Mr Graham on Phosphuretted Hydrogen. 93 



tion of all others, and even of hydrogen and sulphuretted hydro- 

 gen themselves above a certain proportion, distinctly impeded or 

 destroyed the accendibility of this gas. Thus, one volume phos- 

 phuretted hydrogen ceased to be spontaneously inflammable when 

 mixed with the following proportions of different gases : — 



With 5 volumes hydrogen, 



2 ... carbonic acid, 



3 ... nitrogen, 



1 volume olefiant gas, 



sulphuretted hydrogen, 



I 



2 



^5 ... nitric oxide, 

 ^ ... muriatic acid, 

 I ... ammoniacal gas. 



It is to be remarked, however, in reference to the preceding 

 table, that some specimens of phosphuretted hydrogen appear to 

 be more highly accendible than others, and that there is consi- 

 derable latitude in the proportion of foreign gas which may be 

 requisite for destroying the spontaneous inflammability of a given 

 specimen. Often a much smaller portion suffices than is stated 

 in the table. I have found half a volume of carbonic acid or of 

 nitrogen to produce the effect. Of course the introduction of 

 any trace of air, with the gases, must be carefully guarded against. 

 Nitrous acid, when present in hydrogen in too small a proportion 

 to enable that gas to communicate spontaneous inflammability to 

 phosphuretted hydrogen, or to be perceived by the smell, may 

 be detected by the effect of the hydrogen upon a prepared mix- 

 ture of non-accendible phosphuretted hydrogen and air, which 

 mixture may be had quite free from white smoke, and transpa- 

 rent. The addition of hydrogen to this mixture occasions the 

 immediate appearance of a dense white smoke, the oxidation of 

 the phosphorus being partially induced, if even an infinitesimal 

 proportion of nitrous acid exist in the hydrogen. Although the 

 oxidation of the phosphorus takes place at the expense of the air 

 present, and only when air is present, yet the nitrous acid appears 



