the Weight ascribed to Heat. 3 



and in which the air was kept up to the temperature 

 of 61 of Fahrenheit's thermometer, with very little 

 variation. Having suffered the bottles, with their con- 

 tents, to remain in this situation till I conceived they 

 must have acquired the temperature of the circum- 

 ambient air, I wiped them afresh, with a very' clean, 

 dry cambric handkerchief, and brought them into the 

 most exact equilibrium possible, by attaching a small 

 piece of very fine silver wire to the arm of the bal- 

 ance to which the bottle which was the lightest was 

 suspended. 



Having suffered the apparatus to remain in this situa- 

 tion about twelve hours longer, and finding no altera- 

 tion in the relative weights of the bottles, they con- 

 tinuing all this time to be in the most perfect equi- 

 librium, I now removed them into a large uninhab- 

 ited room, fronting the north, in which the air, which 

 was very quiet, was at the temperature of 29 F. ; the 

 air without doors being at the same time at 27 ; and 

 going out of the room, and locking the door after me, 

 I suffered the bottles to remain forty-eight hours, un- 

 disturbed, in this cold situation, attached to the arms 

 of the balance as before. 



At the expiration of that time, I entered the room, 



using the utmost caution not to disturb the balance, 



when, to my great surprise, I found that the bottle 

 A very sensibly preponderated. 



The water which this bottle contained was com- 

 pletely frozen into one solid body of ice ; but the 

 spirit of wine, in the bottle B, showed no signs of 

 freezing. 



I now very cautiously restored the equilibrium by 

 adding small pieces of the very fine wire of which gold 



