286 PROF. W. A. BONE AND OTHEKS ON 



Experimental Method. 



Before each experiment the bomb was thoroughly tested by filling it with either 

 air or hydrogen up to from 30 to 50 atmospheres pressure, and in no case was an 

 experiment proceeded with unless this pressure was held without appreciable loss for 

 a period of twelve hours. At frequent intervals, also, during the investigation, each 

 bomb was tested by exploding in it mixtures of oxygen with excess of hydrogen (the 

 initial partial pressure of the oxygen varying usually from 3 to 10 atmospheres). In 

 the rare event of the observed diminution in pressure exceeding the partial pressure 

 of the oxygon multiplied by 3'0, a circumstance which might be due either to a 

 slight outleakage at one of the valves during the explosion or to the occurrence of 

 rust on the walls of the explosion chamber, the test was repeated until a satisfactory 

 result was obtained. As an indication of the degree of accuracy obtainable when 

 such mixtures are exploded in the apparatus, the following summary of the first 

 22 tests carried out with bomb A, are given below : 



Limits. 



(1) Initial partial pressure of the oxygen varied 



between 3 and 10 atmospheres. 



(2) Tlatios between partial pressures of the 



hydrogen and oxygen in the mixture 



fired varied between 3'0 ,, 8'75 



(3) Ratio of pressure fall on explosion to initial 



partial pressure of oxygen varied 



between 2'85 3'07* 



After a successful preliminary test with either hydrogen or air, and a thorough 

 drying out of the explosion chamber by means of a current of dry air, the bomb and 

 its connections, right up to the standard gauge and the storage cylinders, were 

 exhausted by means of a Geryk pump. It was then filled up to about 5 atmospheres 

 pressure with one of the constituents (usually the oxygen) of the particular explosive 

 mixture under investigation, and after blowing off the excess of pressure, the bomb 

 and its connections were once more exhausted. The first constituent of the proposed 

 mixture was thereupon slowly admitted to the bomb from its storage cylinder until 

 the standard Bourdon gauge indicated the desired pressure. The admission valve of 

 the bomb was then closed and the excess pressure in the outside system between it 

 and the gauge and storage cylinders blown off by momentarily unscrewing the union 

 joint nearest to the bomb. The connections up to the bomb were then repeatedly 

 swept out and finally filled at high pressure (exceeding that of the gas already in the 

 bomb) with the second constituent of the proposed mixture, which was immediately 

 afterwards slowly admitted to the bomb, up to its desired partial pressure, by suitable 

 manipulation of the proper valves. The contents of the bomb were then submitted to 



* In 14 out of the 22 experiments this ratio was 3'0 exactly. 



