102 Mr Graham 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 puff 

 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 

 Thomson. But pure nitric oxide was found by Dr Dalton 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 Dhosnhuretted hydrogen, like that of air upon 



