1920] on Researches at High Pressures and Temperatures 7 



and are made fluid and gas tight by mild steel cups on the ends of 

 the rams. 



If the charge occupies only a short length of the bore as shown, 

 the barrel of the container where the charge lies is supported by the 

 sheer strength of the metal above and below the zone of pressure, in 

 addition to its own strength as a tube ; under these conditions it is as 

 strong or stronger than the crushing strength of the rams, and 

 pressures of 300 tons per square inch may be repeated several times 

 without cracking. 



In a container of this form 7 grains of fulminate of mercury have 

 been placed, imbedded in graphite, and the pressure increased very 

 gradually till it reached 230 tons per square inch (under this treatment 

 fulminate does not usually detonate) ; the die was then heated by gas 

 to over 180° C, the temperature of detonation. After two failures 

 of the experiment, owing to the leakage of the steel cups, the third 

 was successful and no gas escaped, and the container was uninjured. 



Wilo 5t £ £L C"p$. 



Fig. 1. 



Fig. 2. 



The graphite was somewhat caked, but otherwise unaltered. Graphite 

 mixed with sodium nitrate and fulminate was also exploded under 

 the same conditions. 



— Graphite with 15 per cent, of potassium chloride detonated when 

 200 tons per square inch had been reached. 



Many other reactions were tested in a similar manner in larger 

 dies under pressures of from 40 to 200 tons. The action of con- 

 centrated sulphuride acid on sugar was accelerated by a pressure 

 of 50 tons ; but on the whole these experiments in dies failed to 

 produce any interesting results. 



, *. Unfortunately, the heating of the die with its charge cannot be 

 carried much above 500° O. without seriously weakening the strength 

 of the steel and compelling a reduction of pressure. The electrical 

 heating of the charge in such small dies while keeping the die cool 

 presents great difficulties in electrical insulation on so small a scale 

 to withstand such intense pressure, but I think that it might be 

 accomplished in certain instances. 



