226 DESCRIPTIONS OF MINERALS. 
The Dead and Caspian Seas, and the lakes of Khoordistan, 
are salt. From 20-26 per cent. of the weight of the water 
from the Dead Sea are solid salts, of which 10 per cent. are 
common salt. Over the pampas of La Plata and Patagonia 
there are many ponds and lakes of salt water. 
The greater part of the salt made in this country is ob- 
tained by evaporation from salt springs. Those of Salina and 
Syracuse are well known ; and many nearly as valuable are 
worked in Ohio and other Western States. At the best New 
York springs a bushel of salt is obtained from every 40 gal- 
lons. But the discovery of rock salt at Wyoming, west of 
Syracuse, may lead to further discoveries, which will make 
the brines of New York of comparatively little value. ‘To 
obtain the brine, wells from 50 to 150 feet deep are sunk by 
boring. It is then raised by machinery. 
The process of evaporation under the heat of the sun is 
extensively employed in hot climates for making salt from 
sea water, which affords a bushel for every 300 or 350 gal- 
Jons. For this purpose a number of large shallow basins 
are made adjoining the sea; they have a smooth bottom of 
clay, and all communicate with one another. ‘lhe water is 
Jet in at high tide and then shut off for the evaporation to 
go on. This is the simplest mode, and is used even in un- 
civilized countries, as among the Pacific Islands. 

Mirabilite.—Glauber Salt. Hydrous Sodium Sulphate. 
Monoclinic. Occurs in efflorescent crusts of a white or 
yellowish-white color; also in many mineral waters. ‘laste 
cool, then feebly saline and bitter. 
Composition. Na, O,8+10aq = Sulphur trioxide 24°8, 
soda 19°3, water 55°9=100. 
Diff. It is distinguished from Epsom salt, for which it 
is sometimes mistaken, by its coarse erystals, and the yel- 
low color it gives to the blowpipe flame. 
li is made in enormous amounts from common salt, its 
production being one stage in the manufacture of sodium 
carbonate. It is used in medicine, and is known by the 
familar name of “salts.” 
Obs. On Hawaii, one of the Sandwich Islands, in a cave 
at Kailua, Glauber salt is abundant, and is constantly form- 
ing. It is obtained by the natives and used as medicine. ~ 
Glauber sult occurs in efflorescences on the limestone below 

