516. The total division only is genetic and consequently correct.
517. As the classes have originated through that which directly preceded them, namely, the elements; so must the divisions of the classes be determined by the other classes. Such divisions are called orders. Every class necessarily divides into four orders.
| Order 1. | Earths. |
| 2. | Salts. |
| 3. | Inflammables. |
| 4. | Ores. |
CLASS I.
EARTHS.
518. There must be therefore pure earths, haloid or salt-earths, inflammable earths and metallic earths or ores.
1. The Earth-earths must have neither saline, nor inflammable nor metallic properties, and thus also be insoluble in acids. Such is the case with the Silicious earths.
2. The Haloid-earths must have saline properties, dissolve in acids, but not fall to pieces when exposed to air and fire. Such is the behaviour of Argillaceous earth; it admits besides of combining with water, that antetype of the salts.
3. The Inflammable earths must be soluble in acids and exhibit electric or aerial properties. Such is the behaviour of the Talcose earths; its minerals are unctuous, fall when exposed to the air into electric lamellæ, and burn brittle.
4. The Metallic earths must undergo change in acids, air and fire. The calcareous earth dissolves in all acids, burns corrosive and becomes almost a metallic calx. The Orders of earth are consequently: