Dictionarium polygraphicum. Whiteness.

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol II.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
Whiteness is the quality which denominates a body white. But sir Is. Newton shews that whiteness consists in a mixture of all the colours; and that the light of the sun is white, because consisting of rays of all colours.

From the multitude of rings of colours which appear upon compressing two prisms, or object-glasses, or telescopes together, it is manifest, that these do so interfere and mingle with one another at last, as after 8 or 9 reflections, to dilute one another wholly, and constitute an even and uniform whiteness.

From whence, as well as from other experiments, it appears that whiteness is certainly a mixture of all colours; and that the light which conveys it to the eye, is a mixture of rays endued with all those colours.

He also shews that whiteness, if it be most strong and luminous, is to be reckoned of the first order of colours; but if less, as a mixture of the colours of several orders: of the former sort, he reckons white metals; and of the latter, the whiteness of froth, paper, linen, and most other white substances.

And as the white of the first order, is the strongest that can be made by plates oftransparent substances, so it ought to be stronger in the denser substances of metals, than in the rarer ones air, water, and glass.

Gold, or copper, mix'd either by fusion or amalgamation, with a very little mercury, with silver, tin, or regulus or antimony, become white; which shews, both that the particles of white metals have much more surface, and therefore are smaller than those of gold or copper; and also that they are so opake, as not to suffer the particles of gold or copper to shine through them.

And as he doubts not, but that the colours of copper and gold are of the second and third order, therefore the panicles of white metals, cannot be much bigger than is requisite to make them reflect the white of the first order.

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