'd, part in the Sun-beams, and part in the Shade, that part which is not Shin'd on will appear more of Kin to Blackneſs than the other, from which more Light Rebounds to the Eye; And Dark Colours ſeem the Blacker, the leſs Light they are Look'd upon in, and we think all Things Black in the Dark, when they ſend no Beams to make Impreſſions on our Organs of Sight, ſo that Shadows and Darkneſs are near of Kin, and Shaddow we know is but a Privation of Light; and accordingly Blackneſs ſeems to proceed from the Paucity of Beams Reflected from the Black Body to the Eye, I ſay the Paucity of Beams, becauſe thoſe Bodies that we call Black, as Marble, Jeat, &c. are Short of being perfectly ſo, elſe we ſhould not See them at all. But though the Beams that fall on the Sides of thoſe Erected Particles that we have been mentioning, do Few of them return Outwards, yet thoſe that fall upon the Points of thoſe Cylinders, Cones, or Pyramids, may thence Rebound to the Eye, though they make there but a Faint Impreſſion, becauſe they Arrive not there, but Mingl'd with a great Proportion of Little Shades. This may be Confirm'd by my having procur'd a Large piece of Black [pg 122] Marble well Poliſh'd, and brought to the Form of a Large Sphærical and Concave Speculum; For on the Inſide this Marble being well Poliſh'd, was a kind of Dark Looking-glaſs, wherein I could plainly ſee a Little Image of the Sun, when that Shin'd upon it. But this Image was very far from Offending and Dazling my Eyes, as it would have done from another Speculum; Nor, though the Speculum were Large, could I in a Long time, or in a Hot Sun ſet a piece of Wood on Fire, though a far leſs Speculum of the ſame Form, and of a more Reflecting Matter, would have made it Flame in a Trice.
5. And on this Occaſion we may as well in Reference to ſomething formerly deliver'd concerning Whiteneſs, as in Reference to what has been newly ſaid, Subjoyn what we further obſerv'd touching the Differing Reflections of Light from White and Black Marble, namely, that having taking a pretty Large Mortar of White Marble, New and Poliſh'd in the Inſide, and Expos'd it to the Sun, we found that it Reflected a great deal of Glaring Light, but ſo Diſpers'd, that we could not make the Reflected Beams concurr in any ſuch Conſpicuous Focus, as that newly taken notice of in the Black Marble, though [pg 123] perhaps there may enough of them be made to meet near the Bottom, to make ſome Kind of Focus, eſpecially ſince by holding in the Night-time a Candle at a convenient Diſtance, we were able to procure a Concourſe of ſome, though not many of the Reflected Beams, at about two Inches diſtant from the Bottom of the Mortar: But we found the Heat even of the Sunbeams ſo Diſperſedly Reflected to be very Languid, even in Compariſon of the Black Marbles Focus. And the Little Picture of the Sun, that appear'd upon the White Marble as a Speculum, was but very Faint and exceeding ill Defin'd. Secondly, That taking two pieces of Plain and Poliſh'd Surfaces, and caſting on them Succeſſively the Beams of the Same Candle, In ſuch manner, as that the Neighbouring Superficies being Shaded by an Opacous and Perforated Body, the Incident Beams were permitted to paſs but through a Round Hole of about Half an Inch Diameter, the Circle of Light that appear'd on the White Marble was in Compariſon very Bright, but very ill Defin'd; whereas that on the Black Marble was far leſs Luminous, but much more preciſely Defin'd.
6. Thirdly, When you Look upon a piece of Linnen that has Small Holes in it, [pg 124] thoſe Holes appear very Black, and Men are often deceiv'd in taking Holes for Spots of Ink; And Painters to repreſent Holes, make uſe of Black, the Reaſon of which ſeems to be, that the Beams that fall on thoſe Holes, fall into them So Deep, that none of them is Reflected back to the Eye. And in narrow Wells part of the Mouth ſeems Black, becauſe the Incident Beams are Reflected Downwards from one ſide to another, till they can no more Rebound to the Eye.
We may conſider too, that if Differing parts of the ſame piece of Black Velvet be ſtroak'd Oppoſite ways, the piece of Velvet will appear of two Diſtinct kinds of Blackneſs, the one far Darker than the other, of which Diſparity the Reaſon Seems to be, that in the Leſs obſcure part of the Velvet, the Little Silken Piles whereof 'tis made up, being Inclin'd, there is a Greater part of each of them Obverted to the Eye, whereas in the other part the Piles of Silk being more Erected, there are far Fewer Beams Reflected Outwards from the Lateral parts of each Pile, So that moſt of thoſe that Rebound to the Eye, come from the Tops of the Piles, which make but a ſmall part of the whole Superficies, that may be cover'd by the piece of Velvet. [pg 125] Which Explication I propoſe, not that I think the Blackneſs of the Velvet proceeds from the Cauſe aſſign'd, ſince each Single Pile of Silk is Black by reaſon of its Texture, in what Poſition ſoever you Look upon it; But that the Greater Blackneſs of one of theſe Tuffts ſeems to proceed from the Greater Paucity of Beams Reflected from it, and that from the Fewneſs of thoſe Parts of a Surface that Reflect Beams, and the Multitude of thoſe Shaded Parts that Reflect none. And I remember, that I have oftentimes obſerv'd, that the Poſition of Particular Bodies far greater than Piles of Silk in reference to the Eye, may notwithſtanding their having each of them a Colour of its own, make one part of their Aggregate appear far Darker than the other; For I have near Great Towns often taken notice, that a Cart-load of Carrots pack'd up, appear'd of a much Darker Colour when Look'd upon, where the Points of the Carrots were Obverted to the Eye, than where the Sides of them were ſo.
7. Fourthly, In a Darkned Room, I purpoſely obſerv'd, that if the Sun-beams, which came in at the Hole were receiv'd upon White or any other Colour, and directed to a Convenient place of the Room, [pg 126] they would Manifeſtly, though not all Equally, Encreaſe the Light of that Part; whereas if we Subſtituted, either a piece of Black Cloth or Black Velvet, it would ſo Dead the Incident Beams, that the place (newly mention'd) whereto I Obverted the Black Body, would be Leſs Enlightned than it was before, when it received its Light but from the Weak and Oblique Reflections of the Floor and Walls of a pretty Large Room, through which the Beams that came in at the Hole were Confuſedly and Brokenly Diſpers'd.
8. Fifthly, And to ſhew that the Beams that fall on Black Bodies, as they do not Rebound Outwards to the Eye, ſo they are Reflected towards the Body it ſelf, as the Nature of thoſe Erected Particles to which we have imputed Blackneſs, requires, we will add an Experiment that will alſo confirm our Doctrine touching Whiteneſs; Namely, that we took a Broad and Large Tile, and having Whitened over one half of the Superficies of it, and Black'd the other, we expos'd it to the Summer Sun; And having let it lye there a convenient time (for the Difference is more Apparent, if it have not lain there too long) we found, as we expected, that whilſt the Whited part of the Tile remained Cool enough, the [pg 127] Black'd part of the ſame Tile was grown not only Senſible, but very Hot, (ſometimes to a ſtrong Degree.) And to ſatisfie ſome of our Friends the more, we have ſometimes left upon the Surface of the Tile, beſides the White and Black parts thereof, a part that Retain'd the native Red of the Tile it ſelf, and Expoſing them to the Sun, we obſerv'd this Laſt mention'd to have Contracted a Heat in compariſon of the White, but a Heat Inferiour to that of the Black, of which the Reaſon ſeems to be, that the Superficial Particles of Black Bodies, being, as we ſaid, more Erected, than thoſe of White or Red ones, the Corpuſcles of Light falling on their ſides, being for the moſt part Reflected Inwards from one Particle to another, and thereby engag'd as it were and kept from Rebounding Upwards, they communicate their brisk Motion, wherewith they were impell'd againſt the Black Body, (upon whoſe account had they fallen upon a White Body, they would have been Reflected Outwards) to the Small parts of the Black Body, and thereby Produce in thoſe Small parts ſuch an Agitation, as (when we feel it) we are wont to call Heat. I have been lately inform'd, that an Obſervation near of Kin to Ours, has been made by ſome Learned Men in France and [pg 128] Italy, by long Expoſing to a very Hot Sun, two pieces of Marble, the one White, the other Black; But though the Obſervation be worthy of them, and may confirm the ſame Truth with Our Experiment, yet beſides that our Tryal needs not the Summer, nor any Great Heat to ſucceed, It ſeems to have this Advantage above the other, that whereas Bodies more Solid, and of a Cloſer Texture, though they uſe to be more Slowly Heated, are wont to receive a Greater Degree of Heat from the Sun or Fire, than (Cæteris paribus) Bodies of a Slightest Texture; I have found by the Information of Stone-cutters, and by other ways of Enquiry, that Black Marble is much Solider and Harder than White, ſo that poſſibly the Difference betwixt the Degrees of Heat they receive from the Sunbeams will by many be aſcrib'd to the Difference of their Texture, rather than to that of their Colour, though I think our Experiment will make it Probable enough that the greater part of that Difference may well be aſcrib'd to that Diſpoſition of Parts, which makes the one Reflect the Sunbeams Inward; and the other Outwards. And with this Doctrine accords very well, that Rooms hung with Black, are not only Darker than elſe they would be, but are [pg 129] wont to be Warmer too; Inſomuch that I have known a great Lady, whoſe Conſtitution was ſomewhat Tender, complain that ſhe was wont to catch Cold, when ſhe went out into the Air, after having made any long Viſits to Perſons, whoſe Rooms were hung with Black. And this is not the only Lady I have heard complain of the Warmth of ſuch Rooms, which though perhaps it may be partly imputed to the Effluvia of thoſe Materials wherewith the hangings were Dy'd, yet probably the Warmth of ſuch Rooms depends chiefly upon the ſame Cauſe that the Darkneſs does; As (not to repeat what I formerly Noted touching my Gloves,) to ſatisfie ſome Curious Perſons of that Sex, I have convinc'd them, by Tryall, that of two Pieces of Silken Stuff given me by themſelves, and expos'd in their Preſence, to the ſame Window, Shin'd on by that Sun, the White was conſiderably Heated, when the Black was not ſo much as Senſibly ſo.
9. Sixthly, I remember, that Acquainting one Day a Virtuoſo of Unſuſpected Credit, that had Viſited Hot Countries, with part of what I have here Deliver'd concerning Blackneſs, he Related to me by way of Confirmation of it, a very notable [pg 130] Experiment, which he had both others make, and Made himſelf in a Warm Climate, namely, that having carefully Black'd over Eggs, and Expos'd them to the Hot Sun, they were thereby in no very Long time well Roaſted, to which Effect I conceive the Heat of the Climate muſt have Concurr'd with the Diſpoſition of the Black Surface to Reflect the Sunbeams Inward, for I remember, that having made that among other Tryals in England, though in Summer-time, the Eggs I Expos'd, acquir'd indeed a conſiderable Degree of Heat, but yet not ſo Intenſe a One, as prov'd Sufficient to Roaſt them.
10. Seventhly, and Laſtly, Our Conjectures at the Nature of Blackneſs may be ſomewhat Confirm'd by the (formerly mention'd) Obſervation of the Blind Dutch-man, that Diſcerns Colours with his Fingers; for he Says, that he Feels a greater Roughneſs upon the Surfaces of Black Bodies, than upon thoſe of Red, or Yellow, or Green. And I remember, that the Diligent Bartholinus ſays,9 that a Blind Earl of Mansfield could Diſtinguiſh White from Black only by the Touch, which would Sufficiently Argue a great Diſparity in the Aſperities, or other [pg 131] Superficial Textures of Bodies of thoſe two Colours, if the Learn'd Relator had Affirm'd the Matter upon his own Knowledge.
II. Theſe, Pyrophilus, are the chief things that Occurr to me at preſent, about the Nature of Whiteneſs and Blackneſs, which it they have Rendred it ſo much as Probable, that in Moſt; or at leaſt Many Caſes, the Cauſes of theſe Qualities may be ſuch as I have Adventur'd to Deliver, it is as much as I Pretend to; for till I have Opportunity to Examine the Matter by ſome further Tryals, I am not ſure, but that in ſome White and Black Bodies, there may Concurr to the Colour ſome peculiar Texture or Diſpoſition of the Body, whereby the Motion of the Small Corpuſcles that make up the Incident Beams of Light, may be Differingly Modify'd, before they reach the Eye, eſpecially in this, that White Bodies do not only Copiouſly Reflect thoſe Incident Corpuſcles Outwards, but Reflect them Briskly, and do not otherwiſe Alter them in the manner of their Motion. Nor ſhall I now ſtay to Enquire, whether ſome of thoſe other ways, (as a Diſpoſition to Alter the Velocity, the Rotation, or the Order and Manner of Appulſe ſo the Eye of the Reflected Corpuſcles [pg 132] that Compos'd the Incident Beams of Light) which we mention'd when we conſider'd the Production of Colours in General, may not in ſome Caſes be Applicable to thoſe of White and Black Bodies: For I am yet ſo much a Seeker in this Matter, and ſo little Wedded to the Opinions I have propos'd, that what I am to add ſhall be but the Beginning of a Collection of Experiments and Obſervation towards the Hiſtory of Whiteneſs and Blackneſs, without at preſent interpoſing my Explications of them, that ſo, I may aſſiſt your Enquires without much Fore-ſtalling or Biaſſing your Judgment.
Aving promis'd in the 114, and 115. Pages of the foregoing Diſcourſe of
Whiteneſs and Blackneſs, to ſhew, that thoſe two
Colours may by a change of Texture in bodies, each of them apart
Diaphanous and Colourleſs, be at pleaſure and in a trice as
well Generated as Deſtroy'd, We ſhall begin with Experiments
that may acquit us of that promiſe.
Take then what Quantity you pleaſe of Fair Water, and having Heated it, put into it as much good Common Sublimate, as it is able to Diſſolve, and (to be ſure of having [pg 134] it well glutted:) continue putting in the Sublimate, till ſome of it lye Untouch'd in the bottom of the Liquor, Filter this Solution through Cap-paper, to have it cleer and limpid, and into a ſpoonfull or two thereof, (put into a clean glaſs veſſel,) ſhake about four or five drops (according as you took more or leſs of this Solution) of good limpid Spirits of Urine, and immediately the whole mixture will appear White like Milk, to which mixture if you preſently add a convenient proportion of Rectifi'd Aqua Fortis (for the number of drops is hard to determine, becauſe of the Differing Strength of the liquor, but eaſily found by tryal) the Whiteneſs will preſently diſappear, and the whole mixture become Tranſparent, which you may, if you pleaſe, again reduce to a good degree of Whiteneſs (though inferiour to the firſt) onely by a more copious affuſion of freſh Spirit of Urine. N. Firſt, That it is not ſo neceſſary to employ either Aqua Fortis or Spirit of Urine about this Experiment, but that we have made it with other liquors inſtead of theſe, of which perhaps more elſewhere. Secondly, That this Experiment, though not made with the ſame Menſtruums, nor producing the ſame Colour is yet much of Kin to that other to be [pg 135] mentioned in this Tract among our other Experiments of Colours, about turning a Solution of Præcipitate into an Orange-colour, and the Chymical Reaſon being much alike in both, the annexing it to one of them may ſuffice FOR both.
Make a ſtrong Infuſion of broken Galls in Fair Water, and having Filtred it into a clean Vial, add more of the ſame liquor to it, till you have made it ſomewhat Tranſparent, and ſufficiently diluted the Colour, for the credit of the Experiment, leſt otherwiſe the Darkneſs of the liquor might make it be objected, that 'twas already almoſt Ink; Into this Infuſion ſhake a convenient quantity of a Cleer, but very ſtrong Solution of Vitriol, and you ſhall immediately ſee the mixture turn Black almoſt like Ink, and ſuch a way of producing Blackneſs is vulgar enough; but if preſently after you doe upon this mixture drop a ſmall quantity of good oyl of Vitriol, and, by ſhaking the Vial diſperſe it nimbly through the two other liquors, you ſhall (if you perform your part well, and have employ'd oyl of Vitriol Cleer and Strong enough) ſee the Darkneſs of the liquor preſently begin [pg 136] to be diſcuſs'd, and grow pretty Cleer and Tranſparent, loſing its Inky Blackneſs, which you may again reſtore to it by the affuſion of a ſmall quantity of a very ſtrong Solution of Salt of Tartar. And though neither of theſe Atramentous liquors will ſeem other than very Pale Ink, if you write with a clean Pen dipt in them, yet that is common to them with ſome ſorts of Ink that prove very good when Dry, as I have alſo found, that when I made theſe carefully, what I wrote with either of them, eſpecially with the Former, would when throughly Dry grow Black enough not to appear bad Ink. This Experiment of taking away and reſtoring Blackneſs from and to the liquors, we have likewiſe tryed in Common Ink; but there it ſucceeds not ſo well, and but very ſlowly, by reaſon that the Gum wont to be employed in the making it, does by its Tenacity oppoſe the operations of the above mention'd Saline liquors. But to conſider Gum no more, what ſome kind of Præcipitation may have to do in the producing and deſtroying of Inks without it, I have elſewhere given you ſome occaſion and aſſiſtance to enquire; But I muſt not now ſtay to do ſo my ſelf, only I ſhall take notice to you, that though it be taken for granted that bodies will not be Præcipitated by Alcalizat Salts, [pg 137] that have not firſt been diſſolved in ſome Acid Menſtruums, yet I have found upon tryals, which my conjectures lead me to make on purpoſe, That divers Vegetables barely infus'd, or, but ſlightly decocted in common water, would, upon the affuſion of a Strong and Cleer Lixivium of Potaſhes, and much more of ſome other Præcipitating liquors that I ſometimes employ, afford good ſtore of a Crudled matter, ſuch as I have had in the Præcipitations of Vegetable ſubſtances, by the intervention of Acid things, and that this matter was eaſily ſeparable from the reſt of the liquor, being left behind by it in the Filtre; and in making the firſt Ink mention'd in this Experiment, I found that I could by Filtration ſeparate pretty ſtore of a very Black pulverable ſubſtance, that remain'd in the Filtre, and when the Ink was made Cleer again by the Oyl of Vitriol, the affuſion of diſſolv'd Sal Tartari ſeem'd but to Præcipitate, and thereby to Unite and render Conſpicuous the particles of the Black mixture that had before been diſpers'd into very Minute and ſingly Inviſible particles by the Inciſive and reſolving power of the highly Corroſive Oyl of Vitriol.
And to manifeſt, Pyrophilus, that Galls are not ſo requiſite as many ſuppoſe to the making Atramentous Liquors, we have ſometimes made the following Experiment, We took dryed Roſe leaves and Decocted them for a while in Fair Water, into two or three ſpoonfulls of this Decoction we ſhook a few drops of a ſtrong and well filtrated Solution of Vitriol (which perhaps had it been Green would have done as well) and immediately the mixture did turn Black, and when into this mixture preſently after it was made, we ſhook a juſt Proportion of Aqua Fortis, we turn'd it from a Black Ink to a deep Red one, which by the affuſion of a little Spirit of Urine may be reduc'd immediately to an Opacous and Blackiſh Colour. And in regard, Pyrophilus, that in the former Experiments, both the Infuſion of Galls, and the Decoction of Roſes, and the Solution of Copperis employ'd about them, are endow'd each of them with its own Colour, there may be a more noble Experiment of the ſudden production of Blackneſs made by the way mention'd in the Second Section of the Second Part of our Eſſays, for though upon the Confuſion of the two Liquors there mention'd, there do immediately emerge a very Black mixture, yet both the Infuſion of Orpiment and the Solution of Minium were before their being joyn'd together, Limpid and Colourleſs.
[pg 138]If pieces of White Harts-horn be with a competent degree of Fire diſtill'd in a Glaſs-retort, they will, after the avolation of the Flegm, Spirit, Volatile Salt, and the looſer and lighter parts of the Oleagenous ſubſtance, remain behind of a Cole-black colour. And even Ivory it ſelf being skilfully Burnt (how I am wont to do it, I have elſewhere ſet down) affords Painters one of the beſt and deepeſt Blacks they have, and yet in the Inſtance of diſtill'd Harts-horn, the operation being made in Glaſs-veſſels carefully clos'd, it appears there is no Extraneous Black ſubſtance that Inſinuates it ſelf into White Harts-horn, and thereby makes it turn Black; but that the Whiteneſs is deſtroy'd, and the Blackneſs generated, only by a Change of Texture, made in the burnt Body, by the Receſs of ſome parts and the Tranſpoſition of others. And though I remember not that in many Diſtillations of Harts-horn I ever ſound the Cap. Mort. to paſs from Black to a true Whiteneſs, whilſt it continu'd in Clos'd veſſels, yet having taken out the Cole-black fragments, and Calcin'd them in Open veſſels, I could in few hours quite deſtroy that Blackneſs, & without [pg 139] ſenſibly changing their Bulk or Figure, reduce them to great Whiteneſs. So much do theſe two Colours depend upon the Diſpoſition of the little parts, that the Bodies wherein they are to be met with do conſiſt of. And we find, that if Whitewine Tartar, or even the white Cryſtalls of ſuch Tartar be burnt without being truly Calcin'd, the Cap. Mortuum (as the Chymiſts call the more Fixt part) will be Black. But if you further continue the Calcination till you have perfectly Incinerated the Tartar, & kept it long enough in a Strong fire, the remaining Calx will be White. And ſo we ſee that not only other Vegetable ſubſtances, but even White woods, as the Hazel, will yield a Black Charcoal, and afterwards Whitiſh aſhes; And ſo Animal ſubſtances naturally White, as Bones and Eggſhels, will grow Black upon the being Burnt, and White again when they are perfectly Calcin'd.
But yet I much Queſtion whether that Rule delivered by divers, as well Philoſophers as Chymiſts, aduſta nigra, ſed peruſta alba, will hold as Univerſally as is preſum'd, ſince I have ſeveral Examples to allege againſt [pg 140] it: For I have found that by burning Alablaſter, ſo as both to make it appear to boyl almoſt like Milk, and to reduce it to a very fine Powder, it would not at all grow Black, but retain its Pure and Native Whiteneſs, and though by keeping it longer than is uſual in the fire, I produced but a faint Yellow, even in that part of the Powder that lay neareſt the top of the Crucible, yet having purpoſely enquired of an Experienced Stone-cutter, who is Curious enough in tryng Concluſions in his own Trade, he told me he had found that if Alabaſter or Plaſter of Paris be very long kept in a Strong fire, the whole heap of burnt Powder would exchange its Whiteneſs for a much deeper Colour than the Yellow I obſerv'd. Lead being Calcin'd with a Strong fire turns (after having purhaps run thorough divers other Colour) into Minium, whoſe Colour we know is a deep red; and if you urge this Minium, as I have purpoſely done with a Strong fire, you may much eaſier find a Glaſſie and Brittle Body darker than Minium, than any white Calx or Glaſs. 'Tis known among Chymiſts, that the white Calx of Antimony, by the further and more vehement operation of the fire, may be melted into Glaſs, which we have obtain'd of a Red Colour, which is [pg 141] far deeper than that of the Calx of Burnt Antimony, and though common Glafs of Antimony being uſually Adulterated with Borax, have its Colour thereby diluted, oftentimes to a very pale Yellow; yet not onely ours made more ſincerily, was, as we ſaid, of a Colour leſs remote from Black, than was the Calx; but we obſerv'd, that by Melting it once or twice more, and ſo expoſing it to the further operation of the Fire, we had, as we expected, the Colour heightned. To which we ſhall add but this one Inſtance, (which is worth the taking notice of in Reference to Colours:) That, if you take Blew, but Unſophiſticated, Vitriol, and burn it very ſlowly, and with a Gentle degree of Heat, you may obſerve, that when it has Burnt but a Little, and yet ſo far as that you may rub it to Powder betwixt your fingers, it will be of a White or Whitiſh Colour; But if you Proſecute the Calcination, this Body which by a light Aduſtion was made White, will paſs through other Colours, as Gray, Yellowiſh, and Red; and if you further burn it with a Long and Vehement fire, by that time it comes to be Peruſtum, it will be of a dark purple, nearer to Black, not only than the firſt Calx, but than the Vitriol before it at all felt the fire. I might add that Crocus [pg 142] Martis (per ſe as they call it) made by the Laſting violence of the Reverberated flames is not ſo near a Kin to White, as the Iron or Steel that afforded it was before its Calcinations; but that I ſuppoſe, theſe Inſtances may Suffice to ſatisfie you, that Minerals are to be excepted out of the forementioned Rule, which perhaps, though it ſeldome fail in ſubſtances belonging to the Vegetable or Animal Kingdome, may yet be Queſtion'd even in ſome of theſe, if that be true, which the Judicious Traveller Bellonius affirms, that Charcoales made out of the Wood of Oxycæder are White; And I could not find that though in Retorts Hartſhorn and other White Bodies will be Denigrated by Heat, yet Camphire would not at all loſe its Whiteneſs, though I have purpoſely kept it in ſuch a heat, as made it melt and boyl.
[pg 143]And now I ſpeak of Camphire, it puts me in mind of adding this Experiment, That, though as I ſaid in Clos'd Glaſſes, I could not Denigrate it by Heat, but it would Sublime to the ſides and top of the Glaſs, [pg 144] as it was before, yet not only it will, being ſet on fire in the Free Air, ſend forth a Copious ſmoak, but having purpoſely upon ſome of it that was Flaming, clapt a Large Glaſs, almoſt in the form of a Hive, (but more Slender only) with a Hole at the top, (which I caus'd to be made to trye Experiments of Fire and Flame in) it continued ſo long burning that it Lin'd all the Inſide of the Glaſs with a Soot as Black as Ink, and ſo Copious, that the Cloſeneſs of the Veſſel conſider'd, almoſt all that part of the White Camphire that did take Fire, ſeem'd to have been chang'd into that deep Black Subſtance.
