102 Mr Granam on Phosphuretted Hydrogen. 
bubble, however, does not take fire the instant it bursts in the air, 
but after rising to a little height, and then explodes with a puft 
like loose grains of gunpowder, and not with the usual snap, the 
oxidation of the nitric oxide preceding the oxidation of the phos- 
phuretted hydrogen by a sensible interval. Nitric oxide, in a 
considerably smaller proportion than one-twentieth volume, ex- 
hibits a sensible effect in retarding the combustion of self-accen- 
dible gas, but does not altogether prevent it. In the case of 
phosphuretted hydrogen, which was not self-accendible, small ad- 
ditions of nitric oxide, such as 1 to 100, to 500, to 1000, or to 
2000 volumes phosphuretted hydrogen, did not induce self-ac- 
cendibility, when the nitric oxide employed had been previously 
washed with caustic alkali. The experiment was tried with three 
different specimens of washed nitric oxide. But nitric oxide, 
which had not been washed with alkali, particularly if it resulted 
from a turbulent action of the nitric acid on copper, and came 
overcharged with red fumes, and was withal newly collected, was 
pretty often efficient in making the gas self-accendible. ‘The pro- 
per proportion of such nitric oxide for this purpose, was found to 
be 1 volume to a quantity between 1000 and 2000 volumes of 
phosphuretted hydrogen. A greater or a less proportion of the 
nitric oxide failed to produce the desired effect. All these expe- 
riments with nitric oxide were made over water. 
It is well known that a mixture of phosphuretted hydrogen 
and nitric oxide may be exploded by a bubble of oxygen gas, a 
method of firing these gases, first practised, I believe, by Dr 
Tuomson. But pure nitric oxide was found by Dr Darrow to 
oxygenate phosphuretted hydrogen in a gradual manner, when 
the two gases are left together. It is probable, therefore, that 
it is, by acting itself upon phosphuretted hydrogen, that nitric 
oxide prevents atmospheric air from acting upon that gas in our 
experiments. It is conceivable that the oxygenating action of 
nitric oxide upon vhosnhuretted hydrogen, like that of air upon 
