the Crystallization of Saline Solutions. 



rimental examination of the influence of other gases, besides at- 

 mospheric air, in determining crystallization. Their influence 

 was found to be precisely proportionate to the degree in which they 

 are absorbed or dissolved by water and the saline solutions. 



To a solution of sulphate of soda over mercury, which had 

 not been affected by a bubble of atmospheric air, a bubble of car- 

 bonic acid gas was added. Crystallization was instantly deter- 

 mined around the bubble, and thence through the whole mass. 

 Water is capable of dissolving its own volume of carbonic acid 

 gas, and a solution of sulphate of soda as strong as could be em- 

 ployed was found by SAUSSURE to absorb more than half its vo- 

 lume. 



In a solution of sulphate of soda, which was rather weak, 

 both common air and carbonic acid gas failed to destroy the 

 equilibrium ; but a small bubble of ammoniacal gas instantly de- 

 termined crystallization. 



When gases are employed which water dissolves abundantly, 

 such as ammoniacal and sulphurous acid gases, the crystallization 

 proceeds most vigorously. It is not deferred till the bubble of 

 gas reaches the top of the receiver, as always happens with com- 

 mon air, and frequently with carbonic acid gas, but the track of 

 the bubble becomes the common axis of innumerable crystalline 

 planes, upon which it appears to be borne upwards ; and some- 

 times before the ascent is completed, the bubble is entangled and 

 arrested by crystalline arrangements which precede it. 



The number of gases which are less soluble in water than at- 

 mospheric air is not considerable, but of these hydrogen gas was 

 found, to be decidedly less influential in determining crystalliza- 

 tion. 



Minute quantities of foreign liquids soluble in water likewise 

 disposed the saline solution to immediate crystallization, as might 

 be expected, and none with greater effect than alcohol. It is 

 known that alcohol can precipitate sulphate of soda from its 



