r 



Vol. X, No. 6.] An Improved Method of usinq Oil Gas. 217 

 [N.S.] 



The mixture A contains exactly the amount of air necessary 

 for complete combustion, and it is interesting to note that this 

 is not the mixture in which the rate of combustion has reached 

 its maximum value. (Cf. Michelsen, Zeit. phys. Ch. 3, 493) 

 As the quantity of oil gas in the mixture increases bevond 



/c 



% 



and beyond this limit progressive combustion does not take 

 place and the mixture is non-explosive 



A comparison of the values found for mixtures of oil gas 

 and air with those given by Michelsen (loc. cit.) for mixtures 

 of coal gas and air and hydrogen and air is instructive. 



In the following table n = the volume per cent of combus- 

 tible gas in the mixture and u = rate of propagation of com- 

 bustion in centimetres per second. 



Table III. 



Oil gas and air. Coal gas and air. Hydrogen and air 



n u n u n u 



5-8 21-5 11 28 15 40 



71 260 12 38 20 65 



7-5 28-5 13 48 25 140 



8-2 33-5 14 57 30 235 



8-7 31-5 15 64 35 270 



9-2 300 16 68 40 277 



101 202 17 70 45 270 



121 10-8 18 71 50 250 



16-0 03 19 68 55 222 



20 62 60 172 



21 53 65 105 



22 43 70 74 



23 33 



24 24 



25 16 



26 11 



It will be observed that the maximum rate in the coal gas 

 air mixture is more than twice that of the oil gas-air mixture 

 and that the upper explosive limit in the former is much 

 higher than in the latter. The high percentage of hydrogen 

 in coal gas, Table I, is obviously the cause of the difference in 



y o of air with oil 



behaviour between these two gas mixtures. 

 It is possible therefore to mix up to ! 

 gas without danger of forming an explosive mixture. Now as 

 one volume of oil gas requires about 123 volumes of air for its 

 complete combustion, it will be necessary to mix with it 

 about 1-2 volumes of air in order to get a gas mixture which 



