Radiation of Non-Luminous Heat ^9 



The variety of colour is here small ; the radiating powers 

 rank bluish green, dark brown, white, blue ; omitting the second 

 experiment with the carbonate of lead, which is only comparable 

 with the one in which the surface was blackened by hydro-sul- 

 phate of potassa. Comparing these two results, the change of 

 surface appears to have increased the radiating power in the ra- 

 tio of 1.04) to 1. 



The coatings applied to cylinder No. 8 were more varied 

 than those of either of the foregoing. 



The effects of changing the crimson of alkanet to a blue was ap- 

 parently to decrease its radiating power about one per cent., or the 

 change of colour in reality did not alter the power. The car- 

 bonate of lead lost also slightly, or rather was not affected, by 



