Prof. Graham on Phosphuretted Hydrogen. 409 



mixed, but which does not appear unless the proportion of 

 olefiant gas be very considerable. It is probable that aether 

 vapour and the gaseous hydro-carburets have an influence of 

 the same kind. An astonishingly minute quantity of an essen- 

 tial oil suffices to destroy the inflammability of the gas over 

 mercury, if allowed an hour or two to act. Hence it is very 

 difficult to preserve gas in the inflammable state in the mer- 

 curial trough, if any portion of the mercury has been soiled 

 by an essential oil. 



7. The action of potassium on the peculiar principle is 

 equally remarkable. A most minute quantity of this metal or 

 of its amalgam destroys the self-accendibility of the gas in a 

 few minutes, without occasioning any reduction of volume 

 that could be measured. The fact is, that potassium or 

 its amalgam is without effect upon phosphuretted hydrogen 

 itself at the temperature of the air, neither absorbing nor de- 

 composing the gas ; but upon the peculiar principle, the action 

 of this metal is rapid and certain. One grain of potassium 

 amalgamated with fifty pounds of mercury rendered that 

 quantity of mercury quite unfit for retaining gas over it in an 

 inflammable condition for more than a few minutes. In such 

 experiments the interference of naphtha vapour was perfectly 

 excluded. Zinc and tin, either by themselves or in the state of 

 amalgam, have no sensible effect upon the self-accendible gas, 

 at least in a period of five or six hours. Protoxide of mer- 

 cury speedily withdraws the peculiar principle, but afterwards 

 also reacts slowly upon the gas itself. On the other hand, 

 the peroxide of the same metal is in no way injurious to the 

 self-accendible gas. Arsenious acid in powder acts in the 

 same manner as protoxide of mercury. The solution of 

 protosulphate of iron, if previously boiled, to deprive it of 

 air, is without effect upon the gas. The extraordinary action 

 of potassium, and that also, perhaps, of the essential oils, 

 seemed to point to the existence of an oxygenated principle 

 as the cause of the spontaneous inflammability of phosphu- 

 retted hydrogen. It is sufficiently evident that the propor- 

 tion in which this principle exists, to the whole gas, is ex- 

 ceedingly small, too minute to afford any hope of isolating 

 the principle. The nitrous impregnation, too, which was 

 found adequate to render gas spontaneously inflammable, 

 shows to how minute a quantity of matter the spontaneous 

 inflammability of phosphuretted hydrogen may, at times, be 

 owing. It seemed within the bounds of possibility that the 

 gas might owe its spontaneous inflammability in ordinary cir- 

 cumstances, if not to nitrous acid, at least to some other prin- 

 ciple allied to that substance. This led to a careful re- 



Third Series. Vol. 5. No. 30. Dec. 1834. 3 G 



