On Ice and Brines 



135 



localities. It is to be remembered that in these experiments 

 the water was frozen gently that is, the rate of abstraction of 

 heat was low, the temperature of the freezing-bath being 

 regulated so as to be about 2 C. below the freezing tempera- 

 ture of the solution. Much of the error and uncertainty 

 about the freezing of saline solutions arises from the violence 

 of the methods employed. Judging then by the constancy of 

 the relation of the percentage of Cl to SO 3 , we see that in 



TABLE I. Freezing Sea- Water Analyses of Fractions. 



sea-water, frozen at moderate temperatures, the composition 

 of the saline contents of the original water, the mother-liquor, 

 and the ice is identical ; and we are justified in concluding 

 that it is probable that the saltness of the ice is due to 

 unfrozen and concentrated sea-water adhering to it. Ice 

 formed in even very weak saline solutions closely resembles 

 snow (which is ice formed in air), and has the same remark- 

 able power of retaining mechanically several times its weight 

 of water or brine. 



If we assume that the ice formed in freezing sea-water is 

 pure ice, and that the saline ingredients are retained by the 

 portion remaining liquid, we can calculate the amount of ice 

 which has been formed if we know the salinity of the original 

 water and that of the residual brine. In the case of sea-water 

 the salinity varies directly with the percentage of chlorine. 

 The weight of the brine remaining after any freezing operation 

 is found by multiplying the weight of the original water used 

 by the ratio of the chlorine percentage found in the original 



