434 KNOBLAUCH ON RADIANT HEAT. 



diminishes or increases it according as it loosens or condenses 

 the parts concerned. (P. 215.) 



7. The radiating power of a body is independent of the nature 

 of the rays of heat by the absorption of which it becomes heated. 

 (P. 221.) 



8. The heat radiated by the most heterogeneous bodies, of 

 unequal thickness and the surfaces of which are of the most dis- 

 similar nature, has been shown, by the means at present at our 

 command, to be homogeneous and simple, in whatever manner 

 it may be excited in them within the limits of the experiments 

 hitherto made, i. e. between 88° and 234° F. (Pp. 233, 234, 

 427.) 



9. The diffusion which heat experiences on rough surfaces has 

 no connexion with the temperature of its source. (P. 424.) 



10. Radiant heat is altered in very different ways by diffuse 

 reflexion, by some bodies to a great extent, by others it is unaf- 

 fected. In one and the same substance these modifications are 

 independent of the condition of its surface. (P. 400.) 



11. The changes produced in heat by diffuse reflexion are 

 occasioned both by the nature of the sources of heat and the 

 properties of the reflecting bodies. (P. 408.) 



12. They are merely the consequence of a selective absorption 

 of the reflecting bodies for certain rays of heat transmitted to 

 them. 



13. Diffuse reflexion of the calorific rays is not analogous to 

 the reflexion of luminous rays. (P. 424.) 



14. The heterogeneity of the rays of heat emitted by one and 

 the same body is greater at higher than at lower temperatures ; 

 but does not constantly increase with the temperature, and has 

 no perceptible relation to the radiating power. (P. 432.) 



15. The series which certain sources form, when arranged 

 according to the amount of difference in their rays of heat, is the 

 same as that which they exhibit when they are arranged according 

 to the heterogeneous nature of the luminous rays which they 

 emit. (See p. 432.) 



