T. S. Hunt on the Chemistry of Natural Waters. 189 
_ , $27, Gypsum may thus be separated from sea-water by two 
distinct processes,—the one a reaction between sulphate of mag- 
negia and chlorid of calcium, and the other between the same 
sulphate and carbonate of lime. The latter, involving a separa- 
tion of bicarbonate of magnesia, can as we have seen, only take 
place when the whole of the chlorid of calcium has been elim- 
inated ; and if we suppose the ancient ocean, unlike the present, 
to have contained more than an equivalent of lime for each 
equivalent of sulphuric acid, it is evident that a lake or basin of 
sea-water free from lime salts could only have been produced by 
the intervention of carbonate of soda. The action of this must 
have eliminated the whole of the lime as carbonate, or at least 
have so far reduced the amount of this base that the sulphates 
present would be sufficient to separate the remainder by evapo- 
ration, in the form of gypsum, and still leave in the mother- 
liquor a quantity of sulphate of magnesia for reaction gvith bi- 
carbonate of lime 
sa : pene 3 
Mineral waters already enumerated, viz., decaying organic mat- 
of alumina, lime, magnesia, and alkalies. This process of oxy 
ation is cet superficial and local, but the soluble sul- 
- ee formed have probably played a not unimportant 
5 Tt, ($ 9. 
 . $29. Besides these last, which contain chiefly neutral and 
_ Mid salts, there is another class of waters characterized by the 
—— of free sulphuric or chlorhydric acid, or both together. 
| hese acid waters someti r as products . 
eehon, during which both chlorhydric acid and sulphur _ 
often evolved in large quantities. This latter element generally 
€s to the surface as sulphuretted hydrogen, which by the 
ae boteon ee Ob xxviii, 180-186, and further, Geol. Survey of Canada, Report 
Jour. Sct.—Srcoxp Sentes, Vol. XXXIX, No. 116.—Marcu, 1865. 
25 
