Experiments and Considerations Touching Colours (1664) by Robert Boyle

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_EXPERIMENT XLI._

Of Kin to the last or fortieth Experiment is another which I remember I
have sometimes shewn to _Virtuosi_ that were pleas'd not to dislike it. I
took Spirit of Urine made by Fermentation, and with a due proportion of
Copper brought into small parts, I obtain'd a very lovely Azure Solution,
and when I saw the Colour was such as was requisite, pouring into a clean
Glass, about a spoonfull of this tincted Liquor, (of which I us'd to keep a
Quantity by me,) I could by shaking into it some drops of Strong Oyl of
Vitriol, deprive it in a trice of its Deep Colour, and make it look like
Common-water.

_Annotation_.

This Experiment brings into my mind this other, which oftentimes succceds
well enough, though not quite so well as the former; Namely, that if into
about a small spoonfull of a Solution of good French Verdigrease made in
fair Water, I drop't and shak'd some strong Spirit of Salt, or rather
deflegm'd _Aqua Fortis_, the Greenness of the Solution would be made in a
trice almost totally to disappear, & the Liquor held against the Light
would scarce seeme other than Cleer or Limpid, to any but an Attentive Eye,
which is therefore remarkable; because we know that _Aqua-fortis_ corroding
Copper, which is it that gives the Colour to Verdigrease, is wont to reduce
it to a Green Blew Solution. But if into the other altogether or almost
Colourless Liquor I was speaking of, you drop a just quantity either of Oyl
of Tartar or Spirit of Urine, you shall find that after the Ebullition is
ceas'd, the mixture will disclose a lively Colour, though somewhat
differing from that which the Solution of Verdigrease had at first.

_EXPERIMENT XLII._

That the Colour (_Pyrophilus_) of a Body may be chang'd by a Liquor which
of it self is of no Colour, provided it be Saline, we have already
manifested by a multitude of instances. Nor doth it seem so strange,
because Saline Particles swimming up and down in Liquors, have been by many
observ'd to be very operative in the Production and change of Colours. But
divers of our Friends that are not acquainted with Chymical Operations have
thought it very strange that a White Body, and a Dry one too, should
immediately acquire a rich new Colour upon the bare affusion of
Spring-Water destitute as well of adventitious Salt as of Tincture. And yet
(_Pyrophilus_) the way of producing such a change of Colours may be easily
enough lighted on by those that are conversant in the Solutions of Mercury.
For we have try'd, that though by Evaporating a Solution of Quick-Silver in
_Aqua-fortis_, and abstracting the Liquor till the remaining matter began
to be well, but not too strongly dryed, fair Water pour'd on the remaining
_Calx_ made it but somewhat Yellowish; yet when we took good Quick-Silver,
and three or four times its weight of Oyl of Vitriol, in case we in a Glass
Retort plac'd in Sand drew off the Saline _Menstruum_ from the Metalline
Liquor, till there remain'd a dry _Calx_ at the bottome, though this
Precipitate were a Snow White Body, yet upon pouring on it a large quantity
of fair Water, we did almost in a moment perceive it to pass from a Milky
Colour to one of the loveliest Light Yellows that ever we had beheld. Nor
is the Turbith Mineral, that Chymists extol for its power to Salivate, and
for other vertues, of a Colour much inferiour to this, though it be often
made with a differing proportion of the Ingredients, a more troublesome
way. For _Beguinus_,[22] who calls it _Mercurius praecipitatus optimus_,
takes to one part of Quick-Silver, but two of Liquor, and that is Rectifi'd
Oyl of Sulphur, which is (in _England_ at least) far more scarce and dear
than Oyl of Vitriol; he also requires a previous Digestion, two or three
Cohobations, and frequent Ablutions with hot Distill'd Water, with other
prescriptions, which though they may conduce to the Goodness of the
Medicine, which is that he aims at, are troublesome, and, our Tryals have
inform'd you unneccessary to the _obtaining the Lemmon Colour_ which he
regards not. But though we have very rarely seen either in Painters Shops,
or elsewhere a finer Yellow than that which we have divers times this way
produc'd (which is the more considerable, because durable and pleasant
Yellows are very hard to be met with, as may appear by the great use which
Painters are for its Colours sake fain to make of that pernicious and heavy
Mineral, Orpiment) yet I fear our Yellow is too costly, to be like to be
imploy'd by Painters, unless about Choice pieces of Work, nor do I know how
well it will agree with every Pigment, especially, wich Oyl'd Colours. And
whether this Experiment, though it have seem'd somewhat strange to most we
have shown it to, be really of another Nature than those wherein Saline
Liquors are imploy'd, may, as we formerly also hinted, be so plausibly
doubted, that whether the Water pour'd on the _Calx_, do barely by imbibing
some of its Saline parts alter its Colour by altering its Texture, or
whether by dissolving the Concoagulated Salts, it does become a Saline
_Menstruum_, and, as such, work upon the Mercury, I freely leave to you
(_Pyrophilus_) to consider. And that I may give you some Assistance in your
Enquiry, I will not only tell you, that I have several times with fair
Water wash'd from this _Calx_, good store of strongly tasted Corpuscles,
which by the abstraction of the _Menstruum_, I could reduce into Salt; but
I will also subjoyn an Experiment, which I devis'd, to shew among other
things, how much a real and permanent Colour may be as it were drawn forth
by a Liquor that has neither Colour, nor so much as Saline or other Active
parts, provided it can but bring the parts of the Body it imbibes to
convene into clusters dispos'd after the manner requisite to the exhibiting
of the emergent Colour. The Experiment was this.

