Chemical Effects of Caloric, $c. 65 



done during a winter. Hence the equal tem- 

 perature upon the ocean and upon islands, when 

 compared with continents in the same degree of 

 latitude. 



But the equal distribution of caloric or heat 

 does not seem to agree with some phaenomena 

 which frequently occur. The highest parts of 

 the air are the coldest, and the contrary. On 

 the Alps, Pyrenean mountains, &c., the ice and 

 snow are higher than the clouds, and seem to 

 increase, and we are further convinced of the 

 cold of the superior parts of the atmosphere by 

 showers of hail which fall in the summer. 



This distribution of heat has been explained in 

 different ways; but the real principle is as fol- 

 lows : It appears that the sun is the source of 

 heat to this globe, and we must observe that the 

 rays of the sun do not heat a body that is per- 

 fectly transparent. When the body is not per- 

 fectly transparent, and reflects some few of the 

 rays, it is somewhat heated, though nothing in 

 comparison with opake bodies. Hence black 

 bodies are soonest heated. If a burning glass is 

 so placed that the focus falls a little below the 

 surface of a transparent water, it does not heat 

 the water : if then you plunge a stick into that 

 part of the water, it will be immediately burnt 

 to a coal in its interior parts, the surrounding 

 w r ater preserving the exterior ones. The rays of 

 the sun, therefore, not heating transparent bodies, 

 have little effect upon the air; but the upper 



