Experiments and Considerations Touching Colours (1664) by Robert Boyle

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

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SIR,

_Your most Affectionate_

and

_most Faithfull Servant,_

RO. BOYLE.

[30] Benvonuto Cellini _nell Arte del_ Gioiellare, _Lib._ 1. _pag._ 10.

[31] The Narrative in the Authors own words, is this. _Ego_ (sayes he)
_sancte affirmare possum me unam aureo Annulo inclusam perpetuo gestare,
cujus facultatem (si gemmae est) nunquam satis admirari potui. Gestaverat
enim ante Triginta annos Hispanus quidam non procula puternis aedibus
habitans. Is cum vita functus esset, & ipsius suspellex (ut moris apud
nos est) venum exposita esset, inter caetera etiam Turcois exponebatur.
Verum nemo (licet complures eo concurrissent, ut eam propter Coloris
Elegantiam, quam vivo Domino habuerat emerent) sibi emptam voluit,
pristinum enim nitorem & Colorem prorsus amiserat, ut potius Malachites,
quam Turcois videretur. Aderat tum temporis gemmae habendae desiderio etiam
parens & frater meus, qui antea saepius gratiam & elegantiam ipsius
viderant, mirabundi eam nunc tam esse deformem, Emit eam nihilominus
pater, satisque vili pretio, qua omnibus contemptui erat, ac presentes
non eam esse quam Hispanus gestarat, arbitrarentur. Domum reversus Pater,
qui tam turpem Gemmam gestare sibi indecorum putabat, eam mihi dono dat,
inquiens; Quandoquidem, fili mi, vulgi fama est, Turcoidem, ut facultates
suas exercere possit, dono dari debere tibi eam devoveo, ego acceptam
Gemmam sculptori trado, at gentilitia mea insignia illi, quamadmodum
fieri solet, in Jaspide Chalcedono, aliisque Ignobilioribus Gemmis,
insculperat. Turpe enim existimabam, hujusmodi Gemma ornatus gratia, dum
gratiam nullam haberet, uti. Paret Sculptor redditque Gemmam, quam gesto
pro annulo Signatorio. Vix per mensem gestaram, redit illi pristinus
color, sed non ita nitens propter Sculpturam, ac inaequalem superficiem.
Miramur omnes gemmam, atque id praecipue quod color indies pulchrior
fieret. Id quia observabam, nunquam fere eam a manu deposui, ita ut nunc
adhuc candem gestem._

[32] _Olaus Wormius, in Musae. 18º pag. 186._

[33] _Musae. Worm._ pag. 99.

[34] Arte Vetraria, lib. 7 cap. 102.

* * * * *

OBSERVATIONS

Made this 27th.[35]
of _October_ 1663. about
Mr. _Clayton's_
Diamond.[36]

Being look'd on in the Day time, though in a Bed, whose Curtains were
carefully drawn, I could not discern it to Shine at all, though well
Rubb'd, but about a little after Sun-set, whilst the Twilight yet lasted,
Nay, this Morning[37] a pretty while after Sun-rising, (but before I had
been abroad in the more freely inlightned Air of the Chamber) I could upon
a light Affriction easily perceive the Stone to Shine.

[35] These were brought in and Read before the Royal Society, (the Day
following) _Oct._ 28. 1663.

[36] _The Stone it self being to be shown to the Royal Society, when the
Observations were deliver'd, I was willing (being in haste) to omit the
Description of it, which is in short, That it was a Flat or Table
Diamond, of about a third part of an Inch in length, and somewhat less in
breadth, that it was a Dull Stone, and of a very bad Water, having in the
Day time very little of the Vividness of ev'n ordinary Diamonds, and
being Blemished with a whitish Cloud about the middle of it, which
covered near a third part of the Stone._

[37] _Hast made me forget to take notice that I went abroad the same
Morning, the Sun shining forth clear enough, to look upon the Diamond
though a_ Microscope, _that I might try whether by that Magnifying Glass
any thing of peculiar could be discern'd in the Texture of the Stone, and
especially of the whitish Cloud that possest a good part of it. But for
all my attention I could not discover any peculiarity worth mentioning._

Secondly, The Candles being removed, I could not in a Dark place discern
the Stone to have any Light, when I looked on it, without having Rubb'd or
otherwise prepar'd it.

Thirdly, By two white Pibbles though hard Rubb'd one against another, nor
by the long and vehement Affriction of Rock Crystal against a piece of Red
cloath, nor yet by Rubbing two Diamonds set in Ring, as I had Rubb'd this
Stone, I could produce any sensible degree of Light.

