Chapter IV: Appendix: The First

§ 244.

In the preceding pages only the more ſimple combinations occur, whoſe principles are either chemically united or at leaſt ſo ſubtly interwoven that the texture appears perfectly homogeneous. But if two or more of theſe ſpecies, forming little diſtinct maſſes are cemented together, theſe mechanical mixtures, diſcernible by the eye ought to conſtitute a new ſeries, to be diſtinguiſhed by their component parts as the others were by their firſt principles or chemical elements. Such compoſitions may well be excluded from the preſent work, but upon account of their extenſive phyſical, œconomical and metallurgical uſes, I propoſe to give a ſlight ſketch of them here, enumerating the more remarkable Genera.

§ 245.

In a general view it appears that not only ſeveral ſpecies cemented together may be referred to this place, but likewiſe thoſe which are mechanically diffuſed in a powdery or an earthy form.

§246.

From the laws of combination it is evident, that according to the arrangement of foſſils into four claſſes, there can be only TEN Genera compoſed of two, FOUR of three, and ONE of four conſtituent parts. And although ſo many have not yet been detected, yet it is better to mention them here as the induſtry of a future age will probably diſcover more. The ſpecies are formed from the differences of the more ſimple ſpecies and their component parts.

Salts _with_ Salts.

§ 247.

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.

We now proceed to the more compound genera.

Salts _with_ Earths _and_ Inflammables.

§ 257.

This genus can hardly ever occur but in countries formerly expoſed to ſubterranean fires.[77]

Salts _with_ Earths _and_ Metals.

§ 258.

To be expected amongſt volcanic productions.

Salts _with_ Inflammables _and_ Metals.

§259.

To be ſought for in the productions of volcanoes.

Earths _with_ Inflammables _and_ Metals.

§ 260.

Obvious amongſt the productions of volcanoes, otherwiſe extremely rare.

Salts _with_ Earths, Inflammables, _and_ Metals.

§ 261.

Hardly to be expected but in volcanic mountains.