88 Prof. H. E. Armstrong. [June 9, 



The figures given by Dixon are as follows : 



Per cent, of Mean rate in 



Condition of mixture. steam present. metres per second. 



Well dried 



Dried 1305 



Saturated at 10 C 1-2 1676 



20 2-3 1703 



28 3-7 1713 



35 5-6 1738 



45 9-5 1693 



55 15-6 1666 



65 24-9 1526 



75 38-4 1266 



The gradual retardation observed when the proportion of steam is 

 increased beyond 5 '6 per cent, may be due to a variety of causes : to 

 the steam acting as a diluent ; to an increase in the extent to which 

 water is unburnt by the carbon monoxide ; and, perhaps, in no slight 

 measure, also to the tendency of the steam to hold back the oxygen. 



6. It is to this last circumstance that the marked influence of 

 oxygen in retarding combustion is probably attributable. This 

 influence is especially noteworthy in the case of electrolytic gas, 

 inasmuch as excess of hydrogen has precisely the opposite effect and 

 nitrogen retards the explosion less than does an excess of oxygen. 

 According to Dixon, the rates, in metres per second, at which various 

 mixtures of hydrogen and oxygen and of electrolytic gas and nitrogen 

 explode, are as follows : 



4H 2 : J0 2 3532 



3H. 2 :|0 2 3527 



2H 2 : J0 2 3268 



H 2 : lOo 2821 



H 2 : 2 2328 H 2 : J0 2 + JN 2 2426 



H 2 :20 2 1927 H 2 :J0 2 +1JN 2 2055 



H 2 : 30 2 1707 H 2 : J0 2 + 2JN 2 1822 



H 2 : 40, 12.81 



In seeking for an explanation of this remarkable, if not paradoxical, 



behaviour of hydrogen, it is necessary to remember that, whereas 



)th oxygen and water molecules diminish in stability as the tem- 



iture rises, the stability of hydrogen peroxide must be at a 



Kinmm at a high temperature! since its formation from oxygen 



' Phil. Trans.,' A, 1893, vol. 184, p. 97. 



> Nernst, Zeit. phyaikal Chem.,' 1903, vol. 46, p. 720, has endeavoured to 



> numerical estimates of the stability of hydrogen peroxide at high tempera- 



s arrived at, however, are not satisfactory owing to the paucity of 



