the Rarefaction and Condensation of Air, 577 



was first thoroughly stirred, and its temperature taken by the 

 same delicate thermometer which was made use of in the former 

 experiments. The stop-cocks were then opened by means of 

 a proper key, and the air allowed to pass from the full into 

 the empty receiver until equilibrium was established between 

 the two. Lastly, the water was again stirred and its tempe- 

 rature carefully noted. The following Table contains the re- 

 sults of a series of experiments conducted in this way, inter- 

 polated with others to eliminate the effects of stirring, evapo- 

 ration, &c. 



Table III. 



The difference between the means of the experiments and 

 interpolations being exactly such as was found to be due to 

 the increased effect of the temperature of the room in the latter 

 case, we arrive at the conclusion, that no change of temperature 

 occurs iXihen air is allowed to expand in such a man?ier as not to 

 develope mechanical power. 



In order to analyse the above experiments, I inverted the 

 receivers, as shown in fig. 5, and immersed them, as well as the 

 connecting piece, into separate cans of water. One of the re- 

 ceivers had 2828 cubic inches of dry air condensed into it, 

 while the other was vacuous. After equilibrium was restored 

 by opening the cocks, I found that 2 '36 of cold per lb. of 



