402 Prof. Graham on Phosphurctted Hydrogen. 



addition or subtraction of matter that could be perceived. In 

 explanation of their possession of different properties, under 

 the same composition, allusion is made by Rose to isomerism, 

 or the doctrine that two bodies may exist identical in compo- 

 sition, but differing in properties. Certainly the existence of 

 two gases constituted alike, and yet possessing different pro- 

 perties, if established, would afford a firm basis for this doc- 

 trine. 



It was the importance of the theoretical results which might 

 be looked for, that induced me to attempt to continue the in- 

 vestigation beyond the point to which it has been carried by 

 Rose. Holding the general doctrine of isomerism as proble- 

 matical, my inquiries were directed to the discovery, in one or 

 other of the gases, of some adventitious matter, to the presence 

 of which the peculiarities of the species might be attributed. 



It is to be understood that the spontaneously inflammable 

 gas made use of .in my experiments was prepared by the 

 well-known process of heating phosphorus, lime, and water 

 together. This gas is spoken of as " the self-accendible gas," 

 or as " the gas from phosphuret of lime." The other gas, 

 which is not spontaneously inflammable, was prepared by 

 heating hydrated phosphorous acid, or by allowing the pre- 

 ceding species, contained in low receivers, to stand over water 

 for twenty-four hours. It is described as " the non-accendible 

 gas," " the gas from phosphorous acid." The accendibility 

 of the gas was judged of by allowing it to escape in bubbles 

 into the air from the receiver containing it, over either water 

 or mercury. The experiments were all made when the tem- 

 perature of the atmosphere was between 60° and 70° Fahr. 



1. In the process by which the self-accendible gas is pro- 

 cured, free phosphorus distils over, of which a trace in the 

 state of vapour may well be supposed to remain in the gas for 

 some time. Hence the idea has generally presented itself 

 that the free and highly accendible phosphorus present may 

 be the cause of the spontaneous inflammability of the gas. 

 Dr. Dalton, who all along maintained the opinion, which has 

 finally been established by Rose, that the two gases are of 

 the same composition, was in the habit of referring the spon- 

 taneous inflammability of the one species to this cause. The 

 speedy loss of the property in question in the case of gas con- 

 fined over water seemed to favour this view. I find, however, 

 that if a small quantity of phosphuretted hydrogen, when not 

 self-accendible, be added to a confined portion of air, sticks 

 of phosphorus introduced into that air do not smoke, — or that 

 phosphorus has no disposition to combine with oxygen when 

 phosphuretted hydrogen is present. In a transparent mixture 