Fourthly, I found this Diamond hard enough, not only to enable me to write
readily with it upon Glass, but to Grave on Rock Crystal it self.

Fifthly, I found this to have like other Diamonds, an Electrical
faculty.[38]

[38] V. _For it drew light Bodies like Amber, Jet, and other Concretes
that are noted to do so; But its attractive power seem'd inferiour to
theirs._

Sixthly, Being rubb'd upon my Cloaths, as is usual for the exciting of
Amber, Wax, and other Electrical Bodies, it did in the Dark manifestly
shine like Rotten Wood, or the Scales of Whitings, or other putrified Fish.

Seventhly, But this Conspicuousness was Fainter than that of the Scales,
and Slabber (if I may so call it) of Whitings, and much Fainter than the
Light of a Glow-worm, by which I have been sometimes able to Read a short
Word, whereas after an ordinary Affriction of this Diamond I was not able
to discern distinctly by the Light of it any of the nearest Bodies: And
this Glimmering also did very manifestly and considerably Decay presently
upon the ceasing of the Affriction, though the Stone continued Visible some
while after.

Eighthly, But if it were Rubb'd upon a convenient Body for a pretty while,
and Briskly enough, I found the Light would be for some moments much more
considerable, almost like the Light of a Glow-worm, insomuch after I ceased
Rubbing, I could with the Chaf'd stone exhibit a little Luminous Circle,
like that, but not so bright as that which Children make by moving a stick
Fir'd at the end, and in this case it would continue Visible about seven or
eight times as long as I had been in Rubbing it.

Ninthly, I found that holding it a while near[39] the Flame of a Candle,
(from which yet I was carefull to avert my Eyes) and being immediately
remov'd into the Dark, it disclosed some faint Glimmering, but inferiour to
that, it was wont to acquire by Rubbing. And afterward holding it near a
Fire that had but little Flame, I found the Stone to be rather less than
more excited, than it had been by the Candle.

[39] IX. _We durst not hold it in the Flame of a Candle, no more than put
it into a naked Fire; For fear too Violent a Heat (which has been
observ'd to spoil many other precious Stones) should vitiate and impair a
Jewel, that was but borrow'd, and was suppos'd to be the only one of its
Kind._

Tenthly, I likewise indeavour'd to make it Shine, by holding it a pretty
while in a very Dark place, over a thick piece of Iron, that was well
Heated, but not to that Degree as to be Visibly so. And though at length I
found, that by this way also, the Stone acquired some Glimmering, yet it
was less than by either of the other ways above mention'd.

Eleventhly, I also brought it to some kind of Glimmering Light, by taking
it into Bed with me, and holding it a good while upon a warm part of my
Naked Body.

Twelfthly, To satisfie my self, whether the Motion introduc'd into the
Stone did generate the Light upon the account of its producing Heat there,
I held it near the Flame of a Candle, till it was qualify'd to shine pretty
well in the Dark, and then immediately I apply'd a slender Hair to try
whether it would attract it, but found not that it did so; though if it
were made to shine by Rubbing, it was as I formerly noted Electrical. And
for further Confirmation, though I once purposedly kept it so near the hot
Iron I just now mention'd, as to make it sensibly Warm, yet it shin'd more
Dimly than it had done by Affriction or the Flame of a Candle, though by
both those ways it had not acquir'd any warmth that was sensible.

Thirteenthly, Having purposely rubb'd it upon several Bodies differing as
to Colour, and as to Texture, there seem'd to be some little Disparity in
the excitation (if I may so call it) of Light. Upon White and Red Cloths it
seem'd to succeed best, especially in comparison of Black ones.

Fourteenthly, But to try what it would do rubb'd upon Bodies more hard, and
less apt to yield Heat upon a light Affriction, than Cloath, I first rubb'd
it upon a white wooden Box, by which it was excited, and afterwards upon a
piece of purely Glazed Earth, which seem'd during the Attrition to make it
Shine better than any of the other Bodies had done, without excepting the
White ones, which I add, lest the Effect should be wholly ascrib'd to the
disposition White Bodies are wont to have to Reflect much Light.

Fifteenthly, Having well excited the Stone, I nimbly plung'd it under
Water[40], that I had provided for that purpose, and perceiv'd it to Shine
whilst it was beneath the Surface of that Liquor, and this I did divers
times. But when I indeavour'd to produce a Light by rubbing it upon the
lately mentioned Cover of the Box, the Stone and it being both held beneath
the Surface of the Water, I did not well satisfie my self in the Event of
the Trial; But this I found, if I took the Stone out, and Rubb'd it upon a
piece of Cloath, it would not as else it was wont to do, presently acquire
a Luminousness, but needed to be rubb'd manifestly much longer before the
desired Effect was found.

