280 THE CANADIAN NATURALIST. [Aug. 



Bineau, equal to 1 : 30,000 or 1 : 50,000.) We should not there- 

 fore expect to find that water holding chlorid of calcium in solution 

 would yield, by boiling, more than the latter amount of magnesian 

 carbonate; so much might evidently be formed by the action 

 of dissolved carbonate of lime which the water might hold as 

 bicarbonate. I have elsewhere described a series of experiments 

 on the solubility of bicarbonate of lime both in pure water and 

 in saline solutions, and have shown that the presence of salts of soda, 

 lime and magnesia does not increase the amount of bicarbonate of 

 lime which water is capable of holding permanently in solution. In 

 view of these facts it seems at first sight difficult to explain how 

 a mineral water like that of Kingston (§ 36, No. 7)', holding a large 

 quantity of chlorid of calcium, could yield, as appears from Dr. 

 Williamson's analysis, 1.287 grams of carbonate of magnesia, equal 

 to 1.462 of carbonate of lime to the litre. Recent experiments 

 have however shown me that supersaturated solutions of a certain 

 stability may be obtained, in which comparatively large quantities 

 of neutral carbonates of lime and magnesia exist in the presence 

 of sulphates and chlorids of calcium and magnesium, Reserving 

 for another occasion a description of the details of these investiga- 

 tions, I shall briefly state the results obtained. 



§ 56. In a memoir on the salts of lime and magnesia published in 

 1859 (Silliman's Journal [2] xxviii. 171), it was shown that by the 

 addition of bicarbonate of soda to a solution holding chlorids of sodium 

 calcium and magnesium, with or without sulphate of soda, and satu- 

 rated with carbonic acid, it was possible to obtain transparent 

 solutions holding from 3.40 to 4.16 grains of carbonate of lime to 

 the litre ; of which however the greater part was deposited after 

 twenty-four hours ; when the solutions were found to contain some- 

 what less than 1.0 gram in the form of bicarbonate. Boutron and 

 Boudet had previously shown that by saturating lime-water with 

 carbonic acid, solutions were obtained holding in a litre 2.3 grams 

 of carbonate of lime ; of which one half was soon deposited, even 

 when the solution was kept under a pressure of several atmospheres. 

 It would thus seem that saline liquids favor this temporary solu- 

 bility of the carbonate of lime. 



In all of the above experiments, an excess of carbonic acid 

 was present, but this I have since found is not essential, since 

 super-saturated solutions may be obtained holding as much 

 as 1.2 grams of carbonate of lime, together with sulphate of mag- 

 nesium and chlorid of calcium, in a litre of water, without any 



