(29)
diums; concerning Gravity, concerning the Roundness of Fruits, stones, and divers artificial bodies; concerning Springiness and Tenacity; concerning the Original of Fountains; concerning the dissolution of Bodies into Liquors; concerning Filtration, and the ascent of Juices in Vegetables, and the use of their Pores. Here an attempt is made of solving the strange Phænomena of Glass-drops; experiments are alleged to prove the Expansion of Glass by heat, and the Contraction of heated-Glass upon cooling; Des Cartes his Hypothesis of Colours is examined: the cause of Colours, most likely to the Author, is explained: Reasons are produced, that Reflection is not necessary to produce colours, nor a double refraction: some considerable Hypotheses are offered, for the explication of Light by Motion; for the producing of all colours by Refraction; for reducing all sorts of colours to two only, Yellow and Blew; for making the Air, a dissolvent of all Combustible Bodies: and for the explicating of all the regular figures of Salt, where he alleges many notable instances of the Mathematicks of Nature, as having even in those things which we account vile, rude & course, shewed abundance of curiosity and excellent Geometry and Mechanism. And here he opens a large field for inquiries, and proposeth Models for prosecuting them, 1. By making a full collection of all the differing kinds of Geometricall figur'd bodies; 2. By getting with them an exact History of their places where they are generated or found: 3. By making store of Tryals in Dissolutions and Coagulations of several Crystallizing Salts: 4. By making trials on metalls, Minerals and Stones, by dissolving them in severall Menstruums, and Crystallizing them, to see what Figures will arise from those several compositums: 5. By compounding & coagulating several Salts together into the same mass, to observe the Figure of that product: 6. By inquiring the closenes or rarity of the texture of those bodies by examining their gravity, and their refraction, &c. 7. By examining what operations the fire hath upon several kinds of Salts, what changes it causes in their figures, Textures, or
