GASEOUS COMBUSTION AT HIGH PRESSURES. 



281 



fitted with two (upper and lower) coned valves, B and C ; by means of the upper 

 valve, B, connections are made, through the union joint, D, and an external four-way 

 "mixing valve" (shown in plan in fig. 8 and in elevation in fig. 7) with (l) a 

 standard Bourdon pressure gauge and (2), each of three storage cylinders. The lower 

 valve, C, serves as a convenient outlet through which samples of the various gaseous 

 mixtures and products were collected for analysis in glass tubes over mercury. 



The shell of the vessel is bored, about an inch below the top valve, for the reception 

 of a special joint, E, carrying the ignition plug. This plug is insulated by means of 

 an ivory cylinder through whose axis there passes a steel spindle, the end of which 

 forms one electrical pole, the body of the explosion vessel forming the other. 



Fig. 5. 



Ignition is effected electrically by the fusion of a short length of thin platinum wire 

 bridged between the spindle and the outer steel screw of the plug. 



All joints in the explosion vessel are " metal to metal " and are so accurately 

 machined as to be absolutely tight at a test pressure, of 1000 atmospheres. The bomb 

 itself is securely held in a vertical position by four bolts in a massive iron casting, 

 which in turn is bolted down to the experimental table. In order to ensure the 

 perfect mixing of the constituents of a given explosive mixture before firing it, the 

 explosion chamber contains a perfectly smooth bronze sphere of inch diameter 

 which, after the gases have been introduced, is caused to roll up and down the 