[40] XV. _We likewise Plung'd it as soon as we had excited it, under
Liquors of several sorts, as Spirit of Wine, Oyl both Chymical and
express'd, an Acid Spirit, and as I remember an Alcalizate Solution, and
found not any of those various Liquors to destroy its Shining property._

Sixteenthly, I also try'd several times, that by covering it with my warm
Spittle (having no warm Water at hand) it did not lose his Light.[41]

[41] XVI. _Having found by this Observation, that a warm Liquor would not
extinguish Light in the Diamond, I thought fit to try, whether by reason
of its warmth it would not excite it, and divers times I found, that if
it were kept therein, till the Water had leisure to communicate some of
its Heat to it, it would often shine as soon as it was taken out, and
probably we should have seen it Shine more, whilst it was in the Water,
if some degree of Opacity which heated Water is wont to acquire, upon the
score of the Numerous little Bubbles generated in it, had not kept us
from discerning the Lustre of the Stone._

Seventeenthly, Finding that by Rubbing the Stone with the Flat side
downwards, I did by reason of the Opacity of the Ring; and the sudden Decay
of Light upon the ceasing of the Attrition, probably lose the sight of the
Stones greatest Vividness; and supposing that the Commotion made in one
part of the stone will be easily propagated all over, I sometimes held the
piece of Cloath upon which I rubb'd it, so, that one side of the Stone was
exposed to my Eye, whilst I was rubbing the other, whereby it appear'd more
Vivid than formerly, and to make Luminous Tracts by its Motions too and
fro. And sometimes holding the Stone upwards, I rubb'd its Broad side with
a fine smooth piece of Transparent Horn, by which means the Light through
that Diaphanous Substance, did whilst I was actually rubbing the Stone,
appear so Brisk that sometimes and in some places it seem'd to have little
Sparks of fire.

Eighteenthly, I took also a piece of flat Blew Glass, and having rubb'd the
Diamond well upon a Cloath, and nimbly clapt the Glass upon it, to try
whether in case the Light could peirce it, it would by appearing Green, or
of some other Colour than Blew, assist me to guess whether it self were
sincere or no. But finding the Glass impervious to so faint a Light, I then
thought it fit to try whether that hard Bodies would not by Attrition
increase the Diamonds Light so as to become penetrable thereby, and
accordingly when I rubb'd the Glass briskly upon the Stone, I found the
Light to be Conspicuous enough, and somewhat Dy'd in its passage, but found
it not easie to give a Name to the Colour it exhibited.

Lastly, To comply with the Suspition I had upon the whole Matter, that the
chief manifest Change wrought in the Stone, was by Compression of its
parts, rather than Incalescence, I took a piece of white Tile well Glaz'd,
and if I press'd the Stone hard against it, it seem'd though I did not rub
it to and fro, to shine at the Sides: And however it did both very
manifestly and vigorously Shine, if whilst I so press'd it, I mov'd it any
way upon the Surface of the Tile, though I did not make it draw a Line of
above a quarter of an Inch long, or thereabouts. And though I made it not
move to and fro, but only from one end of the short Line to the other,
without any return or Lateral motion. Nay, after it had been often rubb'd,
and suffer'd to lose its Light again, not only it seem'd more easie to be
excited than at the beginning of the Night; but if I did press hard upon it
with my Finger, at the very instant that I drew it briskly off, it would
disclose a very Vivid but exceeding short Liv'd Splendour, not to call it a
little Coruscation.[42] So that a _Cartesian_ would scarce scruple to think
he had found in this Stone no slight Confirmation of his Ingenious Masters
_Hypothesis_, touching the Generation of Light in Sublunary Bodies, not
sensibly Hot.

[42] _I after bethought my self of imploying a way, which produc'd the
desir'd Effect both sooner and better. For holding betwixt my Fingers a
Steel Bodkin, near the Lower part of it, I press'd the point hard against
the Surface of the Diamond, and much more if I struck the point against
it, the Coruscation would be extremely suddain, and very Vivid, though
very Vanishing too, and this way which commonly much surpris'd and
pleas'd the Spectators, seem'd far more proper than the other, to show
that pressure alone, if forcible enough, though it were so suddain, and
short, that it could not well be suppos'd to give the Stone any thing
near a sensible degree of Warmth, as may be suspected of Rubbing, yet
'tis sufficient to generate a very Vivid Light._

* * * * *

A Postscript.

Annexed some Hours after the Observations were Written.

