x NITRE, NITRIC ACID, AND NITROGEN 203 



nitrous acid l is produced, which remains dissolved in the 

 water. Reducing the nitrous gas to its elements, one finds 

 that the proportion of 100 of oxygen to 400 of nitrous gas 

 reduces to : 



Nitrogen 100, 



Oxygen 150 " 



(Annales de C/iimie, 1816, 1, 399 400). 



" It remains now to consider nitric acid, and to determine 

 by what proportion of oxygen and nitrous gas it should be 

 represented ... I worked at first, like Dalton, in tubes of 

 5 millimetres diameter, using an excess of oxygen, and 

 obtained almost exactly the results that he gives, that is to 

 say, an absorption of 134 to 136 parts of nitrous gas for 100 of 

 oxygen ; but I found also that tubes of twice this diameter 

 can be used, provided that one does not shake the water, 

 and that one waits some minutes. The absorption obtained 

 by Dalton being only 130, I will adopt the figure 133, 

 which is also adopted by Davy, and it only remains to 

 determine to what acid it belongs. The red sulphate of 

 manganese, 2 which I have already recommended as a re- 

 agent to test when a body is saturated with oxygen, will 

 fulfil our purpose admirably ; for it is at once decolorised 

 by nitrous acid, but not at all by nitric acid." 



"I began by producing an absorption of 180 parts of 

 nitrous gas and 100 of oxygen, and found that the acid 

 formed .... decolorised the red sulphate of manganese 

 immediately. This salt was also decolorised when the 

 absorption of nitrous gas was 160, 150, and even 138 ; but 

 it no longer took place in the experiment in which only 134 

 parts of nitrous gas were absorbed. It is thus proved that 

 [the product] is ordinary nitric acid, and that it is formed 

 by the proportion of 100 of oxygen gas to 133 of nitrous gas, 

 which reduces to 



Nitrogen 100, 



Oxygen 250" 



(Annaks de Chimie, 1816, 1, 403 404). 



1 Yellow nitric acid saturated with nitric oxide. 



2 A red oxidising agent, probably a permanganate. 



