1903.] on Low Temperature Investigations. 421 



at this low temperature there ought theoretically, if the extrapolation 

 pressure were legitimate, to be no distinction between the solid and 

 liquid forms of water. At temperatures below this limit no amount 

 of pressure would transform ice into water. 



In inferring at what temperature this kind of critical point of 

 the possible transition of ice into water takes place, no consideration 

 of the change in the specific heats of ice and water under the greatly 

 increased pressures have been included. If this is done, then it 

 appears that ice under 50 tons and a corresponding temperature of 

 about — 50° C, would be all transformed into water, so that no lower 

 temperature could be reached by any forced transition. All such 

 speculations based on imperfect data are cleared away by the im- 

 portant experiment made by Tamman, who has shown that ice under 

 a pressure of 20 to 30 tons on the square inch and a temperature of 

 — 22° or — 23° becomes transformed into a new variety of ice, which 

 under the specified conditions of temperature and pressure is denser 

 than water. This new ice has a density greater than water, viz. 

 1*11, so that no amount of pressure on ice below the temperature 

 of —23°, can cause any transition. All the theoretical anticipations 

 of the relatioDS of ice and water at very low temperatures and high 

 pressures have been entirely falsified by the results of Tamman. 



Ice near its melting point can easily be squeezed into the form 

 of wire when forced by hydraulic pressure from a steel cylinder 

 having a small aperture in the bottom. If the temperature of the 

 ice is lowered to —80 C. by embedding the steel cylinder and 

 plunger in solid carbonic acid under a pressure of 50 tons, the flow 

 still takes place. The ice wire was now made up of what looked 

 like a set of disc-like scales, which contrasted strongly in appearance 

 with the transparent clear ice wire got when the experiment was 

 made at 0° C. On cooling the ice and its accessories as above to a 

 temperature approaching that of liquid air, no pressure the apparatus 

 would stand caused any flow, but only intermitteut explosive 

 ejections. 



Water was frozen in a steel cylinder in successive portions so as 

 to include ledd shot in the middle and upper portions of the ice, 

 and the whole cooled to —80° C. It was now subjected to 100 tons 

 pressure in order to see if the lead spheres had fallen partly through 

 the ice. After this great pressure the ice was clear, the lead spheres, 

 however, had nov/ very irregular shapes, but no motion of the kind 

 anticipated had taken place. Thus ice under the pressure of 100 tons, 

 or 15,000 atmospheres, which by theory ought to have lowered the 

 melting point below —80°, show^s no such action. The transparent 

 ice after the experiment showed no increase of density, but during 

 the gradual heating up from — 80°, it became milk-white from some 

 new crystalline arrangement. Such high pressure experiments are 

 greatly favoured by the increased strength of the steel dies and 

 pistons at the lowest temperatures. 



Ice is a highly expansive substance, and as a result transparent 

 blocks dropped into liquid air crack in all directions from the 



