302 PETTERSSON, ON n-ATEH AKD ICE. 



network of the crystallized water, and tliat tlie brine is after- 

 wards separated from the ice by the influence of variations ot 

 temperature. On the nature of this metamorphosis, two dif- 

 ferent hypotheses have been propounded, which are diametri- 

 cally opposite to each other. Dr. Walker^ believed, that the 

 brine was squeezed ont by the contraction of the ice hy colcl. 

 I think the impossibility of this hypothesis is sufnciently 

 proved in the foregoing ehapter. In fact, sea-ice, which con- 

 tains any considerable part of its original saltness, is expand- 

 ed instead of contracted by the cold. Professor Norden- 

 skiöld and Dr. Almqvist are prone to conclude, from their 

 observations du ring the winter 1878 at Pitlekaj, »that the in- 

 cluded brine slowly frets its way to the siirface of the icefloe, 

 where it was found on several ocoasions as a concentrated 

 overflow, which frequently deposited an efflorescence - of crys- 

 tal-needles consisting of an aqueous donble salt of NaCl 

 and CaClo. For this metamorphosis of the salt ice a tempera- 

 ture near the melting point is necessary, as the peculiar con- 

 dition of the ice at those temperatures facilitates the penetra- 

 tion of the bladders and dröps of salt brine to the surface». 

 The general opinion thus seems to be, that the ice, even 

 if it separates from salt water, is chemically entirely free from 

 salt, although it may contain a slight quantity mechanically, 

 which adheres to it as salt-crystals or salt-solution. Although 

 combatted by at least one important authority. Dr. Buchanan 

 of the Challenger expedition, this opinion still predominates 

 among the majority of natural philosophers. One reason at 

 least speaks strongly in its favour, viz. the changeable amount 

 of salt, which is found in the ice. To those, who are prone 

 to limit the dominion of Chemistry to only combinations of 

 tixed proportions, the sea-ice never will appear to be anything 

 but a mechanical mingling of crystallized water with an in- 

 significant c|uantity. of sodium- and calciumsalts etc. I have 

 tried to do full justice to this point of view, just because it 

 is not my own. I do not pretend to see a well defined chemi- 

 cal compound in every bit of floating sea-ice, but I think I 

 can show, that at the formation of the ice of the ocean forces 

 of quite another order, than the mechanical adhesion, are at 

 work to connect the salt with the ice. 



» Of the M'Clintock expedition 1857—59. 



2 The efflorescence of salt crystals npon the surface of newly frozen 

 ice was observed also by Wrangel and is minutely described by Wey- 

 precht a. O. 



