This genus contains the peculiar matrices of metals, a judicious conſideration of which would be particularly uſeful to miners.
Inflammables with Inflammables.
Perhaps, in ſome places, ſulphureous matters are found mixed with mountain pitch.
Inflammables with Metals.
If plumbago (black-lead) or common ſulphur, ſhall ever be found mixed with metallic ſubſtances, ſuch ſpecies muſt ſtand under this genus.
Metals with Metals.
We know that ſome metals, in the boſom of the earth, are almoſt always mixed, whilſt others are rarely, or never, found together. A more accurate knowledge of theſe things, would illuſtrate phyſical geography, as well as metallurgy.