378 On the Heat developed in Combustion 



that the vapour of water in contact with ice frequently 

 freezes, while this same ice is melting by the heat, or 

 that its thaw appears fully established. 



To give an idea of the reliance that may be placed on 

 the results of the experiments made with the new appa- 

 ratus I have just described, I will introduce here the 

 particulars of an experiment made purposely to discover 

 its degree of perfection. 



Having filled two receivers, properly connected with 

 each other, with water at the temperature of the air of 

 the room, 55 F., I burned a wax taper under the mouth 

 of the principal receiver, so that all the products of the 

 combustion passed through the worm of the secondary 

 receiver, after having traversed that of the principal. 

 Each of the receivers contained 2371 grammes [36621.5 

 grains] of water. 



The following are the results of the experiment : 



TIME OF THE OBSERVATION. TEMPERATURE OF THE WATER 



Hours. Min. Sec. ^ P * ^ Reiver .^ 



9 37 55 55 



49 4 2 ' 6 5 55 



56 15 70 



10 2 52 75 



9 32 80 



16 34 85 



23 54 90 

 27 56 



3 1 4 95 5 6 i 



39 35 I0 56| 



47 4 I0 5 56f 



From the results of this experiment it appears that 

 the water in the secondary receiver did not begin to be 

 heated perceptibly till that in the principal receiver had 

 been heated 15 or 20; and, as I had intended from 

 the beginning never to continue an experiment longer 

 than was necessary to raise the temperature of the 



