Radiation of Nori' Luminous Heat. S61 



shewn, by which the place of the white material, sulphate of ba- 

 ryta, is entirely changed ; this is a quality difficult to appre- 

 ciate, and yet here we find it exceeding in influence any other 

 property of the coating. 



A review of these results will shew that we have been able to 

 establish, among the separate series, no order of colour. We 

 have the different orders as follows : — 



A more satisfactory comparison, in respect to the number of 

 substances employed, will be had by using the means, hereto- 

 fore described, for comparing together the results obtained with 

 different cylinders. For example, Nos. 1, 2, and 3, were each 

 coated with carbonate of lead, and through the numbers given 

 by these coatings, those found for the other coatings can be com- 

 pared. Nos. 1 and 4 were coated with vermilion, and Nos. 1 

 and 5 with gamboge. 



The following table presents the comparison, the substances 

 being arranged in the order of their radiating powers :— 



