Tables 429-431 



TABLE 429. — Percentage Reflecting Power of Dry Powdered Pigments 



38l 



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 430. — 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, 

 nsed at an angle of 75°, reflected 90 per cent at 4/x, approached 100 for longer waves, only 10 at i/i, less than 5 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. 



TABLE 431. — Reflectivity of Snow, Sand, Etc. 

 (Hulburt, Journ. Opt. Soc. Amer., 17, 23, 1928.) 



Maine Fla. Crushed Plaster White 



sand * sand t quartz Snow of paris paper 



0.3 to o.4m 8 is 40 35 40 8 



0.4 to 0.8/4 25 40 50 40 S3 30 



0.8 to 2.611 33 SO 53 IS 60 30 



2,6 to 7fi 31 30 28 18 63 15 



7/j. 48 . . . . 26 



Sodium % 

 carbon- Sodium 

 ate chloride 



38 



14 

 28 



35 

 18 



49 

 54 

 55 



White 

 cotton 

 cloth § 



26 

 42 

 40 

 20 



* Yellow white grains of many kinds. 

 Smithsonian Tables 



f Very white. 



f Anhydrous. 



§ Handkerchief. 



