CHAPTER 1. 



Introduction. 



The object of this paper is to account for the physical 

 properties of water in tiie liquid and solid state at tliose tem- 

 peratures, to whicli ice and water are generally exposed in 

 the arctic sea. The author has limited his researches to tem- 

 peratures between — 20° C and + 15° C, as the changes in the 

 volume etc. of ice below — 20° C and water above + 15° C are 

 almost entirely void of interest to the hydrographer. But 

 between the narrow limits thus assigned, it has been the 

 aim of the author, to attain the greatest possible accuracy of 

 measurement. The interest of an hj^drographer of the arctic 

 ocean naturally concentrates upon the formation of ice and 

 the changes in the physical conditions accompanying the 

 freezing of water — a problem, which, stränge to say, has 

 never before been subject to qnantitative researches [as far as 

 regards ice from oceanwater], althongh a great amount of 

 most valuable observations have been collected by arctic ex- 

 plorers. 



Being commissioned by Professor Nordenskiöld to 

 write the hydrographical resnlts of the Vega-expedition, I 

 obtained his permission to insert an introductory paper on 

 the properties of sea-ice and sea-water. In the first place I 

 had to make the choice of an appropriate material for my 

 experiments. I naturally decided to put to the test samples 

 of such kinds of water, as are found to predominate in the 

 arctic seas. In the Siberian sea, from whence the hydrogra- 

 phic material of the Vega-expedition was collected, there may 

 be found water of almost every possible gradation in saltness, 

 from the oceanwater at the bottom, which contains 3.4 per 

 cent of salt, to the fresh water in the upper strata, which is 

 spread widely över the surface of the sea by the powerful 



