406 Prof. Graham On Phosphuretted Hydrogen. 



trous impregnation appeared also from the fact, that phos- 

 phuretted hydrogen, which had lost its spontaneous inflam- 

 mability, was rendered as actively inflammable as ever by 

 passing it, bubble by bubble, into an inverted receiver filled 

 with sulphuric acid recently 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 shallow vessel for a few hours, 

 and thereafter was found unfit for the purpose in question. 

 Phosphuretted hydrogen which had acquired spontaneous in- 

 flammability from a nitrous impregnation, appeared to retain 

 that property as long as the phosphuretted hydrogen which is 

 spontaneously inflammable as first prepared. Hydrogen gas 

 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 inflam- 

 mable. 



From the preceding results and other considerations, it 

 seemed not unlikely that the spontaneous inflammability of 

 phosphuretted hydrogen may be an accidental property, and 

 may depend upon the occasional presence of some foreign body 

 in minute quantity. The inquiry suggests itself, Is there a 

 peculiar principle in the self-accendible gas ? and if so, what 

 is it? 



3. It very soon appeared that a peculiar principle is with- 

 drawn from the gas by porous absorbents, such as wood-char- 

 coal and baked clay, which substances are capable of destroy- 

 ing the inflammability of several hundred times their volume 

 of gas. Thus, in one experiment, to five hundred mea- 

 sures of highly accendible phosphuretted hydrogen, one mea-^ 

 sure of charcoal recently heated to redness, and cooled under 

 the surface of mercury, was passed 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 spontaneously inflam- 

 mable, but ceased to be so in the course of half an hour. It 

 was found, in fact, by different experiments, that wood- char- 

 coal can absorb about ten times its volume of phosphuretted 

 hydrogen itself; that the phosphuretted hydrogen and the 

 peculiar principle are absorbed indiscriminately at first by 

 the charcoalj but that by and by the peculiar principle comes 

 to be entirely absorbed by the charcoal without any further 

 absorption of phosphuretted hydrogen. When the phosphu- 

 retted hydrogen did not exceed fifty or sixty times the bulk 

 of the charcoal, the peculiar principle was entirely withdrawn 