[22] _Beguinus_, Tyr. Chy. Lib. 2º. Cap. 13º.

_EXPERIMENT XLIII._

We took good common Vitriol, and having beaten it to Powder, and put it
into a Crucible, we kept it melted in a gentle heat, till by the
Evaporation of some parts, and the shuffling of the rest, it had quite lost
its former Colour, what remain'd we took out, and found it to be a friable
_Calx_, of a dirty Gray. On this we pour'd fair Water, which it did not
Colour Green or Blew, but only seem'd to make a muddy mixture with it, then
stopping the Vial wherein the Ingredients were put, we let it stand in a
quiet place for some dayes, and after many hours the water having dissolv'd
a good part of the imperfectly calcin'd Body, the Vitriolate Corpuscles
swiming to and fro in the Liquor, had time by their opportune Occursions to
constitute many little Masses of Vitriol, which gave the water they
impregnated a fair Vitriolate Colour; and this Liquor being pour'd off, the
remaining dirty Powder did in process of time communicate the like Colour,
but not so deep, to a second parcel of cleer Water that we pour'd on it.
But this Experiment _Pyrophilus_ is, (to give you that hint by the way) of
too Luciferous a Nature to be fit to be fully prosecuted, now that I am in
haste, and willing to dispatch what remains. And we have already said of
it, as much as is requisite to our present purpose.

