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ESSAY IX.

ON METALLIC MINES.

To treat this subject.as amply as even thepresent state of our knowledge concerningthem would admit, is not my intention;such a treatise would require an entire vo-lume : my purpose is singly to give a generalidea of their formation in the differentstates in which they are known to exist;and of the sort of mineral soil, if I may socall it, or country in which particular kindsof them are most generally situated.

Most metals (under which name I herecomprehend also semimetals) are found infour states, native, sulphurated, calciform,or saliniform.

§ I.

Of Native Metals.

The metallic substances most commonlyfound in a native state, are gold, silver, pla-

tina,