Page:Philosophical Transactions - Volume 004.djvu/255

 once an Experimental proof, that either the Saline steams, which ascend from a heap of Salt, do pierce through very thick stone-walls; Or (which I did much rather conceive,) they generate more Salt, to a great depth of thickness, in the Lime and Mortar of the Walls.

2 Dr Power in his ''Microsc. Obs. pag.'' 62. assures from good Testimony, and common experience, that a Mineral heat in the Subterraneous parts produceth Minerals: And particularly, that in Allum and Coperas-mines, those Minerals being broken, exposed, and moistened, will gather an actual heat; and produce much more of these Minerals, than else the Mine would yield. And there he further proves by an unlucky accident, that Brasse-lumps, (which he saith is a kind of Marcasite,) being layd in heaps and exposed to the moist Air, or sprinkled with water, will smoak, and grow exceeding hot; and sometimes take fire, and burn all that is about them. Thus he. And all sorts of Dung afford a Heate, some less, and some stronger; some speedily, and some more permanently. And store of Nitre may be had from the sweepings of the house, any kind of ashes, shovelings of any sordid place, the cleansings from the back stayrs, and emptying of the Chamber-pots, if always cast as stratum super stratum in a dry Well, or Vault, only so covered and fenced, that the Rain and water gets not in. Dr Power shews here, How Metals or Minerals may be generated; but how far this Generative force will run, and from what Bulke of Materials; and what Materials are aptest to be transformed into what Minerals or Metals, we must refer to further tryal. Of this we are certain, that by a strong Fire, thus raised by Brass-lumps, Stones and Metals may be vitrified, and thence assume another Nature, and Lustre than is ordinary; And by the Gentler heats, (besides the acquest of Salt-peter in the end) there may be Mechanical applications peculiar for the Gradual and slow productions of Chymistry, both for narural effects upon usual Proximities, and for Artificial Contrivances.

3. In your Num. 6. p. 101. you shew us, that there a is place in England, where, without petrifying water, wood is turned into stone, in a Sandy Earth. But can we yet say, whether Vaults digged in such Grounds may not have a Petrifying Spirit, as