AZOTIC GAS. 97 



stead of 60. The third of 57 is only 19, show^ 

 ing that one volume of the oxygen gas pre- 

 sent had escaped combustion. When the 

 quantity of hydrogen gas is greater than 42 to 

 the 100 of air, the diminution of volume some- 

 what exceeds the truth, and it goes on increas- 

 ing till the volume of hydrogen gas is equal to 

 that of the air, beyond which I did not think it 

 worth while to carry the experiment. 50 vo- 

 lumes of air, and 50 of hydrogen gas, being mixed 

 and fired, the diminution of bulk was 32 vo- 

 lumes. The third of this is 10-66. This would 

 raise the bulk of oxygen gas in air to 21^. per 

 cent. This diminution of the volume beyond 

 the proper quantity seems to be owing to the 

 formation of a small quantity of nitric acid or 

 ammonia. The best proportions are 100 volumes 

 air, and 42 volumes hydrogen gas ; with these we 

 always find the diminution of volume 60 indicat, 

 ing 20 per cent, of oxygen gas in air. 



I likewise verified this analysis of air by means 

 of phosphorus : 100 volumes of air were left 

 standing for two days over mercury, with a stick 

 of phosphorus immersed in them. The glass jar 

 with the air was then removed to the water 

 trough, and well washed, to deprive it of any 

 phosphoric acid which might have a tendency 

 to alter its volume. And to facilitate the action 

 of the phosphorus, a little water was added, so 

 that the air was saturated with moisture at the 



VOL, I, G 



