1865.] CHEMISTRY OF NATURAL WATERS. 285 



converted into carbonates, the sulphur being separated either as sul- 

 phuretted hydrogen (giving rise by oxydatiorn to free sulphur,) or 

 as insoluble metallic sulphurets. This reducing action not only de- 

 composes the soluble sulphates of soda, lime and magnesia, but also, 

 as has been pointed out in § 57 may extend to sulphate of baryta 

 and thus sulphuret or carbonate of baryta be ^formed. It is the 

 action of these soluble baryta salts which constitutes the second 

 mode of desulphatizing waters ; and this, if we may judge from 

 the frequence with which baryta salts occur in the saline waters 

 in question, appears to have been the most general process. 



It is a fact worthy of notice that a saline spring at Sabrevois 

 near Lake Champlain, which holds both baryta and strontia in solu- 

 tion, is at the same time slightly impregnated with sulphuretted 

 hydrogen. Another saline and sulphurous spring, which rises 

 within ten feet of this, contains however a portion of sulphates. 

 (Geology of Canada, page 542.) 



§ 62. I am indebted to Prof. Croft of Toronto, for some notes 

 of a recent examination by himself of a saline of the first class, 

 which contains at the same time a soluble sulphuret. This water, 

 from a boring sunk to a depth of several hundred feet through the 

 Devonian limestone at Chatham, Canada West, had a specific gravity 

 of 1039.3, and yielded for a thousand parts about 51.0 of solid 

 matters. It contained large portions of chlorids of calcium and 

 magnesium, with very little sulphate, traces of carbonate, and no 

 free carbonic acid. The water, which gave an alkaline reaction 

 with turmeric, was greenish in color, very sulphurous to the taste, 

 and yielded a purple color with nitro-prussid of sodium, and a black 

 precipitate of sulphuret with a solution of sulphate of iron. A 

 current of carbonic acid rendered the recent water opalescent, and 

 by exposure to the air it deposited sulphur. A quantitative anal- 

 ysis of this water is to be desired. 



§ 63. Borates. — The reddening Of the yellow color of turmeric 

 paper in presence of free hydrochloric acid, affords, with certain 

 precautions, the ordinary means for detecting small portions of boric 

 acid. Most of the waters of the third and fourth classes, and some 

 of those of the second have been tested in this way, and have never 

 failed when reduced to a small volume, and acidulated with hy- 

 drochloric acid, to give this reaction ; which was however most 

 marked with the waters of the fourth class. The determination of 

 the amount of boric acid in saline waters presents no small dif- 

 ficulty. In the case of the alkaline water of Joly (§ 45, No. 3) the 