_So many particulars taken notice of in one Night, may make this Stone
appear a kind of Prodigie, and the rather, because having try'd as I
formerly noted, not only a fine Artificial Crystal, and some also that is
Natural, but a Ruby and two Diamonds, I did not find that any of these
disclos'd the like Glimmering of Light;[43] yet after all, perceiving by
the Hardness, and the Testimony of a Skilfull Goldsmith, that this was
rather a Natural than Artificial Stone; for fear lest there might be some
difference in the way of Setting, or in the shape of the Diamonds I made
use of, neither of which was like this, a flat Table-stone, I thought fit
to make a farther Trial of my own Diamonds, by such a brisk and assiduous
Affriction as might make amends for the Disadvantages above-mention'd, in
case they were the cause of the unsuccessfulness of the former Attempts:
And accordingly I found, that by this way I could easily bring a Diamond I
wore on my Finger to disclose a Light, that was sensible enough, and
continued so though I cover'd it with Spittle, and us'd some other trials
about it. And this will much lessen the wonder of all the formerly
mention'd Observations, by shewing that the properties that are so strange
are not peculiar to one Diamond, but may be found in others also, and
perhaps in divers other hard and_ Diaphanous _Stones. Yet I hope that what
this Discovery takes away from the Wonder of these Observations, it will
add to the Instructiveness of them, by affording pregnants Hints, towards
the Investigation of the Nature of Light._

[43] We afterwards, try'd precious Stones, as Diamonds, Rubies, Saphires,
and Emeralls, &c. but found not any of them to Shine except some
Diamonds, and of these we were not upon so little practice, able to
fore-tell before hand, which would be brought to Shine, and which would
not; For several very good Diamonds, either would not Shine at all, or
much less than others that were farr inferiour to them. And yet those
Ingenious Men are mistaken, that think a Diamond must be foul and cloudy,
as Mr. _Claytons_ was, to be fit for Shining; for as we could bring some
such to afford a Glimmering Light, so with some clear and excellent
Diamonds, we could do the like. But none of those many that we try'd of
all Kinds, were equal to the Diamond on which the Observations were made,
not only considering the degree of Light it afforded, but the easiness
wherewith it was excited, and the Comparatively great duration of its
Shining.

FINIS.

* * * * *

Transcriber's notes.

The Errata of the printed book have all been corrected.
They were as follows:

Pag. 142. l. 20. These words, And to manifest, with the rest of what is by
a mistake further printed in this fourth Experiment, belongeth, and is to
be referred to the end of the second Eperiment, p.137. pag. 145. l. 1. leg.
matter. 146. l. 4. leg. Bolts-head. pag 161. in the marginal note l. 2.
dele de ib. l. 3. lege lib 1. p 163. l. ult. insert where between the words
places and the. p. 164 l. 1. dele that. ibid, l. 8. leg Epidermis. ibid. l.
19 leg. 300. for 200. p. 169. l. 22. leg. into it. p. 170. l. 23. & 24.
leg. Some Solutions hereafter to be mentioned, for the Solutions of
Potashes, and other Lixiviate Salts. p. 171. l. 6. insert part of between
the words most and dissolved p. 176. l. ult. insert the participle it
between the words Judged and not p. 234. l. 4. leg. Woud-wax or Wood-wax.
p. 320 l. 29. leg. urine for urne.

In addition I have corrected the following original typos:

The preface: I devis'd tbem -> I devis'd them
The preface: make Expements -> make Experiments
The Publisher to the reader: made of Eperiments -> made of Experiments
I. Ch. III.6 divers Expements -> divers Experiments
I. Ch. III.13 epecially with some sorts -> especially with some sorts
II. Ch. II.8 Slightet Texture -> Slightest Texture
II. Exp. I two Colonrs -> two Colours
II. Exp. XIII were the change of Colour -> where the change
III. Exp. XII avoiding of Ambignity -> avoiding of Ambiguity
III. Exp. XXIX Juice of this Sipce -> Juice of this Spice
III. Exp. XL forty second Expement -> forty second Experiment
III. Exp. XLIV keep them swimning -> keep them swimming
III. Exp. XLVI it seem'd propable to me -> it seem'd probable to me
III. Exp. XLVII where not comprehended -> were not comprehended
III. Exp. XLVIII frequent Igintion -> frequent Ignition
III. Exp. L I could tell yon -> I could tell you
A Copy of the Letter: nemo unqnam vere -> nemo nunquam vere
(ib.): what is reladed -> what is related
Observations: carefulsy drawn -> carefully drawn

- and emended
Phoenomenon/a to Phaenomenon/a 10 times and
Coeruleous etc. -> Caeruleous 20 times

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