ACIDIF1ABLE COMBUSTIBLES. 



mercury. This gas has a fetid odour, and a 

 specific gravity of 1*1805 : it burns with a blue 

 flame ; and 1 volume of it, for complete combus- 

 tion, requires H volume of oxygen gas. Water 

 is formed, and a quantity of sulphurous acid gas, 

 just equal to the volume of sulphuretted hydro- 

 gen gas, consumed. 



This combustion is sufficient to enable us to 

 determine the composition of sulphuretted hy- 

 drogen gas. It may be proper to mention, in the 

 first place, that when sulphur is heated in hydro- 

 gen gas, the gas is partly converted into sul- 

 phuretted hydrogen ; but no alteration whatever 

 takes place in its volume. From this it is evi- 

 dent, that a volume of sulphuretted hydrogen 

 gas contains just a volume of hydrogen gas. 



This being understood, let us proceed to ana- 

 lyze the composition of this gas from its combus- 

 tion with oxygen. One volume of it requires 

 li volume of oxygen gas, and forms water and a 

 volume of sulphurous acid gas. The half vol- 

 ume of oxygen gas went to the formation of wa- 

 ter and united with a volume of hydrogen gas : 

 the whole volume of oxygen must have gone to 

 the formation of sulphurous acid, and it must 

 have combined with a volume of sulphur vapour. 



Thus, we see that sulphuretted hydrogen gas 

 is a compound of 



1 volume hydrogen gas ) 



> condensed into 1 volume. 

 1 volume sulphur vapour J 



