430 



KNOBLAUCH ON RADIANT HEAT. 



Moreover, the rays of heat reflected by certain surfaces, as 

 e. g. by gypsum and peroxide of copper, which were previously 

 undistinguishable, now appeared heterogeneous. 



Table LIV. 



Since it results from these experiments that the differences 

 apparent under such circumstances were not observed in single, 

 and but slightly decisive instances, but are almost always greater 

 and more varied than those in the case of the red-hot platinum 

 (compare p. 428 and 429), the conclusion appears justified, that 

 the heat emitted by platinum at a yellow heat is more heteroge- 

 neous than that evolved by red-hot platinum. 



Although, as has been frequently mentioned, we cannot always 

 conclude, from a great diiference of two deflections when ob- 

 served between lower degrees than those with which they are 

 compared, that there is a greater difference in the effects of the 

 heat, still in the cases just alluded to {i. e. on comparing the ob- 

 servations. Table LI II. and Table LIV.) this was allowed, be- 

 cause this dissimilarity of the thermoscopic indications does 

 not occur until a certain point ; but the deflections of the needle 

 of the multiplier, within the Umits to which the observations 

 extend, might be considered as proportional to the thermal 

 influences. 



When the heat of platinum, part of which is at a white heat, 



Table LV. 



