VOL. LXXXI.] VHILOSOPHICAL TRANSACTIONS. 59 



our processes, any surplus of either of the 2 kinds of air would only have re- 

 mained unsaturated, and have been found unchanged in the residuum. I claim 

 no merit whatever in this observation. It was in consequence of accidentally 

 finding pure water in what I then imagined to be the same circumstances in 

 which I had always before found acid, and which surprized me not a little at the 

 time, that I was led to vary the proportions of the 2 kinds of air, till at length 

 I succeeded in ascertaining the circumstances on which this remarkable difference 

 in the result depends; but I am by no means able to assign any reason for this 



difference. 



In this state of my experiments I concluded, that nitrous acid, though con- 

 sistino- of the same elements with pure water, contains a greater proportion of 

 dephlogisticated air; and in the last edition of my Observations on Air, vol. 3, p. 

 543, I observed, that " substances, possessed of very different properties, may 

 be composed of the same elements, in different proportions, and different modes 

 of combination. It cannot therefore be said to be absolutely impossible, but 

 that water may be composed of these elements," viz. dephlogisticated and in- 

 flammable air. When I first prepared an account of my late experiments for the 

 E. s., I entertained this idea; but I now consider it as at least uncertain, because 

 when I mix the 2 kinds of air in such proportions as to produce water, I find in 

 the residuum much more phloglsticated air than I do when acid is produced, 

 which affords a suspicion that, in this case, the principle of acidity goes wholly 

 into the phloglsticated air, which, as my former experiments show, actually con- 

 tains it, though it is not easy to ascertain in what proportion. 



Having exploded 3 ounce measures of a mixture of something more than 2 

 parts inflammable air, and 1 of dephlogisticated, and another equal quantity in 

 which the inflammable air bore a less proportion to the dephlogisticated, the 

 former of which I knew would yield water, and the latter acid, I found the re- 

 siduum of the former to be 0.57 oz. m. not affected by nitrous air, and weakly 

 inflammable; and in order to find how much phlogisticated air it contained, I 

 mixed different proportions of phlogisticated and inflammable air, and concluded, 

 from the manner of firing them, and this residuum, that it could not consist of 

 less than 4- of phlogisticated air, viz. O.ip oz. m. But the residuum of the mix- 

 ture which would have produced acid was 0.62 oz. m. of the standard of J.O, 

 which I find by computation to contain not more than 0.002 oz. m. of phlo- 

 gisticated air. I repeated this experiment very many times, and never failed to 

 have a similar result; so that it is very possible that the pure water we find may 

 be nothing more than the basis of the 2 kinds of air; and the principle of aci- 

 dity in the dephlogisticated air, and the phlogiston in the inflammable air, may 

 combine to form a superfluous acid in the one case, and the phlogisticated air in 

 the other. This supposition is strengthened by finding that whether the produce 



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