Temperature on the Colour of Pigments. 



415 



Fe 2 3 , which was measured at three temperatures (see 

 Table IX., fig. 11), could not be properly classified as a red. 

 It was the ordinary, well-known, rust-coloured powder. 



Fier. 11. 



x - 



M 



- 



^y' 





-lr- 





















3 c D E F a 



Table V. — Reflecting-power of Mercuric Iodide in terms of 

 that of the ideal White. Temperatures, 25° and 122° C. 



Wave-lengtbs. 



Red Variety. 



Yellow Variety. 











Intensities 



Intensities 



Intensities at 





at 25° O. 



at 122° C. 



25° O. 



1 



p. 







•7530 



0-895 



0-846 





•6689 



0-771 



0-744 



0-776 



•6080 



0-330 



0-066 



0-635 



•5570 



0050 



0-046 



0-561 



•5185 



0-058 







•4920 



0054 



0-044 





•4500 



0055 



0032 



0-091 



