KNOBLAUCH ON RADIANT HEAT. 



431 



The subjoined table contains the numbers which were found 

 in the individual instances (arithmetical means of three observa- 

 tions) : — 



Table LIV. 



after the insertion when the heat oi platinum at a yellow heat is reflected by 



is reflected by the same bodies as that at a dark red and yellow 

 heat, on transmission through the diathermanous substances it 

 presents still greater differences than the heat of platinum at a 

 yellow heat. Thus, in the previous instances, the needle receded 

 from 20° to ll°'25 on the insertion of the red glass, when these 

 rays were unreflected ; from 20° to 10°*25 when they were re- 

 flected by black paper; and to 14°'l7 when diffusely reflected 

 by carmine ; and on inserting the calcareous spar, the needle of 

 the galvanometer deviates from 20° to 9°*42 when the unre- 

 flected rays act upon the thermal pile, from 20° to 7°'5 when 

 they are reflected by black paper, and to 13°*67 when by car- 

 mine. 



The rays of heat reflected by black velvet and green oil-cloth, 

 which exhibited as little difference when emanating from plati- 

 num at a red as from that at a yellow heat, were now readily 

 distinguishable from each other. In the following table the de- 

 tails of these observations (again the arithmetical means of every 

 three experiments) are contained : — 



Table LV. 



after the insertion when the heat oi platimim partly at a uliite heat is reflected by 



