CALORIFICATION. 353 



the temperature of each are obvious and direct. 

 This fact was proved and established by a long 

 series of experiments, first began by Dr. Hook,, 

 continued and varied by Drs. Franklin and 

 Priestley, by Mr. Cavallo, Mr. Davy, Dr. 

 Herschell, Sir Harry Inglefield, cum multis 

 aliis. 



1. Dr. FRANKLIN placed upon pure snow, 

 pieces of cloth of different colors, viz. white, 

 red, blue, and black, and exposed them to the 

 solar rays : he found that the pieces of cloth 

 sunk in the snow with different degrees of ra- 

 pidity, in proportion to the darkness or light* 

 ness in the color of the cloth; and that this 

 sinking of the cloth in the snow was caused 

 by the heat produced upon the cloth, and 

 thence imparted to the snow, which melted 

 in consequence. 



2. Mr. CAVALLO painted the bulbs of different 

 thermometers, not only with the different pris-* 

 matic colors, but black and white also, and 

 exposed them all, with respect to the rays of 

 the sun, in the same relative situations * he in- 

 variably found, that the mercury in the ther- 

 mometer, whose bulb was either unpainted, 

 or painted white> was lower than in any of 

 the others* the mercury rising, in a regular 

 and progressive ratio, from these to the one 

 which was painted black, which was the highest 

 of the whole. 



A A 



