34 Chemical and Physical Notes 



the laboratory. The temperature of the mixture was observed 

 to rise slowly, and when it arrived again at 4, 4, 4 and 4 

 respectively, samples of the brine were again taken and 

 analysed. The resulting salinities s 4 , s 3 , s 2 , s 1 were found to 

 be identical with those observed at the same temperature 

 during cooling. 



Another solution of the same salt was now made, and of 

 strength represented by salinity s s . It was cooled down to 

 close on 4, and then snow was mixed with it. The vessel 

 having been removed from the cooling bath was exposed to 

 the heat of the laboratory, and the thermometer carefully 

 observed as the temperature rose. When the temperature 

 was exactly 4, 4, 4, 4, samples of brine were taken and 

 analysed, and the resulting salinities s t , s 3 , s 2y ^ were found 

 to be identical with those observed in the two previous 

 experiments. 



It was thus shown that when a saline solution of concen- 

 tration comparable with sea-water is gradually frozen, certain 

 crystals which we call ice-crystals separate out, and during 

 the process the temperature of the mixture gradually falls 

 while its concentration increases. When the mixture of brine 

 and ice-crystals is warmed the ice-crystals gradually melt, 

 the temperature rises and the concentration diminishes ; but 

 when in the process of cooling and freezing the temperature 

 has fallen to a certain point, say t, and the salinity is s, it was 

 found that when the process was reversed and the same 

 temperature t was reached during the process of warming 

 and melting, the solution was found to have the salinity s. 

 Therefore the substance, which forms the ice-crystals which 

 separate out at a temperature / during cooling, melts again 

 at the same temperature and concentration during warming. 

 When the same solution, having the highest concentration 

 which was used in the previous experiments, was cooled 

 down and mixed with snow and then gradually warmed, it 

 was found that the snow melted exactly as the ice-crystals 

 formed in the solution itself had done, and at exactly the same 

 temperature for the same salinity. But it is only a question 

 of whether the salt is in the ice or in the brine. There is no 



