' ( 3 6 4 )

soda, the basis of common salt, are simplesubstances in this sense, as we know of noprocess, either of art or of nature, by whicheither of them can either be decomposedor formed. That soda is not the productof vegetation appears by the experimentsof Mr. Du Hamel. Mem. Par. 1767, ashe found the quantity of soda in kali todecrease progressively in succeffive annualgrowths of the plant sown in lands distantfrom the sea. Both the acid and basismust therefore have originally existed,though in an uncombined state, in thechaotic fluid. Again, of all mineral acids,the most abundant are the marine and vi-triolic ; and of all bases to which they mayunite, calcareous earth, natron, and mag-nesia, are those which are found in thegreatest plenty : iron, it is true, is foundperhaps as plentifully as any of them, butthen its combinations with either of thoseacids would immediately be decomposedby any of the above-mentioned substances*Farther, it cannot be pretended that thevitriolic acid is an original substance; it lSevidently formed of sulphur and pure art,

and this air owed its extrication to volca-nic