18 Dr THOMAS THOMSON on a New Combustible Gas. 



flammable gas has the property of greatly increasing the absor- 

 bability of the nitrous gas in water ; so much so, that a gas, 

 which, when analysed over mercury, was found to contain 63 per 

 cent, of nitrous gas, if it was agitated in water, as long as that 

 liquid continued to absorb it, left no more than 7.5 per cent, of 

 nitrous gas. I abide, therefore, by the analysis over mercury, 

 which, from numerous comparative experiments, cannot deviate 

 very far from the truth. 



100 volumes of the gas, after being washed in water, and in 

 a solution of protosulphate of iron, left 8 per cent, of azotic gas. 



Thus it appears, that the gas extricated from a mixture of 

 aqua regia and pyroxylic spirit, is a mixture of 



New inflammable gas, 29 



Nitrous gas, 63 



Azotic gas, 8 



100 



Whether these proportions be constant, I cannot venture to de- 

 termine. But I analysed gas obtained in ten different processes, 

 without finding any deviation in the proportions of its constitu- 

 ents. I found the specific gravity the same in gas from two dif- 

 ferent processes. 



8. The specific gravity of the gas was taken in a flask which 

 had been twice exhausted, and filled each time with hydrogen 

 gas. It was 1.945, the specific gravity of common air being reck- 

 oned unity. 



It is easy to calculate the specific gravity of the pure inflam- 

 mable gas in this mixture. 



Let A = volume of nitrous and azotic gas ; 



a = specific gravity of a mixture of 63 volumes nitrous 



and 8 azotic gas ; 

 B volume of inflammable gas ; 

 x specific gravity of inflammable gas ; 

 c specific gravity of the mixed gas. 



