in various Substances. 459 



fered it to remain till the contained air was not only 

 warm, but thoroughly saturated with the moisture which 

 it attracted from the linen rag, the mouth of the bottle 

 being well stopped up during this time with a good 

 cork; this being done, I removed the cork, for a mo- 

 ment, to take away the linen rag, and, stopping up the 

 bottle again immediately, I took it out of the warm 

 water, and plunged it into a large cylindrical jar, about 

 12 inches in diameter, and 16 inches high, containing 

 just so much ice-cold water, that, when the bottle was 

 plunged into it, and quite covered by it, the jar was 

 quite full. 



As the jar was of very fine transparent glass, as well 

 as the bottle, and as the cold water contained in the jar 

 was perfectly clear, I could see what passed in the bottle 

 most distinctly; and having taken care to place the jar 

 upon a table near the window, in a very favourable light, 

 I set myself to observe the appearances which should 

 take place, with all that anxious expectation which a 

 conviction that the result of the experiment must be de- 

 cisive naturally inspired. 



I was certain that the air contained in the bottle could 

 not part with its Heat, without at the same time that is 

 to say, at the same moment, and in the same place parting 

 with a portion of its water ; if, therefore, the Heat 

 penetrated the mass of air from the center to the surface, 

 or passed through it from particle to particle, in the same 

 manner as it is probable that it passes through water, 

 and all other unelastic fluids,* by far the greater part of 

 the air contained in the bottle would part with its Heat> 



* This opinion respecting the manner in which Heat is propagated in water, and 

 other unelastic fluids, was afterwards found to be erroneous, as has been shown in the 

 preceding Essay. 



