COLORING MATTERS. 



33 



72. Azo Blue Continued. 



is very indefinite and the maximum 

 appears to be in the yellow. Ab- 

 sorption is like that of solution No. 

 74, except in so far as it is stronger 

 than No. 74 in the orange. Compara- 

 tively weak absorption in the ultra- 

 violet from o.20jii to 0.355/t. There 

 are slight indications of two ultra- 

 violet bands with the intervening re- 

 gion near 0.29/i. Transparent from 

 0.36/4 to 0.49/x. Absorption begins at 

 o.49/t, increases to 0.53/x, then fades 

 to partial transparency near 0.59/1. 

 Weak absorption from 0.59/1 to 0.63/t. 



73. Diamine Black BO. (C.) Sodium salt 



of ethoxy-diphenyl-disazo-bi-amido- 

 naphthol-sulphonic acid. 



Suggested by fig. 22, pi. 6; No. 304, 

 S. & J. 



Black powder. In solution blue, blue. 



7.5 g. per liter. 



Angle 31.2'. Depth o to 0.29 mm. 



Strong absorption in the yellow and 

 orange with diffuse borders. Red is 

 transmitted. The absorption is some- 

 what like that of solution No. 74 

 except in so far as it is stronger than 

 No. 74 in the orange. Absorption 

 decreases from o.20/i to about 0.37/t. 

 Transparent from 0.37/t to 0.51/1. 

 Absorption extends from 0.5 i/t into 

 the clear red. The maximum of ab- 

 sorption is indefinite. 



74. Benzopurpurine 10 B. (A.) Sodium 



salt of dimethoxy-di-phenyl-disazo- 

 bi-napluHonic acid. 



Fig. 22, pi. 6 ; No. 307, S. & J. 



Brownish-red powder. In solution red, 

 pink. 



5.83 g. per liter. 



Angle 23.4'. Depth 0.05 to 0.26 mm. 



Chief absorption in the green. The 

 visible band extends from about 

 0.48/1 to o.55/t with its maximum at 

 0.515/1. The slanting end of the nega- 

 tive denotes general absorption in 

 the orange. 



75. Benzoazurine. Sodium salt of dimeth- 



oxy-diphenyl disazo-bi-a-naphthol-/>- 

 sulphonic acid. 



Somewhat like fig. 22, pi. 6; No. 311, 

 S. & J. 



Bluish-black powder. In solution red- 

 dish blue, blue. 



7.5 g. per hter. 



75. Benzoazurine Continued. 



Angle 25.5'. Depth o to 0.21 mm. 



No very definite, visible band, but a 

 general weakening of the green, yel- 

 low, orange, and red. The ultra- 

 violet absorption is weak and ends 

 near 0.355/*. The region of general 

 absorption begins about 0.5 i/t and 

 continues beyond 0.63/1. There is a 

 weak maximum near 0.53/4. The 

 end of the negative slants to an un- 

 usual degree. The contour of the 

 weak band is V-shaped like the 

 visible band for solution No. 74. 



76. Diamine Green B. (C.) Sodium salt 



of diphenyl - disazo-phenol-disulpho- 

 amidonaphthol-azo-nitrobenzene. 



No. 372, S. & J. * 



Dull-gray, crystalline powder. In solu- 

 tion bluish green, bluish green. 



3 g. per liter. 



Angle 17.0'. Depth o to 0.14 mm. 



Gradual absorption in the orange and 

 red. Very weak absorption in the 

 ultra-violet from 0.20/4 to about 

 0.38/4. No visible or photographic 

 absorption between 0.38/4 and 0.6/1. 

 General absorption begins about 0.6/1. 

 yy. Congo Brown G. (A.) Sodium salt of 

 sulpho - benzene-azo-resorcinol - azo- 

 diphenyl-azo-salicylic acid. 



Figs. 35 and 36, pi. 9 ; No. 379, S. & J. 



Brown powder. In solution light brown, 

 yellow. 



4.67 g. per liter. 



Angle 27.3'. Depth o to 0.25 mm. 



Absorption in violet, blue, and green. 

 Very hazy at green side. Absorp- 

 tion decreases from 0.20/4 to a some- 

 what transparent region around 

 0.295/1. Maximum absorption at 

 0.365/4. Absorption ceases at 0.53/t. 

 A weaker solution (fig. 36) showed 

 transparency from 0.29/4 to 0.315/1. 

 Absorption from 0.315/t to 0.428/4. 

 Maximum absorption at 0.365/4, as 

 before. Transparent to yellow, 

 orange, and red. 

 78. Congo Brown R. (A.) Sodium salt of 

 sulpho-naphthalene-azo-resorcin-azo- 

 diphenyl-azo-salicylic acid. 



Fig. 35,pl. 9;No. 380, S. &J. 



Dark, brownish-red powder. In solu- 

 tion reddish brown, yellow. 



Saturated. 



Angle 29.3'. Depth o to 0.27 mm. 



Spectrogram too indefinite for reproduction. 



