308 



PETTERSSON, ON WATER AND ICE. 



From these and similar observations Nordenskiöld 

 drew the conclusions : 



that the saltness is greatest in the upper layers of the 

 ice-floes and gradually changes its place, from the inner part 

 of the ice, until it reaches the surface; 



that the rise of temperature in sprnig or summer is the 

 chief cause of this metamorphosis. 



It can hardly be denied, that the saltness somehow or 

 other has the power of penetrating througli the mäss of the 

 ice to its surface, and that this is effected, not by any con- 

 traction of the mäss of the ice by cold, but by the thawing 

 process, which, as \ve have seen before, commences in the 

 sea-ice far below its melting point. Therefore the age of the 

 sea-ice has a decided influence on its chemical constitution. 

 This will be seen more clearly from the following titrations 

 on ice-samples from old sea-ice. 



Old sea-ice. 