_EXPERIMENT XLIV._

It may (_Pyrophilus_) somewhat contribute towards the shewing how much some
Colours depend upon the less or greater mixture, and (as it were,)
Contemperation of the Light with shades, to observe, how that sometimes the
number of Particles, of the same Colour, receiv'd into the Pores of a
Liquor, or swiming up and down in it, do seem much to vary the Colour of
it. I could here present you with particular instances to show, how in many
(if not most) consistent Bodyes, if the Colour be not a Light one, as
White, Yellow, or the like, the closeness of parts in the Pigments makes it
look Blackish, though when it is display'd and laid on thinly, it will
perhaps appear to be either Blew, or Green, or Red. But the Colours of
consistent Pigments, not being those which the Preamble of this Experiment
has lead you to expect Examples in, I shall take the instances I am now to
give you, rather from Liquors than Dry Bodyes. If then you put a little
fair Water into a cleer and slender Vial, (or rather into one of those
pipes of Glass, which we shall by and by mention;) and let fall into it a
few drops of a strong Decoction or Infusion of _Cochineel_, or (for want of
that) of _Brazil_; you may see the tincted drops descend like little Clouds
into the Liquor; through which, if, by shaking the Vial, you diffuse them,
they will turn the water either of a Pinck Colour, or like that which is
wont to be made by the washing of raw flesh in fair Water; by dropping a
little more of the Decoction, you may heighten the Colour into a fine Red,
almost like that which ennobles Rubies; by continuing the affusion, you may
bring the Liquor to a kind of a Crimson, and afterwards to a Dark and
Opacous Redness, somewhat like that of Clotted Blood. And in the passage of
the Liquor from one of these Colours to the other, you may observe, if you
consider it attentively, divers other less noted Colours belonging to Red,
to which it is not easie to give Names; especially considering how much the
proportion of the Decoction to the fair Water, and the strength of that
Decoction, together with that of the trajected Light and other
Circumstances, may vary the Phaenomena of this Experiment. For the
convenienter making whereof, we use instead of a Vial, any slender Pipe of
Glass of about a foot or more in length, and about the thickness of a mans
little finger; For, if leaving one end of this Pipe open, you Seal up the
other Hermetically, (or at least stop it exquisitely with a Cork well
fitted to it, and over-laid with hard Sealing Wax melted, and rubb'd upon
it;) you shall have a Glass, wherein may be observ'd the Variations of the
Colours of Liquors much better than in large Vials, and wherein Experiments
of this Nature may be well made with very small quantities of Liquor. And
if you please, you may in this Pipe produce variety of Colours in the
various parts of the Liquor, and keep them swimming upon one another
unmix'd for a good while. And some have marveil'd to see, what variety of
Colours we have sometimes (but I confess rather by chance than skill)
produc'd in those Glasses, by the bare infusion of Brazil, variously
diluted with fair Water, and alter'd by the Infusion of several Chymical
Spirits and other Saline Liquors devoid themselves of Colour, and when the
whole Liquor is reduc'd to an Uniform degree of Colour, I have taken
pleasure to make that very Liquor seem to be of Colours gradually
differing, by filling with it Glasses of a Conical figure, (whether the
Glass have its basis in the ordinary position, or turn'd upwards.) And yet
you need not Glasses of an extraordinary shape to see an instance of what
the vari'd mixture of Light and Shadow can do in the diversifying of the
Colour. For if you take but a large round Vial, with a somewhat long and
slender Neck, and filling it with our Red Infusion of Brazil, hold it
against the Light, you will discern a notable Disparity betwixt the Colour
of that part of the Liquor which is in the Body of the Vial, and that which
is more pervious to the Light in the Neck. Nay, I remember, that I once had
a Glass and a Blew Liquor (consisting chiefly (or only, if my memory
deceive me not,) of a certain Solution of Verdigrease) so fitted for my
purpose, that though in other Glasses the Experiment would not succeed, yet
when that particular Glass was fill'd with that Solution, in the Body of
the Vial it appear'd of a Lovely Blew, and in the neck, (where the Light
did more dilute the Colour,) of a manifest Green; and though I suspected
there might be some latent Yellowness in the substance of the neck of the
Glass, which might with the Blew compose that Green, yet was I not
satisfi'd my self with my Conjecture, but the thing seem'd odd to me, as
well as to divers curious persons to whom it was shown. And I lately had a
Broad piece of Glass, which being look'd on against the Light seem'd clear
enough, and held from the Light appear'd very lightly discolour'd, and yet
it was a piece knock'd off from a great lump of Glass, to which if we
rejoyn'd it, where it had been broken off, the whole Mass was as green as
Grass. And I have several times us'd Bottles and stopples that were both
made (as those, I had them from assur'd me) of the very same Metall, and
yet whilst the bottle appear'd but inclining towards a Green, the Stopple
(by reason of its great thickness) was of so deep a Colour that you would
hardly believe they could possibly be made of the same materials. But to
satisfie some Ingenious Men, on another occasion, I provided my self of a
flat Glass (which I yet have by me,) with which if I look against the Light
with the Broad side obverted to the Eye, it appeares like a good ordinary
window Glass; but if I turn the Edge of it to my Eye, and place my Eye in a
convenient posture in reference to the Light, it may contend for deepness
of Colour with an Emerald. And this Greeness puts me in mind of a certain
thickish, but not consistent Pigment I have sometimes made, and can show
you when you please, which being dropp'd on a piece of White Paper appears,
where any quantity of it is fallen, of a somewhat Crimson Colour, but being
with ones finger spread thinly on the Paper does presently exhibit a fair
Green, which seems to proceed only from its disclosing its Colour upon the
Extenuation of its Depth into Superficies, if the change be not somewhat
help'd by the Colours degenerating upon one or other of the Accounts
formerly mention'd. Let me add, that having made divers Tryals with that
Blew substance, which in Painters shops is call'd _Litmase_, we have
sometimes taken Pleasure to observe, that being dissolv'd in a due
proportion of fair Water, the Solution either oppos'd to the Light, or
dropp'd upon White paper, did appear of a deep Colour betwixt Crimson and
Purple; and yet that being spread very thin on the Paper and suffer'd to
dry on there, the Paper was wont to appear Stain'd of a Fine Blew. And to
satisfie my selfe, that the diversity came not from the Paper, which one
might suspect capable of inbibing the Liquor, and altering the Colour, I
made the Tryal upon a flat piece of purely White Glass'd Earth, (which I
sometimes make use of about Experiments of Colours) with an Event not
unlike the former.

