O. D. von Engeln — Studies on Ice Structure. 465 



the freezing oat of the excess of water in the dilute aqueous 

 solution must take place and the salt content of the snow con- 

 centrated in films between the neve granules. If the tempera- 

 ture of the neve is at or below — 22°C. these films will consist of 

 the cryohydrate solid. But as it is unlikely that so low temper- 

 atures as — 22°C. exist far below the surface in any glacial 

 masses it is much more probable that liquid films of salt solu- 

 tion develop between the pure ice granules and that this salt 

 solution is of a concentration, therefore a thickness, dependent 

 on the temperature and the size of the pure ice granules. At 

 comparatively high temperatures, i. e., near the freezing point 

 of pure water, a comparatively dilute solution must remain in 

 the liquid phase. Again, the smaller the ice grains the greater 

 their total surface area, consequently the thinner the film of 

 salt solution that surrounds each at a given temperature. 

 Since glacier grains are generally observed to increase in size 

 from the surface toward the interior and from the head to the 

 terminus of an ice tongue and the temperature of the interior 

 ice to approach the pressure-temperature melting point, it fol- 

 lows that the interstitial films of salt solution will be progres- 

 sively thicker toward the lower end of the glacier. 



Possibly, also, there is a tendency for the salt solution to 

 drain away from the surface zone of the ice and to be concen- 

 trated in the interior below the limiting depth of crevasses. 

 Except then as the films of salt solution are held by capillarity 

 the surface portions of the ice will be made up of ice grains 

 that are very closely adjacent whereas there will be a corre- 

 sponding concentration of the liquid films between the grains 

 at greater depths. 



Other investigators have argued the presence of saline solu- 

 tions between the pure ice crystals of glacier and pond ice- 

 Buchanan* points out that rain and snow contain seven parts 

 per million of chlorine and that when glacier ice has a temper- 

 ature as high as — 007°C. it will consist of 1 per cent liquid 

 brine or water. To the presence of such films he ascribes 

 the effect of the sun's rays in disarticulating granular glacier 

 ice and in developing the Forel lines that mark out the basal 

 plates of the ice crystals. Thick pond ice similarly becomes 

 " rotten" after a spring thaw and breaks up rapidly because it 

 is disintegrated by melting in the planes of such films. 

 Quincke! characterizes glacier grains as "foam cells" filled 

 with pure ice and separated one from another by walls of 

 " oily " salt solution. The origin of the salt solution he ascribes 



* Buchanan, J. Y. : In and around the Morteratseh Glacier, Scot. Geog, 

 Jour., xxviii, pp. 169-189, 1912 and other earlier papers. 



f Quincke, G.: The Formation of Ice and the Grained Structure of Gla- 

 ciers, Nature, Ixxii, pp. 543-545, 1905. 



Am. Jour. Sci.— Fourth Series, Vol. XL, No. 239.— November, 1915. 

 31 



