30 



ATLAS OF ABSORPTION SPECTRA. 



56. Congo Orange G Continued. 



0.405(a and 0.44/1. A weak, hazy band 

 begins at o.44i. and continues to 

 o.47Sfi. at which point it joins a 

 more intense band. The latter has 

 its maximum at 0.50S/H and then de- 

 creases to transparency at 0.53/*. 

 Transparent from 0.53/x to 0.63/1. 

 More concentrated solutions empha- 

 size all the maxima of absorption 

 just outlined and the minimum at 

 0.42/1. 



57. Chrysamine G. (A.) Sodium salt of 



diphenyl-disazo-bi-salicylic acid. 



Similar to fig. 36, pi. 9 ; No. 220, S. & J. 



Yellowish-brown powder. In solution 

 brownish yellow, faint yellow. 



7 g. per liter (heated and filtered). 



Angle 35.1'. Depth 0.26 to 0.58 mm. 



No visible absorption unless, perhaps, 

 a faint weakening of the extreme 

 violet. Somewhat similar absorption 

 to that of the more dilute solution of 

 No. 77. For the layer used the ab- 

 .sorption is nearly complete from 

 o.20/t to o.2gii. The continuous back- 

 ground is transmitted from 0.29/1 to 

 0.30/1. The limit of the ultra-violet ab- 

 sorption is approximately a straight 

 line joining the wave-lengths 0.365/1 

 and o.395/t at the opposite edges of 

 the negative. Transparent from 

 o.395/t to 0.63/1. More dilute solu- 

 tions and wedges of liquid tapering 

 to infinitesimal thickness show that 

 ultra-violet absorption is very weak. 

 58. Cresotine Yellow G. (M.) Sodium salt 

 of diphenyl - disazo-bi-o-cresol - car- 

 boxylic acid. 

 Similar to fig. 36, pi. 9 : No. 221, S. & J. 



Yellowish-brown powder. Jn solution 



yellow, faint yellow. 

 Saturated. 



Angle 39.0'. Depth o to 0.36 mm. 

 Absorption in violet and indigo. Ab- 

 sorption much like that of the more 

 dilute solution of No. 77. The solu- 

 tion has a peculiar odor. A washed- 

 out band begins at 0.3 i/i, passes 

 through a maximum near 0.355/1, 

 and then fades away at 0.44/1. A 

 rather narrow region of semi-trans- 

 parency, the center of which is near 

 0.30/1, separates this band from a 

 weak, more refrangible ultra-violet 

 band. Transparent from 0.44/1 to 

 0.63/x. 



59. C o n g o R e d. (A.) Sodium salt of 

 diphenyl-disazo-bi-naphthionic acid. 



Similar to fig. 26, pi. 7 ; No. 240, S. & J. 



Reddish-brown powder. In solution 

 red, yellowish red. 



5.9 g. per liter. 



Angle 27.3'. Depth o to 0.25 mm. 



Absorption in blue, blue-green, and 

 green with maximum nearer the 

 green end. Similar absorption to that 

 of solution No. 69. Absorption de- 

 creases from o.20fjL to near 0.28/1 and 

 then increases to a maximum at 

 about 0.325/1. These two partially 

 resolved bands are followed by a re- 

 gion of approximate transparency 

 extending from 0.385/1 to 0.426/1 with 

 its maximum at 0.405/1. Tran.spar- 

 ency is terminated at 0.426/1 by a 

 pair of wide, hazy bands of which 

 the more refrangible is the weaker. 

 The chief maximum is at 0.505/1. 

 Absorption ends at 0.545/1. Trans- 

 parent from 0.545/1 to 0.63/t. More 

 concentrated solutions show that the 

 ultra-violet and visible bands soon 

 run together, whereas the absorption 

 does not advance much towards the 

 orange. 



60. Congo Corinth G. (A.) Sodium_ salt 



of diphenyl - disazo - naphthionic-a- 

 naphthol-sulphonic acid. 



Fig. 23, pi. 6; No. 242, S. & J. 



Greenish-black powder. In solution 

 brownish red, red. 



5.38 g. per liter (heated). 



Angle 27.3'. Depth o to 0.25 nun. 



Absorption in blue-green, green, and 

 yellow. Very general absorption at 

 the red border. .A.bsorption band 

 from 0.46/1 to 0.555/t with its maxi- 

 mum near 0.5 15/1. The end of the 

 negative slants considerably, show- 

 ing that general absorption con- 

 tinues into the orange. Transparent 

 to red. Same empirical formula as 

 No. 61, but different constitution. 



61. Congo Rubine. (A.) Sodium salt of 



diphenyl-disazo-naphthionic acid - ^ - 

 naphthol-sulphonic acid. 



Similar to fig. 19, pi. 5; No. 243, 

 S. & J. 



Greenish, crystalline powder. In solu- 

 tion bluish red. dull red. 



Saturated (warmed). 



Angle 39.0'. Depth 0.26 to 0.62 mm. 



