Chemical and Physical Notes 67 



The proof that the salt does not belong to the ice was 

 furnished by showing that snow or other pure ice, of inde- 

 pendent origin, which contains no salt, behaves in a saline 

 solution in exactly the same way as the alleged ice formed 

 by freezing the solution. 



Again, regarding the boiling of saline solutions, it was 

 observed that the boiling temperature of a saline solution is 

 higher than that of pure water, that the steam produced by it 

 is pure steam, and that a thermometer in the steam above the 

 boiling solution shows the same temperature as it would if 

 immersed in steam above pure boiling water. The question 

 which vexed many minds, was: When the steam is just 

 quitting the solution, has it the temperature indicated by the 

 thermometer immersed in the steam alone, or has it that of 

 the thermometer immersed in the boiling solution ? It was 

 held by some that the temperature of the thermometer 

 immersed in steam must be held to prove that the steam 

 leaves the solution at the temperature of pure boiling water. 

 Others contended that, although we have no means of 

 knowing at what temperature steam would condense on 

 perfectly dry glass, the moment there is the slightest moisture 

 on it the steam is condensing on water, and we know exactly 

 what that temperature is : it is and it must be the tempera- 

 ture of pure boiling water under the existing conditions, and 

 it proves nothing as to the temperature at which the steam 

 actually quitted the solution. 



The proof that the steam must quit the solution at the 

 temperature of the boiling solution is furnished by the 

 following considerations. We observe that when we blow 

 pure steam into a saline solution, it raises its temperature 

 above that of pure boiling water, and until a certain maximum 

 temperature is reached, which depends on the relation between 

 the salt and the water present. As steam continues to pass 

 and to condense in part, owing to the lower temperature of 

 the air outside, the temperature of the boiling solution falls 

 gradually as the amount of water present increases by the 

 condensation of steam. We see then that pure steam of 

 independent origin is condensed by a saline solution having 



5-2 



