22 



Prof. W. M. Thornton on the 

 Table IT. 



Percentage of Gas 

 in Air. 



Maximum Pressure. 



Observed. 



Calculated. 



Eatio. r\. 



6-7 



I. 



40 



51-5 



60 



61 



78 

 87 

 90 



II. 



55 



67 

 75 

 76 

 93 

 102 

 105 



I. 



89-5 



96 

 103 

 112 

 134 

 168 

 192 



II. 



105 



110 

 118 

 127 

 149 

 183 

 209 



I. 



•447 



•535 



•582 

 •545 

 •572 

 •517 

 •468 



II. 



•523 



•602 

 •645 

 •598 

 •625 

 •557 

 •505 



71 



77 



8-3 



100 



12-5 



14-2 













Mean... 



•523 



•579 



I. Glasgow Gas. 



II. Oldham Gas 



These are the only recorded values at different percentages 

 of gas and air readily available. 



Berthelot & Vielle (Annales de Chimie et de Physique, 

 6 e serie, torn. iv. pp. 3-90) obtained the following maximum 

 pressures of explosion (Table III.). Berthelot had previously 

 calculated* the theoretical maxima with values of the specific 

 heats of the products which aro certainly low, and therefore 

 give too high a calculated maximum. The mixtures here are 

 in every case those for perfect combustion. 



From an extended series of measurements on acetylene, 

 Grover found ratios of observed to calculated maximum 

 between 0'42 and 0*73. Berthelot's ratio for this gas is 

 probably low, but retaining it the mean of all the ratios in 

 Tables L, II and III. is 0502. 



(4) Relation of efficiency of explosion to percentage of 

 combustible gas in mixture. 



The simple case considered cannot do more than suggest 

 the chief process in gaseous explosion, for there is the 

 addition of a second atom of oxygen to form carbon dioxide. 

 It is to be noted, however, that this addition does not affect 

 the ratio between translational and rotational energies so 

 much as the first combination. Further, in Table II. the 



* M. Berthelot, ' Explosives and their power. Trans, by Hake and 

 MacNab, pp. 387 and 543. 