And this alſo brings into my mind another Experiment that I made about the production of Blackneſs, whereof, for Reaſons too long to be here deduced, I expected and found a good Succeſs, an it was this: I took Rectifi'd Oyl of Vitriol (that I might have the Liquor Clean as well as Strong) and by degrees mixt with it a convenient proportion of the Eſſential Oyl, as Chymiſts call it, of Wormwood, drawn over with ſtore of Water in a Limbec, and warily Diſtilling the mixture in a Retort, there remain'd [pg 145] a ſcarce credible quantity of dry Matter, Black as a Coal. And becauſe the Oyl of Wormwood, though a Chymical Oyl drawn by a Virtuoſo, ſeem'd to have ſomewhat in it of the Colour of the Plant, I Subſtituted in its Room, the Pure and Subtile Eſſential Oyl of Winter-Savory, and mixing little by little this Liquor, with (if I mis-remember not) an Equal weight of the formerly mention'd Rectifi'd Oyl of Vitriol, and Diſtilling them as before in a Retort, beſides what there paſs'd over into the Receiver, even theſe two clear Liquors left me a Conſiderable Proportion, (though not ſo great as the two former) of a Subſtance Black as Pitch, which I yet Keep by me as a Rarity.
A way of Whiting Wax Cheaply and in Great Quantity may be a thing of good Oeconomical Uſe, and we have elſewhere ſet down the Practice of Trades-men that Blanch it; But here Treating of Whiteneſs only in Order to the Philoſophy of Colours, I ſhall not Examine which of the Slow wayes may be beſt Employ'd, to free Wax from the Yellow Melleous parts, but ſhall rather ſet down a Quick [pg 146] way of making it White, though but in very Small Quantities. Take then a little Yellow Wax, ſcraped or thinly ſliced, and putting it into a Bolts-head or ſome other Convenient Glaſs, pour to it a pretty deal of Spirit of Wine, and placing the Veſſel in Warm Sand, Encreaſe the Heat by degrees, till the Spirit of Wine begin to Simper or to Boyl a little; and continuing that degree of Fire, if you have put Liquor enough, you will quickly have the Wax diſſolv'd, then taking it off the fire, you may either ſuffer it to Cool as haſtily as with Safety to the Glaſs you can, or Pour it whilſt 'tis yet Hot into a Filtre of Paper, and either in the Glaſs where it Cools, or in the Filtre, you will ſoon find the Wax and Menſtruum together reduc'd into a White Subſtance, almoſt like Butter, which by letting the Spirit Exhale will ſhrink into a much Leſſer Bulk, but ſtill retaining its Whiteneſs. And that which is pretty in the working of this Magiſtery of Wax, is, that the Yellowneſs vaniſhes, neither appearing in the Spirit of Wine that paſſes Limpid through the Filtre, nor in the Butter of Wax, if I may ſo call it, that, as I ſaid, is White. [pg 147]
There is an Experiment, Pyrophilus, which though I do not ſo exactly remember, and though it be ſomewhat Nice to make, yet I am willing to Acquaint You with, becauſe the thing Produc'd, though it be but a Curioſity, is wont not a little to pleaſe the Beholders, and it is a way of turning by the help of a Dry Subſtance, an almoſt Golden-Colour'd Concrete, into a White one, the Several Tryals are not at preſent ſo freſh in my Memory to enable me to tell you Certainly, whether an Equal onely or a Double weight of Common Sublimate muſt be taken in reference to the Tinglaſs, but if I miſtake not, there was in the Experiment that ſucceeded beſt, Two parts of the Former taken to One of the Latter. Theſe Ingredients being finely Powdred and Exactly mix'd, we Sublim'd together by degrees of fire (the due Gradation of which is in this Experiment a thing of main Importance) there aſcended a matter of a very peculiar Texture, for it was for the moſt part made up of very Thin, Smooth, Soft and Slippery Plates, almoſt like the fineſt ſort of the Scales of Fiſhes, but of ſo Lovely a White Inclining to [pg 148] Pearl-Colour, and of ſo Curious and Shining a Gloſs, that they appear'd in ſome reſpect little Inferiour to Orient Pearls, and in other Regards, they ſeem'd to Surpaſs them, and were Applauded for a ſort of the Prettieſt Trifles that we had ever prepar'd to Amuſe the Eye. I will not undertake that though you'l hardly miſs changing the Colour of your ſhining Tinglaſs, yet you will the firſt or perhaps the ſecond time hit Right upon the way of making the Gliſtring Sublimate I have been mentioning.
When we Diſſolve in Aqua Fortis a mixture of Gold and Silver melted into one Lump, it uſually happens that the Powder of Gold that falls to the bottom, as not being Diſſoluble by that Menſtruum, will not have its own Yellow, but appear of a Black Colour, though neither the Gold, nor the Silver, nor the Aqua Fortis did before manifeſt any Blackneſs. And divers Alchymiſts, when they make Solutions of Minerals they would Examine, are very Glad, if they ſee a Black Powder Præcipitated to the Bottom, taking it for a Hopefull Sign, that thoſe Particles are of a Golden Nature, [pg 149] which appear in a Colour ſo ordinary to Gold parted from other Metalls by Aqua Fortis, that it is a trouble to the Refiner to Reduce the Præcipitated Calx to its Native Colour. For though, (as we have try'd,) that may be Quickly enough done by Fire, which will make this Gold look very Gloriouſly (as indeed 'tis at leaſt one of the Beſt wayes that is Practis'd for the Refining of Gold,) yet it requires both Watchfulneſs and Skill, to give it ſuch a Degree of Fire as will ſerve to Reſtore it to its Luſtre, without giving it ſuch a One, as may bring it to Fuſion, to which the Minuteneſs of the Corpuſeles it conſiſts of makes the Powder very apt. And this brings into my Mind, that having taken a Flat and Bright piece of Gold, that was Refin'd by a Curious and Skilfull Perſon on purpoſe to Trye to what height of Purity Gold could be brought by Art, I found that this very piece, as Glorious as it look'd, being rubb'd a little upon a piece of fine clean Linnen, did ſully it with a kind of Black; and the like I have obſerv'd in Refin'd Silver, which I therefore mention, becauſe I formerly ſuſpected that the Impurity of the Metall might have been the only Cauſe of what I have divers times obferv'd in wearing Silver-hilted Swords, Namely, that [pg 150] where they rubb'd upon my Clothes, if they were of a Light-Colour'd Cloath, the Affriction would quickly Black them; and Congruouſly hereunto I have found Pens Blackt almoſt all over, when I had a while carri'd them about me in a Silver Ink-caſe. To which I ſhall only add, that whereas in theſe ſeveral Inſtances of Denigration, the Metalls are worn off, or otherwiſe Reduc'd into very Minute Parts, that Circumſtance may prove not Unworthy your Notice.
That a Solution of Silver does Dye Hair of a Black Colour, is a Known Experiment, which ſome perſons more Curious than Dextrous, have ſo Unluckily made upon themſelves as to make their Friends very Merry. And I remember that the other day, I made my ſelf ſome Sport by an Improvement of this Obſervation, for having diſſolv'd ſome Pure Silver in Aqua Fortis, and Evaporated the Menſtruum ad ſiccitatem, as they ſpeak, I caus'd a Quantity of fair Water to be pour'd upon the Calx two or three ſeveral times, and to be at each Evaporated, till the Calx was very Drye, and all the Greeniſh Blewneſs that is wont to appear in Common Cryſtals of Silver, [pg 151] was quite carry'd away. Then I made thoſe I meant to Deceive, Moiſten ſome part of their Skin with their own Spittle, and ſlightly Rub the moiſtned parts with a little of this Prepar'd Silver, Whereupon they Admir'd to ſee, that a Snow-white Body laid upon the White Skin ſhould preſently produce a deep Blackneſs, as if the ſtains had been made with Ink, eſpecially conſidering that this Blackneſs could not, like that produc'd by ordinary Ink, be readily Waſh'd off, but requir'd many Hours, and part of it ſome dayes to its Obliteration. And with the ſame White Calx and a little Fair Water we likewiſe Stain'd the White Hafts of Knives, with a laſting Black in thoſe parts where the Calx was Plentifully enough laid on, for where it was laid on but very Thinly, the Stain was not quite of ſo Deep a Colour.
The Cauſe of the Blackneſs of thoſe many Nations, which by one common Name we are wont to call Negroes, has been long ſince Diſputed of by Learned Men, who poſſibly had not done amiſs, if they had alſo taken into Conſideration, why ſome whole races of other Animals beſides Men, as [pg 152] Foxes and Hares, are Diſtinguiſh'd by a Blackneſs not familiar to the Generality of Animals of the ſame Species; The General Opinion (to be mention'd a little lower) has been rejected even by ſome of the Antient Geographers, and among our Moderns Ortelius and divers other Learned Men have Queſtion'd it. But this is no place to mention what thoughts I have had to and fro about theſe Matters: Only as I ſhall freely Acknowledge, that to me the inquiry ſeems more Abſtruſe than it does to many others, and that becauſe conſulting with Authors, and with Books of Voyages, and with Travellers, to ſatisfie my ſelf in matters of Fact, I have met with ſome things among them, which ſeem not to agree very well with the Notions of the moſt Claſſick Authors concerning theſe things; for it being my Preſent Work to deliver rather matters Hiſtorical than Theorys, I ſhall Annex Some few of my Collections, inſtead of a Solemn Diſputation. It is commonly preſum'd that the Heat of the Climate wherein they live, is the reaſon, why ſo many Inhabitants of the Scorching Regions of Africa are Black; and there is this familiar Obſervation to Countenance this Conjecture, That we plainly ſee that Mowers, Reapers, and other Countrey-people, [pg 153] who ſpend the moſt part of the Hot Summer dayes expos'd to the Sun, have the skin of their Hands and Faces, which are the parts immediately Expos'd to the Sun and Air, made of a Darker Colour than before, and conſequently tending to Blackneſs; And Contrarywiſe we obſerve that the Danes and ſome other people that Inhabit Cold Climates, and even the Engliſh who feel not ſo Rigorous a Cold, have uſually Whiter faces than the Spaniards, Portugalls and other European Inhabitants of Hotter Climates. But this Argument I take to be far more Specious than Convincing; for though the Heat of the Sun may Darken the Colour of the Skin, by that Operation, which we in Engliſh call Sun-burning, yet Experience doth not Evince, that I remember, That that Heat alone can produce a Diſcolouring that ſhall amount to a true Blackneſs, like that of Negroes, and we ſhall ſee by and by that even the Children of ſome Negroes not yet 10. dayes Old (perhaps not ſo much by three quarters of that time) will notwithſtanding their Infancy be of the ſame Hue with their Parents. Beſides, there is this ſtrong Argument to be alleg'd againſt the Vulgar Opinion, that in divers places in Aſia under the ſame Parallel, or even of the ſame [pg 154] Degree of Latitude with the African Regions Inhabited by Blacks, the People are at moſt but Tawny;10 And in Africa it ſelf divers Nations in the Empire of Ethiopia are not Negroes, though Situated in the Torrid Zone, and as neer the Æquinoctial, as other Nations that are ſo (as the Black Inhabitants of Zeylan and Malabar are not in our Globes plac'd ſo near the Line as Amara the Famouſeſt place in Ethiopia.) Moreover, (that which is of no ſmall Moment in our preſent Diſquiſition) I find not by the beſt Navigators and Travellers to the Weſt-Indies, whoſe Books or themſelves I have conſulted on this Subject, that excepting perhaps one place or two of ſmall extent, there are any Blacks Originally Natives of any part of America (for the Blacks now there have been by the Europeans long Tranſplanted thither) though the New World contain in it ſo great a Variety of Climates, and particularly reach quite Croſs the Torri'd Zone from one Tropick to another. And enough it be true that the Danes be a Whiter People than the Spaniards, yet that may proceed rather from other cauſes (not here to be enquired into) than from the Coldneſs of the Climate, ſince not onely the [pg 155] Swedes and other Inhabitants of thoſe Cold Countreys, are not uſually ſo White as the Danes, nor Whiter than other Nations in proportion to their Vicinity to the Pole. [And ſince the Writing of the former part of this Eſſay, having an opportunity on a Solemn occaſion to take Notice of the Numerous Train of Some Extraordinary Embaſſadours ſent from the Ruſſian Emperour to a great Monarch, obſerv'd, that (though it were then Winter) the Colour of their Hair and Skin was far leſs Whitiſh than the Danes who Inhabit a milder Region is wont to be, but rather for the moſt part of a Darkiſh Brown; And the Phyſician to the Embaſſadour with whom thoſe Ruſſes came, being ask'd by me whether in Muſcovy it ſelf the Generality of the People were more inclin'd to have Dark-colour'd Hair than Flaxen, he anſwer'd Affirmatively; but ſeem'd to ſuſpect that the True and Antient Ruſſians, a Sept of whom he told me he had met with in one of the Provinces of that vaſt Empire, were rather White like the Danes, than any thing near ſo Brown as the preſent Muſcovites whom he gueſſes to be deſcended of the Tartars, and to have inherited their Colour from them.] But to Proſecute our former Diſcourſe, I ſhall add for further Proof of the Conjecture I was [pg 156] countenancing that good Authors inform us that there are Negroes in Africa not far from the Cape of good Hope, and conſequently beyond the Southern Tropick, and without the Torrid Zone, much about the ſame Northern Latitude (or very little more) wherein there are divers American Nations that are not Negroes, and wherein the Inhabitants of Candia, ſome parts of Sicily, and even of Spain are not ſo much as Tawny-Mores. But (which is a freſh and ſtrong Argument againſt the common Opinion,) I find by our recent Relations of Greenland (our Accounts whereof we owe to the Curioſity of that Royal Virtuoſo the preſent King of Denmark,) that the Inhabitants are Olive-colour'd, or rather of a Darker Hiew. But if the Caſe were the ſame with Men, and thoſe other kinds of Animals I formerly nam'd, I ſhould offer ſomething as a conſiderable proof, That, Cold may do much towards the making Men White or Black, and however I ſhall let down the Obſervation as I have met with it, as worthy to come into the Hiſtory of Whiteneſs and Blackneſs, and it is, that in ſome parts of Ruſſia and of Livonia it is affirm'd by Olaus Magnus and others, that Hares and Foxes (ſome add Partridges) which before were Black, or Red, or [pg 157] Gray, do in the depth of Winter become White by reaſon of the great Cold; (for that it ſhould be, as ſome conceive, by Looking upon the Snow, ſeems improbable upon divers accounts) And I remember that having purpoſely enquir'd of a Virtuoſo who lately Travell'd through Livonia to Moſco concerning the Truth of this Tradition, he both told me, he believ'd it, and added, that he ſaw divers of thoſe lately nam'd Animals either in Ruſſia or Livonia, (for I do not very well remember whether of the two) which, though White when he ſaw them in Winter, they aſſur'd him had been Black, or of other Colours before the Winter began, and would be ſo again when it was over. But for further ſatisfaction, I alſo conſulted one that had for ſome years been an Eminent Phyſician in Ruſſia, who though he rejected ſome other Traditions that are generally enough believ'd concerning that Countrey, told me nevertheleſs, that he ſaw no cauſe to doubt of this Tradition of Olaus Magnus as to Foxes and Hares, not onely becauſe 'tis the common and uncontroul'd Aſſertion of the Natives, but alſo becauſe he himſelf in the Winter could never that he remember'd ſee Foxes and Hares of any other Colour than White; And I my ſelf having ſeen a ſmall White [pg 158] Fox brought out of Ruſſia into England towards the latter end of Winter, foretold thoſe that ſhew'd him me, that he would change Colour in Summer, and accordingly coming to look upon him again in July, I found that the Back and Sides, together with the upper part of the Head and Tayl were already grown of a Dark Colour, the lower part of the Head and Belly containing as yet a Whiteneſs. Let me add, that were it not for ſome ſcruple I have, I ſhould think more than what Olaus relates, confirm'd by the judicious Olearius, who was twice employ'd into thoſe parts as a Publick Miniſter, who in his Account of Moſcovy has this Paſſage: The Hares there are Gray; but in ſome Provinces they grow white in the Winter. And within ſome few Lines after: It is not very Difficult to find the Cauſe of this Change, which certainly proceeds only from the Outward Cold, ſince I know that even in Summer, Hares will change Colour, if they be kept a competent time in a Cellar; I ſay, were it not for Some Scruple, becauſe I take notice, that in the ſame Page the Author Affirms, that the like change of Colour that happens to Hares in ſome Provinces of Muſcovy, happens to them alſo in Livonia, and yet immediately ſubjoyns, that in Curland the Hares vary not their Colour in Winter, [pg 159] though theſe two laſt named Countries be contiguous, (that is) ſever'd only by the River of Dugna; For it is ſcarce conceivable how Cold alone ſhould have, in Countries ſo near, ſo ſtrangely differing an operation, though no leſs ſtrange a thing is confeſs'd by many, that aſcribe the Complexion of Negroes to the Heat of the Sun, when they would have the River of Cenega ſo to bound the Moors, that though on the North-ſide they are but Tawny, on the other ſide they are Black.
There is another Opinion concerning the Complexion of Negroes, that is not only embrac'd by many of the more Vulgar Writers, but likewiſe by that ingenious Traveller Mr. Sandys, and by a late moſt learned Critick, beſides other men of Note, and theſe would have the Blackneſs of Negroes an effect of Noah's Curſe ratify'd by God's, upon Cham; But though I think that even a Naturaliſt may without diſparagement believe all the Miracles atteſted by the Holy Scriptures, yet in this caſe to flye to a Supernatural Cauſe, will, I fear, look like Shifting off the Difficulty, inſtead of Reſolving it; for we enquire not the Firſt and Univerſal, but the Proper, Immediate, and Phyſical Cauſe of the Jetty Colour of Negroes; And not only we do not find expreſſed in the [pg 160] Scripture, that the Curſe meant by Noah to Cham, was the Blackneſs of his Poſterity, but we do find plainly enough there that the Curſe was quite another thing, namely that he ſhould be a Servant of Servants, that is by an Ebraiſm, a very Abject Servant to his Brethren, which accordingly did in part come to paſs, when the Iſraelites of the poſterity of Sem, ſubdued the Canaanites, that deſcended from Cham, and kept them in great Subjection. Nor is it evident that Blackneſs is a Curſe, for Navigators tell us of Black Nations, who think ſo much otherwiſe of their own condition, that they paint the Devil White. Nor is Blackneſs inconſiſtent with Beauty, which even to our European Eyes conſiſts not ſo much in Colour, as an Advantageous Stature, a Comely Symmetry of the parts of the Body, and Good Features in the Face. So that I ſee not why Blackneſs ſhould be thought ſuch a Curſe to the Negroes, unleſs perhaps it be, that being wont to go Naked in thoſe Hot Climates, the Colour of their Skin does probably, according to the Doctrine above deliver'd, make the Sun-beams more Scorching to them, than they would prove to a people of a White Complexion.
Greater probability there is, That the Principal Cauſe (for I would not exclude [pg 161] all concurrent ones) of the Blackneſs of Negroes is ſome Peculiar and Seminal Impreſſion, for not onely we ſee that Blackmore boyes brought over into theſe Colder Climates loſe not their Colour; But good Authors inform us, That the Off-ſpring of Negroes Tranſplanted out of Africa, above a hundred years ago, retain ſtill the Complexion of their Progenitors, though poſſibly in Tract of time it will decay; As on the other ſide, the White people removing into very Hot Climates, have their Skins by the Heat of the Sun ſcorch'd into Dark Colours; yet neither they, nor their Children have been obſerv'd, even in the Countreys of Negroes, to deſcend to a Colour amounting to that of the Natives; whereas I remember I have Read in Piſos11 excellent account of Braſile, that betwixt the Americans and Negroes are generated a diſtinct ſort of Men, which they call Cabocles, and betwixt Portugalls and Æthiopian women, He tells us, he has ſometimes ſeen Twins, whereof one had a White skin, the other a Black; not to mention here ſome other inſtances, he gives, that the productions of the mixtures of differing people, that is (indeed,) the effects of Seminal Impreſſions which they [pg 162] conſequently argue to have been their Cauſes; and we ſhall not much ſcruple at this, if we conſider, that even Organical parts may receive great Differences from ſuch peculiar Impreſſions, upon what account ſoever they came to be ſetled in the firſt Individual perſons, from whom they are Propogated to Poſterity, as we ſee in the Blobber-Lips and Flat-Noſes of moſt Nations of Negroes. And if we may Credit what Learned men deliver concerning the Little Feet of the Chineſses, the Macrocephali taken notice of by Hippocrates, will not be the only Inſtance we might apply to our preſent purpoſe. And on this occaſion it will not perchance be Impertinent to add ſomething of what I have obſerv'd in other Animals, as that there is a ſort of Hens that want Rumps; And that (not to mention that in ſeveral places there is a ſort of Crows or Daws that are not Cole-black as ours, but partly of a Whitiſh Colour) in ſpight of Porphyries examples of Inſeparable Accidents, I have ſeen a perfectly White Raven, as to Bill as well as Feathers, which I attentively conſidered, for fear of being impos'd upon. And this recalls into my Memory, what a very Ingenious Phyſician has divers times related to me of a young Lady, to whom being call'd, he found that though [pg 163] ſhe much complain'd of want of Health, yet there appear'd ſo little cauſe either in her Body, or her Condition to Gueſs that She did any more than fancy her ſelf Sick, that ſcrupling to give her Phyſick, he perſwaded her Friends rather to divert her Mind by little Journeys of Pleaſure, in one of which going to Viſit St. Winifrids Well, this Lady, who was a Catholick, and devout in her Religion, and a pretty while in the Water to perform ſome Devotions, and had occaſion to fix her Eyes very attentively upon the Red pipple-ſtones, which in a ſcatter'd order made up a good part of thoſe that appear'd through the water, and a while after growing Bigg, ſhe was deliver'd of a Child, whoſe White Skin was Copiouſly ſpeckl'd with ſpots of the Colour and Bigneſſs of thoſe Stones, and though now this Child have already liv'd ſeveral years, yet ſhe ſtill retains them. I have but two things to add concerning the Blackneſs of Negroes, the one is, that the Seat of that Colour ſeems to be but the thin Epidermes, or outward Skin, for I knew a young Negroe, who having been lightly Sick of the Small Pox or Meaſles, (for it was doubted which of the two was his Diſeaſe) I found by enquiry of a perſon that was concern'd for him, that in thoſe places where the little Tumors [pg 164] had broke their paſſage through the Skin, when they were gone, they left Within ſpecks behind them; And the lately commended Piſo aſſures us, that having the opportunity in Braſil to Diſſect many Negroes, he cleerly found that their Blackneſs went no deeper than the very outward Skin, which Cuticula or Epidermis being remov'd, the undermoſt Skin or Cutis appear'd juſt as White as that of Europæan Bodyes. And the like has been affirmed to me by a Phyſician of our own, whom, hearing he had Diſſectcd a Negroe here in England, I conſulted about this particular. The other thing to be here taken notice of concerning Negroes is, That having enquir'd of an Intelligent acquaintance of mine (who keeps in the Indies about 300. of them as well Women as Men to work in his Plantations,) whether their Children come Black into the world; he anſwer'd, That they did not, but were brought forth of almoſt the like Reddiſh Colour with our European Children; and having further enquir'd, how long it was before theſe Infants appear'd Black, be reply'd, that 'twas not wont to be many daies. And agreeable to this account I find that, given us in a freſhly publiſh'd French Book written by a Jeſuit, that had good opportunity [pg 165] of Knowing the Truth of what he Delivers, for being one of the Miſſionaries of his Order into the Southern America upon the Laudable Deſign of Converting Infidels to Chriſtianity, he Baptiz'd ſeveral Infants, which when newly Born, were much of the ſame Colour with European Babes, but within about a Week began to appear of the Hue of their Parents. But more Pregnant is the Teſtimony of our Countrey-man Andrew Battel, who being ſent Priſoner by the Portugalls to Angola, liv'd there, and in the adjoyning Regions, partly as a Priſoner, partly as a Pilot, and partly as a Souldier, near 18. years, and he mentioning the African Kingdom of Longo, peopl'd with Blacks, has this paſſage:12 The Children in this Countrey are Born White, and change their Colour in two dayes to a Perfect Black. As for Example, The Portugalls which dwell in the Kingdome of Longo have ſometimes Children by the Negroe-women, and many times the Fathers are deceived, thinking, when the Child is Born, that it is theirs, and within two dayes it proves the Son or Daughter of a Negroe, which the Portugalls greatly grieve at; And the ſame perſon has elſewhere a Relation, which, if he have made no uſe at all of the [pg 166] liberty of a Traveller, is very well worth our Notice, ſince this, together with that we have formerly mention'd of Seminal Impreſſions, ſhews a poſſibility, that a Race of Negroes might be begun, though none of the Sons of Adam, for many Precedent Generations were of that Complexion. For I ſee not why it ſhould not be at leaſt as poſſible, that White Parents may ſometimes have Black Children, as that African Negroes ſhould ſometimes have laſtingly White ones, eſpecially ſince concurrent cauſes may eaſily more befriend the Productions of the Former kind, than under the ſcorching Heat of Africa thoſe of the Latter. And I remember on the occaſion of what he delivers, that of the White Raven formerly mention'd, the Poſſeſſor affirm'd to me, that in the Neſt out of which he was taken White, they found with him but one other Young one, and that he was of as Jetty a Black as any common Raven. But let us hear our Author himſelf13; Here are (ſayes he, ſpeaking of the formerly mention'd Regions) Born in this Countrey White Children, which is very rare among them, for their Parents are Negroes; And when any of them are Born, they are preſented to the King, and are call'd Dondos; theſe are as White as any [pg 167] White Men. Theſe are the Kings Witches, and are brought up in Witchcraft, and alwayes wait on the King: There is no man that dare meddle with theſe Dondos, if they go to the Market they may take what they lift, for all Men ſtand in awe of them. The King of Longo hath four of them. And yet this Countrey in our Globes is plac'd almoſt in the midſt of the Torrid Zone (four or five Degrees Southward of the Line.) And our Author elſewhere tells us of the Inhabitants, that they are ſo fond of their Blackneſs, that they will not ſuffer any that is not of that Colour (as the Portugalls that come to Trade thither) to be ſo much as Buri'd in their Land, of which he annexes a particular example,14 that may be ſeen in his Voyage preſerv'd by our Induſtrious Countreyman Mr. Purchas. But it is high time for me to diſmiſs Obſervations, and go on with Experiments.
