No. 3. [From the Proceedings of the Royal Society of 

 Edinburgh, 1887, Vol. XIV, p. 129.] 



ON ICE AND BRINES 



THE composition of the ice produced in saline solutions, 

 and more particularly in sea-water, has frequently been the 

 object of investigation and of dispute. It might be thought 

 that to a question of whether ice so formed does or does not 

 contain salt, experiment would at once give a decisive answer. 

 Yet, relying on experiment alone, competent authorities have 

 given contradictory answers. All agree that ice, whether 

 formed artificially in the laboratory by freezing sea-water, or 

 found in nature as one of the varieties of sea- water ice, retains, 

 in one form or another, and with great tenacity, some of the 

 salt existing in solution in the water. The question at issue 

 is whether this salt is to be attributed to the solid matter of 

 the ice or to the liquor mechanically adhering to it, from 

 which it is impossible to free it. Most bodies, and especially 

 those which take a crystalline form, are easily purified and 

 freed from all suspected foreign matter, with a view to analysis, 

 by the simple operation of washing and drying. It is im- 

 possible to wash the crystals, formed by freezing a saline 

 solution, with distilled water, because they melt at a tempera- 

 ture below that at which distilled water freezes. The effect 

 of the addition of a small quantity of distilled water to a 

 quantity of saline ice is at first the anomalous one, that what 

 was a wet sludge is transformed into a dry crystalline powder. 

 It is, of course, impossible to dry the ice by heat, and to do 

 so by more intense freezing would be begging the question. 

 The experimental difficulties therefore account for some of 

 the divergence of opinion on the subject. The mixed 

 character of the substances examined has also much to do 

 with it. As a rule, it may be said that those investigators 



