240 Mr. T. S. Hunt on the Chemical Composition of 



The following analyses were made by me^ three years since, of 

 the waters of the St. Lawrence, and its great tributary the Ottawa, 

 and will serve to illustrate several important facts hitherto but 

 little noticed. 



The waters were collected at the close of the winter season, 

 after three or four months of frost, and before the melting of the 

 snows, and were taken at some distance from the shores, where a 

 rapid current prevented the ice from forming. The water of the 

 Ottawa was collected on the 9th of March, 1854, at St. Anne, 

 near the head of the island of Montreal ; the temperature of the 

 water here flowing from beneath the ice was 33° F., that of the 

 air being the same. The water was entirely free from all sedi- 

 ment, and had a pale amber-yellow colour, very distinct in masses 

 of 6 inches ; when heated, this colour deepens ; and by boiling, 

 a bright brown precipitate appears, which, when the water is eva- 

 porated to one-tenth, is seen to consist of small, brilliant, iri- 

 descent scales. These are not gypsum, of which the water does 

 not contain a trace, but consist of silica with lime, magnesia, 

 carbonic acid, and organic matter. Meanwhile the water becomes 

 much more highly coloured, and exhibits an alkaline reaction 

 with test-papers. When the above precipitate is boiled with a 

 dilute solution of potash, it is in part dissolved, and the alkaline 

 liquid acquires a dee]3 brown colour, which is rendered paler by 

 an excess of acetic acid. Acetate of copper yields no precipitate 

 with the acidulated liquid ; but on subsequently adding carbonate 

 of ammonia and applying heat, a minute white precipitate ap- 

 pears to indicate the crcnic acid of Eerzelivis. This, however, 

 corresponds to but a small portion of the organic matter present 

 in the water, where it probably exists chiefly in the form of 

 humic acid, or some analogous compound. 



The recent water, mingled with hydrochloric acid and a salt 

 of baryta, is at first clear, but after an hour becomes turbid from 

 the precipitation of a trace of sulphate. With nitric acid and 

 nitrate of silver, a slight milkiness from the presence of chloride 

 is perceptible. The chlorine and sulphuric acid were determined 

 upon four litres of the water, reduced by evaporation to a small 

 volume, and acidulated with nitric or hydrochloric acid. The 

 precipitate obtained with nitrate of silver and a few drops of 

 nitric acid in the evajwrated water, was scanty and reddish co- 

 loured ; after twelve hours of repose, it was separated, washed, 

 and dissolved on the filter by caustic ammonia ; from the coloured 

 liquid thus obtained, the chloride of silver was thrown down by 

 a considerable excess of nitric acid, while an organic salt of silver 

 remained in solution. 



The brown matter precipitated by boiling being dissolved in 

 hydrochloric acid, the solution was decolorized by boiling with 



