Mr Graham on Phosphuretted Hydrogen. 95 



ed to redness, and cooled under the surface of mercury, was pass- 

 ed up. In the course of five minutes a contraction of eight or 

 ten measures occurred, without any oxidation of the gas, for no 

 air was introduced with the charcoal. The gas was still sponta- 

 neously inflammable, but ceased to be so in the course of half an 

 hour. It was found, in fact, by different experiments, that wood- 

 charcoal can absorb about ten times its volume of phosphuretted 

 hydrogen gas itself; that the phosphuretted hydrogen and the 

 peculiar principle are absorbed indiscriminately at first by the 

 charcoal, but that by-and-bye the peculiar principle comes to be 

 entirely absorbed by the charcoal, without any farther absorption 

 of phosphuretted hydrogen. 



When the phosphuretted hydrogen did not exceed fifty or 

 sixty times the bulk of the charcoal, the peculiar principle was 

 entirely withdrawn in five minutes, and the gas ceased to be self- 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 separat- 

 ing it from the charcoal. It was quite clear that the peculiar 

 principle formed but a very small proportion of the volume of 

 the phosphuretted 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 principle from a small bulk of the phos- 

 phuretted 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 mer- 

 cury, the inside of which is moistened by a strong solution of 



