VIEWS ON MINERAL SPECIES. 435 



if correctly interpreted should lead to the same classification 

 as the latter. 



Dr. Sterry Hunt next supposed that the specific gravity 

 of any substance, whether gaseous, liquid, or solid, is its 

 molecular weight, and hence that the degree of condensa- 

 tion of any species can be determined from its specific 

 gravity referred to hydrogen gas as unity ; on this 

 hypothesis the degree of condensation is the reciprocal of 



the atomic volume v, and v — ^ where p is the equivalent 



weight and d the specific gravity. 



With these assumptions water is about 1192 H 2 0, 

 and the co-efficient of condensation is 21400; calcite is 

 584 Ca C0 3 , quartz is 950 Si 2 . 



It is next asserted that the hardness of a species varies 

 inversely as the atomic volume, and that the solubility 

 increases with the atomic volume. 



According to this view minerals and the other solid 

 chemical compounds are highly polymerised substances, of 

 which the degree of polymerisation can be determined from 

 the specific gravity and is also indicated by the hardness 

 and solubility. The Mineral Kingdom is thus divided 

 into four classes, Metallaceae, Halidacese, Oxydacese, 

 Pyricaustacese, which are again sub-divided into orders, 

 genera, and species. The orders are based upon chemical 

 composition alone ; thus the Oxydaceae, or oxygen com- 

 pounds, are divided into twenty-two orders, of which 

 Oxidinea, Boratinea, Spinellinea, Carboninea, Silicinea, and 

 Argillinea (more commonly known as Oxides, Borates, 

 Aluminates, Carbonates, Silicates, and Alumo-silicates) are 

 the first six. 



The genera are based upon " natural-historical charac- 

 ters," i.e., lustre, hardness, and atomic volume ; thus in 

 the order Argillinea, Felspar (together with Petalite and 

 Cordierite) constitutes the genus Agrolithus, which is 

 spathoid {i.e., sparry) in appearance, with hardness less than 

 7, and atomic volume greater than 6; Garnet constitutes 

 the genus Granatus, which is adamantoid {i.e., gemmy in 

 appearance and not easily soluble), with hardness greater 



3i 



