the Waters of the St. Lawrence and Ottawa Rivers. 243 



Carbonate of lime .... '8033 grm. 



Carbonate of magnesia . . . "2537 ... 



Chlorine -0242 ... 



Sulphui'ic acid -0687 ... 



Silica -3700 ... 



Chloride of sodium .... -1280 ... 



Chloride of potassium . . . '0220 ... 



Residue dried at 300° F. . . 1-6780 ... 



Residue ignited 1*5380 ... 



When evaporated to one-fortieth, the water still contains in 

 solution silica and lime, but no magnesia ; the amount of silica 

 thus retained was 0*750, and the lime equalled 0-050 of carbon- 

 ate for ten litres. The proportions of sulphuric acid and chlo- 

 rine are much larger than in the Ottawa water, but are insuffi- 

 cient to neutralize the alkaline bases ; so that the lime in the 

 evaporated water must exist in combination with organic acids, 

 or more probably as a soluble silicate. I subjoin the calculated 

 results of the analysis for 10,000 parts, the lime and magnesia 

 being represented as carbonates : — 



Carbonate of lime .... '8083 grm. 



Carbonate of magnesia . . . '2537 ... 



Silica -3700 ... 



Chloride of potassium . . . '0220 ... 



Chloride of sodium .... '0225 ... 



Sulphate of soda .... -1229 ... 



Carbonate of soda .... "0061 ... 

 Oxide of iron and manganese . \ . . 

 Alumina and phosphoric acid .J 



The presence of silicate of lime in an alkaline solution is con- 

 stantly met with in the analysis of alkaline mineral waters. I 

 have signalized it in the Varennes, Chambly, and Fitzroy springs; 

 and Dr. J. L. Smith has remarked a similar fact in his examina- 

 tions of the thermal springs of Asia Minor*. I have found that 

 if such a water is evaporated to dryness with the precipitated 

 carbonates in suspension, the whole of the silica is separated in 

 combination with the earthy bases ; but if the earthy carbonates 

 at first thrown down by boiling are removed, there separates 

 upon subsequent evaporation a silicate of lime, which does not, 

 however, contain the whole of the dissolved silica, a portion re- 

 maining as an alkaline silicate. 



Bischoff has shown that artificial silicate of lime, which is 

 somewhat soluble in water, is decomposed by carbonate of mag- 



* American Journal of Science (2), vol. xii. p. 377- For similar obser- 

 vations see also Bischofif 's ' Chemical Geology,' English edition, vol. i. p. 6. 



S2 



