144 



On Ice and Brines 



separates from sea-water and analogous saline solutions in a 

 condition to enable the question, whether the salt does or 

 does not form part of the solid matter of the crystals, to be 

 solved directly by chemical analysis. 



TABLE VIII. 



So far as chemical analysis is applicable, it is in favour of 

 the salt belonging exclusively to the adhering brine. When 

 sea-water is carefully frozen artificially, the ratio between the 

 chlorine and the sulphuric acid is the same for the solid 

 contents of the original water, the crystals, and the mother- 

 liquor. It is exceedingly unlikely, if part of the salt went 

 into the cystals, leaving the remainder in the brine, that there 

 would be no selective separation of its constituents. 



It has been shown that snow or pure lake ice, which, when 

 melting by itself or immersed in pure water at atmospheric 

 pressure, melts at the constant temperature called o C. or 

 32 Fahr., changes its melting temperature when immersed in 

 a saline solution. The altered melting temperature, however, 

 is the same for solutions of the same composition (no doubt 

 with some allowance for pressure) and different for solutions 

 of different composition. 



The temperature at which pure ice melts in a solution is 

 identical with that at which ice separates from the same 

 solution on being sufficiently cooled. 



