Experiments and Considerations Touching Colours (1664) by Robert Boyle

R >> Robert Boyle >> Experiments and Considerations Touching Colours (1664)

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21

_EXPERIMENT III._

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 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.

_EXPERIMENT IV._

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
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 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_ _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
_Oxycaeder_ 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.

_EXPERIMENT V._

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, 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.

_EXPERIMENT VI_

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 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.

_EXPERIMENT VII._

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 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.

_EXPERIMENT VIII._

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 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.

_EXPERIMENT IX._

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 Praecipitated to the Bottom, taking it
for a Hopefull Sign, that those Particles are of a Golden Nature, 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 Praecipitated
_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
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.

_EXPERIMENT X._

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,
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.

_EXPERIMENT XI_

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 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, 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 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 AEquinoctial, 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 _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
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 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 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, 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.

[10] Olearius Voyage de Mosco. et de Perse _liv_. 3.

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 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.

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21