[5] Exercitat. 325 Parag. 4

* * * * *

THE
EXPERIMENTAL HISTORY
OF COLOURS.

* * * * *

PART.  II.

Of the Nature of Whiteness and
Blackness.

CHAP.  I.

1.  Though after what I have acknowledged, Pyrophilus, of the Abstruse Nature of Colours in particular, you will easily believe, that I pretend not to give you a Satisfactory account of Whiteness and Blackness; Yet not wholly to frustrate your Expectation of my offering something by way of Specimen towards the Explication of some Colours in particular, I shall make choice of These as the most Simple Ones, (and by reason of their mutual Opposition the Least hardly explicable) about which to present you my Thoughts, upon condition you will take them at most to be my Conjectures, not my Opinions.

2.  When I apply’d my Self to consider, how the cause of Whiteness might be explan’d by Intelligible and Mechanical Principles, I remembred not to have met with any thing among the Antient Corpuscularian Philosophers, touching the Quality we call Whiteness, save that Democritus is by Aristotle said to have ascrib’d the Whiteness of Bodies to their Smoothness, and on the contrary their Blackness to their Asperity.[6] But though about the Latter of those Qualities his Opinion be allowable, as we shall see anon, yet that he heeds a Favourable Interpretation in what is Deliver’d concerning the First, (at least if his Doctrine be not Mis-represented in this point, as it has been in many others) we shall quickly have Occasion to manifest.  But amongst the Moderns, the most Learned Gassendus in his Ingenious Epistle publish’d in the Year 1642. De apparente Magnitudine solis humilis & sublimis, reviving the Atomical Philosophy, has, though but Incidentally, deliver’d something towards the Explication of Whiteness upon Mechanical Principles:  And because no Man that I know of, has done so before him, I shall, to be sure to do him Right, give you his Sense in his own Words:[7] Cogites velim (says he) lucem quidem in Diaphano nullius coloris videri, sed in Opaco tamen terminante Candicare, ac tanto magis, quanto densior seu collectior fuerit.  Deinde aquam non esse quidem coloris ex se candidi & radium tamen ex ea reflexum versus oculum candicare.  Rursus cum plana aquae Superficies non nisi ex una parte eam reflexionem faciat:  si contigerit tamen illam in aliquot bullas intumescere, bullam unamquamque reflectionem facere, & candoris speciem creare certa Superficiei parte.  Ad haec Spumam ex aqua pura non alia ratione videri candescere & albescerere quam quod sit congeries confertissima minutissimarum bullarum, quarum unaquaeque suum radium reflectit, unde continens candor alborve apparet.  Denique Nivem nihil aliud videri quam speciem purissimae spumae ex bullulis quam minutissimis & confertissimis cohaerentis.  Sed ridiculam me exhibeam, si tales meas nugas uberius proponem.