PHOSPHORUS. 205 



Thus it appears, that phosphuretted hydrogen 

 gas is a compound of 



Hydrogen 0-0694 or 0-125 

 Phosphorus 0-8333 - 1-5 



But 0*125 represents the weight of an atom of 

 hydrogen, and 1%5 must be the weight of an 

 atom of phosphorus. The gas is obviously a 

 compound of one atom hydrogen, and one atom 

 phosphorus. 



If we mix together one volume of phosphu- 

 retted hydrogen gas with either one volume or 

 1-5 volume of oxygen gas, combustion takes 

 place, and the whole gaseous mixture disappears, 

 being in the first case condensed into water and 

 phosphorous acid, and in the second, into water 

 and phosphoric acid. Let us analyze these com- 

 bustions ; they will give us the composition of 

 both phosphorous and phosphoric acids. 



A volume of phosphuretted hydrogen gas 

 may be considered as composed of one volume 

 hydrogen gas, and one volume phosphorus va- 

 pour condensed into one volume and a volume 

 both of hydrogen gas and of phosphorus va- 

 pour is equivalent to an atom. The volume of 

 hydrogen, in order to be converted into water, 

 requires half a volume of oxygen gas. It is ob- 

 vious from this, that phosphorous acid is a com- 

 pound of one volume phosphorus vapour and 

 half a volume of oxygen gas ; and phosphoric 



