KNOBLAUCH ON RADIANT HEAT. 



403 



of these bodies, by virtue of which they transmit some rays more 

 easily than others. 



2, The next question was, how the modifications of heat pro- 

 duced by diffuse reflexion, which ensue on their transmission 

 through diathermanous substances, would be aflfected by different 

 sources of the heat. 



For this investigation, in addition to an Argand lamp, I 

 made use of platinum at a red heat (p. 163), the flame of 

 alcohol (p. 193), and a metallic cylinder, which was heated 

 by being placed over the flame of the Argand lamp (p. 

 198). 



We know that the rays of heat emitted by them are of different 

 kinds, by the unequal proportions in which they pass through 

 the same diathermanous bodies, and as may also be seen in the 

 following table, in which they are given for different direct de- 

 flections : — 



Table XXXIII. 



are contained in the following table, and require a new arrange- 

 ment for this method of grouping them : — • 



Table XXXIV. 



2 E 2 



