I. Earth-minerals Earths. II. Water- " Salts. III. Air- " Inflammables. IV. Fire- " Ores. a. _Earths_ are those minerals, which admit of being changed neither by water, nor air, nor by fire; i. e. which are neither soluble, combustible, fusible, neither yield colour, nor are particularly heavy. Such minerals have been properly called earths, as silicious, sacrilegious earth, &c. b. _Salts_ are those which have aqueous properties, i. e. are soluble. c. _Inflammables_ are those which have aerial properties, i. e. are inflammable and volatile. d. _Metallic ores_ are those which have the three properties of fire, are superlatively heavy, yielding light or colour, and fusible. 506. The _Earths_ are to be regarded as the proper total earth-element, namely as carbon neutralized by oxygen. The _Salts_ are to be regarded as combinations of the earth-and water-elements; therefore as combinations of carbon with oxygen and hydrogen. The _Inflammables_ are to be regarded as combinations of the earth-element with the air-element, thus of carbon with hydrogen, which supplies the place of nitrogen. The _Metals_ are to be regarded as combinations of the earth-element with the fire-element; therefore as carbon without any other body, only combined with spiritual actions, namely gravity, light and heat. Hence the apparent simplicity of metals, and the great number of special properties, which are absent in the other classes. DEVELOPMENT OF THE CLASSES. 507. As there is not simply a single earth, salt, Inflammable and metal, but in each class many of them; we have to inquire what is the groundwork of their further distinctions or of their systematic division. Here also may we go to work again chemically and philosophically. 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.