IQO PHILOSOPHICAL TRANSACTIONS. [ANNO 1784. 



air, and dephlogisticated air mixed with phlogisticated in such a proportion as to 

 reduce it to the standard of common air ; for some dephlogisticated air from red 

 precipitate, heing reduced to this standard by the addition of perfectly phlogisti- 

 cated air, and then exploded with the same proportion of inflammable air as the 

 common air was in the foregoing experiment, the condensed liquor was not in 

 the least acid. 



From the foregoing experiments it appears, that when a mixture of inflam- 

 mable and dephlogisticated air is exploded in such proportion that the burnt air 

 is not much phlogisticated, the condensed liquor contains a little acid, which is 

 always of the nitrous kind, whatever substance the dephlogisticated air is pro- 

 cured from ; but if the proportion be such that the burnt air is almost entirely 

 phlogisticated, the condensed liquor is not at all acid, but seems pure water, with- 

 out any addition whatever ; and as, when they are mixed in that proportion, 

 very little air remains after the explosion, almost the whole being condensed, it 

 follows, that almost the whole of the inflammable and dephlogisticated air is 

 converted into pure water. It is not easy indeed to determine from these experi- 

 ments what proportion the burnt air, remaining after the explosions, bore to the 

 dephlogisticated air employed, as neither the small nor the large globe could be 

 perfectly exhausted of air, and there was no saying with exactness what quantity 

 was left in them ; but in most of them, after allowing for this uncertainty, the true 

 quantity of burnt air seemed not more than T ' T of the dephlogisticated air employed, 

 or -5V of the mixture. It seems however unnecessary to determine this point 

 exactly, as the quantity is so small, that there can be little doubt but that it 

 proceeds only from the impurities mixed with the dephlogisticated and inflam- 

 mable air, and consequently, that if those airs could be obtained perfectly pure, 

 the whole would be condensed. 



With respect to common air, and dephlogisticated air reduced by the addition of 

 phlogisticated air to the standard of common air, the case is different ; as the liquor 

 condensed in exploding them with inflammable air, I believe I may say in any 

 proportion, is not at all acid ; perhaps, because if they are mixed in such a pro- 

 portion as that the burnt air is not much phlogisticated, the explosion is too 

 weak, and not accompanied with sufficient heat. 



All the foregoing experiments, on the explosion of inflammable air with com- 

 mon and dephlogisticated airs, except those which relate to the cause of the acid 

 found in the water, were made in the summer of the year 1781, and were men- 

 tioned by me to Dr. Priestley, who in consequence of it made some experiments 

 of the same kind, as he relates in a paper printed in the preceding volume of 

 the Transactions. During the last summer also, a friend of mine gave some 

 account of them to M. Lavoisier, as well as of the conclusion drawn from them, 

 that dephlogisticated air is only water deprived of phlogiston ; but at that time 



