Land Ice of Arctic and Sub- Arctic Regions 53 



bubbles of air are not so many, they are round or egg-shaped, and 

 they are irregularly distributed. Upon melting, this ice also divides 

 into rounded polyhedral grains of an average diameter of 5 mm., 

 and altogether they are smaller than those of the first samples (A). 

 Under the microscope we see the same images as before. The air 

 contained was 50 cu. cm. per kilo of ice, the remains of clay 0.24%, 

 i. e., 2.5 grams per kilo. The specific weight was 0.878. 



" The first conclusion we may arrive at from these observations 

 is that the ice just described cannot have been formed directly from 

 water. Ice coming from the surface of water, for instance from a 

 pond, shows a parallel increase of long-stalked crystals, whose 

 optical axes are perpendicular to the freezing surface. A section 

 taken from such ice shows under the microscope all the properties 

 of a crystal. When melting, such ice divides into a series of irregu- 

 lar prisms some decimeters long The freezing of water is 



much more complex than might appear when we observe an already 

 formed piece of ice. But this relates only to the first phase of the 

 formation of ice. Later on the freezing goes on in a much simpler 

 and more regular way, so an ice is formed which in its principal 

 mass is characterized by its prismatic structure and thereby can be 

 easily distinguished from snow ice, as has been known for a long 

 time, and recently once more clearly shown by Prof. E. Drygalski *^ 

 in his study of the materials of the Greenland expedition. The 

 large quantity of air of the ice coming from the Beresowka differen- 

 tiates it also from ice coming from ordinary freezing of water, and 

 confirms its snowy nature, as is shown by the great number of 

 observations carried on chiefly on ice of glaciers. 



" The well-known works of Agassiz and Nicolet have shown that 

 one kilo of snow on changing into neve contains 64 cu. cm. of air ; 

 one kilo of white glacier ice 15 cu. cm. and one kilo' of blue ice 

 I cu. cm 



" It is easy to see that the quantity of air contained in the ice 

 of the Beresowka approaches that of white glacier ice and even to 

 neve ice, especially for the first sample (A). 



" Its structure, which we have described above, resembles that of 

 glacier ice, though in comparison to the ice of the Alpine glaciers, 

 the grains are very minute. But in comparing it with the ice of the 

 interior of Greenland, we do not notice this difference so much." 



" The characteristic structure of neve ice — a conglomerate of ice 

 grains kept together by an ice cement formed of very small grains — 



" Gronland-Expedition, B. I, XVIII Kapitel. Die Structur des Eises. 



