Ice and its Natural History 237 



only in virtue of adhering sea-water of slightly greater con- 

 centration, the saline contents of the water adhering to the 

 ice-crystals must have the same composition as that of the 

 water before freezing. Having found that this was not the 

 case, he was apparently justified in concluding that the act of 

 freezing in sea-water has a selective or distributive effect on 

 its saline ingredients. But, in freezing, the solution is sepa- 

 rated only into two parts, the crystals and the mother-liquor. 

 If there is found to be a deficiency of a saline ingredient in 

 the mother-liquor, this can be due only to its transference 

 to the crystals. Therefore, the crystals must contain salt 

 solidly. 



This reasoning is perfectly valid if we admit what is 

 tacitly assumed, that the samples of ice analysed were pro- 

 duced by the primary freezing of sea-water of the composition 

 of the samples of unaltered sea-water, which were analysed 

 at the same time. But it was perfectly evident to me that 

 this was not the case, especially as regarded the samples 

 brought home by the "Vega" which were characteristic 

 samples of the ice encountered by a ship having her Arctic 

 experience. From the records of this expedition, which agree 

 with those of all other Arctic voyages, primary sea-ice is to 

 be seen only at the beginning of winter, or the commence- 

 ment of freezing. Almost before the ice is a day old secondary 

 changes take place and become more and more pronounced 

 as the season advances and the ice thickens. An excellent 

 idea of the nature of these changes is furnished by Dr Fetters- 

 son's investigations and by those of Dr Karl Weyprecht 1 . 



But the question of the nature of the ice formed by 

 freezing non-saturated saline solutions can be solved only by 

 the phenomena attending their primary congelation, where 

 all secondary complications are excluded. I therefore made 

 a number of experiments in which different samples of sea- 

 water, in sufficient quantity (300 grms.), were frozen in a bath 

 having a temperature between two and three degrees lower 

 than the probable freezing-point of the sea-water. Freezing 

 was continued until about one-third of the solution had passed 



1 Die Metamorphosen des Polareises, Wien, 1879. 