And now I speak of _Litmass_, I will add, that having this very day taken a
piece of it, that I had kept by me these several years, to make Tryals
about Colours, and having let fall a few drops of the strong Infusion of it
in fair water, into a fine Crystal Glass, shap'd like an inverted Cone, and
almost full of fair Water, I had now (as formerly) the pleasure to see, and
to show others, how these few tincted drops variously dispersing themselves
through the Limpid Water, exhibited divers Colours, or varieties of Purple
and Crimson. And when the Corpuscles of the Pigment seem'd to have equally
diffus'd themselves through the whole Liquor, I then by putting two or
three drops of Spirit of Salt, first made an odd change in the Colour of
the Liquor, as well as a visible commotion among its small parts, and in a
short time chang'd it wholly into a very Glorious Yellow, like that of a
Topaz. After which if I let fall a few drops of the strong and heavy
Solution of Pot-ashes, whose weight would quickly carry it to the sharp
bottome of the Glass, there would soon appear four very pleasant and
distinct Colours; Namely, a Bright, but Dilute Colour at the picked bottome
of the Glass; a Purple, a little higher; a deep and glorious Crimson,
(which Crimson seem'd to terminate the operation of the Salt upward) in the
confines betwixt the Purple and the Yellow; and an Excellent Yellow, the
same that before enobled the whole Liquor, reaching from thence to the top
of the Glass. And if I pleas'd to pour very gently a little Spirit of Sal
Armoniack, upon the upper part of this Yellow, there would also be a Purple
or a Crimson, or both, generated there, so that the unalter'd part of the
Yellow Liquor appear'd intercepted betwixt the two Neighbouring Colours.

