59

Analysis No. 1 gives the composition of what is probably the same material,
but after it had been exposed to the weather for many years. The analysis
indicates the presence of 98 per cent of NaeCO;.5H.0, some water in
excess, and less than one-fifth of 1 per cent of sodium sulphate.

Sodium carbonate! crystallizes from solution with 1, 2, 3, 5, 6, 7,
10, and 15 molecules of water, depending on the temperature of crystal-
lization and free exposure to the air. Analysis No. 2 was made of a trans-
lucent, colourless salt and, therefore, the material was presumably taken
from the interior of the stock pile, whereas sample 1 was collected from
the surface of the pile which after exposure for a few winter months in a
heated building had been converted into a fine white powder. The analysis
(No. 1) probably represents the salt in an intermediate stage in the con-
version from natron to a carbonate with less water, thermonatrite, NasCOs
.H.O and this is said to be the composition of the material existing as a
white efflorescence on the shores of all the soda lakes in this area. The
manufactured soda from the lake just west of 70 Mile House is of much
the same composition except for the presence of a small percentage of
chlorides -and a proportion of crystalline water that indicates Na»CO3
3H.O rather than the higher hydrates. Since this salt was also freely
exposed to the air before sampling, it probably represents another stage
in the change from natron to thermonatrite.

The crust of salt from Last Chance lake carries 5 per cent of sodium
sulphate. /

An analysis of the brine from Goodenough lake, Table IX, No. 2,
shows 0-7 per cent of potassium, brine from the Last Chance 3-32 per
cent potash out of a total of 15-9 per cent solids in solution. The brine
from Hutchinson lake, sample 1, Table IX, is a relatively pure sodium
carbonate water, but of comparatively low concentration.

2 Table VIII.—Analyses of Salts from Soda Lakes.

1 a 3 4

oT 1 Zoe s nites aichgi. Fete tek ete eer eee rep on emer oe Pe ge Reg OCs NazO 31:36) -2- 36 fe 37-83
Pre bees es ee ee Nae ISN es Sree Sear K:O Eras ee ee es 0-05
Masnesia. {oo ok Ref SERS Beane Ree re ee MgO 0:04) oe ee 0-09
rhe ol tarry eee ek Eh ee eee oe SiOe trace. 0-0L sae
MINS ANG: HON ee ES AlsOsFe2O3FeO. races a ee ee a
Carbon GiOMdes foe Sk Oe ae CO2 22-08 15:46. 2 26-70
SHEET GBIOMGE © 4 see a ere ee SOs; 0-11 0-08 ses). 0-04
Phosphorus pentoxide..... ee ee oe ee ate ee Pie ise OG: 0t es See
Proren GHIOXIde sos ee rt ea ares BOge 3s eee EPACC LS fee eee
Clnlorune sre at Re A Oe eg oe eee Cl: .| trace OO toe tece: 0-37
Water above fons ica a EP es oe ee eee 4. (US 3s Seer 0-61
Wiriter peliwo lt Gnd s a oa ee Pe aa ee QncQiea ee Pre 33-98

99-902) = 99796 [n= 99-67

1Chatard, Thos. M., ‘‘Natural soda, its occurrence and utilization.’’ U.S.G.S. Bull. 60, 1890, p. 31.