by Means (t/" Doebereiner's Eudiometer. 279 



volume of an explosive mixture insensible to the action of 

 the sponge, and in other cases indicates the number which 

 may be added without preventing immediate combination. In 

 the first column, the numbers marked with an asterisk were 

 determined by Sir Humphry Davy ; the remaining numbers 

 in that column, and the whole of the second, are derived from 

 my own experiments. 



1 vol. of Explosive Mixture was ren- Effect of adding the same gases 

 dered incapable of being inflamed by to 1 vol. of Explosive Mixture 



electricity when mixed with on the action of the sponge. 



* About 8 vol. of Hydrogen not prevented by many vol. 



ditto 



not prevented by 10 vol. 



ditto 



prevented by 1 vol. 



not prevented by 10 vol. 



prevented by h vol. 



prevented by 1*5 vol. 



not prevented by 6 vol. 



not pi-evented by 10 vol. 



ditto 



From the foregoing table it appears that carbonic oxide 

 produces the greatest effect, in the smallest proportion, to an 

 explosive mixture of oxygen and hydrogen, in preventing the 

 action of those gases on each other, when exposed to the 

 sponge at temperatures below the boiling point of mercury. 

 In general those gases which either do not unite with oxy- 

 gen, or unite with it only at high temperatures, have little ef- 

 fect in restraining the efficiency of the sponge. There is an 

 apparent exception, however, in cyanogen, which it would re- 

 quire more research than I have yet had time to devote to an 

 object merely collateral, to reconcile it, if it be capable of being 

 reconciled, with the general principle. 



From the fact that carbonic oxide, olefiant gas, and carbu- 

 retted hydrogen, when brought to unite with oxygen by means 

 of the platinum sponge, assisted by heat, undergo this change 

 at different temperatures, it seemed an obvious conclusion, 

 that by exposing a mixture of those gases with each other and' 

 with oxygen to a regulated temperature, the correct analysisi 

 of such mixtures might probably be accomplished. Mixtures 

 of two or more of the combustible gases were therefore ex- 

 |X)sed, in contiict with oxygen gas and the platinum sponge, 

 in tubes bent into the shape of retorts, which were inunersed 

 in a mercurial bath. This bath was gradually heated to the 

 required temperatures, and by proper management of the 

 source of heat was prevented from rising above tliat degree. 



J St. 



