57

data as to thickness are available, no close estimate of the tonnage can be
made. If every year an inch of epsomite grows uniformly over all the
present salt areas, the increase should amount to between 1,500 and 2,000
tons per annum. From the conditions obtaining at Kruger mountain
it would seem possible that other epsomite layers may occur in the under-
lying mud.

SODIUM CARBONATE.

Between the west end of Meadow lake and a point about 5 miles east
of 70 Mile House, there are a number of saline lakes with brines consisting
predominantly of sodium carbonate. These lakes lie in an almost per-
fectly straight line trending slightly north of west. Other soda lakes occur
southeast from Meadow lake toward Little White lake and also north of
70 Mile House.

VARIETIES.

Sodium carbonate is marketed! in the following inne (1) soda ash,
NasCOs; (2) salsoda, also known as washing soda, crystal carbonate, or
natron, Na2CO3. 10H.O; (3) bicarbonate of soda or baking soda, or saleratus,
NaHCoO;; (4) sodium carbonate monohydrite, or thermonatrite NazCQ3.
H.O; (5) trona or sodium sesquicarbonate, NasCO3. NaHCOQO3.2H,0.

~ (1) Soda ash is manufactured from sodium sulphate, limestone, and
coal, by the Leblanc process; by the Solvay process it is made from a
sodium chloride brine saturated with ammonia into which carbon dioxide
is introduced, thereby causing the precipitation of sodium bicarbonate
which is calcined to produce soda ash. Soda ash is also manufactured
from the mineral eryolite and from natural deposits of sodium carbonate.

(2) Salsoda is made by dissolving soda ash and reprecipitating the
salt at a temperature below 32 degrees Centigrade. It is also found in
natural deposits.

(3) Baking soda or bicarbonate of soda, NaHCO;, is made by the
Solvay process and is a partial constituent of many natural deposits.

Table VII.—Production of Sodium Carbonate in the United States.

1916. 1917.
Short tons.| Value. Short tons.| Value.
e $ $
Boduimt-pacnruonate.-. 115,177 | 2,303,540 174,212 | 5,292,374
i RR a eS ee ss ee aes 1,324,208 | 18,283,866 | 1,578,889 | 38,374,199

INCI ee go ee Se A oe Bo WAS ee Oh ee 77,939 | 1,698,520

1Wells, Roger C., ‘‘Sodium salts in 1917.’’ Mineral resources of the United States, 1917, pt. Il, ¢ pp. 305 to 341,
Information regarding uses, etc., from same publication.