The way, Pyrophilus, of producing Whiteneſs by Chymical Præcipitations is very well worth our obſerving, for thereby Bodyes of very Differing Colours as well as Natures, though diſſolv'd in Several Liquors, [pg 168] are all brought into Calces or Powders that are White. Thus we find that not only Crabs-eyes, that are of themſelves White, and Pearls that are almoſt ſo, but Coral and Minium that are Red, being diſſolv'd in Spirit of Vinegar, may be uniformly Præcipitated by Oyl of Tartar into White Powders. Thus Silver and Tin ſeparately diſſolv'd in Aqua Fortis, will the one Præcipitate it ſelf, and the other be Præcipitated by common Salt-water into a White Calx, and ſo will Crude Lead and Quickſilver firſt diſſolv'd likewiſe in Aqua Fortis. The like Calx will be afforded as I have try'd by a Solution of that ſhining Mineral Tinglaſs diſſolv'd in Aqua Fortis, and Præcipitated out of it; and divers of theſe Calces may be made at leaſt as Fair and White, if not better Colour'd, if inſtead of Oyl of Tartar they were Præcipitated with Oyl of Vitriol, or with another Liquor I could Name. Nay, that Black Mineral Antimony it ſelf, being reduc'd by and with the Salts that concurr to the Compoſition of common Sublimate, into that Cleer though Unctuous Liquor that Chymiſts commonly call Rectifi'd Butter of Antimony, will by the bare affuſion of ſtore of Fair Water be ſtruck down into that Snow-white Powder, which when the adhering Saltneſs is well waſh'd [pg 169] off, Chymiſts are pleas'd to call Mercurius Vitæ, though the like Powder may be made of Antimony, without the addition of any Mercury at all. And this Lacteſcence if I may ſo call it, does alſo commonly enſue when Spirit of Wine, being Impregnated with thoſe parts of Gums or other Vegetable Concretions, that are ſuppos'd to abound with Sulphureous Corpuſcles, fair Water is ſuddenly pour'd upon the Tincture or Solution. And I remember that very lately I did, for Tryal ſake, on a Tincture of Benjamin drawn with Spirit of Wine, and brought to be as Red as Blood, pour ſome fair Water, which preſently mingling with the Liquor, immediately turn'd the whole Mixture White. But if ſuch Seeming Milks be ſuffer'd to ſtand unſtirr'd for a convenient while, they are wont to let fall to the bottome a Reſinous Subſtance, which the Spirit of Wine Diluted and Weakned by the Water pour'd into it , was unable to ſupport any longer. And ſomething of Kin to this change of Colour in Vegetables is that, which Chymiſts are wont to obſerve upon the pouring of Acid Spirits upon the Red Solution of Sulphur, diſſolv'd in an Infuſion of Pot-aſhes, or in ſome other ſharp Lixivium, the Præcipitated Sulphur before it ſubſides, immediately turning the Red Liquor [pg 170] into a White one. And other Examples might be added of this way of producing Whiteneſs in Bodyes by Præcipitating them out of the Liquors wherein they have been Diſſolv'd; but I think it may be more uſefull to admoniſh you, Pyrophilus, that this obſervation admits of Reſtrictions, and is not ſo Univerſal, as by this time perhaps you have begun to think it; For though moſt Præcipitated Bodyes are White, yet I know ſome that are not; For Gold Diſſolv'd in Aqua Regis, whether you Præcipitate it with Oyl of Tartar, or with Spirit of Sal Armoniack, will not afford a White but a Yellow Calx. Mercury alſo though reduc'd into Sublimate, and Præcipitated with Liquors abounding with Volatile Salts, as the Spirits drawn from Urine, Harts-horn, and other Animal ſubſtances, yet will afford, as we Noted in our firſt Experiment about Whiteneſs and Blackneſs, a White Præcipitate, yet with ſome Solutions hereafter to be mentioned, it will let fall an Orange-Tawny Powder. And ſo will Crude Antimony, if, being diſſolv'd in a ſtrong Lye, you pour (as farr as I remember) any Acid Liquor upon the Solution newly Filtrated, whilſt it is yet Warm. And if upon the Filtrated Solution of Vitriol, you pour a Solution of [pg 171] one of theſe fix'd Salts, there will ſubſide a Copious ſubſtance, very farr from having any Whiteneſs, which the Chymiſts are pleas'd to call, how properly I have elſewhere examin'd, the Sulphur of Vitriol. So that moſt part of Diſſolv'd Bodyes being by Præcipitation brought to White Powders, and yet ſome affording Præcipitates of other Colours, the reaſon of both the Phænomena may deſerve to be enquir'd into.
Some Learned Modern Writers15 are of Opinion, that the Account upon which Whiteneſs and Blackneſs ought to be call'd, as they commonly are, the two Extreme Colours, is, That Blackneſs (by which I preſume is meant the Bodyes endow'd with it) receives no other Colours; but Whiteneſs very eaſily receives them all; whence ſome of them compare Whiteneſs to the Aristotelian Materia prima, that being capable of any ſort of Forms, as they ſuppoſe White Bodyes to be of every kind of Colour. But not to Diſpute about Names or Expreſſions, the thing it ſelf that is affirm'd as Matter of Fact, ſeems to be True enough in moſt Caſes, not in all, or ſo, [pg 172] as to hold Univerſally. For though it be a common obſervation among Dyers, That Clothes, which have once been throughly imbu'd with Black, cannot ſo well afterwards be Dy'd into Lighter Colours, the præexiſtent Dark Colour infecting the Ingredients, that carry the Lighter Colour to be introduc'd, and making it degenerate into Some more Sad one; Yet the Experiments lately mention'd may ſhew us, that where the change of Colour in Black Bodies is attempted, not by mingling Bodyes of Lighter Colours with them, but by Addition of ſuch things as are proper to alter the Texture of thoſe Corpuſcles that contain the Black Colour, 'tis no ſuch difficult matter, as the lately mention'd Learned Men imagine, to alter the Colour of Black Bodyes. For we ſaw that Inks of ſeveral Kinds might in a trice be depriv'd of all their Blackneſs; and thoſe made with Logwood and Red-Roſes might alſo be chang'd, the one into a Red, the other into a Reddiſh Liquor; and with Oyl of Vitriol I have ſometimes turn'd Black pieces of Silk into a kind of Yellow, and though the Taffaty were thereby made Rotten, yet the ſpoyling of that does no way prejudice the Experiment, the change of Black Silk into Yellow, being never the leſs True, becauſe [pg 173] the Yellow Silk is the leſs good. And as for Whiteneſs, I think the general affirmation of its being ſo eaſily Deſtroy'd or Tranſmuted by any other Colour, ought not to be receiv'd without ſome Cautions and Reſtrictions. For whereas, according to what I formerly Noted, Lead is by Calcination turned into that Red Powder we call Minium; And Tin by Calcination reduc'd to a White Calx, the common Putty that is ſold and us'd ſo much in Shops, inſtead of being, as it is pretended and ought to be, only the Calx of Tin, is, by the Artificers that make it, to ſave the charge of Tin, made, (as ſome, of themſelves have confeſs'd, and as I long ſuſpected by the Cheap rate it may be bought for) but of half Tin and half Lead, if not far more Lead than Tin, and yet the Putty in ſpight of ſo much Lead is a very White Powder, without diſcloſing any mixture of Minium. And ſo if you take two parts of Copper, which is a High-colour'd Metall, to but one of Tin, you may by Fuſion bring them into one Maſs, wherein the Whiteneſs of the Tin is much more Conſpicuous and Predominant than the Reddiſhneſs of the Copper. And on this occaſion it may not be Impertinent to mention an Experiment, which I relate upon the Credit of a very Honeſt man, [pg 174] whom I purpoſely enquir'd of about it, being my ſelf not very fond of making Tryals with Arſenick, the Experiment is this, That if you Colliquate Arſenick and Copper in a due proportion, the Arſenick will Blanch the Copper both within and without, which is an Experiment well enough Known; but when I enquir'd, whether or no this White mixture being skilfully kept a while upon the Cupel would not let go its Arſenick, which made Whiteneſs its prædominant Colour, and return to the Reddiſhneſs of Copper, I was aſſur'd of the Affirmative; ſo that among Mineral Bodyes, ſome of thoſe that are White, may be far more capable, than thoſe I am reaſoning with ſeem to have known, of Eclipſing others, and of making their Colour Prædominant in Mixtures. In further Confirmation of which may be added, that I remember that I alſo took a lump of Silver and Gold melted together, wherein by the Æſtimate of a very Experienced Refiner, there might be about a fourth or third part of Gold, and yet the Yellow Colour of the Gold was ſo hid by the White of the Silver, that the whole Maſs appear'd to be but Silver, and when it was rubb'd upon the Touchſtone, an ordinary beholder could ſcarce have diſtinguiſh'd it from the Touch of common [pg 175] Silver; though if I put a little Aqua Fortis upon any part of the White Surface it had given the Touchſtone, the Silver in the moiſtned part being immediately taken up and conceal'd by the Liquor, the Golden Particles would preſently diſcloſe that native Yellow, and look rather as if Gold, than if the above mention'd mixture, had been rubb'd upon the Stone.
I took a piece of Black-horn, (poliſh'd as being part of a Comb) this with a piece of broken glaſs I ſcrap'd into many thin and curdled flakes, ſome ſhorter and ſome longer, and having laid a pretty Quantity of theſe ſcrapings together, I found, as I look'd for, that the heap they compos'd was White, and though, if I laid it upon a clean piece of White Paper, its Colour ſeem'd ſomewhat Eclips'd by the greater Whiteneſs of the Body it was compar'd with, looking ſomewhat like Linnen that had been ſulli'd by a little wearing, yet if I laid it upon a very Black Body, as upon a Beaver Hatt, it then appear'd to be of a good White, which Experiment, that you may in a trice make when you pleaſe, ſeems very much to Disfavour both their Doctrine [pg 176] that would have Colours to flow from the Subſtantial Forms of Bodyes, and that of the Chymiſts alſo, who aſcribe them to one or other of their three Hypoſtatical Principles; for though in our Caſe there was ſo great a Change made, that the ſame Body without being ſubſtantially either Increas'd or Leſſened, paſſes immediately from one extreme Colour to another (and that too from Black to White) yet this ſo great and ſudden change is effected by a ſlight Mechanical Tranſpoſition of parts, there being no Salt or Sulphur or Mercury that can be pretended to be Added or Taken away, nor yet any ſubſtantial Form that can reaſonably be ſuppos'd to be Generated and Deſtroy'd, the Effect proceeding only from a Local Motion of the parts which ſo vary'd their Poſition as to multiply their diſtinct Surfaces, and to Qualifie them to Reflect far more Light to the Eye, than they could before they were ſcrap'd off from the entire piece of Black horn.
And now, Pyrophilus, it will not be improper for us to take ſome notice of an Opinion touching the cauſe of Blackneſs, which I judged it not ſo ſeaſonable to Queſtion, till I [pg 177] I had ſet down ſome of the Experiments, that might juſtifie my diſſent from it. You know that of late divers Learned Men, having adopted the three Hypoſtatical Principles, beſides other Notions of the Chymiſts, are very inclinable to reduce all Qualities of Bodies to one or other of thoſe three Principles, and Particularly aſſign for the cauſe of Blackneſs the Sootie ſteam of adust or torrifi'd Sulphur. But I hope that what we have deliver'd above to countenance the Opinion we have propos'd about the Cauſe of Blackneſs, will ſo eaſily ſupply you with ſeveral Particulars that may be made uſe of againſt this Opinion, that I ſhall now repreſent to You but two things concerning it.
And Firſt it ſeems that the favourers of the Chymicall Theories might have pitcht upon ſome more proper term, to expreſs the Efficient of Blackneſs than Sulphur adust; for we know that common Sulphur, not only when Melted, but even when Sublim'd, does not grow Black by ſuffering the Action of the fire, but continues and aſcends Yellow, and rather more than leſs White, than it was before its being expos'd to the fire. And if it be ſet on fire, as when we make that acid Liquor, that Chymiſts call Oleum Sulphuris per campanam, it affords [pg 178] very little Soot, and indeed the flame yeelds ſo little, that it will ſcarce in any degree Black a ſheet of White Paper, held a pretty while over the flame and ſmoak of it, which is obſerved rather to Whiten than Infect linnen, and which does plainly make Red Roſes grow very Pale, but not at all Black, as far as the Smoak is permitted to reach the leaves. And I can ſhew you of a ſort of fixt Sulphur made by an Induſtrious Laborant of your acquaintance, who aſſur'd me that he was wont to keep it for divers weeks together night and day in a naked and Violent fire, almoſt like that of the Glaſs-houſe, and when, to ſatisfie my Curioſity, I made him take out a lump of it, though it were glowing hot (and yet not melted,) it did not, when I had ſuffered it to cool, appear Black, the true Colour of it being a true Red. I know it may be ſaid, that Chymiſts in the Opinion above recited mean the Principle of Sulphur, and not common Sulphur which receives its name, not from its being all perfectly of a Sulphureous Nature, but for that plenty and Predominancy of the Sulphureous Principle in it. But allowing this, 'tis eaſie to reply, that ſtill according to this very Reaſon, torrifi'd Sulphur ſhould afford more Blackneſs, than moſt other concretes, [pg 179] wherein that Principle is confeſs'd to be far leſs copious. Alſo when I have expos'd Camphire to the fire in Cloſe Veſſels, as Inflamable, and conſequenly (according to the Chymiſts) as Sulphureous a Body as it is, I could not by ſuch a degree of Heat, as brought it to Fuſion, and made it Boyl in the glaſs, impreſs any thing of Blackneſs, or of any other Colour, than its own pure White, upon this Vegetable concrete. But what ſhall we ſay to Spirit of Wine, which being made by a Chymical Analyſis of the Liquor that affords it, and being totally Inflamable, ſeems to have a full right to the title they give it of Sulphur Vegetabile, & yet this fluid Sulphur not only contracts not any degree of Blackneſs by being often ſo heated, as to be made to Boyl, but when it burns away with an Actual flame, I have not found that it would diſcolour a piece of White Paper held over it, with any diſcernable ſoot. Tin alſo, that wants not, according to the Chymiſts, a Sulphur Joviale, when throughly burned by the fire into a Calx, is not Black, but eminently White. And I lately noted to you out of Bellonius, that the Charcoals of Oxy-cedar are not of the former of theſe two Colours, but of the latter. And the Smoak of our Tinby coals here in England, has been [pg 180] uſually obſerv'd, rather to Blanch linnen then to Black it. To all which, other Particulars of the like nature might be added, but I rather chooſe to put you in mind of the third Experiment, about making Black Liquors, or Inks, of Bodies that were non of them Black before. For how can it be ſaid, that when thoſe Liquors are put together actually Cold, and continue ſo after their mixture, there intervenes any new Adustion of Sulphur to produce the emergent Blackneſs? (and the ſame queſtion will be appliable to the Blackneſs produc'd upon the blade of a Knife, that has cut Lemmons and ſome kind of Sowr apples, if the juyce (though both Actually and Potentially Cold) be not quickly wip'd of) And when by the inſtilling either of a few drops of Oyl of Vitriol as in the ſecond Experiment, or of a little of the Liquor mention'd in the Paſſage pointed at in the fourth Experiment, (where I teach at once to Deſtroy one black Ink, and make another) the Blackneſs produc'd by thoſe Experiments is preſently deſtroy'd; if the Colour proceeded only from the Plenty of Sulphurous parts, torrify'd in the Black Bodies, I demand, what becomes of them, when the Colour ſo ſuddenly diſſappears? For it cannot Reaſonably be ſaid, that all thoſe that [pg 181] ſuffic'd to make ſo great a quantity of Black Matter, ſhould reſort to ſo very ſmall a proportion of the Clarifying Liquor, (if I may ſo call it) as to be deluted by it, with out at all Denigrating it. And if it be ſaid that the Inſtill'd Liquor diſpers'd thoſe Black Corpuſcles, I demand, how that Diſperſion comes to deſtroy their Blackneſs, but by making ſuch a Local Motion of their parts, as deſtroys their former Texture? which may be a Matter of ſuch moment in caſes like ours, that I remember that I have in few houres, without addition, from Soot it ſelf, attain'd pretty ſtore of Cryſtalline Salt, and good ſtore of Tranſparent Liquor, and (which I have on another occaſion noted as remarkable) this ſo Black Subſtance had its Colour ſo alter'd, by the change of Texture it receiv'd from the fire, wherewith it was diſtill'd, that it did for a great while afford ſuch plenty of very white Exhalations, that the Receiver, though large, ſeem'd to be almoſt fill'd with Milk.
Secondly, But were it granted, as it is in ſome caſes not Improbable, that divers Bodies may receive a Blackneſs from a Sootie Exhalation, occaſion'd by the Aduſtion of their Sulphur, which (for the Reaſons lately mention'd I ſhould rather call their Oyly parts;) yet ſtill this account [pg 182] is applicable but to ſome Particular Bodies, and will afford us no General Theory of Blackneſs. For if, for example, White Harts-horn, being, in Veſſels well luted to each other, expos'd to the fire, be ſaid to turn Black by the Infection of its own Smoak, I think I may juſtly demand, what it is that makes the Smoak or Soot it ſelf Black, ſince no Such Colour, but its contrary, appear'd before in the Harts-horn? And with the ſame Reaſon, when we are told, that torrify'd Sulphur makes bodies Black, I deſire to be told alſo, why Torrefaction makes Sulphur it ſelf Black? nor will there be any Satisfactory Reaſon aſſign'd of theſe Quæries, without taking in thoſe Fertile as well as intelligible Mechanical Principles of the Poſition and Texture of the Minute parts of the body in reference to the Light and the Eye; and theſe applicable Principles may Serve the turn in many caſes, where the Aduſtion of Sulphur cannot be pretended; as in the appearing Blackneſs of an Open window, lookt upon at a ſomewhat remote diſtance from the houſe, as alſo in the Blackneſs Men think they ſee in the Holes that happen to be in White linnen, or Paper of the like Colour; and in the Increaſing Blackneſs immediatly Produc'd barely by ſo rubbing Velvet, [pg 183] whoſe Piles were Inclin'd before, as to reduce them to a more Erected poſture, in which and in many other caſes formerly alleg'd, there appears nothing requiſite to the Production of the Blackneſs, but the hindering of the incident Beams of Light from rebounding plentifully enough to the Eye. To be ſhort, thoſe I reaſon with, do concerning Blackneſs, what the Chymiſts are wont alſo to do concerning other Qualities, namely to content themſelves to tell us, in what Ingredient of a Mixt Body, the Quality enquir'd after, does reſide, inſtead of explicating the Nature of it, which (to borrow a compariſon from their own Laboratories) is much as if in an enquiry after the cauſe of Salivation, they ſhould think it enough to tell us, that the ſeveral Kinds of Præcipitates of Gold and Mercury) as likewiſe of Quick-ſilver and Silver (for I know that make and uſe of ſuch Precipitates alſo) do Salivate upon the account of the Mercury, which though Diſguis'd abounds in them, whereas the Difficulty is as much to know upon what account Mercury it ſelf, rather than other Bodies, has that power of working by Salivation. Which I ſay not, as though it were not ſomething (and too often the moſt we can arrive at) to diſcover in which of the [pg 184] Ingredients of a Compounded Body, the Quality, whoſe Nature is ſought, reſides, but becauſe, though this Diſcovery it ſelf may paſs for ſomething, and is oftentimes more than what is taught us about the ſame ſubjects in the Schools, yet we ought not to think it enough, when more Clear and Particular accounts are to be had.
[pg 185]
Ecauſe that, according to the Conjectures I have above propos'd,
one of the moſt General Cauſes of the Diverſity of Colours
in Opacous Bodyes, is, that ſome reflect the Light mingl'd with
more, others with leſs of Shade (either [pg 186] as to Quantity, or
as to Interruption) I hold it not unfit to mention in the firſt
place, the Experiments that I thought upon to examine this Conjecture.
And though coming to tranſcribe them out of ſome
Phyſiological Adverſaria I had written in looſe
Papers, I cannot find one of the chief Records I had of my Tryals of this
Nature, yet the Papers that ſcap'd miſcarrying, will, I
preſume, ſuffice to manifeſt the main thing for which I
now allege them; I find then Among my Adverſaria, the
following Narrative.
October the 11. About ten in the Morning in Sun-ſhiny Weather, (but not without fleeting Clouds) we took ſeveral ſorts of Paper Stain'd, ſome of one Colour, and ſome of another; and in a Darken'd Room whoſe Window look'd Southward, we caſt the Beams that came in at a hole about three Inches and a half in Diameter, upon a White wall that was plac'd on one ſide, about five foot diſtance from them.
The White gave much the Brighteſt Reflection.
The Green, Red, and Blew being Compar'd together, the Red gave much the ſtrongeſt Reflection, and manifeſtly enough alſo threw its Colour upon the Wall; The Green and Blew were ſcarce Diſcernable [pg 187] by their Colours, and ſeem'd to reflect an almoſt Equal Light.
The Yellow Compar'd with the two laſt nam'd, Reflected ſomewhat more Light.
The Red and Purple being Compar'd together, the former manifeſtly Reflected a good deal more Light.
The Blew and Purple Compar'd together, the former ſeem'd to Reflect a little more Light, though the Purple Colour were more manifeſtly ſeen.
A Sheet of very well fleck'd Marbl'd Paper being Apply'd as the others, did not caſt any or its Diſtinct Colours upon the Wall; nor throw its Light upon it with an Equal Diffuſion, but threw the Beams Unſtain'd and Bright to this and that part of the Wall, as if it's Poliſh had given it the Nature of a ſpecular Body. But comparing it with a ſheet of White Paper, we found the Reflection of the latter to be much Stronger, it diffuſing almoſt as much Light to a good Extent as the Marble Paper did to one part of the Wall.
The Green and Purple left us ſomewhat in ſuſpence which Reflected the moſt Light; only the Purple ſeem'd to have ſome little Advantage over the Green, which was Dark in its kind.
Thus much I find in our above mention'd [pg 188] Collections, among which there are alſo ſome Notes concerning the Production of Compounded Colours, by Reflection from Bodyes differingly Colour'd. And theſe Notes we intended ſhould ſupply us with what we ſhould mention as our ſecond Experiment: but having loſt the Paper that contain'd the Particulars, and remembring onely in General, that if the Objects which Reflected the Light were not Strongly Colour'd and ſomewhat Gloſſy, the Reflected Beams would not manifeſtly make a Compounded Colour upon the Wall, and even then but very Faintly, we ſhall now ſay no more of that Matter, only reſerving our ſelves to mention hereafter the Compoſition of a Green, which we ſtill retain in Memory.
We may add, Pyrophilus, on this Occaſion, that though a Darken'd Room be Generally thought requiſite to make the Colour of a Body appear by Reflection from another Body, that is not one of thoſe that are commonly agreed upon to be Specular (as Poliſh'd Metall, Quick ſilver, Glaſs, Water, &c.) Yet I have often obſerv'd that when I wore Doublets Lin'd with ſome ſilken [pg 189] Stuff that was very Gloſſy and Vividly Colour'd, eſpecially Red, I could in an Inlightned Room plainly enough Diſcern the Colour, upon the Pure White Linnen that came out at my Sleeve and reach'd to my Cufs; as if that Fine White Body were more Specular, than Colour'd and Unpoliſh'd Bodyes are thought Capable of being.
Whilſt we were making the newly mention'd Experiments, we thought fit to try alſo what Compoſition of Colours might be made by Altering the Light in its Paſſage to the Eye by the Interpoſition not of Perfectly Diaphanous Bodies, (that having been already try'd by others as well as by us (as we ſhall ſoon have occaſion to take notice) but of Semi-opacous Bodyes, and thoſe ſuch as look'd upon in an ordinary Light, and not held betwixt it and the Eye, are not wont to be Diſcriminated from the reſt of Opacous Bodyes; of this Tryal, our mention'd Adverſaria preſent us the following Account.
Holding theſe Sheets, ſometimes one ſometimes the other of them, before the Hole betwixt the Sun and the Eye, with [pg 190] the Colour'd ſides obverted to the Sun; we found them ſingle to be ſomewhat Tranſparent, and appear of the ſame Colour as before, onely a little alter'd by the great Light they were plac'd in; but laying two of them one over another and applying them ſo to the Hole, the Colours were compounded as follows.
