As concerning therefore the original of the acidity as well volatile, as corporeal, as also the heat of Baths, know that is not one, and the same; for else each would have the same properties, but daily experience testifies the contrary: For it is manifest that some Baths help some diseases, and others are hurtful for them, which comes from nothing else but from the difference of the properties of the mineral waters proceeding from a diversity of mines impregnating those waters. In a word, sweet waters attract their powers, and vertues in the caverns of mountains from some metal and minerals of divers kinds, that have naturally a most acid spirit of salt, as are divers kinde of marcasites containing copper and iron, and sometimes gold and silver; also kinds of vitriol and Allome called by the ancients _Misii_, _Rarii_, _Chalcitis_, _Melanteria_, and _Pyritis_, whereof some are found white like metals, but others dispersed in a fat earth, of a round figure in greater or lesser pieces: which sulphureous salt mines whilest the water run through, and humectates, that spirit of salt is stirred up, having got a _vehiculum_, and falls upon the mines by dissolving them, in which solution the water waxeth warm, as if it had been poured on quick lime, or like spirit of vitriol, or salt mixed with water, and poured on iron, and other metals; where continually and daily that water running through the mines whose nature and properties it imitates, carrys something with it: wherefore there are so many, and such various kinds of Baths as are the mines by which the water is heated. Let him that will not believe take any mineral of the aforesaid quality, and wrap it up in a wet linen cloth for a little while, and he will see it experimentally that the mineral stone will be heated by the water, and so heated, as if it were in the fire, so as thou canst scarce hold it in thy hand, which at length also by a longer action will cleave in sunder and be consumed like quick lime. I will publish some time or other (God willing) more fully, and clearly in a peculiar treatise this my opinion, which I have now delivered in very few words. Although to the sick it be all one, and it matters not them, from what cause the baths come, and whence they borrow their vertues, if so be they may use them; this controversie being left to natural Philosophers that will controvert it, which none of them can better decide than a skilful Chymist, that hath the knowledg of minerals, metals, and salts. _And first of sulphureous Baths that have a subtil acidity._