110 DESCRIPTION AND ANALYSIS OP A MINERAL, ETC. 
period be of immense advantage to that portion of the coun- 
try in an agricultural point of view. 
THE SALT. 
The following observations accompanied the saline matter, 
viz. : " This species of salt was taken from a pond, near El 
Paso del Norte, in the department of Chihuahua. This pond 
spreads over two or three acres of ground. During the wet 
season the water only is strongly impregnated with the salt ; 
but when dry weather comes on, it crystallizes on the surface 
of the water, and presents the appearance of a pond of limpid 
ice. When a hatchet is struck into it, it chips out with about 
the same facility and brittleness as that substance: In some 
parts of the pond it is found crystallized to the depth of five or 
six inches. I have heard it said that the natives sometimes 
use it as a purgative. Many of these ponds or lakes occur on 
the route to the Rocky Mountains, but none of them are so 
highly impregnated with the salt as the one from which the 
specimen was obtained." 
Description. — The specimen, as presented to view, was a 
white povvder, having all the appearance of an effloresced salt; 
a saline disagreeable taste, without odor, and completely and 
readily soluble in water, except about one per cent, of impu 
rities. 
When the solution is evaporated till a pellicle forms, it be- 
comes nearly a solid mass of prismatic crystals by cooling. 
When the mother waters are suffered to drain off, and evapo- 
rated, more crystals are obtained. 
Twenty-eight grains of the crystallized salt was subjected to 
a gentle heat, until deprived of its water of crystallization, and 
yielded 12.5 grains of anhydrous salt. This was dissolved in 
water and treated with solution of chloride of barium, until a 
precipitate ceased to be produced. This precipitate, when col- 
lected on a filter, washed till the water that passed remained 
unaffected by nitrate of silver, dried and weighed, amounted 