My scope in this 3d. Experiment (_Pyrophilus_) is manifold, as first to
invite you to be wary in judging of the Colour of Liquors in such Glasses
as are therein recommended to you, and consequently as much, if not more,
when you imploy other Glasses. Secondly, That you may not think it strange,
that I often content my self to rub upon a piece of White paper, the Juice
of Bodies I would examine, since not onely I could not easily procure a
sufficient Quantity of the juices of divers of them; but in several Cases
the Tryals of the quantities of such Juices in Glasses would make us more
lyable to mistakes, than the way that in those cases I have made use of.
Thirdly, I hope you will by these and divers other particulars deliver'd in
this Treatise, be easily induc'd to think that I may have set down many
Phaenomena very faithfully, and just as they appear'd to me, and yet by
reason of some unheeded circumstance in the conditions of the matter, and
in the degree of Light, or the manner of trying the Experiment, you may
find some things to vary from the Relations I make of them. Lastly, I
design'd to give you an opportunity to free your self from the amazement
which possesses most Men, at the Tricks of those Mountebancks that are
commonly call'd Water-drinkers. For though not only the vulgar, but ev'n
many persons that are far above that Rank, have so much admir'd to see, a
man after having drunk a great deal of fair water, to spurt it out again in
the form of Claret Wine, Sack, and Milk, that they have suspected the
intervening of Magick, or some forbidden means to effect what they
conceived above the power of Art; yet having once by chance had occasion to
oblige a Wanderer that made profession of that and other Jugling Tricks, I
was easily confirm'd by his Ingenious confession to me, That this so much
Admir'd Art, indeed consisted rather in a few Tricks, than in any great
Skill, in altering the Nature and Colours of things. And I am easy to be
perswaded; that there may be a great deal of Truth in a little Pamphlet
Printed divers years ago in English, wherein the Author undertakes to
discover, and that (if I mistake not) by the confession of some of the
Complices themselves, That a famous Water-drinker then much Admir'd in
_England_, perform'd his pretended Transmutations of Liquors by the help of
two or three inconsiderable preparations and mixtures of not unobvious
Liquors, and chiefly of an Infusion of Brazil variously diluted and made
Pale or Yellowish, (and otherwise alter'd) with Vinegar, the rest of their
work being perform'd by the shape of the Glasses, by Craft and Legerdemane.
And for my part, that which I marvel at in this business, is, the Drinkers
being able to take down so much Water, and spout it out with that violence;
though Custome and a Vomit seasonably taken before hand, may in some of
them much facilitate the work. But as for the changes made in the Liquors,
they were but few and slight in comparison of those, that the being
conversant in Chymical Experiments, and dextrous in applying them to the
Transmuting of Colours, may easily enough enable a man to make, as ev'n
what has been newly deliver'd in this, and the foregoing Experiment;
especially if we add to it the things contained in the XX, the XXXIX and
the XL. Experiments, may perhaps have already perswaded You.