The Blew and Yellow ſcarce exhibited any thing but a Darker Yellow, which we aſcrib'd to the Coarſeneſs of the Blew Papers, and its Darkneſs in its Kind. For applying the Blew parts of the Marbl'd Paper with the Yellow Paper after the ſame manner, they exhibited a good Green.
The Yellow and Red look'd upon together gave us but a Dark Red, ſomewhat (and but a little,) inclining to an Orange Colour.
The Purple and Red look'd on together appear'd more Scarlet.
The Purple and Yellow made an Orange.
The Green and Red made a Dark Orange Tawny.
The Green and Purple made the Purple appear more Dirty.
The Blew and Purple made the Purple more Lovely, and far more Deep.
The Red parts of the Marbl'd Paper look'd upon with the Yellow appear'd of a [pg 191] Red far more like Scarlet than without it.
But the Fineneſs or Coarſeneſs of the Papers, their being carefully or ſlightly Colour'd, and divers other Circumſtances, may ſo vary the Events of ſuch Experiments as theſe, that if, Pyrophilus, you would Build much on them, you muſt carefully Repeat them.
The Triangular Priſmatical Glaſs being the Inſtrument upon whoſe Effects we may the moſt Commodiouſly ſpeculate the Nature of Emphatical Colours, (and perhaps that of Others too;) we thought it might be uſefull to obſerve the ſeveral Reflections and Refractions which the Incident Beams of Light ſuffer in Rebounding from it, and Paſſing through it. And this we thought might be Beſt done, not (as is uſual,) in an ordinary Inlightn'd Room, where (by reaſon of the Difficulty of doing otherwiſe) ev'n the Curious have left Particulars Unheeded, which may in a convenient place be eaſily taken notice of; but in a Darken'd Room, where by placing the Glaſs in a convenient Poſture, the Various Reflections and Refractions may be Diſtinctly obſerv'd; and where it may appear what Beams are Unting'd; [pg 192] and which they are, that upon the Bodyes that terminate them, do Paint either the Primary or Secondary Iris. In purſuance of this we did in the above mention'd Darken'd Room, make obſervation of no leſs than four Reflections, and three Refractions that were afforded us by the ſame Priſm, and thought that notwithſtanding what was taught us by the Rules of Catoptricks and Dioptricks, it would not be amiſs to find alſo, by hiding ſometimes one part of the Priſm, and ſometimes another, and obſerving where the Light or Colour Vaniſh'd thereupon, by which Reflection and by which Refraction each of the ſeveral places whereon the Light rebounding from, or paſſing through, the Priſm appear'd either Sincere or Tincted, was produc'd. But becauſe it would be Tedious and not ſo Intelligible to deliver this in Words, I have thought fit to Referr You to the Annexed Scheme where the Newly mention'd particulars may be at one View taken Notice of.
 The Explication of the Scheme. |
PPP. An Aequilaterotriangular Cryſtalline Priſm, one of whoſe edges P. is placed directly towards the Sun. A B & α β Two rays from the Sun falling on the Priſm at B β. and thence partly reflected towards C & γ. and partly refracted towards D & δ. B C & β γ. Thoſe reflected Rays. B D & β δ. Thoſe refracted Rays which are partly refracted towards E & ε. and there paint an Iris 1 2 3 4 5. denoting the five conſecutions of colours Red, Yellow, Green, Blew, and Purple; and are partly reflected towards F & ζ. D F & δ ζ. Thoſe Reflected Rays which are partly refracted towards G & η. colourleſs, and partly reflected, towards H & θ. F H & ζ θ. Thoſe reflected Rays which are refracted towards I & ι. and there paint an other fainter Iris, the colours of which are contrary to the former 5 4 3 2 1. ſignifying Purple, Blew, Green, Yellow, Red, ſo that the Priſm in this poſture exhibits four Rainbows. |
I know not whether you will think it Inconſiderable to annex to this Experiment, That we obſerv'd in a Room not Darken'd, that the Priſmatical Iris (if I may ſo call it) might be Reflected without loſing any of its ſeveral Colours (for we now conſider not their Order) not onely from a plain Looking-glaſs and from the calm Surface of Fair Water, but alſo from a Concave Looking-glaſs; and that Refraction did as little Deſtroy thoſe Colours as Reflection. For by the help of a large (double Convex) Burning-glaſs through which we Refracted the Suns Beams, we found that one part of the Iris might be made to appear either beyond, or on this ſide of the other Parts of the ſame Iris; but yet the ſame Vivid Colours would appear in the Diſplac'd part (if I may ſo term it) as in the other. To which I ſhall add, that having, by hiding the ſide of the Priſm, obverted to the Sun with an Opacous Body, wherein only one ſmall hole was left for the Light to paſs through, reduc'd the Priſmatical Iris (caſt upon White Paper) into a very narrow compaſs, and look'd upon it througn a Microſcope; the Colours appear'd the ſame as to kind that they did to the naked Eye.
[pg 194]It may afford matter of Speculation to the Inquiſitive, ſuch as you, Prophilus, that as the Colours of outward Objects brought into a Darken'd Room, do ſo much depend for their Viſibility upon the Dimneſs of the Light they are there beheld by; that the ordinary Light of the day being freely let in upon them, they immediately diſappear: ſo our Tryals have inform'd us, that as to the Priſmatical Iris painted on the Floor by the beams of the Sun Trajected through a Triangular-glaſs; though the Colours of it appear very Vivid ev'n at Noon-day, and in Sun ſhiny Weather, yet by a more Powerfull Light they may be made to diſappear. For having ſometimes, (in proſecution of ſome Conjectures of mine not now to be Inſiſted on,) taken a large Metalline Concave Speculum, and with it caſt the converging Beams of the Sun upon a Priſmatical Iris which I had caus'd to be projected upon the Floor, I found that the over-powerfull Light made the Colours of the Iris diſappear. And if I ſo Reflected the Light as that it croſs'd but the middle of the Iris, in that part only the Colours vaniſh'd or were made Inviſible; thoſe [pg 195] parts of the Iris that were on the right and left hand of the Reflected Light (which ſeem'd to divide them, and cut the Iris aſunder) continuing to exhibit the ſame Colours as before. But upon this we muſt not now ſtay to Speculate.
I have ſometimes thought it worth while to take notice, whether or no the Colours of Opacous Bodies might not appear to the Eye ſomewhat Diverſify'd, not only by the Diſpoſition of the Superficial parts of the Bodyes themſelves and by the Poſition of the Eye in Reference to the Object and the Light, (for theſe things are Notorious enough;) but according alſo to the Nature of the Lucid Body that ſhines upon them. And I remember that in Proſecution of this Curioſity, I obſerv'd a manifeſt Difference in ſome Kinds of Colour'd Bodyes look'd on by Day-light, and afterwards by the light of the Moon; either directly falling on them or Reflected upon them from a Concave Looking-glaſs. But not finding at preſent in my Collections about Colours any thing ſet down of this Kind, I ſhall, till I have opportunity to repeat them, content my ſelf to add what I find Regiſter'd concerning [pg 196] Colours look'd on by Candle-light, in regard that not only the Experiment is more eaſie to be repeated, but the Objects being the Same Sorts of Colour'd Paper laſtly mention'd, the Collation of the two Experiments may help to make the Conjectures they will ſuggeſt ſomewhat the leſs uncertain.
Within a few dayes of the time above mention'd, divers Sheets of Colour'd Paper that had been look'd upon before in the Sunſhine were look'd upon at night by the light of a pretty big Candle, (ſnuff'd) and the Changes that were obſerv'd were theſe.
The Yellow ſeem'd much fainter than in the Day, and inclinable to a pale Straw Colour.
The Red ſeem'd little Chang'd; but ſeem'd to Reflect Light more ſtrongly than any other Colour (for White was none of them.)
A fair Deep Green look'd upon by it ſelf ſeem'd to be a Dark Blew: But being look'd upon together with a Dark Blew, appear'd Greeniſh; and beheld together with a Yellow appear'd more Blew than at firſt.
The Blew look'd more like a Deep Purple or Murray than it had done in the Daylight.
[pg 197] The Purple ſeem'd very little alter'd.The Red look'd upon with the Yellow made the Yellow look almoſt like Brown Cap-paper.
N. The Caution Subjoyned to the third Experiments is alſo Applicable to this.
But here I muſt not omit to ſubjoyn, that to ſatisfie our Selves, whether or no the Light of a Candle were not made unſincere, and as it were Ting'd with a Yellow Colour by the Admixtion of the Corpuſcles it aſſumes from its Fuel; we did not content our ſelves with what appears to the Naked Eye, but taking a pretty thick Rod or Cylinder (for thin Peeces would not ſerve the turn) of deep Blew Glaſs, and looking upon the Candles flame at a Convenient diſtance througn it, we perceiv'd as we expected, the Flame to look Green; which as we often note, is the Colour wont to emerge from the Compoſition of Opacous Bodies, which were apart one of them Blew, and the other Yellow. And this perchance may be the main Reaſon of that which ſome obſerve, that a ſheet of very White Paper being look'd upon by Candle light, 'tis not eaſie at firſt to diſcern it from [pg 198] a light Yellow or Lemon Colour; White Bodyes (as we have elſewhere obſerv'd) having more than thoſe that are otherwiſe Colour'd, of a Specular Nature; in regard that though they exhibit not, (unleſs they be Poliſh'd,) the ſhape of the Luminary that ſhines on them, yet they Reflect its Light more Sincere and Untroubl'd, by either Shades or Refractions, than Bodyes of other Colours (as Blew, or Green, or Yellow or the like.)
We took a Leaf of Such Foliated Gold as Apothecaries are wont to Gild their Pills with; and with the Edge of a Knife, (lightly moyſten'd by drawing it over the Surface of the Tongue, and afterwards) laid upon the edge of the Gold Leaf; we ſo faſten'd it to the Knife, that being held againſt the light, it conctinu'd extended like a little Flagg. This Leaf being held very near the Eye, and obverted to the Light, appear'd ſo full of Pores, that it ſeem'd to have ſuch a kind of Tranſparency as that of a Sive, or a piece of Cyprus, or a Love-Hood; but the Light that paſs'd by theſe Pores was in its Paſſages So Temper'd with Shadow, and Modify'd, that the Eye diſcern'd [pg 199] no more a Golden Colour, but a Greeniſh Blew. And for other's ſatisfaction, we did in the Night look upon a Candle through ſuch a Leaf of Gold; and by trying the Effect of Several Proportions of Diſtance betwixt the Leaf, the Eye and the Light, we quickly hit upon ſuch a Poſition for the Leaf of Gold, as that the flame, look'd on through it, appear'd of a Greeniſh Blew, as we have ſeen in the Day time. The like Experiment try'd with a Leaf of Silver ſucceeded not well.
We have ſometimes found in the Shops of our Druggiſts, a certain Wood, which is there called Lignum Nephriticum, becauſe the Inhabitants of the Country where it grows, are wont to uſe the Infuſion of it made in fair Water againſt the Stone of the Kidneys, and indeed an Eminent Phyſician of our Acquaintance, who has very Particularly enquir'd into that Diſeaſe, aſſures me, that he has found ſuch an Infuſion one of the moſt effectual Remedyes, which he has ever tried againſt that formidable Diſeaſe. The ancienteſt Account I have met with of this Simple, is given us by the Experienc'd Monardes in theſe Words. [pg 200] Nobis, ſays he,16 Nova Hiſpania mittit quoddam ligni genus craſſum & enode, cujus uſus jam diu receptus fuit in his Regionibus ad Renum vitia & urinæ difficultates ac arenulas pellendas. Fit autem hac ratione, Lignum aſſulatim & minutim conciſum in limpidiſſima aqua fontana maceratur, inque ea relinquitur, donec aqua à bibentibus abſumpta ſit, dimidia hora post injectum lignum aqua cæruleum colorem contrabit, qui ſenſim intenditur pro temporis diuturnitate, tametſi lignum candidum fit. This Wood, Pyrophilus, may afford us an Experiment, which beſides the ſingularity of it, may give no ſmall aſſiſtance to an attentive Conſiderer towards the detection of the Nature of Colours. The Experiment as we made it is this. Take Lignum Nephriticum, and with a Knife cut it into thin Slices, put about a handfull of theſe Slices into two three or four pound of the pureſt Spring-water, let them infuſe there a night, but if you be in haſt, a much ſhorter time may ſuffice; decant this Impregnated Water into a clear Glaſs Vial, and if you hold it directly between the Light and your Eye, you ſhall ſee it wholly Tincted (excepting the very top of the Liquor, wherein you will ſome times diſcern a Sky-colour'd Circle) with [pg 201] an almoſt Golden Colour, unleſs your Infuſion have been made too Strong of the Wood, for in that caſe it will againſt the Light appear ſomewhat Dark and Reddiſh, and requires to be diluted by the addition of a convenient quantity of fair Water. But if you hold this Vial from the Light, ſo that your Eye be plac'd betwixt the Window and the Vial, the Liquor will appear of a deep and lovely Cæruleous Colour, of which alſo the drops, if any be lying on the outſide of the Glaſs, will ſeem to be very perfectly; And thus far we have try'd the Experiment, and found it to Succeed even by the Light of Candles of the larger ſize. If you ſo hold the Vial over againſt your Eyes, that it may have a Window on one ſide of it, and a Dark part of the Room both before it and on the other ſide, you ſhall ſee the Liquor partly of a Blewiſh and partly of a Golden Colour. If turning your back to the Window, you powr out ſome of the Liquor towards the Light and towards your Eyes, it will ſeem at the comming out of the Glaſs to be perfectly Cæruleous, but when it is fallen down a little way, the drops may ſeem Particolour'd, according as the Beams of Light do more or leſs fully Penetrate and Illuſtrate them. If you take a Baſon about [pg 202] half full of Water, and having plac'd it ſo in the Sun-beams Shining into a Room, that one part of the Water may be freely illuſtrated by the Beams of Light, and the other part of it Darkned by the ſhadow of the Brim of the Baſon, if then I ſay you drop of our Tincture, made ſomewhat ſtrong, both into the Shaded and Illuminated parts of the Water, you may by looking upon it from ſeveral places, and by a little Agitation of the water, obſerve divers pleaſing Phænomena which were tedious to particularize. If you powr a little of this Tincture upon a ſheet of White Paper, ſo as the Liquor may remain of ſome depth upon it, you may perceive the Neighbouring drops to be partly of one Colour, and partly of the other, according to the poſition of your Eye in reference to the Light when it looks upon them, but if you powr off all the Liquor, the Paper will ſeem Dy'd of an almoſt Yellow Colour. And if a ſheet of Paper with ſome of this Liquor in it be plac'd in a window where the Sunbeams may ſhine freely on it, then if you turn your back to the Sun and take a Pen or ſome ſuch ſlender Body, and hold it over-thwart betwixt the Sun and the Liquor, you may perceive that the Shadow projected by the Pen upon the Liquor, will not all of it be a vulgar [pg 203] and Dark, but in part a curiouſly Colour'd ſhadow, that edge of it, which is next the Body that makes it, being almoſt of a lively Golden Colour, and the remoter verge of a Cæruleous one.
Theſe and other Phænomena, which I have obſerv'd in this delightfull Experiment, divers of my friends have look'd upon not without ſome wonder, and I remember an excellent Oculiſt finding by accident in a friends Chamber a fine Vial full of this Liquor, which I had given that friend, and having never heard any thing of the Experiment, nor having any Body near him that could tell him what this ſtrange Liquor might be, was a great while apprehenſive, as he preſently after told me, that ſome ſtrange new diſtemper was invading his Eyes. And I confeſs that the unuſualneſs of the Phænomena made me very ſollicitous to find out the Cauſe of this Experiment, and though I am far from pretending to have found it, yet my enquiries have, I ſuppoſe, enabled me to give ſuch hints, as may lead your greater ſagacity to the diſcovery of the Cauſe of this wonder. And firſt finding that this Tincture, if it were too copious in the water, Kept the Colours from being ſo lively, and their Change from being ſo diſcernable, and [pg 204] finding alſo that the Impregnating Virtue of this Wood did by its being frequently Infus'd in New Water by degrees Decay, I Conjectur'd that the Tincture afforded by the Wood muſt proceed from ſome Subtiler parts of it drawn forth by the Water, which ſwimming too and fro in it did ſo Modifie the Light, as to exhibit ſuch and ſuch Colours; and becauſe theſe Subtile parts were ſo eaſily Soluble even in Cold water, I concluded that they muſt abound with Salts, and perhaps contain much of the Eſſential Salt, as the Chymiſts call it, of the Wood. And to try whether theſe Subtile parts were Volatile enough to be Diſtill'd, without the Diſſolution of their Texture, I carefully Diſtill'd ſome of the Tincted Liquor in very low Veſſels, and the gentle heat of a Lamp Furnace; but found all that came over to be as Limpid and Colourleſs as Rock-water, and the Liquor remaining in the Veſſel to be ſo deeply Cæruleous, that it requir'd to be oppos'd to a very ſtrong Light to appear of any other Colour. I took likewiſe a Vial with Spirit of Wine, and a little Salt of Harts-horn, and found that there was a certain proportion to be met with betwixt the Liquor and the Salt, which made the Mixture fit to exhibit ſome little Variety [pg 205] of Colours not Obſervable in ordinary Liquors, as it was variouſly directed in reference to the Light and the Eye, but this Change of Colour was very far ſhort from that which we had admir'd in our Tincture. But however, I ſuſpected that the Tinging Particles did abound with ſuch Salts, whoſe Texture, and the Colour ſpringing from it, would probably be alter'd by peircing Acid Salts, which would in likelihood either make ſome Diſſipation of their Parts, or Aſſociate themſelves to the like Bodies, and either way alter the Colour exhibited by them; whereupon Pouring into a ſmall Vial full of Impregnated Water, a very little Spirit of Vinegar, I found that according to my Expectation, the Cæruleous Colour immediately vaniſh'd, but was deceiv'd in the Expectation I had, that the Golden Colour would do ſo too; for, which way ſoever I turned the Vial, either to or from the Light, I found the Liquor to appear always of a Yellowiſh Colour and no other: Upon this I imagin'd that the Acid Salts of the Vinegar having been able to deprive the Liquor of its Cæruleous Colour, a Sulphureous Salt being of a contrary Nature, would be able to Mortifie the Saline Particles of Vinegar, and Deſtroy their [pg 206] Effects; And accordingly having plac'd my Self betwixt the Window, and the Vial, and into the Same Liquor dropt a few drops of Oyl of Tartar per Deliquium, (as Chymiſts call it) I obſerv'd with pleaſure, that immediately upon the Diffuſion of this Liquor, the Impregnated Water was reſtor'd to its former Cæruleous Colour; And this Liquor of Tartar being very Ponderous, and falling at firſt to the Bottom of the Vial, it was eaſie to obſerve that for a little while the Lower part of the Liquor appear'd deeply Cæruleous; whilſt all the Upper part retain'd its former Yellowneſs, which it immediately loſt as ſoon as either Agitation or Time had made a competent Diffuſion of the Liquor of Tartar through the Body of the former Tincture; and this reſtored Liquor did, as it was Look'd upon againſt or from the Light, exhibit the Same Phænomena as the Tincted Water did, before either of the Adventitious Liquors was pour'd into it.
Having made, Pyrophilus, divers Tryals upon this Nephritick Wood, we found mention made of it by the Induſtrious Jeſuit Kircherus, who having received a Cup Turned of it from the Mexican Procurator of his Society, has probably receiv'd alſo from him the Information he gives us concerning [pg 207] that Exotick Plant, and therefore partly for that Reaſon, and partly becauſe what he Writes concerning it, does not perfectly agree with what we have deliver'd, we ſhall not Scruple to acquaint you in his own Words, with as much of what he writes concerning our Wood, as is requiſite to our preſent purpoſe. Hoc loco (ſays he)17 neutiquam omittendum duximus quoddam ligni candidi Mexicani genus, quod Indigenæ Coalle & Tlapazatli vocant, quod etſi experientia hucuſque non niſi Cæruleo aquam colore tingere docuerit, nos tamen continua experientia invenimus id aquam in omne Colorum genus transformare, quod merito cuipiam Paradoxum videri poſſet; Ligni frutex grandis, ut aiunt, non rarò in molem arboris excreſcit, truncus illius eft craſſus, enodis, inſtar piri arboris, folia ciceris foliis, aut rutæ haud abſimilia, flores exigui, oblongi, lutei & ſpicatim digeſti; eſt frigida & humida planta, licet parum recedat à medio temperamento. Hujus itaque deſcriptæ arboris lignum in poculum efformatum, aquam eidem infuſam primo in aquam intenſe Cæruleam, colore floris Bugloſſæ; tingit, & quo diutius in eo ſteterit, tanto intenſiorem colorem acquirit. Hanc igitur aquam si Vitreæ Sphæræ infuderis, lucique expoſueris, ne ullum quidem Cærulei coloris [pg 208] veſtigium apparebit, ſed inſtar aquæ puræ putæ fontanæ limpidam claramque aspicientibus ſe præbebit. Porro ſi hanc phialam vitream verſus locum magis umbroſum direxeris, totus humor gratiſſimum virorem referet; ſi adhuc umbroſioribus locis, ſubrubrum, & ſic pro rerum objectarum conditione, mirum dictu, colorem mutabit; in tenebris verò vel in vaſe opaco poſita, Cæruleum colorem ſuum reſumet.
In this paſſage we may take notice of the following Particulars. And firſt, he calls it a White Mexican Wood, whereas (not to mention that Mornardes informs us that it is brought out of Nova Hiſpania) the Wood that we have met with in ſeveral places, and employ'd as Lignum Nephriticum, was not White, but for the moſt part of a much Darker Colour, not unlike that of the Sadder Colour'd Wood of Juniper. 'Tis true, that Monardes himſelf alſo ſays, that the Wood is White; and it is affirm'd, that the Wood which is of a Sadder Colour is Adulterated by being Imbu'd with the Tincture of a Vegetable, in whoſe Decoction it is ſteep'd. But having purpoſely enquir'd of the Eminenteſt of our Engliſh Druggiſts, he peremptorily deny'd it. And indeed, having conſider'd ſome of the faireſt Round pieces of this [pg 209] Wood that I could meet with in theſe Parts, I had Opportunity to take notice that in one or two of them it was the External part of the Wood that was White, and the more Inward part that was of the other Colour, the contrary of which would probably have appear'd, if the Wood had been Adulterated after the afore-mention'd manner. And I have at preſent by me a piece of ſuch Wood, which for about an Inch next the Bark is White, and then as it were abruptly paſſes to the above-mention'd Colour, and yet this Wood by the Tincture, it afforded us in Water, appears to have its Colour'd part Genuine enough; for as for the White part, it appears upon tryal of both at once, much leſs enrich'd with the tingent Property.
Next, whereas our Author tells us, that the Infuſion of this Wood expos'd in a Vial to the Light, looks like Spring-water, in which he afterwards adds, that there is no Tincture to be ſeen in it, our Obſervation and his agree not, for the Liquor, which oppoſed to the Darker part of a Room exhibits a Sky-colour, did conſtantly, when held againſt the Light, appear Yellowiſh or Reddiſh, according as its Tincture was more Dilute or Deep; and [pg 210] then, whereas it has been already ſaid, that the Cæruleous Colour was by Acid Salts aboliſhed, this Yellowiſh one ſurviv'd without any conſiderable Alteration, ſo that unleſs our Author's Words be taken in a very Limited Senſe, we muſt conclude, that either his Memory mis-inform'd him, or that his White Nephritick Wood, and the Sadder Colour'd one which we employ'd, were not altogether of the ſame Nature: What he mentions of the Cup made of Lignum Nephriticum, we have not had Opportunity to try, not having been able to procure pieces of that Wood great enough, and otherwiſe fit to be turned into Cups; but as for what he ſays in the Title of his Experiment, that this Wood tinges the Water with all Sorts of Colours, that is much more than any of thoſe pieces of Nephritick Wood that we have hitherto employ'd, was able to make good; The change of Colours diſcernable in a Vial full of Water, Impregnated by any of them, as it is directed towards a place more Lightſome or Obſcure, being far from affording a Variety anſwerable to ſo promiſing a Title. And as for what he tells us, that in the Dark the Infuſion of our Wood will reſume a Cæruleous Colour, I wiſh he had Inform'd us how he Try'd it.
[pg 211]But this brings into my mind, that having ſometimes for Curioſity ſake, brought a round Vial with a long Neck fill'd with the Tincture of Lignum Nephriticum into the Darken'd Room already often mention'd, and holding it ſometimes in, ſometimes near the Sun-beams that enter'd at the hole, and ſometimes partly in them, and partly out of them, the Glaſs being held in ſeveral poſtures, and look'd upon from ſeveral Neighbouring parts of the Room, diſclos'd a much greater Variety of Colours than in ordinary inlightn'd Rooms it is wont to do; exhibiting, beſides the uſual Colours, a Red in ſome parts, and a Green in others, beſides Intermediate Colours produc'd by the differing Degrees, and odd mixtures of Light and Shade.
