Temperature on the Colour of Pigments. 



413 



Table IV. — Reflecting-power of Massicot (PbO) in terms of 

 that of the ideal White. Temperatures, 25°, 540°, and 

 825° C. 



Wave-lengths. 



Intensities 



Intensities 



Intensities 



at25°0. 



at 540° C. 



at 825° C. 



■7530 



0-585 



0-488 



0-255 



•6685 



0-502 



0-414 



0199 



•6080 



0-393 



324 



0-117 



•5570 



0-356 



0-175 



0-066 



•4920 



0239 



0059 



0-057 



•4500 



0-096 



0-057 





•4250 



0-060 





0-040 



In addition to the results of measurements made upon the 

 yellow iodide of mercury, Table V. contains data for the red 

 variety at 25° and at 122°. The other red pigments subjected 

 to investigation were : — Red lead (Table VI., fig. 8), sulphide 



Fig. 8. 



/°^rO u 



\ \ \ 



If- 6A S/- 



A 3 C D £ f £ 



of mercury, Hg 2 S (Table VII., fig. 9), and mercuric oxide, 



