VOL. LXXIV.] PHILOSOPHICAL TRANSACTIONS. 48J 



of the common air employed ; so that, as common air cannot be reduced to a 

 much less bulk, than that, by any method of phlogistication, we may safely con- 

 clude, that when they are mixed in this proportion, and exploded, almost all the 

 inflammable air, and about J- part of the common air, lose their elasticity, and 

 are condensed into the dew which lines the glass. 



The better to examine the nature of this dew, 500000 grain measures of in- 

 flammable air were burnt with about 2\ times that quantity of common air, and 

 the burnt air made to pass through a glass cylinder 8 feet long and 4. of an inch 

 in diameter, in order to deposit the dew. The 2 airs were conveyed slowly into 

 this cylinder by separate copper pipes, passing through a brass plate which stopped 

 up the end of the cylinder; and as neither inflammable nor common air can burn 

 by themselves, there was no danger of the flame spreading into the magazines 

 from which they were conveyed. Each of these magazines consisted of a large 

 tin vessel, inverted into another vessel just large enough to receive it. The inner 

 vessel communicated with the copper pipe, and the air was forced out of it by 

 pouring water into the outer vessel ; and in order that the quantity of common 

 air expelled should be 2-±- times that of the inflammable, the water was let into 

 the outer vessels by 1 holes in the bottom of the same tin pan, the hole which 

 conveyed the water into that vessel in which the common air was confined being 

 1\ times as large as the other. In trying the experiment, the magazines being 

 first filled with their respective airs, the glass cylinder was taken off", and water 

 let, by the 2 holes, into the outer vessels, till the airs began to issue from the 

 ends of the copper pipes; they were then set on fire by a candle, and the cylinder 

 put on again in its place. By this means upwards of 135 grs. of water were con- 

 densed in the cylinder, which had no taste nor smell, and which left no sensible 

 sediment when evaporated to dryness; neither did it yield any pungent smell 

 during the evaporation; in short, it seemed pure water. 



In my first experiment, the cylinder near that part where the air was fired was 

 a little tinged with a sooty matter, but very slightly so; and that little seemed to 

 proceed from the putty with which the apparatus was luted, and which was 

 heated by the flame; for in another experiment, in which it was contrived so 

 that the luting should not be much heated, scarcely any sooty tinge could be 

 perceived. By the experiments with the globe it appeared, that when inflam- 

 mable and common air are exploded in a proper proportion, almost all the inflam- 

 mable air, and near -f of the common air, lose their elasticity, and are condensed 

 into dew. And by this experiment it appears, that this dew is plain water, and 

 consequently that almost all the inflammable air, and about \ of the common air, 

 are turned into pure water. 



In order to examine the nature of the matter condensed on firing a mixture of 

 dephlogisticated and inflammable air, I took a glass globe, holding 8800 grain 



