Mr Granam 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entirely withdrawn in five minutes, and the gas ceased to be self- 
aecendible. 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 
