COMPOUNDS OF CALCIUM. 209 
easily, with sulphuric acid and heat, a gas that corrodes 
glass. 
Obs. Fluorite occurs in gneiss, mica schist, clay slate, 
limestone, and sparingly in beds of coal either in veins 
or occupying cavities, or as imbedded masses. It is the 
gangue in some lead mines. 
Cubic crystals of a greenish color, over a foot each way, 
have been obtained at Muscolonge Lake, St. Lawrence 
County, N. Y.; near Shawneetown on the Ohio, a beautiful 
purple fluor in grouped cubes of large size is obtained from 
limestone and the soil of the region ; at Westmoreland, N. 
H., at the Notch in the White Mountains, Blue Hill Bay, 
Maine, Putney, Vt., and Lockport, N. Y., are other locali- 
ties. The chlorophane variety is found with topaz at ‘Tram- 
bull, Conn. 
In Derbyshire, England, fluor spar is abundant, and hence 
it has received the name of Derbyshire spar. It is a com- 
mon mineral in the mining districts of Saxony. 
Calcium fluoride also exists in the enamel of teeth, in 
bones and some other parts of animals ; also in certain parts 
of many plants ; and by vegetable or animal decomposition 
it is afforded to the soil, to rocks, and also to coal beds in 
which it has been detected. 
Massive fluor receives a high polish, and is worked into 
vases, candlesticks and various ornaments, in Derbyshire, 
England. Some of the varieties from this locality, consist- 
ing “of rich purple shades banded with yellowish white, are 
very beautiful. The mineral is difficult to work because 
brittle. Fluor spar is also used for obtaining hydrofluoric 
acid, which is employed in etching. ‘To etch glass, a pic- 
ture, or whatever design it is desired to etch, is traced in 
the thin coating of wax with which the glass is first covered; 
a very small quantity of the liquid hydrofluoric acid is then 
washed over it ; on removing the wax, in a few minutes, the 
picture is found to be engraved on the glass. The same 
process is used for etching seals, and any siliceous stone 
will be attacked with equal facility. This application of 
fluor spar depends upon the strong affinity between fluorine 
and silicon. Fluor spar is also used as a flux to aid in re- 
ducing copper and other ores, and hence the name flwor. 
