104 CLASSICS OF MODERN SCIENCE 

 elude, that when they are mixed in this proportion, and exploded, 

 almost all the inflammable air, and about one-fifth 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, 500,000 grain meas- 

 ures of inflammable air were burnt with about two and one-half 

 times the quantity of common air, and the burnt air made to pass 

 through a glass cylinder eight feet long and three-quarters of an inch 

 in diameter, in order to deposit the dew. The two airs were con- 

 veyed 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 big 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 two and one-half 

 times that of the inflammable, the water was let into the outer vessels 

 by two holes in the bottom of the same tin pan, the hole which con- 

 veyed the water into that vessel in which the common air was con- 

 fined being two and one-half times as big as the other. 



In trying the experiment, the magazines being first filled with their 

 respective airs, the glass cylinder was taken ofif, and water let, by the 

 two holes, into the outer vessel, 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 

 grains of water were condensed 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 smeU during 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 sooty matter, but very slightly so ; 

 and that little seemed to proceed from the putty with which the ap- 

 paratus was luted, and which was heated by the flame ; for in another 

 experiment, in which it is contrived so that the luting should not be 

 much heated, scarce any sooty tinge could be perceived. 



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



