Tables 361-362. 



REFLECTING POWER OF PIGMENTS- 



TABLE 361. — Percentage Reflecting Power of Dry Powdered Pigments. 



299 



Taken from "The Physical Basis of Color Technology," Luckiesh, J. Franklin Inst., 1917. The total reflecting 

 power depends on the distribution of energy in the illuminant and is given in the last three columns for noon sun, blue 

 sky, and for a 7.9 lumens/ watt tungsten filament. 



TABLE 362. — Infra-red Diffuse Percentage Reflecting Powers of Dry Pigments. 



* Non -monochromatic means from Coblentz, Bui. Bureau Standards 9, p. 283, 1912. 



For the reflecting (and transmissive) power of roughened surfaces at various angles of incidence, see Gorton, 

 Physical Review, 7, p. 66, 1916. A surface of plate glass, ground uniformly with the finest emery and then silvered, 

 used at an angle of 75°, reflected 90 per cent at 4/x. approached 100 for longer waves, only 10 at iju, less than s in the 

 visible red and approached o for shorter waves. Similar results were obtained with a plate of rock salt for transmitted 

 energy when roughened merely by breathing on it. In both cases the finer the surface, the more suddenly it cuts off 

 the short waves. 



Smithsonian Tables. 



