IX.] CHEMISTRY OF NATURAL WATERS. 163 



phur corresponding to the dissolved sulphide of arsenic being 

 provisionally estimated as sulphide of sodium. We have thus 

 for 1,000 parts of the water, as follows : 



Chloride of sodium 14.4460 



Chloride of potassium .... .3350 



Chloride of calcium .... 3.1830 



Chloride of magnesium . . . 5.7950 



Sulphate of lime 3.0580 



Sulphide of sodium .... .8797 | _ ,QQQ T 



Sulphide of hydrogen . . . . .0767) 



27.7734 



Waters like this of Bothwell are not unfrequently met with in 

 the borings in the adjacent region, especially in those in Ennis- 

 killen, where in a well at Petrolia, at a depth of 471 feet from 

 the surface, and 171 feet from the summit of the Corniferous 

 limestone, a copious spring of this kind was struck, which 

 filled the bore of the well, and flowed in a copious stream, 

 bearing with it a little petroleum. It was a very bitter sa- 

 line, which dissolved sulphide of arsenic, and gave a purple 

 color with nitroprusside of sodium, but was less strongly sul- 

 phurous than that of Bothwell. Waters apparently similar 

 are pumped from several of the oil-wells in the vicinity. 



From the facts observed in these wells of Bothwell, Petrolia, 

 and that of Chatham mentioned already in 62, it would ap- 

 pear that these waters occur beneath the Corniferous limestone, 

 and in the upper part of the Onondaga or saliferous formation of 

 the region. The great density of that of Chatham, which much 

 surpasses that of sea-water, shows it to be derived from a bittern, 

 the result of the evaporation of the waters of an ancient sea. 

 The sulphurous impregnation is doubtless to be ascribed to the 

 reducing action of hydrocarbonaceous matters upon the sul- 

 phates which these waters contain. It may therefore happen 

 that the proportion of sulphides in them will be found subject 

 to considerable variations. 



