246 Mr. J. Y, Buchanan [May 8, 



while, in those of the sea ice, it varied within very wide limits ; and 

 he justly observes that, if it is claimed that the ice of sea- water is salt 

 only in virtue of adhering sea-water of slightly greater concentration, 

 the saUne contents of the water adhering to the ice crystals must 

 have the same composition as that of the water before freezing. 

 Having found tliat 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 solu- 

 tion is separated 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 produced by the 

 immary 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 Avas 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 commencement 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. Pettersson's investigations and by those of Dr. Karl 

 Weyprecht.* 



But the question of the nature of the ice formed by freezing non- 

 saturated saline solutions can be solved only by the phenomena attend- 

 ing 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 grm.) 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 into 

 the crystalline state. The mother-liquor was drawn off, as perfectly 

 as possible, before removing the beaker, in which the 'freezing had 

 been effected, from the bath. The crystals were transferred quickly 

 to a funnel, and drained by means of the jet pump. The chlorine 

 and sulphuric acid were then determined in each fraction, and the 

 ratio CI : SO3 calculated (CI = 100). As an example, the /ollowing 

 values of this ratio were obtained for water from the Firth of Forth : 

 [n the original water 11 'So, in the* mother-liquor 11 "67, and in the 

 crystals 11 * 62. In water from the Firth of Clyde the ratios were, in 

 the original water 11 '58, in the motlier-Uquor 11 "57, and in the 



Die Metamorphosen des Polareises, Wien, 1879. 



