TRANSACTIONS OF SECTION B. 673 



This alloy has not shown any signs of disinteofration since it was made. 



^^^lether the difierence iu composition hetween the two portions is the result 

 of the great difficulty in mixing aluminium with the heavier metals, or has been 

 produced hy separation, is not quite clear ; if the carbon may be taken as a guide, 

 it seems to show not only separation but also actual loss of this element. 



FRIDAY, AUGUST 5. 



The following Papers were read : — 



1. The Explosion of Ethylene tvith less than its own Volume of Oxygen. By 

 B. Lean, B.A., B.Sc. (Dalton Ghemical Scholar of Owens College), and 

 W. A Bone, B.Sc. (Felloiv of Victoria Zfiiiversity). 



Our investigations arose out of experiments to determine the rate of explosion 

 of hydrocarbons witli deficiency of oxygen, and were made at the suggestion of 

 Professor H. B. Dixon. On exploding ethylene with less than its own volume of 

 oxygen there is invariably a considerable increase in pressure. In the case of a 

 mixture of 100 volumes ethylene with 96 5 volumes oxygen, the pressure increased 

 I'rom 756 mm. to 1,503 mm. of mercury, indicating that the oxygen had mainly 

 gone to the carbon and not to the hydrogen. This result is in accordance with 

 Dalton's experiments (1810), with those of J. Daw, Kersten (1861), and E. von 

 Meyer (1874). 



On carefully analysing the products of explosion we found that, in addition to 

 hydrogen, carbon monoxide, and small percentages of carbonic acid and unsaturated 

 hydrocarbons, there was always present a small amount of marsh gns. 



We made and tired five ditl'erent mixtures of ethylene and oxygen, containing 

 100 volumes ethylene with 70 to 96'5 volumes oxygen. We invariably found 

 marsh gas present in the products of the explosion, and the percentage of this 

 increased as the percentage of oxygen in the original mixture decreased. 



The quantity of marsh gas present in the products of explosion of 100 volumes 

 of ethylene with 70 volumes of oxygen was 5'53 per cent., and, in the case of the 

 mixture containing 100 volumes ethylene with 96'5 volumes of oxygen, we found 

 1-01 per cent, of marsh gas in the products. 



AYith regard to the unsaturated hydrocarbons present in the products, a 

 qualitative examination revealed the presence of acetylene. Whether ihis con- 

 stitutes the whole of the unsaturated hydrocarbons present we are not prepared to 

 say ; it is certainly present in not inconsiderable quantities. 



The main reaction which doubtless occurs is a combination between the oxygen 

 and part of the ethylene with the formation of carbon monoxide and hydrogen, 

 according to the equation — 



aH, + 0., = 2CO + 2H, (1) 



The heat liberated by this reaction produces a decomposition of some of the 

 unburnt ethylene analogous to the decomposition which ethylene undergoes when 

 passed through a red-hot tube into marsh gas and carbon, according to the 

 equation — 



C,H, = CH, + C (2) 



Marsh gas might also be produced in another way, by partial oxidation, accord- 

 ing to the equation — 



2C3H, + 0., = 2CHj + 2C0 (3) 



With regard to the formation of acetylene, Professor Dixon suggested that it 

 is possibly due to a secondary reaction between the nascent hydrogen formed 

 according to equation (1), and the carbon liberated according to equation (2) — 



2C + ir, = C,,H, (4) 



1892. X X 



