Part 29

This compoſition can hardly ever conſtitute a genus, if it muſt be made in a dry and concrete form; for excepting gypſum, the other native ſalts readily diſſolve in water, and by evaporation are ſo mixed together as not readily to be diſcerned by the eye. Yet the foſſil alkaly mixed with common ſalt will perhaps find a place here. The contents of mineral waters may likewiſe be referred here, ſince every material difference in them depends upon the particles diſſolved.

Salts with Earths.

§ 248.

This mixture is hardly to be found but where bits of gypſum are concreted to matters of an earthy nature.

Salts with Inflammables.

§ 249.

May perhaps be found in volcanoes.

Salts with Metals.

§ 250.

If gypſum forms the matrix of any metal, it muſt be placed here.

Earths with Earths.

§ 251.

To this head belong moſt of the ſaxa (ſtones), enumerated by Mr. Cronſtedt, which form the immenſe bulk of mountains, and deſerve our particular attention, in order that, being better acquainted with the nature and ſtructure of the ſhell of the earth, we may be able to point out the coverings of minerals, and convert them all to our uſe.

Earths with Inflammables.

§ 252.

Lumps of mountain pitch are frequently connected with ſtones, and ſulphureous matters are found diffuſed through earthy materials.

Earths with Metals.

§ 253.

This genus contains the peculiar matrices of metals, a judicious conſideration of which would be particularly uſeful to miners.

Inflammables with Inflammables.

§ 254.

Perhaps, in ſome places, ſulphureous matters are found mixed with mountain pitch.

Inflammables with Metals.

§ 255.

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.

§ 256.

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.