169 



■150 



-200 



250 



•27 3 



0.5 0.4 0.3 0.2 0.1 



Fig. 27. Specific heat of ice in terms of temperatui-e. (Curve drawn from 

 the data of Maass and Barnes, 1927, and of Xernst, 1910.) 



obtained, from 0° to -80°, by Maass and Barnes (1927) 

 and, from - 100° to - 200°, by Nernst (1910) . As an aver- 

 age between - 188° and - 252.5°, Dieterici (1903) gives the 

 value 0.146°. Since the curve is practically a straight line 

 at the temperatures plotted, one can, in calculations involv- 

 ing the amount of heat withdrawn for cooling some mate- 

 rial between two points within this range of temperatures, 

 take the average specific heat between the two points. 



The heat conductivity of ice at 0° is 0.00573, according 

 to Neumann (1862) ; that of water at 0° is 0.00120, accord- 

 ing to H. F. Weber (1880). 



The difference in conductivity along the axis of the 

 crystals and in a perpendicular direction was found by 

 Trouton (1898) to be practically negligible, the ratio of the 

 two being 22 : 21. 



We did not find any data on the heat conductivity of ice 

 at very low temperatures. Lees (1908) has investigated 



