The Study of Mineralogy. 241 
native sulphids of zinc, cadmium and arsenic, and the sin- 
gular metallic character assumed by the complex tungstates _ 
or Tungstometalloids, known as tungsten bronzes. These, 
with the not less remarkably complex soluble tungstates or 
Tungstosalinoids, and the native tungstic species, make the 
Tungstates one of the most instructive orders known. 
§ 7. The author has elsewhere proposed to divide the 
mineral kingdom into four classes, including (1) Metalline, 
(2) Oxydized, (3) Haloid, (4) Pyricaustate (combustible or 
fire-making) species. Hach of these classes is again divided 
into orders, tribes, genera and species. In the first class a 
single order includes two sub-orders and nine tribes, named 
(1) Metalloideze ; (2) Galenoidez, including three sub-tribes 
corresponding to sulphur, selenium, and tellurium com- 
pounds; (3) Bournonoidee; (4) Pyritoidee; (5) Smal- 
toidee; (6) Arsenopyritidee; (7) Spatometalloidex ; (8) 
Sphaleroidex; (9) Proustoidex ; each tribe including one 
or more genera. Again, in the second class are grouped 
under different orders, Oxyds, Silicates, Carbonates, Borates, 
Sulphates, Phosphates, Tungstates, &c. Three sub-orders 
of silicates include protoxyd, protoperoxyd and peroxyd 
silicates; among peroxyd bases being reckoned aluminic, 
ferric, manganic, chromic, bismuthic, and also, for special 
reasons, zirconic oxyd. Recognising in each sub-order va- 
rious types designated Hydrospathoid, Spathoid, Adaman- 
toid or gem-like, Phylloid or micaceous, and Porodic or 
colloidal; the tribes may be named Pectolitoid, Willemoid, 
Amphiboloid, Talcoid, Ophitoid, Zeolitoid, Feldspathoid, 
Granatoid (garnet-like), Micoid, Pinitoid, Perzeolitoid, 
Julyioid, Topazoid, Pyrophilloid and Argilloid. Soluble 
saline species in any order are referred to a salinoid type, 
as Borosalinoid, Tungstosalinoid. The extension of this 
system to the Haloid and Pyricaustate classes is easy, and 
has been elsewhere explained. 
The work of arranging in genera and species, with a 
Latin binomial nomenclature, and the determination for 
each species of the value of v, is now nearly complete for 
the first two classes; and the whole will probably soon 
