GALLERY.] NATURAL HISTORY. 125 
which was by some mistaken for pure alumina, and by 
others for hydrate of alumina with mechanically admixed 
sulphate of lime: it must not be confounded with another 
substance also called cduminite or alum-stone (alunite of 
some mineralogists,) from Tolfa, &c., which is a basic sul¬ 
phate of alumina and potassa. 
Case 59 contains the fluorides, of which by far the most 
important species is the fluoride of calcium, generally 
called fluate of lime and fluor spar : among its numerous 
varieties may be particularized, the rose-coloured crystals 
from Chamouni; the phosphorescent massive fluor spar, 
called chlorophane, from Siberia; the varieties called forti¬ 
fication fluor; earthy and compact fluor, &c., chiefly from 
Derbyshire and Saxony.— Fluoride of calcium, yttrium and 
cerium;—yttrocerite; and some related minerals from 
Finbo and Brodbo near Fahlun in Sweden. Fluoride of 
sodium and aluminum, called cryolite, found in West 
Greenland : pure and mixed with brown iron stone, 
galena, &c. 
Case 60 contains the chlorides.—Chloride of sodium 
( muriate of soda), or rock salt: the most interesting speci¬ 
mens here deposited of this important mineral substance, 
are the crystallized varieties, the massive and fibrous 
coloured varieties, the red chiefly from Hallein in Tyrol, 
the blue and violet from Ischel in Upper Austria; the 
stalactical rock salt from Mexico, &c.— Chloride of am¬ 
monium or sal ammoniac, from Vesuvius, Saint Etienne en 
Forez, &c.— Chlorides of lead: to these belong, the co- 
tunnite from Vesuvius; the basic muriate of lead from 
Mendip; and, the murio-carbonaie of lead from Derby¬ 
shire, of which most rare substance a considerable suite is 
deposited in this glass Case.— Chloride of copper or ataca- 
mite, in crystallized splendid groups, chiefly from Remo- 
linos, Solidad and Veta negra della pampa larga, in Chili; 
what was originally termed sable vert de Perou, or ataca- 
mite (being obtained from the desert of Atacama between 
Chili and Peru) is now known to be artificially produced 
by pounding the crystallized and laminar varieties for the 
purpose of using the sand (arenilla) instead of blotting 
paper.— Chloride (or muriate) of silver, called also horn- 
silver and corneous silver : amorphous, botryoidal, in 
laminae, and crystallized in minute cubes and octahedrons, 
