COLORING MATTERS. 



6i. Congo Rubine Continued. 



Absorption in bhie-green. Absorption, 

 especially in the visible spectrum, 

 similar to that of solution No. io6. 

 A layer about 2 mm. deep absorbs 

 all the visible si)cctrum except the 

 orange and red. Complete absorp- 

 tion at 0.20^ decreases to a minimum 

 near 0.275(11, then increases to a maxi- 

 mum at about 0.31/1, and finally van- 

 ishes in transparency at 0.345(11. Ab- 

 sorption band from 0.485/x to 0.55ft 

 with its maximum at 0.52/1. Trans- 

 parent from 0.55/t to 0.63/1. Same 

 empirical formula as No. 60, but dif- 

 ferent constitution. 



62. Anthracene Red. (I.) S o d i u m salt 



of nitrodiphenyl - disazo - salicylic-a- 

 naphthol-sulphonic acid. 



Similar to fig. 56, pi. 14; No. 262, 

 S. &J. 



Brownish-red powder. In solution deep 

 red, pink. 



7.5 g. per liter. 



Angle 27.3'. Depth o to 0.25 mm. 



Hazy-edged band in the blue-green 

 and green. Similar absorption to 

 that of solution No. 51. Absorption 

 decreases from 0.20/1 to semi-trans- 

 parency at 0.29/1. About 0.31/1 a well- 

 rounded, hazy-edged band starts, 

 passes through its maximum near 

 0.36/t, and ceases at 0.42/*. Partial 

 transparency from 0.42/1 to 0.465/1. 

 A symmetrical absorption band pre- 

 vents transmission from 0.465/1 to 

 0.55/1. Its maximum is near 0.51/1. 

 Transparent from 0.55/1 to 0.63/1. 

 Less concentrated solutions show 

 that the ultra-violet absorption is 

 comparatively weak. 



63. Congo Orange R. (A.) Sodium salt of 



ditolyl - disazo - phenetol-j8-naphthyl- 

 amine-disulphonic acid. 



Similar to fig. 11, pi. 3 : No. 275, S. & J. 



Yellowish-red powder. In solution 

 brown, yellowish brown. 



5 g. per liter (warmed and filtered). 



Angle 39.0'. Depth o to 0.36 mm. 



Indefinite, -general absorption in the 

 blue and blue-green. The liquid is 

 not clear, but behaves somewhat like 

 an emulsion. Similar absorption to 

 that of solution No. 47. Absorption 

 decreases from 0.20/1 to about 0.29/1 

 and then remains about constant as 

 far as 0.365/t. From this point it de- 



63. Congo Orange R Continued. 



creases to very weak, general ab- 

 sorption at 0.43/1. A slight increase 

 in absorption has its maximum at 

 0.515/1. It is partly, but not entirely, 

 due to the weak spot of the Seed 

 emulsion. Transparent from 0.54/1 

 to 0.63/1. Deeper layers of greater 

 concentration show the minimum of 

 absorption to be the region around 



0.455^- 



64. Benzopurpurine 6 B. (A.) Sodium 



salt of ditolyl - disazo - bi-a-naphthyl- 

 amine-sulphonic acid. 



Similar to fig. 26, pi. 7 ; No. 278, S. & J. 



Red powder. In solution red, brownish 

 red. 



7.78 g. per liter (filtered). 



Angle 29.3'. Depth o to 0.27 mm. 



Hazy-edged band in blue and green. 

 Similar absorption to that of solu- 

 tion No. 69. Strong absorption from 

 0.415/1 to 0.55/1. The chief maximum 

 of absorption is at 0.51/1. Probably 

 two hazy, unresolved bands, with 

 more refrangible, weaker component. 

 Transparent from 0.55/1 to 0.63/1. 

 Weaker solutions show more rapid 

 increase of transparency on the ultra- 

 violet side of the visible band than 

 on the red side. 



65. Benzopurpurine B. (A.) Sodium salt 



of ditoIyl-disazo-bi-/?-naphthylamine- 

 /?-sulphonic acid. 



Similar to fig. 26, pi. 7 ; No. 279, S. & J. 



Brown powder. In solution reddish 

 brown, brown. 



8.75 g. per liter. 



Angle 25.4'. Depth o to 0.23 mm. 



Same visible and photographic absorp- 

 tion as No. 69. Identical visible ab- 

 sorption to that of solution No. 64. 

 Solutions Nos. 65 and 69 seem to 

 have only one region of absorption 

 in the ultra-violet, whereas solution 

 No. 64 has a slight minimum of ab- 

 sorption near 0.275/1. Nos. 64 and 

 65 have the same empirical formulae, 

 but different chemical constitution. 



66. Diamine Red B. (A.) Deltapurpurine 



5 B. (M.) Sodium salt of ditolyl- 



disazo-bi-)3-naphthylamine - sulphonic 



acid. 

 Similar to fig. 26, pi. 7 ; No. 280, S. & J. 

 Reddish-brown powder. In solution 



yellowish red, pink. 



