Page:Theophrastus - History of Stones - Hill (1774).djvu/290

 any Thing inflammable, it contitutes the Sulphurs; and when united with calcareous Earth, the Selenites.

Now, as this Acid can unite with Clay, and with Chalk; there is nothing contradictory to Reaon, in uppoing it may join alo with an earthy or tony Subtance, neither argillaceous or calcareous:

And as uniting with Clay it forms Alums, and with Chalk Selenites; if united with an Earth totally different in its Nature from thee two, it will form a Body alo different both from Alum, and from Selenite.

I am therefore led to uppoe, that this Stone is a Combination of the univeral Acid, with an Earth, differing from thoe wherewith we have at other Times een it joined.

And from

1. The unctuous Quality of the Stone;

2. Its Difficulty of Fuion;

3. Its tenacious and gelatinous Nature in the Fire;

4. From its various Colours;

I think it mot probable; that it is the Mineral Acid united with the Steatite; or Soap Rock.

For the Steatites has preciely all the Colours which we ee in this Stone; and has no others: It is unctuous like it; it cratches like it, in the hardet Pieces; it will not diolve in Acids; nor trike Fire with Steel: And in the lat fiery Trial it has jut this refractory Quality; only that here it is rendered a little more tractable by the Acid. A Stone