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

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 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 Quaeries, 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, 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 Praecipitates 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 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.

* * * * *

THE
Experimental History
OF
COLOURS
Begun.

* * * * *

The Third PART.

* * * * *

Containing
Promiscuous Experiments
About
COLOURS.

* * * * *

EXPERIMENT I.

Because 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 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 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 _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.

_EXPERIMENT II._

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 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.

_EXPERIMENT III._

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 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 Red far more like Scarlet than without it.

[Page 191]
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.

_EXPERIMENT IV._

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; 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.

_EXPERIMENT V._

[Illustration: _The Explication of the Scheme._]

_PPP_. An Aequilaterotriangular Crystalline Prism, one of whose edges _P_.
is placed directly towards the Sun.

_A B_ & [alpha] [beta] Two rays from the Sun falling on the Prism at _B_
[beta]. and thence partly reflected towards _C_ & [gamma]. and partly
refracted towards _D_ & [delta].

_B C_ & [beta] [gamma]. Those reflected Rays.

_B D_ & [beta] [delta]. Those refracted Rays which are partly refracted
towards _E_ & [epsilon]. 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_ & [zeta].

_D F_ & [delta] [zeta]. Those Reflected Rays which are partly refracted
towards _G_ & [eta]. colourless, and partly reflected, towards _H_ &
[theta].

_F H_ & [zeta] [theta]. Those reflected Rays which are refracted towards
_I_ & [iota]. 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.

_EXPERIMENT VI._

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 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.

_EXPERIMENT VII._

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 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.

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.

_EXPERIMENT VIII._

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 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.)

_EXPERIMENT IX._

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 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.

* * * * *

_EXPERIMENT X._

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. _Nobis,_ says he,[16] _Nova Hispania
mittit quoddam ligni genus crassum & enode, cujus usus jam diu receptus
fuit in his Regionibus ad Renum vitia & urinae difficultates ac arenulas
pellendas. Fit autem hac ratione, Lignum assulatim & minutim concisum in
limpidissima aqua fontana maceratur, inque ea relinquitur, donec aqua a
bibentibus absumpta sit, dimidia hora post injectum lignum aqua caeruleum
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 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 Caeruleous 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 Caeruleous, 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 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 Phaenomena 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
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 Caeruleous one.

[16] _Nicolaus Monardes_ lib _simplic. ex India allatis_, cap. 27.

These and other Phaenomena, 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
Phaenomena 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 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 Caeruleous, 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 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 Caeruleous 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 Caeruleous Colour, a Sulphureous Salt being of a contrary
Nature, would be able to Mortifie the Saline Particles of Vinegar, and
Destroy their 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 Caeruleous 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 Caeruleous; 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 _Phaenomena_ as the Tincted
Water did, before either of the Adventitious Liquors was pour'd into it.

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