_EXPERIMENT XLV._

You may I presume (_Pyrophilus_) have taken notice, that in this whole
Treatise, I purposely decline (as far as I well can) the mentioning of
Elaborate Chymical Experiments, for fear of frighting you by their
tediousness and difficulty; but yet in confirmation of what I have been
newly telling you about the possibility of Varying the Colours of Liquors,
better than the Water-drinkers are wont to do, I shall add, that _Helmont_
used to make a preparation of Steel, which a very Ingenious Chymist, his
Sons Friend, whom you know, sometimes employes for a succedaneum to the
Spaw-waters, by Diluting this _Essentia Martis Liquida_ (as he calls it)
with a due proportion of Water. Now that for which I mention to you this
preparation, (which as he communicated to me, I know he will not refuse to
_Pyrophilus_) is this, that though the Liquor (as I can shew you when you
please) be almost of the Colour of a German (not an Oriental) Amethyst, and
consequently remote enough from Green, yet a very few drops being let fall
into a Large proportion of good Rhenish, or (in want of that) White Wine
(which yet do's not quite so well) immediately turn'd the Liquor into a
lovely Green, as I have not without delight shown several curious Persons.
By which _Phaenomenon_ you may learn, among other things, how requisite it
is in Experiments about the changes of Colours heedfully to mind the
Circumstances of them; for Water will not, as I have purposely try'd,
concurr to the production of any such Green, nor did it give that Colour to
moderate Spirit of Wine, wherein I purposely dissolv'd it, and Wine it self
is a Liquor that few would suspect of being able to work suddenly any such
change in a Metalline preparation of this Nature; and to satisfie my self
that this new Colour proceeds rather from the peculiar Texture of the Wine,
than from any greater Acidity, that Rhenish or White-wine (for that may not
absurdly be suspected) has in comparison of Water; I purposely sharpen'd
the Solution of this Essence in fair Water, with a good quantity of Spirit
of Salt, notwithstanding which, the mixture acquir'd no Greenness. And to
vary the Experiment a little, I try'd, that if into a Glass of Rhenish Wine
made Green by this Essence, I dropp'd an Alcalizate Solution, or Urinous
Spirit, the Wine would presently grow Turbid, and of an odd Dirty Colour;
But if instead of dissolving the Essence in Wine, I dissolv'd it in fair
Water sharpen'd perhaps with a little Spirit of Salt, then either the
Urinous Spirit of Sal Armoniack, or the solution of the fix'd Salt of
Pot-ashes would immediately turn it of a Yellowish Colour, the fix'd or
Urinous Salt Precipitating the Vitriolate substance contain'd in the
Essence. But here I must not forget to take notice of a circumstance that
deserves to be compar'd with some part of the foregoing Experiment, for
whereas our Essence imparts a Greenness to Wine, but not to Water, the
Industrious _Olaus Wormius_[23] in his late _Musaeum_ tells us of a rare
kind of Turn-Sole which he calls _Bezetta Rubra_ given him by an Apothecary
that knew not how it was made, whose lovely Redness would be easily
communicated to Water, if it were immers'd in it; but scarce to Wine, and
not at all to Spirit of Wine, in which last circumstance it agrees with
what I lately told you of our Essence, notwithstanding their disagreement
in other particulars.

[23] Libr. 2do Cap. 34.

_EXPERIMENT XLVI._

We have often taken notice, as of a remarkable thing, that Metalls as they
appear to the Eye, before they come to be farther alter'd by other Bodyes,
do exhibit Colours very different from those which the Fire and the
_Menstruum_, either apart, or both together, do produce in them; especially
considering that these Metalline Bodyes are after all these disguises
reducible not only to their former Metalline Consistence and other more
radical properties, but to their Colour too, as if Nature had given divers
Metalls to each of them a double Colour, an _External_, and an _Internal_;
But though upon a more attentive Consideration of this difference of
Colours, it seem'd probable to me, that divers (for I say not all) of those
Colours which we have just now call'd _Internal_, are rather produc'd by
the Coalition of Metalline Particles with those of the Salts, or other
Bodyes employ'd to work on them, than by the bare alteration of the parts
of the Metalls themselves: and though therefore we may call the obvious
Colours, Natural or Common, & the others Adventitious, yet because such
changes of Colours, from whatsoever cause they be resolv'd to proceed may
be properly enough taken in to illustrate our present Subject, we shall not
scruple to take notice of some of them, especially because there are among
them such as are produc'd without the intervention of Saline _Menstruums_.
Of the Adventitious Colours of Metalline Bodies the Chief sorts seem to be
these three. The first, such Colours as are produc'd without other
Additaments by the Action of the fire upon Metalls. The next such as emerge
from the Coalition of Metalline Particles with those of some _Menstruum_
imploy'd to Corrode a Metall or Precipitate it; And the last, The Colours
afforded by Metalline Bodyes either Colliquated with, or otherwise
Penetrating into, other Bodies, especially fusible ones. But these
(_Pyrophilus,_) are only as I told you, the _Chief_ sorts of the
adventitious Colours of Metalls, for there may others belong to them, of
which I shall hereafter have occasion to take notice of some, and of which
also there possibly may be others that I never took notice of.

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