By all this You may ſee, Pyrophilus, the reaſonableneſs of what we elſewhere had occaſion to mention, when we have divers times told you, that it is uſefull to have New Experiments try'd over again, though they were, at firſt, made by Knowing and Candid Men, ſuch Reiterations of Experiments commonly exhibiting ſome New Phænomena, detecting ſome Miſtake or hinting ſome Truth, in reference to them, that was not formerly taken notice of. And ſome of our friends have been pleas'd to [pg 212] think, that we have made no unuſefull addition to this Experiment, by ſhewing a way, how in a moment our Liquor may be depriv'd of its Blewneſs, and reſtor'd to it again by the affuſion of a very few drops of Liquors, which have neither of them any Colour at all of their own. And that which deſerves ſome particular wonder, is, that the Cæruleous Tincture of our Wood is ſubject by the former Method to be Deſtroy'd or Reſtor'd, the Yellowiſh or Reddiſh Tincture continuing what it was. And that you may ſee, that Salts are of a conſiderable uſe in the ſtriking of Colours, let me add to the many Experiments which may be afforded us to this purpoſe by the Dyers Trade, this Obſervation; That as far as we have hitherto try'd, thoſe Liquors in general that are ſtrong of Acid Salts have the Power of Deſtroying the Blewneſs of the Infuſion of our Wood, and thoſe Liquors indiſcriminatly that abound with Sulphureous Salts, (under which I comprehend the Urinous and Volatile Salts of Animal Subſtances, and the Alcaliſate or fixed Salts that are made by Incineration) have the vertue of Reſtoring it.
[pg 213]A Corollary of the Tenth Experiment.
That this Experiment, Pyrophilus, may be as well Uſefull as Delightfull to You, I muſt mind You, Pyrophilus, that in the newly mention'd Obſervation, I have hinted to You a New and Eaſie way of Diſcovering in many Liquors (for I dare not ſay in all) whether it be an Acid or Sulphureous Salt, that is Predominant; and that ſuch a Diſcovery is oftentimes of great Difficulty, and may frequently be of great Uſe, he that is not a Stranger to the various Properties and Effects of Salts, and of how great moment it is to be able to diſtinguiſh their Tribes, may readily conceive. But to proceed to the way of trying other Liquors by an Infuſion of our Wood, take it briefly thus. Suppoſe I have a mind to try whether I conjecture aright, when I imagine that Allom, though it be plainly a Mixt Body, does abound rather with Acid than Sulphureous Salt. To ſatisfie my ſelf herein, I turn my back to the Light, and holding a ſmall Vial full of the Tincture of Lignum Nephriticum, which look'd upon in that Poſition, appears Cæruleous, I drop into it a little of a ſtrong Solution of Allom made in Fair Water, and finding upon the [pg 214] Affuſion and ſhaking of this New liquor, that the Blewneſs formerly conſpicuous in our Tincture does preſently vaniſh, I am thereby incited to ſuppoſe, that the Salt Prædominant in Allom belongs to the Family of Sour Salts; but if on the other ſide I have a mind to examine whether or no I rightly conceive that Salt of Urine, or of Harts-horn is rather of a Saline Sulphureous (if I may ſo ſpeak) than of an Acid Nature, I drop a little of the Saline Spirit of either into the Nephritick Tincture, and finding that the Cæruleous Colour is rather thereby Deepned than Deſtroy'd, I collect that the Salts, which conſtitute theſe Spirits, are rather Sulphureous than Acid. And to ſatisfie my ſelf yet farther in this particular, I take a ſmall Vial of freſh Tincture, and placing both it and my ſelf in reference to the Light as formerly, I drop into the Infuſion juſt as much Diſtill'd Vinegar, or other Acid liquor as will ſerve to Deprive it of its Blewneſs (which a few drops, if the Sour Liquor be ſtrong, and the Vial ſmall will ſuffice to do) then without changing my Poſture, I drop and ſhake into the ſame Vial a ſmall proportion of Spirit of Hartſhorn or Urine, and finding that upon this affuſion, the Tincture immediately recovers its Cæruleous Colour, I am thereby confirm'd [pg 215] firm'd in my former Opinion, of the Sulphureous Nature of theſe Salts. And ſo, whereas it is much doubted by Some Modern Chymiſts to what ſort of Salt, that which is Prædominant in Quick-lime belongs, we have been perſwaded to referr it rather to Lixiviate than Acid Salts, by having obſerv'd, that though an Evaporated Infuſion of it will ſcarce yield ſuch a Salt, as Aſhes and other Alcalizate Bodyes are wont to do, yet if we deprive our Nephritick Tincture of its Blewneſs by juſt ſo much Diſtill'd Vinegar as is requiſite to make that Colour Vaniſh, the Lixivium of Quick-lime will immediately upon its Affuſion recall the Baniſhed Colour; but not ſo Powerfully as either of the Sulphureous Liquors formerly mention'd. And therefore I allow my ſelf to gueſs at the Strength of the Liquors examin'd by this Experiment, by the Quantity of them which is ſufficient to Deſtroy or Reſtore the Cæruleous Colour of our Tincture. But whether concerning Liquors, wherein neither Acid nor Alcaliſate Salts are Eminently Prædominant, our Tincture will enable us to conjecture any thing more than that ſuch Salts are not Prædominant in them, I take not upon me to determine here, but leave to further Tryal; For I find not that Spirit of [pg 216] Wine, Spirit of Tartar freed from Acidity, or Chymical Oyl of Turpentine, (although Liquors which muſt be conceiv'd very Saline, if Chymiſts have, which is here no place to Diſpute, rightly aſcrib'd taſts to the Saline Principle of Bodyes,) have any Remarkable Power either to deprive our Tincture of its Cæruleous Colour, or reſtore it, when upon the Affuſion of Spirit of Vinegar it has diſappear'd.
And here I muſt not omit, Pyrophilus, to inform You, that we can ſhew You even in a Mineral Body ſomething that may ſeem very near of Kin to the Changeable Quality of the Tincture of Lignum Nephriticum, for we have ſeveral flat pieces of Glaſs, of the thickneſs of ordinary Panes for Windows one of which being interpoſed betwixt the Eye and a clear Light, appears of a Golden Colour, not much unlike that of the moderate Tincture of our Wood, but being ſo look'd upon as that the Beams of light are not ſo much Trajected thorough it as Reflected from it to the Eye, that Yellow ſeems to degenerate into a pale Blew, ſomewhat like that of a Turquoiſe. And what which may alſo appear ſtrange, is this, [pg 217] that if in a certain poſture you hold one of theſe Plates Perpendicular to the Horizon, ſo that the Sun-beams ſhine upon half of it, the other half being Shaded, You may ſee that the part Shin'd upon will be of a much Diluter Yellow than the Shaded part which will appear much more Richly Colour'd; and if You alter the Poſture of the Glaſs, ſo that it be not held Perpendicular, but Parallel in reference to the Horizon, You may ſee, (which perhaps you will admire) the Shaded part look of a Golden Colour, but the other that the Sun ſhines freely on, will appear conſiderably Blew, and as you remove any part of the Glaſs thus held Horizontally into the Sun-beams or Shade, it will in the twinkling of an Eye ſeem to paſs from one of the above mention'd Colours to the other, the Sun-beams Trajected through it upon a ſheet of White Paper held near it, do colour it with a Yellow, ſomewhat bordering upon a Red, but yet the Glaſs may be ſo oppos'd to the Sun, that it may upon Paper project a mix'd Colour here and there more inclin'd to Yellow, and here and there more to Blew. The other Phænomena of this odd Glaſs, I fear it would be ſcarce worth while to Record, and therefore I ſhall rather advertiſe You, Firſt that in the trying of theſe Experiments [pg 218] with it, you muſt take notice that one of the ſides has either alone, or at leaſt principally its Superficial parts diſpos'd to the Reflection of the Blew Colour above nam'd, and that therefore you muſt have a care to keep that ſide neareſt to the Eye. And next, that we have our ſelves made Glaſſes not unfit to exhibit an Experiment not unlike that I have been ſpeaking of, by laying upon pieces of Glaſs ſome very finely foliated Silver, and giving it by degrees a much ſtronger Fire than is requiſite or uſual for the Tinging of Glaſſes of other Colours. And this Experiment, not to mention that it was made without a Furnace in which Artificers that Paint Glaſs are wont to be very Curious, is the more conſiderable, becauſe, that though a Skilfull Painter could not deny to me that 'twas with Silver he Colour'd his Glaſſes Yellow; yet he told me, that when to Burn them (as they ſpeak) he layes on the plates of Glaſs nothing but a Calx of Silver Calcin'd without Corroſive Liquors, and Temper'd with Fair Water, the Plates are Ting'd of a fine Yellow that looks of a Golden Colour, which part ſoever of it you turn to or from the Light; whereas (whether it be what an Artificer would call Over-doing, or Burning, or elſe the imploying the Silver [pg 219] Crude that makes the Difference,) we have found more than once, that ſome Pieces of Glaſs prepar'd as we have related, though held againſt the Light they appear'd of a Tranſparent Yellow, yet look'd on with ones back turn'd to the Light they exhibited an Untranſparent Blew.
If you will allow me, Pyrophilus, for the avoiding of Ambiguity, to imploy the Word Pigments, to ſignifie ſuch prepared materials (as Cochinele, Vermilion, Orpiment,) as Painters, Dyers and other Artificers make uſe of to impart or imitate particular Colours, I ſhall be the better underſtood in divers paſſages of the following papers, and particularly when I tell you, That the mixing of Pigments being no inconſiderable part of the Painters Art, it may ſeem an Incroachment in me to meddle with it. But I think I may eaſily be excus'd (though I do not altogether paſs it by) if I reſtrain my ſelf to the making of a Tranſient mention of ſome few of their Practices about this matter; and that only ſo far forth, as may warrant me to obſerve to you, that there are but few Simple and Primary Colours (if I may ſo call them) [pg 220] from whoſe Various Compoſitions all the reſt do as it were Reſult. For though Painters can imitate the Hues (though not always the Splendor) of thoſe almoſt Numberleſs differing Colours that are to be met with in the Works of Nature, and of Art, I have not yet found, that to exhibit this ſtrange Variety they need imploy any more than White, and Black, and Red, and Blew, and Yellow; theſe five, Variouſly Compounded, and (if I may ſo ſpeak) Decompounded, being ſufficient to exhibit a Variety and Number of Colours, ſuch, as thoſe that are altogether Strangers to the Painters Pallets, can hardly imagine.
Thus (for Inſtance) Black and White differingly mix'd, make a Vaſt company of Lighter and Darker Grays.
Blew and Yellow make a huge Variety of Greens.
Red and Yellow make Orange Tawny.
Red with a little White makes a Carnation.
Red with an Eye of Blew, makes a Purple; and by theſe ſimple Compoſitions again Compounded among themſelves, the Skilfull Painter can produce what kind of Colour he pleaſes, and a great many more than we have yet Names for. But, as I intimated above, 'tis not my Deſign [pg 221] to proſecute this Subject, though I thought it not unfit to take ſome Notice of it, becauſe we may hereafter have occaſion to make uſe of what has been now deliver'd, to illuſtrate the Generation of Intermediate Colours; concerning which we muſt yet ſubjoyn this Caution, that to make the Rules about the Emergency of Colours, fit to be Relied upon, the Corpuſcles whereof the Pigments conſiſt muſt be ſuch as do not Deſtroy one anothers Texture, for in caſe they do, the produced Colour may be very Different from that which would Reſult from the Mixture of other harmleſs Pigments of the ſame Colours, as I ſhall have Occaſion to ſhew ere long.
It may alſo give much light to an Enquirer into the Nature of Colours, to know that not only in Green, but in many (if not all) other Colours, the Light of the Sun paſſing through Diaphanous Bodies of differing Hues may be tinged of the ſame Compound Colour, as if it came from ſome Painters Colours of the ſame Denomination, though this later be exhibited by Reflection, and be (as the [pg 222] former Experiment declares) manifeſtly Compounded of material Pigments. Wherefore to try the Compoſition of Colours by Trajection, we provided ſeveral Plates of Tinged Glaſs, which being laid two at a time one on the top of another, the Object look'd upon through them both, appear'd of a Compounded Colour, which agrees well with what we have obſerv'd in the ſecond Experiment, of Looking againſt the Light through differingly Colour'd Papers. But we thought the Experiment would be more Satisfactory, if we procur'd the Sun-beams to be ſo Ting'd in their paſſage through Plates of Glaſs, as to exhibit the Compounded Colour upon a Sheet of White Paper. And though by reaſon of the Thickneſs of the Glaſſes, the Effect was but Faint, even when the Sun was High and Shin'd forth clear, yet, we eaſily remedied that by Contracting the Beams we caſt on them by means of a Convex Burning-glaſs, which where it made the Beams much converge Increas'd the Light enough to make the Compounded Colour very manifeſt upon the Paper. By this means we obſerv'd, that the Beams trajected through Blew and Yellow compos'd a Green, that an intenſe and moderate Red did with Yellow make differing [pg 223] degrees of Saffron, and Orange Tawny Colours, that Green and Blew made a Colour partaking of both, ſuch as that which ſome Latin Writers call Pavonaceus, that Red and Blew made a Purple, to which we might add other Colours, that we produc'd by the Combinations of Glaſſes differingly Ting'd, but that I want proper Words to expreſs them in our Language, and had not when we made the Tryals, the Opportunity of conſulting with a Painter, who perchance might have Suppli'd me with ſome of the terms I wanted.
I know not whether it will be requiſite to ſubjoyn on this Occaſion, what I tried concerning Reflections from Colour'd Glaſſes, and other Tranſparent Bodies, namely, that having expos'd four or five ſorts of them to the Sun, and caſt the Reflected Beams upon White Paper held near at hand, the Light appear'd not manifeſtly Ting'd, but as if it had been Reflected from the Impervious parts of a Colourleſs Glaſs, only that Reflected from the Yellow was here and there ſtain'd with the ſame Colour, as if thoſe Beams were not all Reflected from the Superficial, but ſome from the Internal parts of the Glaſs; upon which Occaſion you may take notice, that a Skilfull Tradeſman, who makes ſuch Colour'd [pg 224] Glaſs told me, that where as the Red Pigment was but Superficial, the Yellow penetrated to the very midſt of the Plate. But for further Satisfaction, not having the Opportunity to Foliate thoſe Plates, and ſo turn them into Looking-glaſſes, we Foliated a Plate of Muſcovy Glaſs, and then laying on it a little Tranſparent Varniſh of a Gold Colour, we expos'd it to the Sun-beams, ſo as to caſt them upon a Body fit to receive them, on which the Reflected Light, appearing, as we expected, Yellow, manifeſted that Rebounding from the Specular part of the Selenitis, it was Ting'd in its return with the Colour of the Tranſparent Varniſh through which it paſs'd.
After what we have ſaid of the Compoſition of Colours, it will now be ſeaſonable to annex ſome Experiments that we made in favour of thoſe Colours, that are taught in the Schools not to be Real, but only Apparent and Phantaſtical; For we found by Tryals, that theſe Colours might be Compounded, both with True and Stable Colours, and with one another, as well as unqueſtionably Genuine and Laſting Colours, and that the Colours [pg 225] reſulting from ſuch Compoſitions, would reſpectively deſerve the ſame Denominations.
For firſt, having by the Trajection of the Sun-beams through a Glaſs-priſm thrown an Iris on the Floor, I found that by placing a Blew Glaſs at a convenient diſtance betwixt the Priſm and the Iris, that part of the Iris that was before Yellow, might be made to appear Green, though not of a Graſs Green, but of one more Dilute and Yellowiſh. And it ſeems not improbable, that the narrow Greeniſh Liſt (if I may ſo call it) that is wont to be ſeen between the Yellow and Blew parts of the Iris, is made by the Confuſion of thoſe two Bordering Colours.
Next, I found, that though the want of a ſufficient Livelineſs in either of the Compounding Colours, or a light Error in the manner of making the following Tryals, was enough to render ſome of them Unſucceſsfull, yet when all neceſſary Circumſtances were duely obſerv'd, the Event was anſwerable to our Expectation and Deſire.
And (as I formerly Noted) that Red and Blew compound a Purple, ſo I could produce this laſt nam'd Colour, by caſting at ſome Diſtance from the Glaſs the Blew [pg 226] part of the Priſmatical Iris (as I think it may be call'd for Diſtinction ſake) upon a Lively Red, (for elſe the Experiment ſucceeds not ſo well.) And I remember, that ſometimes when I try'd this upon a piece of Red Cloath, that part of the Iris which would have been Blew, (as I try'd by covering that part of the Cloath with a piece of White Paper) and Compounded with the Red, wherewith the Cloath was Imbued before, appear'd of a fair Purple, did, when I came to View it near at hand, look very Odly, as if there were ſome ſtrange Reflection or Refraction or both made in the Hairs of which that Cloath was compoſed.
Calling likewiſe the Priſmatical Iris upon a very Vivid Blew, I found that part of it, which would elſe have been the Yellow, appear Green. (Another ſomewhat differing Tryal, and yet fit to confirm this, you will find in the fifteenth Experiment.)
But it may ſeem ſomewhat more ſtrange, that though the Priſmatical Iris being made by the Refraction of Light through a Body that has no Colour at all, muſt according to the Doctrine of the Schools conſiſt of as purely Emphatical Colours, as may be, yet even theſe may be Compounded with one another, as well as Real Colours in [pg 227] the Groſſeſt Pigments. For I took at once two Triangular Glaſſes, and one of them being kept fixt in the ſame Poſture, that the Iris it projected on the Floor might not Waver, I caſt on the ſame Floor another Iris with the other Priſm, and Moving it too and fro to bring what part of the ſecond Iris I pleas'd, to fall upon what part of the firſt I thought fit, we did ſometimes (for a ſmall Errour ſuffices to hinder the Succeſs) obtain by this means a Green Colour in that part of the more Stable Iris, that before was Yellow, or Blew, and frequently by caſting thoſe Beams that in one of the Iris's made the Blew upon the Red parts of the other Iris, we were able to produce a lovely Purple, which we can Deſtroy or Recompoſe at pleaſure, by Severing and Reapproaching the Edges of the two Iris's.
On this occaſion, Pyrophilus, I ſhall add, that finding the Glaſs-priſm to be the uſefulleſt Inſtrument Men have yet imploy'd about the Contemplation of Colours, and conſidering that Priſms hitherto in uſe are made of Glaſs, Tranſparent and Colourleſs, I thought it would not be amiſs to try, [pg 228] what change the Superinduction of a Colour, without the Deſtruction of the Diaphaneity, would produce in the Colours exhibited by the Priſm. But being unable to procure one to be made of Colour'd Glaſs, and fearing alſo that if it were not carefully made, the Thickneſs of it would render it too Opacous, I endeavoured to ſubſtitute one made of Clarify'd Roſin, or of Turpentine brought (as I elſewhere teach) to the conſiſtence of a Tranſparent Gum. But though theſe Endeavours were not wholly loſt, yet we found it ſo difficult to give theſe Materials their true Shape, that we choſe rather to Varniſh over an ordinary Priſm with ſome of theſe few Pigments that are to be had Tranſparent; as accordingly we did firſt with Yellow, and then with Red, or rather Crimſon, made with Lake temper'd with a convenient Oyl, and the Event was, That for want of good Tranſparent Colours, (of which you know there are but very few) both the Yellow and the Red made the Glaſs ſo Opacous, (though the Pigment were laid on but upon two Sides of the Glaſs, no more being abſolutely neceſſary) that unleſs I look'd upon an Inlightned Window, or the Flame of a Candle, or ſome other Luminous or very Vivid object, [pg 229] I could ſcarce diſcern any Colours at all, eſpecially when the Glaſs was cover'd with Red. But when I did look on ſuch Objects, it appear'd (as I expected) that the Colour of the Pigment had Vitiated or Drown'd ſome of thoſe which the Priſm would according to its wont have exhibited, and mingling with others, Alter'd them: as I remember, that both to my Eyes, and others to whom I ſhow'd it, when the Priſm was cover'd with Yellow, it made thoſe Parts of bright Objects, where the Blew would elſe have been Conſpicuous, appear of a light Green. But, Pyrophilus, both the Nature of the Colours, and the Degree of Tranſparency, or of Darkneſs in the Pigment, beſides divers other Circumſtances, did ſo vary the Phænomena of theſe Tryals, that till I can procure ſmall Colour'd Priſms, or Hollow ones that may be filled with Tincted Liquor, or obtain Some better Pigments than thoſe I was reduc'd to imploy, I ſhall forbear to Build any thing upon what has been delivered, and ſhall make no other uſe of it, than to invite you to proſecute the Inquiry further.
[pg 230]And here, Pyrophilus, ſince we are treating of Emphatical Colours, we ſhall add what we think not unworthy your Obſervation, and not unfit to afford ſome Exerciſe to the Speculative. For there are ſome Liquors, which though Colourleſs themſelves, when they come to be Elevated, and Diſpers'd into Exhalations, exhibit a conſpicuous Colour, which they loſe again, when they come to be Reconjoyn'd into a Liquor, as good Spirit of Nitre; or upon its account ſtrong Aqua-fortis, though devoid of all appearance of Redneſs whilſt they continue in the form of a Liquor, if a little Heat chance to turn the Minute parts of them into Vapour, the Steam will appear of a Reddiſh or deep Yellow Colour, which will Vaniſh when thoſe Exhalations come to reſume the form of Liquor.
And not only if you look upon a Glaſs half full of Aqua-fortis, or Spirit of Nitre, and half full of Nitrous ſteams proceeding from it, you will ſee the Upper part of the Glaſs of the Colour freſhly mention'd, if through it you look upon the Light. But which is much more conſiderable, I [pg 231] have tried, that putting Aqua-fortis in a long clear Glaſs, and adding a little Copper or ſome ſuch open Metall to it, to excite Heat and Fumes, the Light trajected through thoſe Fumes, and caſt upon a ſheet of White Paper, did upon that appear of the Colour that the Fumes did, when directly Look'd upon, as if the Light were as well Ting'd in its paſſage through theſe Fumes, as it would have been by paſſing through ſome Glaſs or Liquor in which the ſame Colour was Inherent.
To which I ſhall further add, that having ſometimes had the Curioſity to obſerve whether the Beams of the Sun near the Horizon trajected through a very Red Sky, would not (though ſuch redneſſes are taken to be but Emphatical Colours) exhibit the like Colour, I found that the Beams falling within a Room upon a very White Object, plac'd directly oppoſite to the Sun, diſclos'd a manifeſt Redneſs, as if they had paſs'd through a Colour'd Medium.
The emergency, Pyrophilus, of Colours upon the Coalition of the Particles of ſuch Bodies as were neither of them of the Colour of that Mixture whereof they are the [pg 232] Ingredients, is very well worth our attentive Obſervation, as being of good uſe both Speculative and Practical; For much of the Mechanical uſe of Colours among Painters and Dyers, doth depend upon the Knowledge of what Colours may be produc'd by the Mixtures of Pigments ſo and ſo Colour'd. And (as we lately intimated) 'tis of advantage to the contemplative Naturaliſt, to know how many and which Colours are Primitive (if I may ſo call them) and Simple, becauſe it both eaſes his Labour by confining his moſt ſollicitous Enquiry to a ſmall Number of Colours upon which the reſt depend, and aſſiſts him to judge of the nature of particular compounded Colours, by ſhewing him from the Mixture of what more Simple ones, and of what Proportions of them to one another, the particular Colour to be conſider'd does reſult. But becauſe to inſiſt on the Proportions, the Manner and the Effects of ſuch Mixtures would oblige me to conſider a greater part of the Painters Art and Dyers Trade, than I am well acquainted with, I confin'd my ſelf to make Trial of ſeveral ways to produce Green, by the compoſition of Blew and Yellow. And ſhall in this place both Recapitulate moſt of the things I have Diſperſedly deliver'd [pg 233] already concerning that Subject, and Recruit them.
And firſt, whereas Painters (as I noted above) are wont to make Green by tempering Blew and Yellow, both of them made into a ſoft Conſiſtence, with either Water or Oyl, or ſome Liquor of Kin to one of thoſe two, according as the Picture is to be Drawn with thoſe they call water Colours, or thoſe they term Oyl Colours, I found that by chooſing fit Ingredients, and mixing them in the form of Dry Powders, I could do, what I could not if the Ingredients were temper'd up with a Liquor; But the Blew and Yellow Powders muſt not only be finely Ground, but ſuch as that the Corpuſcles of the one may not be too unequal to thoſe of the other, leſt by their Diſproportionate Minuteneſs the Smaller cover and hide the Greater. We us'd with good ſucceſs a ſlight Mixture of the fine Powder of Biſe, with that of Orpiment, or that of good Yellow Oker, I ſay a ſlight Mixture, becauſe we found that an exquiſite Mixture did not do ſo well, but by lightly mingling the two Pigments in ſeveral little Parcels, thoſe of them in which the Proportion and Manner of Mixture was more Lucky, afforded us a good Green.
[pg 234]2. We alſo learn'd in the Dye-houſes, that Cloth being Dy'd Blew with Woad, is afterwards by the Yellow Decoction of Luteola or Woud-wax or Wood-wax Dy'd into a Green Colour.
3. You may alſo remember what we above Related, where we intimated, that having in a Darkn'd Room taken two Bodies, a Blew and a Yellow, and caſt the Light Reflected from the one upon the other, we likewiſe obtain'd a Green.
4. And you may remember, that we obſerv'd a Green to be produc'd, when in the ſame Darkn'd Room we look'd at the Hole at which alone the Light enter'd, through the Green and Yellow parts of a ſheet of Marbl'd Paper laid over one another.
5. We found too, that the Beams of the Sun being trajected through two pieces of Glaſs, the one Blew and the other Yellow, laid over one another, did upon a ſheet of White paper on which they were made to fall, exhibit a lovely Green.
6. I hope alſo, that you have not already forgot, what was ſo lately deliver'd, concerning the compoſition of a Green, with a Blew and Yellow; of which moſt Authors would call the one a Real, and the other an Emphatical.
[pg 235]7. And I preſume, you may have yet freſh in your memory, what the fourteenth Experiment informs you, concerning the exhibiting of a Green, by the help of a Blew and Yellow, that were both of them Emphatical.
