94 Mr Granam on Phosphuretted Hydrogen. 
to be speedily consumed ; the fumes soon ceasing, but appearing 
again on every subsequent addition of active hydrogen, till seve- 
ral volumes have been added, or till the oxygen of the air pre- 
sent is exhausted. 
That the influence of hydrogen was referable to the nitrous 
impregnation, appeared also from the fact, that phosphuretted 
hydrogen, which had lost its spontaneous inflammability, was 
rendered as actively inflammable as ever by passing it, bubble by 
bubble, into an inverted receiver filled with sulphuric acid, re- 
cently diluted with three measures of water and cooled. The 
gas was now capable of igniting spontaneously, when passed into 
air, without the intervention of hydrogen. The same diluted 
acid lost the smell of nitrous acid, by exposure to air in a shal- 
low vessel for a few hours, and thereafter was found unfit for the 
purpose in question. Phosphuretted hydrogen, which had ac- 
quired spontaneous inflammability from a nitrous impregnation, 
appeared to retain that property as long as the phosphuretted 
hydrogen, which is spontaneously inflammable as first prepared. 
Hydrogen gas, too, which had received a nitrous impregnation 
by being passed through a diluted sulphuric acid, retained, in one 
case, after being confined for twenty-four hours over water, the 
power of rendering phosphuretted hydrogen spontaneously in- 
flammable. From the preceding results and other considera- 
tions, it seemed not unlikely that the spontaneous inflammability 
of phosphuretted hydrogen may be an accidental property, and 
depend upon the occasional presence of some foreign body in mi- 
nute quantity. “The inquiry suggests itself, is there a peculiar 
principle in the self-accendible gas, and what is it ? 
3. It was very soon found that a peculiar principle is with- 
drawn from the! gas by porous absorbents, such as wood, charcoal, 
and baked clay, which substances are capable of destroying the 
inflammability of several hundred times: their volume of ‘gas. 
Thus, in one experiment, to 500 measures of highly accendible 
phosphuretted hydrogen, one measure of charcoal, recently heat- 
