Volume 2

The philosophical works of ... Robert Boyle / ... abridged, methodized, and disposed under the general heads of physics, statics, pneumatics, natural history, chymistry, and medicine. The whole illustrated with notes, containing the improvements made in ... natural and experimental knowledge since his time ... By Peter Shaw.

Robert Boyle

Date:: 1725

Credit: The philosophical works of ... Robert Boyle / ... abridged, methodized, and disposed under the general heads of physics, statics, pneumatics, natural history, chymistry, and medicine. The whole illustrated with notes, containing the improvements made in ... natural and experimental knowledge since his time ... By Peter Shaw. Source: Wellcome Collection.

33/796 page 9

$made a liquor, which, when well fettled ina clofe vial, is tranfparent Puystcs. and colourlefs ; but as foon as the glafs is unitopped, begins to fly away \ very plentifully in a white, opake fume: and there are other bodies, whofe fumes, when they fill a receiver, would make one fufpect it contain’d milk ; and yet thefe fumes become a liquor that is not white, but tran{- parent. And fuch white fumes I have feen afforded by unftopping a liquor, which is itfelf diaphanous and red; nor are thefe the only inftances of this kind that our experiments.can fupply us with. And if the fuperficial corpuicles be of the groffer fort, and fo framed, that their differing fides may exhibit differing colours, then the motion or reft of thofe corpuicles may be confiderable, as to the colour of the {uperficies they compofe ; be- caufe fometimes more, fometimes fewer of the fides difpofed to exhibit fuch a colour, may by this means become or continue more obverted to the eye than the reft, and compofe a phyfical furface more or lefs fenfibly inter- rupted. “hus I remember, that in fome forts of plants, whofe leaves. were thick fet by one another, and the two fides of each leaf of a fomewhat dife- rent colour, there would appear a notable difference in their colour, if look’d upon, firft when the leaves being at reft, had their true upper fides obverted to the eye ; and again, when a breath of wind pafling thorough them, made great numbers of the fides of the leaves, that are ufually hidden, become con{picuous. And tho’ the little bodies above-mentioned, may fingly and a-part feem almoft colourlefs ; yet when many of them are placed by one- another fo near, that the eye does not difcern an interruption in a fenfible fpace, they may exhibit a colour: as we fee, that tho’ a flender thread of dy d {carlet filk,whilft look’d on fingly, feems almoft quite devoid of rednefs; yet when numbers of thefe threads are brought together into.a skein, that colour then becomes glaring. And in changeable taflaties, where we fee differing colours arife and vanih upon ruffling the fame piece of filk; ] have often, with pleafure, obferved, by means of a.convenient microfcope, their component threads to pafs under and over each other, in almoft in- numerable points: and if I thus look’d upon any confiderable portion of the ftuff that, for example, appeared red to the naked eye, I could plainly fee, that in fuch a pofition the red threads were con{picuous, and re- flected a vivid light : and tho’ I could alfo perceive.that there were green ones, yet, by reafon of their difadvantageous pofition in the phyfical furface of the filk, they were in part hid by the more protuberant threads of the other colour; and, for the fame reafon, the reflection from as much of the green as was difcover'd, appear’d but dim and faint. And if, on the contrary, I look’d thro’ the microfcope upon any part that appear’d green, I could plainly fee the red threads were lefs fully expofed to the eye, and obfcured by the green ones, which, therefore, made the predomi- nant.colour. And by obferving the texture of the filk, I could eafily fo expofe the threads either of the one colour or the other to my eye, as at pleature to exhibit the appearance of red or green, or make thofe colours fucceed each other :: fo.that, obférving their fucceffion, I could mark how the predominant ‘colour ftarted ‘up, when the threads that exhibited it; ox. IT. C | came$

Licence and re-use

Contents

Volumes