8. Wherefore we will proceed to take notice, that we alſo devis'd a way of trying whether or no Metalline Solutions though one of them at leaſt had its Colour Adventitious, by the mixture of the Menstruum employ'd to diſſolve it, might not be made to compound a Green after the manner of other Bodies. And though this ſeem'd not eaſie to be perform'd by reaſon of the Difficulty of finding Metalline Solutions of the Colour requiſite, that would mix without Præcipitating each other; yet after a while having conſider'd the matter, the firſt Tryal afforded me the following Experiment. I took a High Yellow Solution of good Gold in Aqua-Regis, (made of Aqua-fortis, and as I remember half its weight of Spirit of Salt) To this I put a due Proportion of a deep and lovely Blew Solution of Crude Copper, (which I have elſewhere taught to be readily Diſſoluble in ſtrong Spirit of Urine) and theſe two Liquors though at firſt they ſeem'd a little to Curdle one another, yet being throughly mingl'd by Shaking, [pg 236] they preſently, as had been Conjectur'd, united into a Tranſparent Green Liquor, which continu'd ſo for divers days that I kept it in a ſmall Glaſs wherein 'twas made, only letting fall a little Blackiſh Powder to the Bottom. The other Phænomena of this Experiment belong not to this place, where it may ſuffice to take notice of the Production of a Green, and that the Experiment was more than once repeated with Succeſs.
9. And laſtly, to try whether this way of compounding Colours would hold ev'n in Ingredients actually melted by the Violence of the Fire, provided their Texture were capable of ſafely induring Fuſion, we caus'd ſome Blew and Yellow Ammel to be long and well wrought together in the Flame of a Lamp, which being Strongly and Inceſſantly blown on them kept them in ſome degree of Fuſion, and at length (for the Experiment requires ſome Patience as well as Skil) we obtain'd the expected Ammel of a Green Colour.
I know not, Pyrophilus, whether it be worth while to acquaint you with the ways that came into my Thoughts, whereby in ſome meaſure to explicate the firſt of the mention'd ways of making a Green; for I have ſometimes Conjectur'd, that the mixture [pg 237] of the Biſe and the Orpiment produc'd a Green by ſo altering the Superficial Aſperity, which each of thoſe Ingredients had apart, that the Light Incident on the mixture was Reflected with differing Shades, as to Quantity, or Order, or both, from thoſe of either of the Ingredients, and ſuch as the Light is wont to be Modify'd with, when it Reflects from Graſs, or Leaves, or ſome of thoſe other Bodies that we are wont to call Green. And ſometimes too I have doubted, whether the produced Green might not be partly at leaſt deriv'd from this, That the Beams that Rebound from the Corpuſcles of the Orpiment, giving one kind of ſtroak upon the Retina, whoſe Perception we call Yellow, and the Beams Reflected from the Corpuſcles of the Biſe, giving another ſtroak upon the ſame Retina, like to Objects that are Blew, the Contiguity and Minuteneſs of theſe Corpuſcles may make the Appulſe of the Reflected Light fall upon the Retina within ſo narrow a Compaſs, that the part they Beat upon being but as it were a Phyſical point, they may give a Compounded ſtroak, which may conſequently exhibit a Compounded and new Kind of Senſation, as we ſee that two Strings of a Muſical Inſtrument being ſtruck together, making two [pg 238] Noiſes that arrive at the Ear at the ſame time as to Senſe, yield a Sound differing from either of them, and as it were Compounded of both; Inſomuch that if they be Diſcordantly ton'd, though each of them ſtruck apart would yield a Pleaſing Sound, yet being ſtruck together they make but a Harſh and troubleſome Noiſe. But this not being ſo fit a place to proſecute Speculations, I ſhall not inſiſt, neither upon theſe Conjectures nor any others, which the Experiment we have been mentioning may have ſuggeſted to me. And I ſhall leave it to you, Pyrophilus, to derive what Inſtruction you can from comparing together the Various ways whereby a Yellow and a Blew can be made to Compound a Green. That which I now pretend to, being only to ſhew that the firſt of thoſe mention'd ways, (not to take at preſent notice of the reſt) does far better agree with our Conjectures about Colours, than either with the Doctrine of the Schools, or with that of the Chymiſts, both which ſeem to be very much Disfavour'd by it.
For firſt, ſince in the Mixture of the two mention'd Powders I could by the help of a very excellent Microſcope (for ordinary ones will ſcarce ſerve the turn) diſcover that which ſeem'd to the naked Eye a Green [pg 239] Body, to be but a heap of Diſtinct, though very ſmall Grains of Yellow Orpiment and Blew Biſe confuſedly enough Blended together, it appears that the Colour'd Corpuſcles of either kind did each retain its own Nature and Colour; By which it may be gueſs'd, what meer Tranſpoſition and Juxtapoſition of Minute and Singly unchang'd Particles of Matter can do to produce a new Colour; For that this Local Motion and new Diſpoſition of the ſmall parts of the Orpiment did Intervene is much more manifeſt than it is eaſie to Explicate how they ſhould produce this new Green otherwiſe than by the new Manner of their being put together, and conſequently by their new Diſpoſition to Modifie the Incident Light by Reflecting it otherwiſe than they did before they were Mingl'd together.
Secondly, The Green thus made being (if I may ſo ſpeak) Mechanically produc'd, there is no pretence to derive it from I know not what incomprehenſible Subſtantial Form, from which yet many would have us believe that Colours muſt flow; Nor does this Green, though a Real and Permanent, not a Phantaſtical and Vanid Colour, ſeem to be ſuch an Inherent Quality as they would have it, ſince not only each part of [pg 240] the Mixture remains unalter'd in Colour, and conſequently of a differing Colour from the Heap they Compoſe, but if the Eye be aſſiſted by a Microſcope to diſcern things better and more diſtinctly than before it could, it ſees not a Green Body, but a Heap of Blew and Yellow Corpuſcles.
And in the third place, I demand what either Sulphur, or Salt, or Mercury has to do in the Production of this Green; For neither the Biſe nor the Orpiment were indu'd with that Colour before, and the bare Juxtapoſition of the Corpuſcles of the two Powders that work not upon each other, but might if we had convenient Inſtruments be ſeparated, unalter'd, cannot with any probability be imagin'd either to Increaſe or Diminiſh any of the three Hypoſtatical Principles, (to which of them ſoever the Chymiſts are pleas'd to aſcribe Colours) nor does there here Intervene ſo much as Heat to afford them any colour to pretend, that at leaſt there is made an Extraverſion (as the Helmontians ſpeak) of the Sulphur or of any of the two other ſuppoſed Principles; But upon this Experiment we have already Reflected enough, if not more than enough for once.
[pg 241]But here, Pyrophilus, I muſt advertiſe you, that 'tis not every Yellow and every Blew that being mingl'd will afford a Green; For in caſe one of the Ingredients do not Act only as endow'd with ſuch a Colour, but as having a power to alter the Texture of the Corpuſcles of the other, ſo as to Indiſpoſe them to Reflect the Light, as Corpuſcles that exhibit a Blew or a Yellow are wont to Reflect it, the emergent Colour may be not Green, but ſuch as the change of Texture in the Corpuſcles of one or both of the Ingredients qualifies them to ſhew forth; as for inſtance, if you let fall a few Drops of Syrrup of Violets upon a piece of White Paper, though the Syrrup being ſpread will appear Blew, yet mingling with it two or three Drops of the lately mention'd Solution of Gold, I obtain'd not a Green but a Reddiſh mixture, which I expected from the remaining Power of the Acid Salts abounding in the Solution, ſuch Salts or Saline Spirits being wont, as we ſhall ſee anon, though weakn'd, ſo to work upon that Syrrup as to change it into a Red or Reddiſh Colour. And to confirm that for which I allege the former [pg 242] Experiment, I ſhall add this other, that having made a very ſtrong and high-colour'd Solution of Filings of Copper with Spirit of Urine, though the Menſtruum ſeem'd Glutted with the Metall, becauſe I put in ſo much Filings that many of them remain'd for divers days Undiſſolv'd at the Bottom, yet having put three or four Drops of Syrrup of Violets upon White Paper, I found that the deep Blew Solution proportionably mingl'd with this other Blew Liquor did not make a Blew mixture, but, as I expected, a fair Green, upon the account of the Urinous Salt that was in the Menſtruum.
To ſhew the Chymiſts, that Colours may be made to Appear or Vaniſh, where there intervenes no Acceſſion or Change either of the Sulphureous, or the Saline, or the Mercurial principle (as they ſpeak) of Bodies: I ſhall not make uſe of the Iris afforded by the Glaſs-priſm, nor of the Colours to be ſeen in a fair Morning in thoſe drops of Dew that do in a convenient manner Reflect and Refract the Beams of Light to the Eye; But I will rather mind them of what they may obſerve in their [pg 243] own Laboratories, namely, that divers, if not all, Chymical Eſſential Oyls, as alſo good Spirit of Wine, being ſhaken till they have good ſtore of Bubbles, thoſe Bubbles will (if attentively conſider'd) appear adorn'd with various and lovely Colours, which all immediately Vaniſh, upon the relapſing of the Liquor that affords thoſe Bubbles their Skins, into the reſt of the Oyl, or Spirit of Wine, ſo that a Colourleſs Liquor may be made in a trice to exhibit variety of Colours, and may loſe them in a moment without the Acceſſion or Diminution of any of its Hypoſtatical Principles. And, by the way, 'tis not unworthy our notice, that ſome Bodies, as well Colourleſs, as Colour'd, by being brought to a great Thinneſs of parts, acquire Colours though they had none before, or Colours differing from them they were before endued with: For, not to inſiſt on the Variety of Colours, that Water, made ſomewhat Glutinous by Sope, acquires, when 'tis blown into ſuch Sphærical Bubbles as Boys are wont to make and play with; Turpentine (though it have a Colour deep enough of its own) may (by being blown into after a certain manner) be brought to afford Bubbles adorn'd with variety of Orient Colours, which though [pg 244] they Vaniſh after ſome while upon the breaking of the Bubbles, yet they would in likelihood always exhibit Colours upon their Superfices, (though not always the ſame in the ſame Parts of them, but Vary'd according to the Incidence of the Sight, and the Poſition of the Eye) if their Texture were durable enough: For I have ſeen one that was Skill'd at faſhioning Glaſſes by the help of a Lamp, blowing ſome of them ſo ſtrongly as to burſt them, whereupon it was found, that the Tenacity of the Metall was ſuch, that before it broke it ſuffer'd it ſelf to be reduc'd into Films ſo extremely thin, that being kept clean they conſtantly ſhew'd on their Surfaces (but after the manner newly mention'd) the varying Colours of the Rain-bow, which were exceedingly Vivid, as I had often opportunity to obſerve in ſome, that I caus'd purpoſely to be made, to keep by me.
But leſt it ſhould be objected, that the above mentioned Inſtances are drawn from Tranſparent Liquors, it may poſſibly appear, not impertinent to add, what I have ſometimes thought upon, and ſeveral times tried, when I was conſidering the Opinions of the Chymiſts about Colours, I took then a Feather of a convenient Bigneſs [pg 245] and Shape, and holding it at a fit diſtance betwixt my Eye and the Sun when he was near the Horizon, me thought there appear'd to me a Variety of little Rain-bows, with differing and very vivid Colours, of which none was conſtantly to be ſeen in the Feather; the like Phænomenon I have at other times (though not with altogether ſo good ſucceſs) produc'd, by interpoſing at a due diſtance a piece of Black Ribband betwixt the almoſt ſetting Sun and my Eye, not to mention the Trials I have made to the ſame purpoſe, with other Bodies.
Take good Syrrup of Violets, Imprægnated with the Tincture of the flowers, drop a little of it upon a White Paper (for by that means the Change of Colour will be more conſpicuous, and the Experiment may be practis'd in ſmaller Quantities) and on this Liquor let fall two or three drops of Spirit either of Salt or Vinegar, or almoſt any other eminently Acid Liquor, and upon the Mixture of theſe you ſhall find the Syrrup immediatly turn'd Red, and the way of Effecting ſuch a Change has not been unknown to divers Perſons [pg 246] who have produc'd the like, by Spirit of Vitriol, or juice of Limmons, but have Groundleſsly aſcrib'd the Effect to ſome Peculiar Quality of thoſe two Liquors, whereas, (as we have already intimated) almoſt any Acid Salt will turn Syrrup of Violets Red. But to improve the Experiment, let me add what has not (that I know of) been hitherto obſerv'd, and has, when we firſt ſhew'd it them, appear'd ſomething ſtrange, even to thoſe that have been inquiſitive into the Nature of Colours; namely, that if inſtead of Spirit of Salt, or that of Vinegar, you drop upon the Syrrup of Violets a little Oyl of Tartar per Deliquium, or the like quantity of Solution of Potaſhes, and rubb them together with your finger, you ſhall find the Blew Colour of the Syrrup turn'd in a moment into a perfect Green, and the like may be perform'd by divers other Liquors, as we may have occaſion elſewhere to Inform you.
Annotation upon the twentieth Experiment.
The uſe of what we lately deliver'd concerning the way of turning Syrrup of Violets, Red or Green, may be this; That, though it be a far more common and procurable [pg 247] Liquor than the Infuſion of Lignum Nephriticum, it may yet be eaſily ſubſtituted in its Room, when we have a mind to examine, whether or no the Salt predominant in a Liquor or other Body, wherein 'tis Looſe and Abundant, belong to the Tribe of Acid Salts or not. For if ſuch a Body turn the Syrrup of a Red or Reddiſh Purple Colour, it does for the moſt part argue the Body (eſpecially if it be a diſtill'd Liquor) to abound with Acid Salt. But if the Syrrup be made Green, that argues the Predominant Salt to be of a Nature repugnant to that of the Tribe of Acids. For, as I find that either Spirit of Salt, or Oyl of Vitriol, or Aqua-fortis, or Spirit of Vinegar, or Juice of Lemmons, or any of the Acid Liquors I have yet had occaſion to try, will turn Syrrup of Violets, of a Red, (or at leaſt, of a Reddiſh Colour, ſo I have found, that not only the Volatile Salts of all Animal Subſtances I have us'd, as Spirit of Harts-horn, of Urine, of Sal-Armoniack, of Blood, &c. but alſo all the Alcalizate Salts I have imploy'd, as the Solution of Salt of Tartar, of Pot-aſhes, of common Wood-aſhes, Lime-water, &c. will immediately change the Blew Syrrup, into a perfect Green. And by the ſame way (to hint that upon [pg 248] the by) I elſewhere ſhow you, both the changes that Nature and Time produce, in the more Saline parts of ſome Bodies, may be diſcover'd, and alſo how ev'n ſuch Chymically prepar'd Bodies, as belong not either to the Animal Kingdome, or to the Tribe of Alcali's, may have their new and ſuperinduc'd Nature ſucceſsfully Examin'd. In this place I ſhall only add, that not alone the Changing the Colour of the Syrrup, requires, that the Changing Body be more ſtrong, of the Acid, or other ſort of Salt that is Predominant in it, than is requiſite for the working upon the Tincture of Lignum Nephriticum; but that in this is alſo, the Operation of the formerly mention'd Salts upon our Syrrup, differs from their Operation upon our Tinctures, that in this Liquor, if the Cæruleous Colour be Deſtroy'd by an Acid Salt, it may be Restor'd by one that is either Volatile, or Lixiviate; whereas in Syrrup of Violets, though one of theſe contrary Salts will destroy the Action of the other, yet neither of them will reſtore the Syrrup to its native Blew; but each of them will Change it into the Colour which it ſelf doth (if I may ſo ſpeak) affect, as we ſhall have Occaſion to ſhow in the Notes on the twenty fifth Experiment.
[pg 249]There is a Weed, more known to Plowmen than belov'd by them, whoſe Flowers from their Colour are commonly call'd Blew-bottles, and Corn-weed from their Growing among Corn18. Theſe Flowers ſome Ladies do, upon the account of their Lovely Colour, think worth the being Candied, which when they are, they will long retain ſo fair a Colour, as makes them a very fine Sallad in the Winter. But I have try'd, that when they are freſhly gather'd, they will afford a Juice, which when newly expreſs'd, (for in ſome caſes 'twill ſoon enough degenerate) affords a very deep and pleaſant Blew. Now, (to draw this to our preſent Scope) by dropping on this freſh Juice, a little Spirit of Salt, (that being the Acid Spirit I had then at hand) it immediately turn'd (as I predicted) into a Red. And if inſtead of the Sowr Spirit I mingled with it a little ſtrong Solution of an Alcalizate Salt, it did preſently diſcloſe a lovely Green; the ſame Changes being by thoſe differing ſorts of Saline Liquors, producible in this Natural juice, that we lately mention'd to [pg 250] have happen'd to that factitious Mixture, the Syrrup of Violets. And I remember, that finding this Blew Liquor, when freſhly made, to be capable of ſerving in a Pen for an Ink of that Colour, I attempted by moiſtning one part of a piece of White Paper with the Spirit of Salt I have been mentioning, and another with ſome Alcalizate or Volatile Liquor, to draw a Line on the leiſurely dry'd Paper, that ſhould, e'vn before the Ink was dry, appear partly Blew, partly Red, and partly Green: But though the latter part of the Experiment ſucceeded not well, (whether becauſe Volatile Salts are too Fugitive to be retain'd in the Paper, and Alcalizate ones are too Unctuous, or ſo apt to draw Moiſture from the Air, that they keep the Paper from drying well) yet the former Part ſucceeded well enough; the Blew and Red being Conſpicuous enough to afford a ſurprizing Spectacle to thoſe, I acquaint not with (what I willingly allow you to call) the Trick.
Annotation upon the one and twentieth Experiment.
But leſt you ſhould be tempted to think (Pyrophilus) that Volatile or Alcalizate [pg 251] Salts change Blews into Green, rather upon the ſcore of the eaſie Tranſition of the former Colour into the latter, than upon the account of the Texture, wherein moſt Vegetables, that afford a Blew, ſeem, though otherwiſe differing, to be Allied, I will add, that when I purpoſely diſſolv'd Blew Vitriol in fair Water, and thereby imbu'd ſufficiently that Liquor with that Colour, a Lixiviate Liquor, and a Urinous Salt being Copiouſly pour'd upon diſtinct Parcels of it, did each of them, though perhaps with ſome Difference, turn the Liquor not Green, but of a deep Yellowiſh Colour, almoſt like that of Yellow Oker, which Colour the Precipitated Corpuſcles retain'd, when they had Leiſurely ſubſided to the Bottom. What this Precipitated Subſtance is, it is not needfull now to Enquire in this place, and in another, I have ſhown you, that notwithſtanding its Colour, and its being Obtainable from an Acid Menſtruum by the help of Salt of Tartar, it is yet far enough from being the true Sulphur of Vitriol.
Our next Experiment (Pyrophilus) will perhaps ſeem to be of a contrary Nature [pg 252] to the two former, made upon Syrrup of Violets, and Juice of Blew-bottles. For as in them by the Affuſion of Oyl of Tartar, a Blewiſh Liquor is made Green, ſo in this, by the ſole Mixture of the ſame Oyl, a Greeniſh Liquor becomes Blew. The hint of this Experiment was given us by the practice of ſome Italian Painters, who being wont to Counterfeit Ultra-marine Azure (as they call it) by Grinding Verdigreaſe with Sal-Armoniack, and ſome other Saline Ingredients, and letting them Rot (as they imagine) for a good while together in a Dunghill, we ſuppos'd, that the change of Colour wrought in the Verdigreaſe by this way of Preparation, muſt proceed from the Action of certain Volatile and Alcalizate Salts, abounding in ſome of the mingled Concretes, and brought to make a further Diſſolution of the Copper abounding in the Verdigreaſe, and therefore we Conjectur'd, that if both the Verdigreaſe, and ſuch Salts were diſſolv'd in fair Water, the ſmall Parts of both being therein more ſubdivided, and ſet at liberty, would have better acceſs to each other, and thereby Incorporate much the more ſuddenly; And accordingly we found, that if upon a ſtrong Solution of good French Verdigreaſe (for 'tis that we [pg 253] are wont to imploy, as the beſt) you pour a juſt quantity of Oyl of Tartar, and ſhake them well together, you ſhall immediately ſee a notable Change of Colour, and the Mixture will grow thick, and not tranſparent, but if you ſtay a while, till the Groſſer part be Precipitated to, and ſetled in the Bottom, you may obtain a clear Liquor of a very lovely Colour, and exceeding delightfull to the Eye. But, you muſt have a care to drop in a competent Quantity of Oyl of Tartar, for elſe the Colour will not be ſo Deep, and Rich; and if inſtead of this Oyl you imploy a clear Lixivium of Pot-aſhes, you may have an Azure ſomewhat Lighter or Paler than, and therefore differing from, the former. And if inſtead of either of theſe Liquors, you make uſe of Spirit of Urine, or of Harts-horn, you may according to the Quantity and Quality of the Spirit you pour in, obtain ſome further Variety (though ſcarce conſiderable) of Cæruleous Liquors. And yet lately by the help of this Urinous Spirit we made a Blew Liquor, which not a few Ingenious Perſons, and among them, ſome, whoſe Profeſſion makes them very Converſant with Colours, have looked upon with ſome wonder. But theſe Azure Colour'd Liquors [pg 254] ſhould be freed from the Subſiding matter, which the Salts of Tartar or Urine precipitate out of them, rather by being Decanted, than by Filtration. For by the latter of theſe ways we have ſometimes found, the Colour of them very much Impair'd, and little Superiour to that of the groſſer Subſtance, that it left in the Filtre.
That Roſes held over the Fume of Sulphur, may quickly by it be depriv'd of their Colour, and have as much of their Leaves, as the Fume works upon, burn'd pale, is an Experiment, that divers others have tried, as well as I. But (Pyrophilus) it may ſeem ſomewhat ſtrange to one that has never conſider'd the Compounded nature of Brimſtone, That, whereas the Fume of Sulphur will, as we have ſaid, Whiten the Leaves of Roſes; That Liquor, which is commonly call'd Oyl of Sulphur per Campanam, becauſe it is ſuppos'd to be made by the Condenſation of theſe Fumes in Glaſſes ſhap't like Bells, into a Liquor, does powerfully heighten the Tincture of Red Roſes, and make it more Red and Vivid, as we have eaſily tried by putting ſome Red-Roſe Leaves, [pg 255] that had been long dried, (and ſo had loſt much of their Colour) into a Vial of fair Water. For a while after the Affuſion of a convenient Quantity of the Liquor we are ſpeaking of, both the Leaves themſelves, and the Water they were Steep'd in, diſcover'd a very freſh and lovely Colour.
It may (Pyrophilus) ſomewhat ſerve to Illuſtrate, not only the Doctrine of Pigments, and of Colours, but divers other Parts of the Corpuſcular Philoſophy; as that explicates Odours, and many other things, not as the Schools by Aery Qualities, but by Real, though extremely Minute Bodies; to examine, how much of a Colourleſs Liquor, a very ſmall Parcel of a Pigment may Imbue with a diſcernable Colour. And though there be ſcarce any thing of Preciſeneſs to be expected from ſuch Trials, yet I preſum'd, that (at leaſt) I ſhould be able to ſhow a much further Subdiviſion of the Parts of Matter into Viſible Particles, than I have hitherto found taken notice of, and than moſt men would imagine; no Body, that I know of, having yet attempted to reduce this Matter to any Meaſure.
[pg 256]The Bodies, the moſt promiſing for ſuch a purpoſe, might ſeem to be the Metalls, eſpecially Gold, becauſe of the Multitude, and Minuteneſs of its Parts, which might be argu'd from the incomparable Cloſeneſs of its Texture: But though we tried a Solution of Gold made in Aqua Regia firſt, and then in fair Water; yet in regard we were to determine the Pigment we imploy'd, not by Bulk but Weight, and becauſe alſo, that the Yellow Colour of Gold is but a faint one in Compariſon of the deep Colour of Cochineel, we rather choſe this to make our Trials with. But among divers of theſe it will ſuffice to ſet down one, which was carefully made in Veſſels conveniently Shap'd; (and that in the preſence of a Witneſs, and an Aſſiſtant) the Sum whereof I find among my Adverſaria, Regiſtred in the following Words. To which I ſhall only premiſe, (to leſſen the wonder of ſo ſtrange a diffuſion of the Pigment) That Cochineel will be better Diſſolv'd, and have its Colour far more heightn'd by Spirit of Urine, than (I ſay not by common Water, but) by Rectify'd Spirit of Wine it ſelf.
The Note I ſpoke off is this. [One Grain of Cochineel diſſolv'd in a pretty Quantity of Spirit of Urine, and then diſſolv'd [pg 257] further by degrees in fair Water, imparted a diſcernable, though but a very faint Colour, to about ſix Glaſs-fulls of Water, each of them containing about forty three Ounces and an half, which amounts to above a hundred twenty five thouſand times its own Weight.]
