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any Thing inflammable, it conſtitutes 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 Reaſon, in ſuppoſing it may join alſo with an earthy or ſtony Subſtance, 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 theſe two, it will form a Body alſo different both from Alum, and from Selenite.
I am therefore led to ſuppoſe, that this Stone is a Combination of the univerſal Acid, with an Earth, differing from thoſe wherewith we have at other Times ſeen it joined.
And from
1. The unctuous Quality of the Stone;
2. Its Difficulty of Fuſion;
3. Its tenacious and gelatinous Nature in the Fire;
4. From its various Colours;
I think it moſt probable; that it is the Mineral Acid united with the Steatite; or Soap Rock.
For the Steatites has preciſely all the Colours which we ſee in this Stone; and has no others: It is unctuous like it; it ſcratches like it, in the hardeſt Pieces; it will not diſſolve in Acids; nor ſtrike Fire with Steel: And in the laſt fiery Trial it has juſt this refractory Quality; only that here it is rendered a little more tractable by the Acid.
A Stone
