Page:Philosophical Transactions - Volume 004.djvu/257

 5. You offer something that may pertain to this purpose in your Tract of N. 49. p. 982. concerning the Generation of Christal. And I think, I could shew, by at rain or list of proofs, a strong probability, that, as Heat vitrifies, so Durable Frosts, with some Concomitants of like nature, by some alternative oppositions of Heate, or perhaps by coincidence of extreams, do Chrystallize, or more firmly Petrify the moisture or sweat of Rocks and Quarries. The petrifying spirit crispeth by an acuter angle into a firmer solidity, than can be performed by any Frosts to us known. And the Marcasite is formed by a constipation stronger than that which petrifyeth; and sometimes where Marcasites are generated, there are found also some parcels of very pure, firm, and ponderous Copper, which requir'd a stronger Compression, as by an acuter Angle, for the Generation of the Copper, then for the Generation of the Marcasite is necessary.

6. And that Frosts also alter the Nature of Liquors, we had now some experience in this snowy season: For we saw the water of dissolved Snow perform a quick cure, in taking out the fire, when the flesh was burnt by a warming pan of Brass; which Metal commonly makes the burning more difficult to be cured: Which did put me in mind, to examine the figures of the Snow, which now fell in this extreame Frost. I expected, that we might see through the small particles, at least as through Lice, Heas, Cheese-mites, &c. by some kind of transparence; but I was deceived: My assistants could make nothing of it, either by an ordinary or extraordinary Microscope. I was invited to the Inquiry by your N. 39, p 774. reporting, that in Germany March 1666, or about that time, Snow fell there, having the shape of Pillars, some Tetragonal, and some Hexagonal, a neat Basis, and a larger head, as in Columns. Perhaps a more skilful search by the best Microscopes may discover, either in what shape the Rorid particles are, when they are frozen into Snow, or into what figures or Angles the particles of the Snow are compressed by Frosts. If the Clouds were continued an intire body of water, they could not quite hinder the sight of the Sun and Stars; for a good depth of clear water will not hinder it: but the particles, being divided in the