It may afford a conſiderable Hint (Pyrophilus) to him, that would improve the Art of Dying, to know what change of Colours may be produc'd by the three ſeveral ſorts of Salts already often mention'd, (ſome or other of which may be procur'd in Quantity at reaſonable Rates) in the Juices, Decoctions, Infuſions, and (in a word) the more ſoluble parts of Vegetables. And, though the deſign of this Diſcourſe be the Improvement of Knowledge, not of Trades: yet thus much I ſhall not ſcruple to intimate here, That the Blew Liquors, mention'd in the twentieth and one and twentieth Experiments, are far from being the only Vegetable Subſtances, upon which Acid, Urinous, and Alcalizate Salts have the like Operations to thoſe recited in thoſe two Experiments. For Ripe Privet Berries (for inſtance) being cruſh'd [pg 258] upon White Paper, though they ſtain it with a Purpliſh Colour, yet if we let fall on ſome part of it two or three drops of Spirit of Salt, and on the other part a little more of the Strong Solution of Pot-aſhes, the former Liquor immediately turn'd that part of the Thick juice or Pulp, on which it fell, into a lovely Red, and the latter turn'd the other part of it into a delightfull Green. Though I will not undertake, that thoſe Colours in that Subſtance ſhall not be much more Orient, than Laſting; and though (Pyrophilus) this Experiment may ſeem to be almoſt the ſame with thoſe already deliver'd concerning Syrrup of Violets, and the Juice of Blew-bottles, yet I think it not amiſs to take this Occaſion to inform you, that this Experiment reaches much farther, than perhaps you yet imagine, and may be of good Uſe to thoſe, whom it concerns to know, how Dying Stuffs may be wrought upon by Saline Liquors. For, I have found this Experiment to ſucceed in ſo many Various Berries, Flowers, Bloſſoms, and other finer Parts of Vegetables, that neither my Memory, nor my Leiſure ſerves me to enumerate them. And it is ſomewhat ſurprizing to ſee, by how Differingly-colour'd Flowers, or Bloſſoms, (for example) the Paper being [pg 259] ſtain'd, will by an Acid Spirit be immediately turn'd Red, and by any Alcaly or any Urinous Spirit turn'd Green; inſomuch that ev'n the cruſh'd Bloſſoms of Meſerion, (which I gather'd in Winter and froſty Weather) and thoſe of Peaſe, cruſh'd upon White Paper, how remote ſoever their Colours be from Green, would in a moment paſs into a deep Degree of that Colour, upon the Touch of an Alcalizate Liquor. To which let us add, That either of thoſe new Pigments (if I may ſo call them) may by the Affuſion of enough of a contrary Liquor, be preſently chang'd from Red into Green, and from Green into Red, which Obſervation will hold alſo in Syrrup of Violets, Juices of Blew-bottles, &c.
Annotation.
After what I have formerly deliver'd to evince, That there are many Inſtances, wherein new Colours are produc'd or acquir'd by Bodies, which Chymiſts are wont to think deſtitute of Salt, or to whoſe change of Colours no new Acceſſion of Saline Particles does appear to contribute, I think we may ſafely enough acknowledge, [pg 260] that we have taken notice of ſo many Changes made by the Intervention of Salts in the Colours of Mix'd Bodies, that it has leſſen'd our Wonder, That though many Chymiſts are wont to aſcribe the Colours of Such Bodies to their Sulphureous, and the reſt to their Mercurial Principle; yet Paracelſus himſelf directs us in the Indagation of Colours, to have an Eye principally upon Salts, as we find in that paſſage of his, wherein he takes upon him to Oblige his Readers much by Inſtructing them, of what things they are to expect the Knowledge from each of the three diſtinct Principles of Bodies. Alias (ſays he) Colorum ſimilis ratio eſt: De quibus brevem inſtitutionem hanc attendite, quod ſcilicet colores omnes ex Sale prodeant. Sal enim dat colorem, dat Balſamum.19 And a little beneath. Iam natura Ipſa colores protrathit ex ſale, cuique ſpeciei dans illum, qui ipſi competit, &c. After which he concludes; Itaque qui rerum omnium corpora cognoſcere vult, huic opus eſt, ut ante omnia cognoſcat Sulphur, Ab hoc, qui deſiderat noviſſe Colores is ſcientiam iſtorum petat à Sale, Qui ſcire vult Virtutes, is ſcrutetur arcana Mercurii. Sic nimirum fundamentum hauſerit Myſteriorum, in quolibet creſcenti indagandorum, [pg 261] prout natura cuilibet ſpeciei ea ingeſſit. But though Paracelſus aſcribes to each of his belov'd Hypoſtatical Principles, much more than I fear will be found to belong to it; yet if we pleaſe to conſider Colours, not as Philoſophers, but as Dyers, the concurrence of Salts to the ſtriking and change of Colours, and their Efficacy, will, I ſuppoſe, appear ſo conſiderable, that we ſhall not need to quarrel much with Paracelſus, for aſcribing in this place (for I dare not affirm that he uſes to be ſtill of one Mind) the Colours of Bodies to their Salts, if by Salts he here underſtood, not only Elementary Salts, but ſuch alſo as are commonly taken for Salts, as Allom, Cryſtals of Tartar, Vitriol, &c. becauſe the Saline principle does chiefly abound in them, though indeed they be, as we elſewhere declare, mix'd Bodies, and have moſt of them, beſides what is Saline, both Sulphureous, Aqueous, and Groſs or Earthy parts.
But though (Pyrophilus) I have obſerv'd a Red and Green to be produc'd, the former, by Acid Salts, the later by Salts not Acid, in the expreſs Juices of ſo many differing Vegetable Subſtances, that the Obſervation, if perſued, may prove (as I ſaid) of good Uſe: yet to ſhow you how much e'vn theſe Effects depend upon the [pg 262] particular Texture of Bodies, I muſt ſubjoyn ſome caſes wherein I (who am ſomewhat backwards to admit Obſervations for Univerſal) had the Curioſity to diſcover, that the Experiments would not Uniformly ſucceed, and of theſe Exceptions, the chief that I now remember, are reducible to the following three.
And, (firſt) I thought fit to try the Operation of Acid Salts upon Vegetable Subſtances, that are already and by their own Nature Red. And accordingly I made Trial upon Syrrup of Clove-july-flowers, the clear expreſs'd Juice of the ſucculent Berries of Spina Cervina, or Buckthorn (which I had long kept by me for the ſake of its deep Colour) upon Red Roſes, Infuſion of Brazil, and divers other Vegetable Subſtances, on ſome of which cruſh'd (as is often mention'd) upon White Paper, (which is alſo to be underſtood in moſt of theſe Experiments, if no Circumſtance of them argue otherwiſe) Spirit of Salt either made no conſiderable Change, or alter'd the Colour but from a Darker to a Lighter Red. How it will ſucceed in many other Vegetable Juices, [pg 263] and Infuſions of the ſame Colour, I have at preſent ſo few at hand, that I muſt leave you to find it out your ſelf. But as for the Operation of the other ſorts of Salts upon theſe Red Subſtances, I found it not very Uniform, ſome Red, or Reddiſh Infuſions, as of Roſes, being turn'd thereby into a dirty Colour, but yet inclining to Green. Nor was the Syrrup of Clove-july-flowers turn'd by the ſolution of Pot-aſhes to a much better, though ſomewhat a Greener, Colour. Another ſort of Red Infuſions was by an Alcaly not turn'd into a Green, but advanc'd into a Crimſon, as I ſhall have occaſion to note ere long. But there were other ſorts, as particularly the lovely Colour'd juice of Buckthorn Berries, that readily paſs'd into a lovely Green.
Among other Vegetables, which we thought likely to afford Exceptions to the General Obſervation about the differing Changes of Colours produc'd by Acid and Sulphureous Salts, we thought fit to make Trial upon the Flowers of Jaſmin, they being both White as to Colour, and eſteem'd to be of a more Oyly nature than other Flowers. Whereupon having taken [pg 264] the White parts only of the Flowers, and rubb'd them ſomewhat hard with my Finger upon a piece of clean Paper, it appear'd very little Diſcolour'd. Nor had Spirit of Salt, wherewith I moiſten'd one part of it, any conſiderable Operation upon it. But Spirit of Urine, and ſomewhat more effectually a ſtrong Alcalizate Solution, did immediately turn the almoſt Colourleſs Paper moiſten'd by the Juice of the Jaſmin, not as thoſe Liquors are wont to do, when put upon the Juices of other Flowers, of a good Green, but of a Deep, though ſomewhat Greeniſh Yellow, which Experiment I did afterwards at ſeveral times repeat with the like ſucceſs. But it ſeems not that a great degree of Unctuouſneſs is neceſſary to the Production of the like Effects, for when we try'd the Experiment with the Leaves of thoſe purely White Flowers that appear about the end of Winter, and are commonly call'd Snow drops, the event, was not much unlike that, which, we have been newly mentioning.
Another ſort of Inſtances to ſhow, how much changes of Colour effected by Salts, depend upon the particular Texture of the [pg 265] Colour'd Bodies, has been afforded me by ſeveral Yellow Flowers, and other Vegetables, as Mary-gold Leaves, early Prim-roſes, freſh Madder, &c. For being rubb'd upon White Paper, till they imbued it with their Colour, I found not, that by the addition of Alcalizate Liquors, nor yet by that of an Urinous Spirit, they would be turn'd either Green or Red: nor did ſo Acid a Spirit, as that of Salt, conſiderably alter their Colour, ſave that it ſeem'd a little to Dilute it. Only in ſome early Prim-roſes it deſtroy'd the greateſt part of the Colour, and made the Paper almoſt White agen. And Madder alſo afforded ſome thing peculiar, and very differing from what we have newly mention'd: For having gather'd Some Roots of it, and, (whilſt they were recent) expreſs'd upon White Paper the Yellow Juice, an Alcalizate Solution drop'd upon it did not turn it either Green or White, but Red. And the bruis'd Madder it ſelf being drench'd with the like Alcalizate Solution, exchang'd alſo its Yellowiſhneſs for a Redneſs.
[pg 266]An admonition touching the four preceding Experiments.
Having thus (Pyrophilus) given you divers Inſtances, to countenance the General obſervation deliver'd in the twenty fifth Experiment, and divers Exceptions whereby it ought to be Limited; I muſt leave the further Inquiry into theſe Matters to your own Induſtry. For not remembring at preſent many of thoſe other Trials, long ſince made to ſatisfie my ſelf about Particulars, and not having now the Opportunity to repeat them, I muſt content my Self to have given you the Hint, and the ways of proſecuting the ſearch your Self; and only declare to you in general, that, As I have made many Trials, unmention'd in this Treatiſe, whoſe Events were agreeable to thoſe mention'd in the twenty fifth Experiment, ſo (to name now no other Inſtances) what I have try'd with Acid and Sulphureous Salts upon the Pulp of Juniper Berries, rubb'd upon White Paper, inclines me to think, That among that vaſt Multitude, and ſtrange Variety of Plants that adorn the face of the Earth, perhaps many other Vegetables may be found, on which ſuch Menſtruums may not [pg 267] have ſuch Operations, as upon the Juice of Violets, Peaſe-bloſſoms, &c. no nor upon any of thoſe three other ſorts of Vegetables, that I have taken notice of in the three fore-going Experiments. It ſufficiently appearing ev'n by theſe, that the effects of a Salt upon the Juices of particular Vegetables do very much depend upon their particular Textures.
It may be of ſome Uſe towards the diſcovery of the nature of theſe Changes, which the Alimental Juice receives in ſome Vegetables, according to the differing degrees of their Maturity, and according to the differing kinds of Plants of the ſame Denomination, to obſerve what Operation Acid, Urinous, and Alcalizate Salts will have upon the Juices of the ſeveral ſorts of the Vegetable ſubſtances I have been mentioning.
To declare my meaning by an Example, I took from the ſame Cluſter, one Blackberry full Ripe, and another that had not yet gone beyond a Redneſs, and rubbing apiece of white Paper, with the former, I obſerv'd, that the Juice adhering to it was of adark Reddiſh Colour, full of little [pg 268] Black Specks; and that this Juice by a drop of a ſtrong Lixivium, was immediately turn'd into a Greeniſh Colour deep enough, by as much Urinous Spirit into a Colour much of Kin to the former, though ſomewhat differing, and fainter; and by a drop of Spirit of Salt into a fine and lightſome Red: where as the Red Berry being in like manner rubb'd upon Paper, left on it a Red Colour, which was very little alter'd by the Acid Spirit newly nam'd, and by the Urinous and Lixiviate Salts receiv'd changes of Colour differing from thoſe that had been juſt before produc'd in the dark Juice of the Ripe Blackberry.
I remember alſo, that though the Infuſion of Damask-Roſes would as well, though not ſo much, as that of Red, be heightned by Acid Spirits to an intenſe degree of Redneſs, and by Lixiviate Salts be brought to a Darkiſh Green; yet having for Trials ſake taken a Roſe, whoſe Leaves, which were large and numerous, like thoſe of a Province Roſe, were perfectly Yellow, though in a Solution of Salt of Tartar, they afforded a Green Blewiſh Tincture, yet I did not by an Acid Liquor obtain a Red one; all that the Saline Spirit I imploy'd, perform'd, being (if I much miſremember [pg 269] not) to Dilute Somewhat the Yellowneſs of the Leaves. I would alſo have tried the Tincture of Yellow Violets, but could procure none. And if I were in thoſe Iſlands of Banda, which are made Famous as well as Rich, by being the almoſt only places, where Cloves will proſper, I ſhould think it worth my Curioſity to try, what Operation the three differing Kinds of Salts, I have ſo often mention'd, would have upon the Juice of this Spice, (expreſs'd at the ſeveral Seaſons of it) as it grows upon the Tree. Since good Authors inform us, (of what is remarkable) that theſe whether Fruits, or Rudiments of Fruits, are at firſt White, afterward Green, and then Reddiſh, before they be beaten off the Tree, after which being Dry'd before they are put up, they grow Blackiſh as we ſee them. And one of the recenteſt Herbariſts informs us, that the Flower grows upon the top of the Clove it ſelf, conſiſting of four ſmall Leaves, like a Cherry Bloſſom, but of an excellent Blew. But (Pyrophilus) to return to our own Obſervations, I ſhall add, that I the rather chooſe, to mention to you an Example drawn from Roſes, becauſe that though I am apt to think, as I elſewhere advertiſe, that ſomething may be gueſs'd at about [pg 270] ſome of the Qualities of the Juices of Vegetables, by the Reſemblance or Diſparity that we meet with in the Changes made of their Colours, by the Operation of the ſame kinds of Salts; yet that thoſe Conjectures ſhould be very warily made, may appear among other things, by the Inſtance I have choſen to give in Roſes. For though, (as I formerly told you) the Dry'd Leaves, both of the Damask, and of Red ones, give a Red Tincture to Water ſharpen'd with Acid Salts, yet the one ſort of Leaves is known to have a Purgative faculty,20 and the other are often, and divers ways, imploy'd for Binding.
And I alſo chooſe (Pyrophilus) to ſubjoyn this twenty ninth Experiment to thoſe that precede it, about the change of the Colours of Vegetables by Salts, for theſe two reaſons: The firſt, that you may not eaſily entertain Suſpitions, if in the Trials of an Experiment of ſome of the Kinds formerly mention'd, you ſhould meet with an Event ſomewhat differing from what my Relations may have made you expect. And the ſecond, That you may hereby be invited to diſcern, that it may not be amiſs to take notice of the particular Seaſons wherein you gather the Vegetables which [pg 271] in Nicer Experiments you make uſe of. For, it I were not hindred both by haſte and ſome juſtifiable Conſiderations, I could perhaps add conſiderable Inſtances, to thoſe lately deliver'd, for the making out of this Obſervation; but for certain reaſons I ſhall at preſent ſubſtitute a remarkable paſſage to be met with in that Laborious Herbariſt Mr. Parkinſon, where treating of the Virtues of the (already divers times mention'd) Buckthorn Berries, he ſubjoyns the following account of ſeveral Pigments that are made of them, not only according to the ſeveral ways of Handling them, but according to the differing Seaſons of Maturity, at which they are Gather'd; Of theſe Berries, (ſays he) are made three ſeveral ſorts of Colours as they ſhall be gather'd, that is, being gather'd while they are Green, and kept Dry, are call'd Sapberries, which being ſteep'd into ſome Allom-water, or freſh bruis'd into Allom-water, they give a reaſonable fair Yellow Colour which Painters uſe for their Work, and Book-binders to Colour the edges of Books, and Leather-dreſſers to Colour Leather, as they uſe alſo to make a Green Colour, call'd Sap-green, taken from the Berries when they are Black, being bruis'd and put into a Braſs or Copper Kettle or Pan, and there ſuffer'd to abide three or four [pg 272] Days, or a little heated upon the Fire, and ſome beaten Allom put unto them, and afterwards preſs'd forth, the Juice or Liquor is uſually put in great Bladders tied with ſtrong thred at the Head and hung up untill it be Dry, which is diſſolv'd in Water or Wine, but Sack (he affirms) is the beſt to preſerve the Colour from Starving, (as they call it) that is, from Decaying, and make it hold freſh the longer. The third Colour (where of none (ſays he) that I can find have made mention but only Tragus) is a Purpliſh Colour, which is made of the Berries ſuffer'd to grow upon the Buſhes untill the middle or end of November, that they are ready to drop from the Trees.
And, I remember (Pyrophilus) that I try'd, with a ſucceſs that pleas'd me well enough, to make ſuch a kind of Pigment, as Painters call Sap-green, by a way not unlike that, deliver'd here by our Author, but I cannot now find any thing relating to that matter among my looſe Papers. And my Trials were made ſo many years ago, that I dare not truſt my Memory for Circumſtances, but will rather tell you, that in a noted Colour-ſhop, I brought them by Queſtions to confeſs to me, that they made their Sap-green much after the ways by our Botaniſt here mention'd. And on this occaſion [pg 273] I ſhall add an Obſervation, which though it does not ſtrictly belong to this place, may well enough be mention'd here, namely, that I find by an account given us by the Learned Cluſius, of Alaternus, that ev'n the Groſſer Parts of the ſame Plant, are ſome of them one Colour, and ſome another; For ſpeaking of that Plant, he tells us, that the Portugalls uſe the Bark to Dye their Nets into a Red Colour, and with the Chips of the Wood, which are Whitiſh, they Dye a Blackiſh Blew.
Among the Experiments that tend to ſhew that the change of Colours in Bodies may proceed from the Vary'd Texture of their Parts, and the conſequent change of their Diſpoſition to Reflect or Refract the Light, that ſort of Experiments muſt not be left unmention'd, which is afforded us by Chymical Digeſtions. For, if Chymiſts will believe ſeveral famous Writers about what they call the Philoſophers Stone, they muſt acknowledge that the ſame Matter, ſeald up Hermetically in a Philoſophical Egg, will by the continuance of Digeſtion, or if they will have it ſo (for it is not Material in our caſe which of the two it be) [pg 274] of Decoction, run through a great Variety of differing Colours, before it come to that of the Nobleſt Elixir; whether that be Scarlet, or Purple, or what ever other Kind of Red. But without building any thing on ſo Obtruſe and Queſtionable an Operation, (which yet may be pertinently repreſented to thoſe that believe the thing) we may obſerve, that divers Bodies digeſted in carefully-clos'd Veſſels, will in tract of time, change their Colour: As I have elſewhere mention'd my having obſerv'd ev'n in Rectify'd Spirit of Harts-horn, and as is evident in the Precipitations of Amalgams of Gold, and Mercury, without Addition, where by the continuance of a due Heat the Silver-Colour'd Amalgam is reduc'd into a ſhining Red Powder. Further Inſtances of this Kind you may find here and there in divers places of my other Eſſays. And indeed it has been a thing, that has much contributed to deceive many Chymiſts, that there are more Bodies than one, which by Digeſtion will be brought to exhibit that Variety and Succeſſion of Colours, which they imagine to be Peculiar to what they call the True matter of the Philoſophers. But concerning this, I ſhall referr you to what you may elſewhere find in the Diſcourſe written touching the [pg 275] paſſive Deceptions of Chymiſts, and more about the Production of Colours by Digeſtion you will meet with preſently. Wherefore I ſhall now make only this Obſervation from what has been deliver'd, That in theſe Operations there appears not any cauſe to attribute the new Colours emergent to the Action of a new Subſtantial form, nor to any Increaſe or Decrement of either the Salt, Sulphur, or Mercury of the Matter that acquires new Colours: For the Veſſels are clos'd, and theſe Principles according to the Chymiſts are Ingenerable and Incorruptible; ſo that the Effect ſeems to proceed from hence, that the Heat agitating and ſhuffling the Corpuſcles of the Body expos'd to it, does in proceſs of time ſo change its Texture, as that the Tranſpoſed parts do Modifie the incident Light otherwiſe, than they did when the Matter appear'd of another Colour.
Among the ſeveral changes of Colour, which Bodies acquire or diſcloſe by Digeſtion, it it very remarkable, that Chymiſts find a Redneſs rather than any other Colour in moſt of the Tinctures they Draw, and ev'n in the more Groſs Solutions they [pg 276] make of almoſt all Concretes, that abound either with Mineral or Vegetable Sulphur, though the Menſtruum imploy'd about theſe Solutions or Tinctures be never ſo Limpid or Colourleſs.
This we have obſerv'd in I know not how many Tinctures drawn with Spirit of Wine from Jalap, Guaicum, and ſeveral other Vegetables; and not only in the Solutions of Amber, Benzoin, and divers other Concretes made with the ſame Menſtruum, but alſo in divers Mineral Tinctures. And, not to urge that familiar Inſtance of the Ruby of Sulphur, as Chymiſts upon the ſcore of its Colour, call the Solution of Flowers of Brimſtone, made with the Spirit of Turpentine, nor to take notice of other more known Examples of the aptneſs of Chymical Oyls, to produce a Red Colour with the Sulphur they extract, or diſſolve; not to inſiſt (I ſay) upon Inſtances of this nature, I ſhall further repreſent to you, as a thing remarkable, that, both Acid and Alcalizate Salts, though in moſt other caſes of ſuch contrary Operations, in reference to Colours, will with many Bodies that abound with Sulphureous, or with Oyly parts, produce a Red; as is manifeſt partly in the more Vulgar Inſtances of the Tinctures, or Solutions of [pg 277] Sulphur made with Lixiviums, either of Calcin'd Tartar or Pot-aſhes, and other Obvious examples, partly by this, that the true Glaſs of Antimony extracted with ſome Acid Spirits, with or without Wine, will yield a Red Tincture, and that I know an Acid Liquor, which in a moment will turn Oyl of Turpentine into a deep Red. But among the many Inſtances I could give you of the eaſie Production of Redneſs by the Operation of Saline Spirit, as well as of Spirit of Wine; I remember two or three of thoſe I have tried, which ſeem remarkable enough to deſerve to be mention'd to you apart.
But before we ſet them down, it will not perhaps appear impertinent to premiſe;
That there ſeems to be a manifeſt Diſparity betwixt Red Liquors, ſo that ſome of them may be ſaid to have a Genuine Redneſs in compariſon of others, that have a Yellowiſh Redneſs: For if you take (for example) a good Tincture of Chochineel, dilute it never ſo much with fair Water, you will not (as far as I can judge by what I have tried) be able to make it a Yellow Liquor. Inſomuch that a Single [pg 278] drop of a rich Solution of Cochineel in Spirit of Urine, being Diluted with above an Ounce of fair Water, exhibited no Yellowiſhneſs at all, but a fair (though ſomewhat faint) Pinck or Carnation; and even when Cochineel was by degrees Diluted much beyond the newly mention'd Colour, by the way formerly related to you in the twenty fourth Experiment, I remember not, that there appear'd in the whole Trial any Yellow. But if you take Balſom of Sulphur (for Inſtance) though it may appear in a Glaſs, where it has a good Thickneſs, to be of a deep Red, yet if you ſhake the Glaſs, or pour a few drops on a ſheet of White Paper, ſpreading them on it with your Finger, the Balſom that falls back along the ſides of the Glaſs, and that which ſtains the Paper, will appear Yellow, not Red. And there are divers Tinctures, ſuch as that of Amber made with Spirit of Wine, (to name now no more) that will appear either Yellow or Red, according as the Veſſels that they fill, are Slender or Broad.
But to proceed to the Experiments I was about to deliver; Firſt; Oyl or Spirit [pg 279] of Turpentine, though clear as fair Water, being Digeſted upon the purely White Sugar of Lead, has, in a ſhort time, afforded us a high Red Tincture, that ſome Artiſts are pleas'd to call the Balſom of Saturn, which they very much (and probably not altogether without cauſe) extoll as an excellent Medicine in divers Outward affections.
Next, take of common Brimſtone finely powdred five Ounces, of Sal-Armoniack likewiſe pulveriz'd an equal weight, of beaten Quick-lime ſix Ounces, mix theſe Powders exquiſitely, and Diſtill them through a Retort plac'd in Sand by degrees of Fire, giving at length as intenſe a Heat as you well can in Sand, there will come over (if you have wrought well) a Volatile Tincture of Sulphur, which may probably prove an excellent Medicine, and ſhould have been mention'd among the other Preparations of Sulphur, which we have elſewhere imparted to you, but that it is very pertinent to our preſent Subject, The change of Colours. For though none of the Ingredients be Red, the Diſtill'd Liquor will be ſo: and this Liquor if it [pg 280] be well Drawn, will upon a little Agitation of the Vial firſt unſtop'd (eſpecially if it be held in a Warmer hand) lend forth a copious Fume, not Red, like that of Nitre, but White; And ſometimes this Liquor may be ſo Drawn, that I remember, not long ſince, I took pleaſure to obſerve in a parcel of it, that Ingredients not Red, did not only yield by Diſtillation a Volatile Spirit that was Red, but though that Liquor did upon the bare opening of the Bottle it was kept in, drive us away with the plenty and ſulphureous ſent of a White ſteam which it ſent forth, yet the Liquor it ſelf being touch'd by our Fingers, did immediately Dye them Black.
