Prof. Graham on Phosphuretted Hydrogen. 407 



in five minutes, so that the gas ceased to be self-accendible. 

 Charcoal which had been drenched in water was without 

 effect upon the gas. On heating the charcoal saturated with 

 gas in a retort filled with water, phosphuretted hydrogen was 

 given off, which, however, was not self-accendible ; and all 

 my attempts failed to isolate the peculiar principle by sepa- 

 rating it from the charcoal. It was quite clear that the pecu- 

 liar principle formed but a very small proportion of the phos- 

 phuretted hydrogen, evidently much less than one per cent, 

 of the bulk of the gas. Spongy platinum introduced into the 

 gas did not exercise any sensible absorbent effect, and no 

 quantity of it seemed sufficient to withdraw the peculiar prin- 

 ciple from a small bulk of phosphuretted hydrogen. Stucco, 

 likewise, was without effect upon the gas, at least when access 

 of air was guarded against at the same time. But both of 

 these substances are known to possess a very low absorbent 

 power. 



4. Phosphuretted hydrogen transferred to a receiver over 

 mercury, the inside of which has been moistened by a solu- 

 tion of caustic potash, always loses its spontaneous accendi- 

 bility, although by no means rapidly, several hours being ge- 

 nerally required. 



5. Certain acids appear to have a remarkable power in 

 withdrawing the principle of inflammability from phosphuret- 

 ted hydrogen. Let phosphuretted hydrogen be transferred 

 into a jar inverted over mercury, of which jar the inner sur- 

 face has been moistened with concentrated phosphorous acid. 

 A small quantity of the milk-white matter immediately appears 

 in the acid where exposed to the gas, and in two or three 

 minutes the gas has ceased to be spontaneously inflammable 

 in air, without any appreciable diminution of its volume hav- 

 ing occurred. This white matter, although very sensible to 

 the eye, exists only in the most minute quantity. It is not 

 crystalline, and perhaps not even solid. The introduction of 

 concentrated phosphoric acid into the gas was attended by 

 similar phaenomena, and the gas lost its spontaneous inflam- 

 mability in the course of half an hour. A strong solution of 

 arsenic acid acts as rapidly in withdrawing the peculiar prin- 

 ciple as phosphorous acid does; but the arsenic acid soon be- 

 gins to react upon the phosphuretted hydrogen itself, a dark 

 copper-coloured incrustation soon forming upon the surface 

 of the gas-receiver, which matter is probably a phosphuret of 

 arsenic. Concentrated sulphuric acid is capable of absorbing 

 phosphuretted hydrogen itself, which the preceding acids are 

 not; but even sulphuric acid appears to absorb the peculiar 

 principle in the first instance, by a more active affinity than 



