58 PHILOSOPHICAL TRANSACTIONS. [aNNO I79I. 



Sciences for August 28, \7Q0, in the 7th volume of the Annales de Chimie, in 

 which a distinct account is given of a large quantity of very pure water procured 

 from the slow combustion of the 2 kinds of air above mentioned: for before this 

 it was acknowledged, that some little acid was always found in the water so pro- 

 cured. 



But my late experiments, besides ascertaining the fact of the production of 

 nitrous acid from the decomposition of dephlogisticated and inflammable air, 

 throw some further light on the subject, and may in some measure explain their 

 result; for I am now able to procure, in my own process, either nitrous acid or 

 pure water, from the same materials. I constantly observe, that if there be a 

 surplus of dephlogisticated air, the result of the explosion is always the acid 

 liquor; but that if there be a surplus of inflammable air, the result is simply water. 

 That pblogisticated air is not in all cases affected by this process, I completely 

 ascertained, by admitting a little common air into that mixture of the 2 kinds of 

 air which always produced water, and finding nothing but water in the result. 



I find however that, agreeably to the experiments of Mr. Cavendish, pblogis- 

 ticated air is decomposed in this process, when there is not enough of inflam- 

 mable air to saturate the dephlogisticated air; though when there is a redundancy 

 of inflammable air, there is even a production of pblogisticated air. Putting 

 0.5 oz. m. of pblogisticated air to a mixture of 2 ounce measures of inflamma- 

 ble air, and 1.5 oz. m. of dephlogisticated air, the whole was reduced by ex- 

 plosion to 1.05 oz. m. of the standard of 1.1, with 2 measures of dephlogisticated 

 air, which appears by computation to contain no more than 0.38S oz. m. of 

 pblogisticated air; so that 0.112 oz. m. had been decomposed in the process. 

 When there is a sufficient quantity of inflammable air, the pblogisticated air al- 

 ways remains unaffected in this process, as appears by mixing any quantity of it 

 with the 2 kinds of air to be exploded, and finding the very same quantity, as I 

 have repeatedly done, in the residuum. 



That when there was a sufliciency of inflammable air for the purpose, pblo- 

 gisticated air is even produced in this process, was evident from my never being 

 able to diminish any quantity of dephlogisticated air by inflammable air so far as 

 by good nitrous air, and the residuum always containing pblogisticated air. 

 Having exploded 2 measures of inflammable air with I of dephlogisticated air, 

 which by a mixture of 2 measures of nitrous air was reduced to 0.04, there was 

 a residuum of 0.1, of the standard of 1.3, which appears by computation to 

 contain 0.07 67 oz. m. of pblogisticated air. 



The reason why, in my former experiments, I always procured more or less 

 acid, must have been that, without any intention, or suspecting that any thing 

 depended on it, I must have had some surplus of dephlogisticated air. M. La- 

 voisier I also perceive to have taken it for granted, as I didj that after either of 



