When making the calculations, we find that with an increase 1 bar of pressure (or, in other 

 words 1. 02 kg/cm^) the freezing temperature decreases by 0. 0074° or, in other words, the freezing 

 temperature decreases by 1° with an increase in pressure of 134. 6 bars. 



The experimental data for distilled water are as follows: 



Pressure in atmosphere .... 1 



Pressure in bars 1.01 



Freezing temperature 0°.0 



A decrease in the freezing temperature with an increase in pressure causes the regelation 

 and fluidity of ice. 



The regelation phenomenon consists of the fact that with each rise in pressure, the ice melts 

 slightly and as soon as the pressure stops, it freezes together again. If a heavy object is placed 

 on the ice, it melts the ice under it and squeezing out the water film which forms under it, it finally 

 passes through the ice. Passing a wire with a weight tied to it through a beam of ice is a familiar 

 experiment; and the beam of ice is, so to speak, cut through. The regelation phenomenon has a 

 very characteristic effect on glacier ice. The ice flowing along the bed of the glacier undergoes 

 either an increase or a decrease in pressure in turning, but due to its fluidity and the regelation 

 phenomenon, the ice does not break. Thus, fluidity creates glacier movements, similar to river 

 currents. If a row of pebbles is placed across a frozen river in the autumn, in the spring, these 

 pebbles on the ice will be located in a curve convex down stream, which proves that the ice covers 

 of rivers also "flow. " All these phenomena are so characteristic that they permit a comparison of 

 ice with a liquid which has a very high coefficient of viscosity. 



Regelation appears in other instances also. Thus, under pressure of one piece of ice over 

 another, they fuse with each other. 



It should be emphasized that actually ice is the only body in nature whose cleavage can be 

 eradicated by means of pressure under ordinary temperatures. If it is added to the fact that inside 

 natural ice (especially during the winter the temperature is considerably lower than the freezing 

 temperature) every crack in the ice is immediately reinforced by water which penetrates these 

 cracks and freezes there. 



Therefore, it follows that it is possible to apply to natural ice the formulas and theories based 

 on studies of the mechanical properties of other materials only with the corresponding limitations. 



LITERATURE: 25, 62, 



Section 74. Mechanical Properties 



We have seen that the physical properties of sea ice change sharply in connection with the 

 conditions of its formation and are a function of its temperature, salinity, and porosity. It is clear 

 that the mechanical properties of sea ice, i. e. , its ability to resist the action of any external 

 forces, depend on the same factors. Furthermore, this ability also depends on the duration of an 

 action by a given force. 



In spite of the great practical significance of the mechanical properties of ice, as far as I 

 know, there have been no systematic investigations of these properties. 



183 



