On Ice and Brines 145 



When sea-water is frozen to the extent of 1 5 per cent, of 

 its mass, and the crystals so formed are allowed to melt in 

 the liquid in which they have been produced, they melt 

 exactly as they have been formed. If snow or pure ice be 

 immersed in the brine formed by partially freezing sea-water, 

 it melts at the same temperature as the ice which had been 

 formed by freezing the sea-water, so long as the chemical 

 composition remains the same in each case. 



The heat removed in freezing sea-water to the extent of 

 15 per cent, of its mass accounted for the production of the 

 same amount of ice as was given by calculation on the basis 

 of the chlorine found in the mother-liquor. 



When some saline solutions are cooled for a sufficient 

 length of time at a sufficiently low temperature, there arrives 

 a certain concentration at a certain temperature, when further 

 removal of heat causes solidification of the brine as a whole 

 (cryohydrate). 



The concentration necessary for the solidification of even 

 the cryohydrate of highest melting temperature is such that 

 in the primary freezing of the water of the sea no such body 

 can be formed. It would follow from this consideration alone 

 that the first ice formed on the sea in Arctic regions consists 

 of pure ice, and it is also certain that it would retain a large 

 quantity of the residual sea-water in its interstices. During 

 the winter this inclosed liquor would solidify in the interstices 

 of the crystals to ice and cryohydrates, in so far as the 

 temperature and the nature of the salts in solution would 

 permit. From my experiments with chloride of calcium, and 

 the existence of brines observed to remain liquid at 30 C. 

 at the winter-quarters of the " Vega," it is unlikely that sea- 

 water, as a whole, can ever be completely solidified in nature. 

 The presence of unfreezable or difficultly freezable brine in 

 freshly- formed sea-water ice, explains its eminently plastic 

 character even at very low temperatures. 



The fact that cryohydrates of different salts solidify and 

 melt at different temperatures, sufficiently explains the various 

 composition of different specimens of old sea-ice. 



The apparent expansion, near the melting-point, of ice 



