1865.] CHEMISTRY OF NATURAL WATERS. 165 



brines whose analyses are given in the above table, and such we 

 suppose to have been their origin. The complete absence of sul- 

 phates from many of these waters points to the separation of large 

 quantities of earthy sulphates in the Lower Silurian strata fro-n 

 which these saline springs issue ; and the presence in many of the 

 dolomitic beds of the Calciferous sand-rock of abundantly dissemina- 

 ted small masses of gypsum, is an evidence of the elimination of 

 the sulphates by evaporation. The frequent occurrence of crys- 

 talline masses of sulphate of strontian in the Chazy and Black 

 River limestones of this region, is also to be noted as another 

 means by which the sulphates were separated from the waters of 

 the Lower Silurian seas. From the proportions of chlorid of 

 sodium, varying from about one third to more than two thirds of 

 the solid contents of the above waters, it is apparent that 

 in most cases the process of evaporation had gone so far as to 

 separate a part of the common salt ; and thus successive strata of 

 this ancient saliferous formation must be impregnated with solid 

 or dissolved salts of unlike composition. The mingling of these 

 in varying proportions affords the only apparent explanation of the 

 differences in the relative amounts of the several chlorids in 

 waters from the same region, and even from adjacent sources. These 

 differences are seen on comparing the waters from the different 

 wells of St. Catherines, Hallowell and Kingston, with each other. 



§ 38. The great solubility of chlorid of calcium renders it diffi- 

 cult to suppose its separation from the mother-liquors so as to be 

 deposited in a solid state in the strata. The same remark applies 

 to chlorid of magnesium. It is however to be remarked that the 

 double chlorid of potassium and magnesium (carnallite) is decom- 

 posed by deliquesence into solid chlorid of potassium and a solu- 

 tion of chlorid of magnesium ; and thus strata like those which at 

 Stassfurth contain large quantities^ of carnallite (§ 22), might give 

 rise to solutions of magnesian chlorid. This however would require 

 the presence of a large amount of chlorid of potassium in the early 

 seas. It will be observed by referring to the analyses above given, 

 that the chlorid of magnesium sometimes surpasses in amount the 

 chlorid of calcium ; and sometimes, on the contrary, is equal to only 

 one half or one fourth of the latter salt. While it is not impossible 

 that the predominance of the magnesian chlorid in some waters 

 may be traced to the decomposition of carnallite, it is undoubtedly 

 in most cases connected with the action of solutions of carbonate 

 of soda ; the effect of which, as already pointed out, is to first 



