156 University Geological Survey of Kansas. 
one of the Hutchinson brines made in the laboratory of the 
University shows that it has the following composition, ex- 
pressed in parts per 1000 : 
ANALYSIS OF HUTCHINSON BRINES. 
Sodium eh lOrideye se Vy Ne ee Me aN ere ne) man en am 273.560 
Tnsoluble residue wy sees pa essere icle wear ue au ee ale 025 
Calcium: sulphates ees io cay Sy ete eA ek acer Tee ae 5.855 
Magnesumchlorideaine aay ae. pee ee eee 2.450 
Caleium Chloride cere ee tea get ee Tea ea .226 
Water (bycdifierence) Garver sha eee Ce eee 717.884 
TPO Gales ae te eRe cues RS eRe ane nee ERS Tae 1000 
In regard to the composition of calcium sulphate, a late author- 
ity,” says: ‘‘This substance was known from early times as a 
mineral closely resembling cale-spar, because like the latter it 
became brittle on burning. In 1764 Pott described these two 
substances as being different earths, and stated that some chem- 
ists assumed that the substance artificially produced by the 
union of sulphuric acid with lime was gypsum, and termed it 
gypsum artefactum. In 1750 Marggraf showed that these two 
substances were identical.”’ 
‘¢Gypsum is sparingly soluble in water, one part of CaSO,-++ 
2H.O dissolving, according to Marignac,™ at 0° C. in 4155 at 18°in 
368: at 24.1n 378) abo2 im37il at 381m 368)- at 4 sind 70 sama 
at 53° in 375 parts of water. The point of maximum solubility 
lies therefore between 32° and 41° C. In the presence of many 
other salts calcium sulphate dissolves more readily, probably ow- 
ing to the formation of double salts. Thus, according to Anton, 
1 part of gypsum dissolves in 122 parts of a saturated solution 
of sodium chloride. Gypsum is tolerably soluble in boiling 
hydrochloric and nitric acid, and separates out from the acid 
solution on cooling in glittering silky needles.’’ From the 
above it may be seen that although some authors state that the 
presence of salt tends to precipitate the gypsum, really it assists 
greatly in the solution, and the analysis of the brine given above 
would seem to confirm this statement. The rule was long ago 
538. Roscoe and Schorlemmer, Vol. II, p. 487. 
54. Ann. Chim. Phys. 1874, (5) 1274. 
