202 



KNOBLAUCH ON RADIANT HEAT. 



Table IV. 



)-5 



1-4 

 1-4 

 02 

 01 

 1-3 

 4-4 

 3-7 

 1-4 

 0-2 



Substances 

 inserted. 



Deflection 

 by direct 



I radiation. 



1-5 

 1-4 

 1-4 

 0-2 

 01 

 1-3 

 4-4 

 37 

 1-4 

 0-2 



1-5 

 1-4 

 14 

 02 

 01 

 1-3 

 4-4 

 3-7 

 1-4 

 0-2 



Red glass 



Blue glass 



Alum 



White mica . . . 

 Green mica ... 

 White glass ... 



Rock salt 



Calcareous spar 



Gypsum 



Glass paper ... 



Red glass 



Blue glass 



Alum 



White mica ... 

 Green mica . . . 

 White glass ... 



Rock salt 



Calcareous spar 



Gypsum 



Glass paper ... 



Red glass 



Blue glass 



Alum 



White mica ... 

 Green mica . . . 

 White glass ... 



Rock salt 



Calcareous spar 



Gypsum 



Glass paper . . . 



20° 



20° 



20° 



20° 



Deflection after the insertion, by 



Platinum 

 at a dark 

 red heat. 



775 



7-37 



C37 



1275 



1375 



6-12 



13-50 



575 



6-20 



9-62 



Platinum 

 at an 



evident 

 red heat. 



9-50 

 870 

 650 

 16-50 

 16-87 

 10 37 

 16-62 

 8-50 

 6-50 

 10-50 



yellow 

 heat. 



900 



7-87 



4-50 



1725 



17-50 



10-37 



15-50 



700 



3-12 



11-00 



Platinum 

 partly at a 

 white heat. 



11-00 

 9-50 

 7-50 

 17-75 

 17-75 

 12-50 

 16-88 

 1037 

 700 

 12-00 



35° 



35° 



35° 



35° 



21-31 

 18-40 

 12-40 

 30-60 

 30-81 

 21-12 

 30-25 

 17-00 

 12-70 

 19-12 



40° 



40° 



40° 



40° 



2312 

 19-62 

 12-50 

 35-62 

 35-75 

 24-88 

 35-75 

 2000 

 15-12 

 23-25 



The numbers which refer to the direct deviation of 20° are 

 each the arithmetic mean of two observations, those for 35° the 

 mean of four, and those for 40° also of two experiments. The 

 results of the individual series thus combined agreed so per- 

 fectly with each other, that the above numbers may be regarded 

 as accurate to within half a degree. 



Hence it is experimentally placed beyond all doubt, that the 

 passage of radiant heat through diathermanous bodies is not in 

 immediate connexion loith the temperature of its source, as was 

 probable from previous experiments, but is alone dependent upon 

 the structure of the diathermanous substance, which is penetrated 



