352 M. Bert/toilet's Experiments on the Proportion [Nov. 



The volume of gas disengaged added to that of the air in the 

 vessels before the experiment forms a total volume of 5*07 litres, 

 which, according to the preceding analysis, are composed of 

 3-3716 litres of oxygen and 1-7354 of azote, from which we must 

 subtract 0-0629 of oxygen and 0-2368 of azote, which consti- 

 tuted the atmospherical air of the apparatus. Hence the nitric 

 acid was composed of 3*3037 litres (201*92 cubic inches) of 

 oxygen and 1-4986 litres (91*456 cubic inches) of azote. This 

 makes the composition of nitric acid in volume 



Azote 100*00 



Oxygen 220*78 



The experiment was repeated with the same quantity of nitre ; 

 but to avoid the sublimation which took place in the former one, 

 the fire was much more cautiously raised ; and in fact no subli- 

 mation took place. To ascertain the capacity of the retort and 

 tube with more precision, it was filled with water after the expe- 

 riment, which was afterwards poured into a graduated cylinder. 



The result of this experiment was, that in nitric acid 100 

 litres of azote are combined with 222*96 of oxygen. 



From a third experiment it results, that 100 litres of azote are 

 combined with 222-58 of oxygen. 



The mean of the three experiments gives for 100 of azote 

 222-10 of oxygen. ■ 



If we convert these proportions into weights, we find that 

 nitric acid is composed of 



Oxygen. Azote. 



69-92 + 30-38 

 100-00 + 43.65 



My experiments give a proportion of oxygen a little smaller 

 than that which is adopted by Dal ton, who admits for 100 

 measures of azote 133 measures of oxygen, a proportion which 

 differs little from the results of Cavendish and Davy. 



Towards the end of the decomposition of the nitrate, the 

 receiver acquires a red colour ; but as the nitrous gas indicated 

 by that colour is found in contact with an excess of oxygen, it 

 ought to be again converted (at least chiefly) into nitric acid, 

 and of course produce little alteration in the ratio of the oxygen 

 and azote as indicated by the experiment. 



This quantity of nitric acid which is again fonned is so small 

 that it cannot even alter sensibly the absolute weight of the 

 acid, as determined by the weight of the gases disengaged. 

 This I ascertained by passing through a small quantity of water 

 all the gas disengaged during the process. This fact had been 

 already constated by Lavoisier and Bacquet, who were em- 

 ployed by the Academy of Sciences to examine the memoir of 

 which I have spoken. 



If we employ the products of this decomposition to determine 



