394 KxNOBLAUCH ON RADIANT HEAT. 



Table XXV. 



III. 



Thick- 

 ness in 

 milli- 

 metres. 



Substances 

 inserted. 



Deflec- 

 tion by 

 direct 

 radia- 

 tion. 



Deflection 

 after the 

 insertion 



by the un- 

 reflected 



rays of the 

 Argand 

 lamp. 



Deflection after the insertion 



when the heat of the Argand lamp 



is reflected by 



White 

 paper. 



Blue 

 paper. 



Black 

 paper. 



Deflection 

 after the 

 insertion 



by the un- 

 reflected 



rays of the 

 Argand 

 lamp. 



1-5 



1-4 

 1-4 



4-4 

 3-7 



1-4 



Red glass 



Blue glass 

 Alum 



13° 



Rock salt 



Calcareous spar . 



25° 



Gypsum 



7-46 



5-04 

 3-71 



2219 

 14-56 



12-00 



1-29 



5-25 

 4-92 



22-75 

 19-81 



16-62 



;-29 



4-91 

 4-84 



22-68 

 19-81 



16-62 



612 



4-38 

 3-17 



21-06 

 13-38 



10-88 



7-75 



4-92 

 3-67 



22-38 

 14-38 



11-81 



Differences were also perceptible on reflexion by bodies of the 

 same colour. 



On comparing together a number of white surfaces, I found 

 e. g. that the heat diffusely reflected by ivory, the direct deflec- 

 tion of which produced a deviation of 13° in the needle after 

 the insertion of the red glass, produced a deflection of 7°'37 in 

 the therm o-multiplier, that reflected by white velvet 9°'04. On 

 inserting the calcareous spar, in the first instance, a recess of 



Table XXVI. 



I also made the same experiments with 

 the white. It was then found, that e. g. 



black surfaces as with 

 the heat reflected by 



