551 



TABLE 579.— PERCENTAGE REFLECTION FROM METALS, VIOLET END OF 



SPECTRUM m 



Wavelength in m 05 



Ni electroplated 



" vac. fused 



Ag (min. 7%, 33fi) 



Stellite (Co, Cr, Mo) 



Stainless steel, 13% Cr 



Cobalt 



Speculum 



Beryllium (98.7%) 46 



Chromium on steel 69 



172 Coblentz, Stair, Nat. Bur. Standards Journ. Res., Vol. 2, p. 343, 1929. 



TABLE 580.— PERCENTAGE REFLECTING FACTOR OF DRY POWDERED 



PIGMENTS 



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. 



Spectrum color Vio- Blue Green Yellow Orange Red 



Wavelength in n .44 .46 .48 .50 .52 .54 .56 .58 .60 .62 .64 .66 .68 .70 



American vermilion... 8 6 5 5 6 6 9 11 24 39 53 61 66 65 



Venetian red 5 5 5 5 5 6 7 12 19 24 28 30 32 32 



Tuscan red 7 7 7 8 8 8 8 12 16 18 20 22 23 24 



Indian red 8 7 7 7 7 7 7 11 15 18 20 22 23 24 



Burnt sienna 4 4 4 4 5 6 9 14 18 20 21 23 24 25 



Raw sienna 12 13 13 13 18 26 35 43 46 46 45 44 45 43 



Golden ochre 22 22 23 27 40 53 63 71 75 74 73 73 73 72 



Chrome yellow ochre.. 8 9 7 7 10 19 30 46 60 62 66 82 81 80 



Yellow ochre 20 20 21 24 32 42 53 63 64 61 60 59 59 59 



Chrome yellow medium 5 5 6 8 18 48 66 75 78 79 81 81 81 81 



Chrome yellow light.. 13 13 18 30 56 82 88 89 90 89 88 87 85 84 



Chrome green light... 10 10 14 23 26 23 20 17 14 11 9 8 7 6 



Chrome green medium 7 7 10 21 21 17 13 11 9 7 6 6 6 5 



Cobalt blue 59 58 49 35 23 15 11 10 10 10 11 15 20 25 



Ultramarine blue 67 54 38 21 10 6 4 3 3 4 5 7 10 17 



TABLE 581.— INFRARED DIFFUSE PERCENTAGE REFLECTING FACTORS 



OF DRY PIGMENTS 



* Nonmonochtomatic means from Coblentz. 



A surface of plate glass, ground uniformly with the finest emery and then silvered, used at an angle 

 of 75°, reflected 90 percent at 4ft., approached 100 for longer waves, only 10 at ljt, less than 5 in the 

 visible red and approached 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. 



■yuiTHSONIAN PHYSICAL TABLES 



