a. Chemical Division.
The Metals, chemically regarded, do not admit of being separated into constituent parts. They exhibit only physical differences in gravity, colour, hardness, malleability, conducting power, tension or their mutual polarity. If it be endeavoured to arrange them according to these respects, nothing but disorder results. The same is the case in reference to their affinity for oxygen, sulphur, the acids and other metals. Rather more order is at once displayed if their philosophical composition, namely as carbon and fire, be submitted to our consideration.
508. In consequence of this view, the Metals must divide into Earth-metals and Fire-metals; and the latter again into three subdivisions, nearly as follows:—
A. Earth-metals—difficultly fusible and invariably oxydized—Sidereometalla, e. g. Iron—Manganese, Wolfram, Uranium, Titanium, Chromium, &c.
B. Fire-metals.
a. Heavy metals; difficultly fusible, unoxydized or noble metals, e. g. Platinum, Nickel, Cobalt.
b. Light metals; the easily fused noble metals—e. g. Gold, Silver, &c.
c. Heat-metals; the easily fused, ignoble and frequently volatile metals, e. g. Lead, Tin, Antimony, Zinc, Arsenic, &c.
509. The Inflammables divide under a chemical point of view into two groups—into the varieties of Coal and Sulphur, whereof the Earthy lies at the basis of the former which is non-fusible; the Aerial at that of the latter. They do not admit of being divided, unless a mean betwixt the two be taken, the combinations of carbon and hydrogen in the resins.
510. The Salts admit of a better dismemberment. Their constituent parts are alkalies and acids, the former the Earthy, the latter the Aqueous. The mean condition is exhibited by the neutral salts, so that three orders are the result.