The third and laſt Experiment I ſhall now mention to ſhew, how prone Bodies abounding in Sulphureous parts are to afford a Red Colour, is one, wherein by the Operation of a Saline Spirit upon a White or Whitiſh Body, which according to the Chymiſts ſhould be altogether Sulphureous, a Redneſs may be produc'd, not (as in the former Experiments) ſlowly, but in the twinkling of an Eye. We took then of the Eſſential Oyl of Anniſeeds, [pg 281] which has this Peculiarity, that in Cold weather it loſes its Fluidity and the greateſt part of its Tranſparency, and looks like a White or Whitiſh Oyntment, and near at hand ſeems to conſiſt of a Multitude of little ſoft Scales: Of this Coagulated Stuff we ſpread a little with a Knife upon a piece of White Paper, and letting fall on it, and mixing with it a drop or two of Oyl of Vitriol, immediately (as we fore-ſaw) there emerg'd together with ſome Heat and Smoak, a Blood-Red Colour, which therefore was in a trice produc'd by two Bodies, whereof the one had but a Whitiſh Colour, and the other (if carefully rectify'd) had no Colour at all.
But on this Occaſion (Pyrophilus) we muſt add once for all, that in many of the above-recited Experiments, though the changes of Colour happen'd as we have mention'd them: yet the emergent or produc'd Colour is oft times very ſubject to Degenerate, both quickly and much. Notwithſtanding which, ſince the Changes, we have ſet down, do happen preſently upon the Operation of the Bodies upon each other, or at the times by us ſpecify'd; [pg 282] that is ſufficient both to juſtifie our Veracity, and to ſhew what we Intend; it not being Eſſential to the Genuineneſs of a Colour to be Durable. For a fading Leaf, that is ready to Rot, and moulder into Duſt, may have as true a Yellow, as a Wedge of Gold, which ſo obſtinately reſiſts both Time and Fire. And the reaſon, why I take occaſion from the former Experiment to ſubjoyn this general Advertiſement, is, that I have ſeveral times obſerv'd, that the Mixture reſulting from the Oyls of Vitriol, and of Anniſeeds, though it acquire a thicker conſiſtence than either of the Ingredients had, has quickly loſt its Colour, turning in a very ſhort time into a dirty Gray, at leaſt in the Superficial parts, where 'tis expos'd to the Air; which laſt Circumſtance I therefore mention, becauſe that, though it ſeem probable, that this Degeneration of Colours may oft times and in divers caſes proceed from the further Action of the Saline Corpuſcles, and the other Ingredients upon one another, yet in many caſes much of the Quick change of Colours ſeems aſcribeable to the Air, as may be made probable by ſeveral reaſons: The firſt whereof may be fetcht from the newly recited Example of the two Oyls; The next may be, that we have ſometimes obſerv'd [pg 283] long Window-Curtains of light Colours, to have that part of them, which was expos'd to the Air, when the Window was open, of one Colour, and the lower part, that was ſheltred from the Air by the Wall, of another Colour: And the third Argument may be fetch'd from divers Obſervations, both of others, and our own; For of that Pigment ſo well known in Painters Shops, by the name of Turnſol, our Induſtrious Parkinſon, in the particular account he gives of the Plant that bears it, tells us alſo, That the Berries when they are at their full Maturity, have within them between the outer Skin and the inward Kirnel or Seed, a certain Juice or Moiſture, which being rubb'd upon Paper or Cloath, at the first appears of a freſh and lovely Green Colour, but preſently changeth into a kind of Blewiſh Purple, upon the Cloath or Paper, and the ſame Cloath afterwards wet in Water, and wrung forth, will Colour the Water into a Claret Wine Colour, and theſe (concludes he) are thoſe Raggs of Cloath, which are uſually call'd Turnſol in the Druggiſts or Grocers Shops21. And to this Obſervation of our Botanist we will add an Experiment of our own, (made before we met with That) which, though in many Circumſtances, very [pg 284] differing, ſerves to prove the ſame thing; for having taken of the deeply Red Juice of Buckthorn Berries, which I bought of the Man that uſes to ſell it to the Apothecaries, to make their Syrrup de Spina Cervina, I let ſome of it drop upon a piece of White Paper, and having left it there for many hours, till the Paper was grown dry again, I found what I was inclin'd to ſuſpect, namely, That this Juice was degenerated from a deep Red to a dirty kind of Greyiſh Colour, which, in a great part of the ſtain'd Paper ſeem'd not to have ſo much as an Eye of Red: Though a little Spirit of Salt or diſſolv'd Alcaly would turn this unpleaſant Colour (as formerly I told you it would change the not yet alter'd Juice) into a Red or Green. And to ſatisfie my ſelf, that this Degeneration of Colour did not proceed from the Paper, I drop'd ſome of the deep Red or Crimſon Juice upon a White glaz'd Tile, and ſuffering it to dry on there, I found that ev'n in that Body, on which it could not Soak, and by which it could not be Wrought, it nevertheleſs loſt its Colour. And theſe Inſtances (Pyrophilus) I am the more carefull to mention to you, that you may not be much Surpris'd or Diſcourag'd, if you ſhould ſometimes miſs of performing [pg 285] punctually what I affirm my ſelf to have done in point of changing Colours; ſince in theſe Experiments the over-ſight or neglect of ſuch little Circumſtances, as in many others would not be perhaps conſiderable, may occaſion the mis-carrying of a Trial. And I was willing alſo to take this occaſion of Advertiſing you in the repeating of the Experiments mention'd in this Treatiſe, to make uſe of the Juices of Vegetables, and other things prepar'd for your Trials, as ſoon as ever they are ready, leſt one or other of them grow leſs fit, if not quite unfit by delay; and to eſtimate the Event of the Trials by the Change, that is produc'd preſently upon the due and ſufficient Application of Actives to Paſſives, (as they ſpeak) becauſe in many caſes the effects of ſuch Mixtures may not be laſting, and the newly produc'd Colour may in a little time degenerate. But, (Pyrophilus) I forgot to add to the two former Obſervations lately made about Vegetables, a third of the ſame Import, made in Mineral ſubſtances, by telling you, That the better to ſatisfie a Friend or two in this particular, I ſometimes made, according to ſome Conjectures of mine, this Experiment; That having diſſolv'd good Silver in Aqua-fortis, and Precipitated it with Spirit of Salt, upon [pg 286] the firſt Decanting of the Liquor, the remaining Matter would be purely White; but after it had lain a while uncover'd, that part of it, that was Contiguous to the Air, would not only loſe its Whiteneſs, but appear of a very Dark and almoſt Blackiſh Colour, I ſay that part that was Contiguous to the Air, becauſe if that were gently taken off, the Subjacent part of the ſame Maſs would appear very White, till that alſo, having continu'd a while expos'd to the Air, would likewiſe Degenerate. Now whether the Air perform theſe things by the means of a Subtile Salt, which we elſewhere ſhow it not to be deſtitute of, or by a peircing Moiſture, that is apt eaſily to inſinuate it ſelf into the Pores of ſome Bodies, and thereby change their Texture, and ſo their Colour; Or by ſolliciting the Avolation of certain parts of the Bodies, to which 'tis Contiguous; or by ſome other way, (which poſſibly I may elſewhere propoſe and conſider) I have not now the leiſure to diſcourſe. And for the ſame reaſon, though I could add many other Inſtances, of what I formerly noted touching the emergency of Redneſs upon the Digeſtion of many Bodies, inſomuch that I have often ſeen upon the Borders of France (and probably we may have the like in [pg 287] England) a ſort of Pears, which digeſted for ſome time with a little Wine, in a Veſſel exactly clos'd, will in not many hours appear throughout of a deep Red Colour, (as alſo that of the Juice, wherein they are Stew'd, becomes) but ev'n on pure and white Salt of Tartar, pure Spirit of Wine, as clear as Rock-water, will (as we elſewhere declare) by long Digeſtion acquire a Redneſs; Though I ſay ſuch Inſtances might be Multiply'd, and though there be ſome other Obvious changes of Colours, which happen ſo frequently, that they cannot but be as well Conſiderable as Notorious; ſuch as is the Blackneſs of almoſt all Bodies burn'd in the open Air: yet our haſte invites us to reſign you the Exerciſe of enquiring into the Cauſes of theſe Changes. And certainly, the reaſon both why the Soots of ſuch differing Bodies are almoſt all of them all Black, why ſo much the greater part of Vegetables ſhould be rather Green than of any other Colour, and particularly (which more directly concerns this place) why gentle Heats do ſo frequently in Chymical Operations produce rather a Redneſs than another Colour in digeſted Menſtruums, not only Sulphureous, as Spirit of Wine, but Saline, as Spirit of Vinegar, may be very well worth [pg 288] a ſerious Inquiry; which I ſhall therefore recommend to Pyrophilus and his Ingenious Friends.
It may ſeem ſomewhat ſtrange, that if you take the Crimſon Solution of Cochineel, or the Juice of Black Cherries, and of ſome other Vegetables that afford the like Colour, (which becauſe many take but for a deep Red, we do with them ſometimes call it ſo) and let ſome of it fall upon a piece of Paper, a drop or two of an Acid Spirit, ſuch as Spirit of Salt, or Aqua-fortis, will immediately turn it into a fair Red. Whereas if you make an Infuſion of Brazil in fair Water, and drop a little Spirit of Salt or Aqua-fortis into it, that will deſtroy its Redneſs, and leave the Liquor of a Yellow, (ſometimes Pale) I might perhaps plauſibly enough ſay on this occaſion, that if we conſider the caſe a little more attentively, we may take notice, that the action of the Acid Spirit ſeems in both caſes, but to weaken the Colour of the Liquor on which it falls. And ſo though it deſtroy Redneſs in the Tincture of Brazil, as well as produce Red in the Tincture of Chochineel, its Operations may be Uniform [pg 289] enough, ſince as Crimſon ſeems to be little elſe than a very deep Red, with (perhaps) an Eye of Blew, ſo ſome kinds of Red ſeem (as I have lately noted) to be little elſe than heightned Yellow. And conſequently in ſuch Bodies, the Yellow ſeems to be but a diluted Red. And accordingly Alcalizate Solutions and Urinous Spirits, which ſeem diſpos'd to Deepen the Colours of the Juices and Liquors of moſt Vegetables, will not only reſtore the Solution of Cochineel and the Infuſion of Brazil to the Crimſon, whence the Spirit of Salt had chang'd them into a truer Red; but will alſo (as I lately told you) not only heighthen the Yellow Juice of Madder into Red, but advance the Red Infuſion of Brazil to a Crimſon. But I know not whether it will not be much ſafer to derive theſe Changes from vary'd Textures, than certain kinds of Bodies; and you will perhaps think it worth while, that I ſhould add on this occaſion, That it may deſerve ſome Speculation, why, notwithſtanding what we have been obſerving, though Blew and Purple ſeem to be deeper Colours than Red, and therefore the Juices of Plants of either of the two former Colours may (congruouſly enough to what has been juſt now noted) be turn'd Red by [pg 290] Spirit of Salt or Aqua-fortis, yet Blew Syrrup of Violets and ſome Purples ſhould both by Oyl of Tartar and Spirit of Urine be chang'd into Green, which ſeems to be not a deeper but a more diluted Colour than Blew, if not alſo than Purple.
It would much contribute to the Hiſtory of Colours, if Chymiſts would in their Laboratories take a heedfull notice, and give us a faithfull account of the Colours obſerv'd in the Steams of Bodies either Sublim'd or Diſtill'd, and of the Colours of thoſe Productions of the Fire, that are made up by the Coalition of thoſe Steams. As (for Inſtance) we obſerve in the Diſtilling of pure Salt peter, that at a certain ſeaſon of the Operation, the Body, though it ſeem either Cryſtalline, or White, affords very Red Fumes: whereas though Vitriol be Green or Blew, the Spirit of it is obſerv'd to come over in Whitiſh Fumes. The like Colour I have taken notice of in the Fumes of ſeveral other Concretes of differing Colours, and Natures, eſpecially when Diſtill'd with ſtrong Fires. And we elſewhere note, that ev'n Soot, as Black as it is, has fill'd our Receivers [pg 291] with ſuch copious White Fumes, that they ſeem'd to have had their In-ſides waſh'd with Milk. And no leſs obſervable may be, the Diſtill'd Liqours, into which ſuch Fumes convene, (for though we will not deny, that by skill and care a Reddiſh Liqour may be obtain'd from Nitre) yet the common Spirit of it, in the making ev'n of which ſtore of theſe Red Fumes are wont to paſs over into the Receiver, appears not to be at all Red. And beſides, that neither the Spirit of Vitriol, nor that of Soot is any thing White; And, beſides alſo, that as far as I have obſerv'd, moſt (for I ſay not all) of the Empyreumatical Oyls of Woods, and other Concretes, are either of a deep Red, or of a Colour between Red and Black; beſides this, I ſay, 'tis very remarkable that notwithſtanding that great Variety of Colours to be met with in the Herbs, Flowers, and other Bodies wont to be Diſtill'd in Balneo: yet (as far at leaſt as our common Diſtillers Experience reacheth) all the Waters and Spirits that firſt come over by that way of Diſtillation, leave the Colours of their Concretes behind them, though indeed there be one or two Vegetables not commonly taken notice of, whoſe Diſtill'd Liqours I elſewhere obſerve to carry over [pg 292] the Tincture of the Concrete with them. And as in Diſtillations, ſo in Sublimations, it were worth while to take notice of what comes up, in reference to our preſent ſcope, by purpoſely performing them (as I have in ſome cafes done) in conveniently ſhap'd Glaſſes, that the Colour of the aſcending Fumes may be diſcern'd; For it may afford a Naturaliſt good Information to obſerve the Congruities or the Differences betwixt the Colours of the aſcending Fumes, and thoſe of the Flowers, they compoſe by their Convention. For it is evident, that theſe Flowers, do many of them in point of Colour, much differ, not only from one another, but oft times from the Concretes that afforded them. Thus, (not here to repeat what I formerly noted of the Black Soots of very differingly Colour'd Bodies) though Camphire and Brimſtone afford Flowers much of their own Colour, ſave that thoſe of Brimſtone are wont to be a little Paler, than the Lumps that yielded them; yet ev'n of Red Benzoin, that ſublim'd Subſtance, which Chymiſts call its Flowers, is wont to be White or Whitiſh. And to omit other Inſtances, ev'n one and the ſame Black Mineral, Antimony, may be made to afford Flowers, ſome of them Red, and ſome Grey, and, which is more ſtrange, [pg 293] ſome of them purely White. And 'tis the Preſcription of ſome Glaſs-men by exquiſitely mingling a convenient proportion of Brimſtone, Sal-Armoniack, and Quickſilver, and Subliming them, together, to make a Sublimate of an excellent Blew; and though having caus'd the Experiment to be made, we found the produc'd Sublimate to be far from being of a lovely Colour, (as was promis'd) that there and there, it ſeem'd Blewiſh, and at leaſt was of a Colour differing enough from either of the Ingredients, which is ſufficient for our preſent purpoſe. But a much finer Colour is promis'd by ſome of the Empiricks, that pretend to Secrets, who tell us, that Orpiment, being Sublim'd, will afford among the Parts of it that fly Upward, ſome little Maſſes, which, though the Mineral it ſelf be of a good Yellow, will be Red enough to emulate Rubies, both in Colour and Tranſlucency. And this Experiment may, for ought I know, ſometimes ſucceed; for I remember, that having in a ſmall Bolt-head purpoſely ſublim'd ſome powder'd Orpiment, we could in the Lower part of the Sublimate diſcern here and there ſome Reddiſh Lines, though much of the Upper part of the Sublimate conſiſted of a matter, which was not alone purely [pg 294] Yellow, but tranſparent almoſt like a Powder. And we have alſo this way obtain'd a Sublimate, the Lower part whereof though it conſiſted not of Rubies, yet the ſmall pieces of it, which were Numerous enough, were of a pleaſant Reddiſh Colour, and Glitter'd very prettily. But to inſiſt on ſuch kind of Trials and Obſervations (where the aſcending Fumes of Bodies differ in Colour from the Bodies themſelves) though it might indeed Inrich the Hiſtory of Colours, would Robb me of too much of the little time I have to diſpatch what I have further to tell you concerning them.
Take the dry'd Buds (or Bloſſoms) of the Pomegranate Tree, (which are commonly call'd in the Shops Balauſtiums) pull off the Reddiſh Leaves, and by a gentle Ebullition of them in fair Water, or by a competent Infuſion of them in like Water well heated, extract a faint Reddiſh Tincture, which if the Liquor be turbid, you may Clarifie it by Filtrating it Into this, if you pour a little good Spirit of Urine, or ſome other Spirit abounding in the like ſort of Volatile Salts, the Mixture will [pg 295] preſently turn of a dark Greeniſh Colour, but if inſtead of the fore-mention'd Liquor, you drop into the ſimple Infuſion a little rectify'd Spirit of Sea-Salt, the Pale and almoſt Colourleſs Liquor will immediately not only grow more Tranſparent, but acquire a high Redneſs, like that of Rich Claret Wine, which ſo ſuddenly acquir'd Colour, may as quickly be Deſtroy'd and turn'd into a dirty Blewiſh Green, by the affuſion of a competent quantity of the above-mention'd Spirit of Urine.
Annotation.
This Experiment may bring ſome Light to, and receive ſome from a couple of other Experiments, that I remember I have met with in the ingenious Gaſſendus's Animadverſions upon Epicurus's Philoſophy, whilſt I was turning over the Leaves of thoſe Learned Commentaries; (my Eyes being too weak to let me read ſuch Voluminous Books quite thorough) And I the leſs ſcruple (notwithſtanding my contrary Cuſtom in this Treatiſe) to ſet down theſe Experiments of another, becauſe I ſhall a little improve the latter of them, and becauſe by comparing there with that which I have laſt recited, we may be aſſiſted to Conjecture [pg 296] upon what account it is, that Oyl of Vitriol heightens the Tincture of Red-roſe Leaves, ſince Spirit of Salt, which is a highly Acid Menſtruum, but otherwiſe differing enough from Oyl of Vitriol, does the ſame thing. Our Authors Experiments then, as we made them, are theſe; We took about a Glaſs-full of luke-warm Water, and in it immerg'd a quantity of the Leaves of Senna, and preſently upon the Immerſion there did not appear any Redneſs in the Water, but dropping into it a little Oyl of Tartar, the Liquor ſoon diſcover'd a Redneſs to the watchfull Eye, whereas by a little of that Acid Liquor of Vitriol, which is like the former, undeſervedly called Oyl, ſuch a Colour would not be extracted from the infuſed Senna. On the other ſide we took ſome Red-roſe Leaves dry'd, and having ſhaken them into a Glaſs of fair Water, they imparted to it no Redneſs, but upon the affuſion of a little Oyl of Vitriol the Water was immediately turn'd Red, which it would not have been, if inſtead of Oyl of Vitriol, we had imployed Oyl of Tartar to produce that Colour: That theſe were Gaſſendus his Experiments, I partly remember, and was aſſur'd by a Friend, who lately Tranſcribed them out of Gaſſendus his Book, which I [pg 297] therefore add, becauſe I have not now that Book at hand. And the deſign of Gaſſendus in theſe Experiments our Friend affirms to be, to prove, that of things not Red a Redneſs may be made only by Mixture, and the Varied poſition of parts, wherein the Doctrine of that Subtil Philoſopher doth not a little Authorize, what we have formerly delivered concerning the Emergency and Change of Colours. But the inſtances, that we have out of him ſet down, ſeem not to be the moſt Eminent, that may be produced of this truth: For our next Experiment will ſhew the production of ſeveral Colours out of Liquors, which have not any of them any ſuch Colour, nor indeed any diſcernable one at all; and whereas though our Author tells us, that there was no Redneſs either in the Water, or the Leaves of Senna, or the Oyl of Tartar; And though it be true, that the Predominant Colour of the Leaves of Senna be another than Red, yet we have try'd, that by ſteeping that Plant a Night even in Cold water, it would afford a very deep Yellow or Reddiſh Tincture without the help of the Oyl of Tartar, which ſeems to do little more than aſſiſt the Water to extract more nimbly a plenty of that Red Tincture, wherewith the Leaves of Senna [pg 298] do of themſelves abound, and having taken off the Tincture of Senna, made only with fair Water, before it grew to be Reddiſh, and Decanted it from the Leaves, we could not perceive, that by dropping ſome Oyl of Tartar into it, that Colour was conſiderable, though it were a little heightned into a Redneſs; which might have been expected, if the particles of the Oyl did eminently Co-operate, otherwiſe than we have expreſſed, to the production of this Redneſs.
And as for the Experiment with Red-roſe Leaves, the ſame thing may be alleged, for we found that ſuch Leaves by bare Infuſion for a Night and Day in fair Water, did afford us a Tincture bordering at leaſt upon Redneſs, and that Colour being conſpicuous in the Leaves themſelves, would not by ſome ſeem ſo much to be produc'd as to be extracted by the affuſion of Oyl of Vitriol. And the Experiment try'd with the dry'd Leaves of Damask-roſes ſucceeded but imperfectly, but that is indeed obſervable to our Authors purpoſe, that Oyl of Tartar will not perform in this Experiment what Oyl of Vitriol doth; but becauſe this laſt named Liquor is not ſo eaſily to be had, give me leave to Advertiſe you, that the Experiment will ſucceed, [pg 299] if inſtead of it you imploy Aqua-fortis. And though ſome Trials of our own formerly made, and others eaſily deducible from what we have already deliver'd, about the different Families and Operations of Salt, might enable us to preſent you an Experiment upon Red-roſe Leaves, more accommodated to our Authors purpoſe, than that which he hath given us; yet our Reverence to ſo Candid a Philoſopher, invites us rather to improve his Experiment, than ſubſtitute another in its place. Take therefore of the Tincture of Red-roſe Leaves, (for with Damask-roſe Leaves the Experiment ſucceedeth not well) made as before hath been taught with a little Oyl of Vitriol, and a good quantity of fair Water, pour off this Liquor into a clear Vial, half fill'd with Limpid water; till the Water held againſt the Light have acquir'd a competent Redneſs, without loſing its Tranſparency, into this Tincture drop leiſurely a little good Spirit of Urine, and ſhaking the Vial, which you muſt ſtill hold againſt the Light, you ſhall ſee the Red Liquor immediately turn'd into a fine Greeniſh Blew, which Colour was not to be found in any of the Bodies, upon whoſe Mixture it emerg'd, and this Change is the more obſervable, becauſe in many Bodies [pg 300] the Degenerating of Blew into Red is uſual enough, but the turning of Red into Blew is very unfrequent. If at every drop of Spirit of Urine you ſhake the Vial containing the Red Tincture, you may delightfully obſerve a pretty variety of Colours in the paſſage of that Tincture from a Red to a Blew, and ſometimes we have this way hit upon ſuch a Liquor, as being look't upon againſt and from the Light, did ſeem faintly to emulate the above-mention'd Tincture of Lignum Nephriticum. And if you make the Tincture of Red-roſes very high, and without Diluting it with fair Water, pour on the Spirit of Urine, you may have a Blew ſo deep, as to make the Liquor Opacous, but being dropt upon White Paper the Colour will ſoon diſcloſe it ſelf. Alſo having made the Red, and conſequently the Blew Tincture very Tranſparent, and ſuffer'd it to reſt in a ſmall open Vial for a Day or two, we found according to our Conjecture, that not only the Blew but the Red Colour alſo was Vaniſh'd; the clear Liquor being of a bright Amber Colour, at the bottom of which ſubſided a Light, but Copious feculency of almoſt the ſame Colour, which ſeems to be nothing but the Tincted parts of the Roſe Leaves drawn out by the Acid [pg 301] Spirits of the Oyl of Vitriol, and Precipitated by the Volatile Salt of the Spirit of Urine, which makes it the more probable, that the Redneſs drawn by the Oyl of Vitriol, was at leaſt as well an extraction of the Tinging parts of the Roſes, as a production of Redneſs; and laſtly, if you be deſtitute of Spirit of Urine, you may change the Colour of the Tincture of Roſes with many other Sulphureous Salts, as a ſtrong Solution of Pot-aſhes, Oyl of Tartar, &c. which yet are ſeldome ſo free from Feculency, as the Spirituous parts of Urine becomes by repeated Diſtillation.
Annotation.
On this, occaſion, I call to mind, that I found, a way of producing, though not the ſame kind of Blew, as I have been mentioning, yet a Colour near of Kin to it, namely, a fair Purple, by imploying a Liquor not made Red by Art, inſtead of the Tincture of Red-roſes, made with an Acid Spirit; And my way was only to take Log-wood, (a Wood very well known to Dyers) having by Infuſion the Powder of it a while in fair Water made that Liquor Red, I dropt into it a Tantillum of an Urinous Spirit, as that of Sal-Armoniack, [pg 302] (and I have done the ſame thing with an Alcali) by which the Colour was in a moment turn'd into a Rich, and lovely Purple. But care muſt be had, that you let not fall into a Spoonfull above two or three Drops, leſt the Colour become ſo deep, as to make the Liquor too Opacous. And (to anſwer the other part of Gaſſendus his Experiment) if inſtead of fair Water, I infus'd the Log-wood in Water made ſomewhat ſowr by the Acid Spirit of Salt, I ſhould obtain neither a Purple Liquor, nor a Red, but only a Yellow one.
The Experiment I am now to mention to you, Pyrophilus, is that which both you, and all the other Virtuoſi that have ſeen it, have been pleas'd to think very ſtrange; and indeed of all the Experiments of Colours, I have yet met with, it ſeems to be the fitteſt to recommend the Doctrine propos'd in this Treatiſe, and to ſhew that we need not ſuppoſe, that all Colours muſt neceſſarily be Inherent Qualities, flowing from the Subſtantial Forms of the Bodies they are ſaid to belong to, ſince by a bare Mechanical change of Texture in the Minute parts of Bodies; two Colours may in [pg 303] a moment be Gen