[ 332 ' ] 



Gieflen very nearly agree, for according to him the latent heat 

 of the vapour of water, barometer 29,84 inches, and the heat 

 212*^, is 5,33 times greater than its fenfible heat above the 

 freezing point, now 180 x 5i33 = 959'4-*- The difference or 

 excefs in his experiment proceeds from the preffure of the atmof- 

 pherc being fomewhat lower, as Mr. Watt's experiments prove. 



Mr. Watt difcovered that the latent heat of fteam diminillied 

 in proportion as its fenfible heat increafed, Phil. Tranf 1784, p. 

 335. Now the fenfible heat of fteam exceeds 180*' above the 

 freezing point when the barometer ftands above thirty inches, and 

 is lefs than 180'' when the barometer ftands lower than thirty 

 inches, as Mr. De Luc firft difcovered, and may be fcen in Sir 

 George Schuckburg's and Mr. De Luc's tables, Phil. Tranf 1 779, 

 p. 375. From thefe I have deduced the following table: 



•4 Gren'3 Phys. Journal, p. 315. 



I 



Heat 



