GASEOUS COMBUSTION AT HIGH PRESSURES. 309 



hydrogen; or (ii.) uniting with each other forming acetylene; or (iii.) decomposing 

 into carbon and hydrogen, according to the experimental conditions.* 



In the presence of a sufficient oxygen supply, however, there is a " non-stop " run 

 through the monohydroxy to the dihydroxy stage which, on subsequent thermal 

 decomposition, would give rise, first of all to formaldehyde, and then to carbon 

 monoxide and hydrogen. The scheme of the " oxygen attack " is as follows, with the 

 proviso that no decomposition occurs in " running through " stage A when there is 

 sufficient oxygen to complete the transition to stage B. 



/ i 



2CH 4 C 2 H 2 



It occurred to us that it would be of great interest to study the behaviour of 

 mixtures C 2 H 4 + O 2 + H 2 in the bomb apparatus at initial high pressures, because 

 successive additions of hydrogen would, according to the above scheme, operate in two 

 distinct ways, namely (i.) by participating, more and more, in proportion to its active 

 mass, in the initial oxygen distribution, it would prevent some of the hydrocarbon 

 completing the A to B transformation, and so bringing about some decomposition at 

 A; and (ii.) by participating in any "A" decomposition in such a manner as to 

 " hydrogenise " the CH residues, and so counteracting, and perhaps even suppressing 

 altogether, separation of carbon. 



Such a twofold influence would be marked by (i.) an increasing steam and methane 

 formation in the products with successive initial additions of hydrogen; and (ii. ) a 

 restraint or even total prevention of carbon deposition. 



On actually putting matters to the experimental test it was found possible to add 

 as much hydrogen as would correspond to C 2 H 4 + 2 +8H 2 without causing any 

 deposition of carbon whatever on explosion, and is it probable that an even larger 

 proportion of hydrogen could have been added without producing such a result. 

 Progressive additions of hydrogen did, indeed, have the anticipated effects in regard 

 to steam and methane formation as the following results will illustrate ; there was, 

 however, never any trace of acetylene found in the products. 



* See also BONE and COWARD on " The Thermal Decomposition of Hydrocarbons," ' Trans. Chem. 

 Soc.,' 1908, vol. 93, pp. 1198 to 1225. 



2 S 2 



