24 



ATLAS OF ABSORPTION SPECTRA. 



20. Coccinine B Continued. 



a weak absorption band seems to 

 have the limits 0.315JL1 and 0.355/x, 

 with a maximum at 0.33/i. Intense 

 band from 0.465^ to 0.555/u, with a 

 maximum at o.5iOfi. Transparent 

 from 0.555/i to 0.63/i. Very concen- 

 trated solutions or deeper layers 

 show that the transparent region on 

 both sides of 0.4111 becomes opaque 

 much faster than the orange and red 

 region. Red is transmitted when all 

 shorter wave-lengths are absorbed 

 completely. The solution exhibits 

 strong dispersive power. 



21. Eosamine B. (A.) Sodium salt of p- 



cresol - methyl -ether-azo-a-naphthol- 

 disulphonic acid. 



Fig. 52, pi. 13; No. 74, S. & J. 



Reddish-brown powder. In solution 

 yellowish red, pink. 



8.89 g. per liter. 



Angle 21.3'. Depth o to 0.18 mm. 



Strong band in blue-green and green. 

 Intense, round band from 0.465/1 to 

 0.565(11, with its maximum at about 

 0.52/i. Transparent from 0.565/1 to 

 0.63/1. Same empirical formula as 

 No. 20. 



22. Erika B. (A.) Sodium salt of methyl- 



benzenyl - amido - thio-xylenol-azo-a- 

 naphthol-disulphonic acid. 



Fig. 57. pl-i5;No.78, S. &J. 



Reddish-brown powder. In solution 

 red, pink. 



6.67 g. per liter. 



Angle 19.5'. Depth o to 0.18 mm. 



Strong absorption in blue, green, and 

 green-yellow. Two unresolved bands 

 absorb strongly from 0.46/1 to 0.59/t. 

 The more refrangible band shows 

 greater intensity than its companion 

 and has its maximum at 0.52/1. Slight 

 absorption in the orange is followed 

 by greater transparency in the red. 



23. Emin Red. (A.) Sodium salt of methyl- 



benzenyl - amido - thioxylenol-azo-/?- 



naphthol-sulphonic acid. 

 Fig. 29, pi. 8 ; No. 80, S. & J. 

 Red powder. In solution red, pink. 

 Saturated (heated). 

 Angle 31.2'. Depth o to 0.29 mm. 

 Weak, hazy absorption in blue and 



green. Strong absorption from o.20/<. 



to about 0.35/1, then a rather rapid 



decrease in absorption sets in. From 



23. Emin Red Continued. 



0.38/t to 0.45/1 a semi-transparent re- 

 gion exists. A round band extends 

 from 0.45/1 to 0.54/1. Its maximum 

 is near 0.495/1. The less refrangible 

 side of this band is far more definite 

 than its ultra-violet edge. Trans- 

 parent from 0.54/1 to 0.63/1. 



24. Janus Green. (M.) Chloride of safra- 



nine-azo-dimethylaniline. 



No. 81, S. & J. 



Olive-green, crystalline powder. In so- 

 lution blue, blue. 



4.6 g. per liter. 



Angle 17.0'. Depth o to 0.14 mm. 



Band in orange and orange-red. Trans- 

 parent to pure red. Very general ab- 

 sorption in ultra-violet, decreasing 

 gradually from o.20/t to 0.40/1. Trans- 

 parent from 0.40/1 to 0.515/1. The 

 absorption band begins at 0.515/1. 



25. Tropffioline O. (C.) Sodium salt of p- 



sulphobenzene-azo-resorcinol. 



Similar to fig. 37, pi. 10 ; No. 84, S. & J. 



Brown powder. In solution wine-color, 

 yellow. 



Saturated (heated). 



Angle 25.5'. Depth o to 0.21 mm. 



Faint absorption in the violet. Similar 

 absorption to that of solution No. 81. 

 Weak absorption from 0.20/1 to 

 0.275/1. Transparent from 0.275/1 to 

 0.325/1. A weak, hazy band extends 

 from 0.325/1 to 0.41/1 with its maxi- 

 mum around 0.37/1. Transparent 

 from 0.41/1 to 0.63/1. 



26. Tropreoline OOO No. i. Sodium salt of 



/i-sulphobenzene-azo-a-naphthol. 



Similar to fig. 31, pi. 8; No. 85, S. & J. 



Reddish-brown powder. In solution 

 red, salmon pink. 



6.67 g. per liter. 



Angle 21.3'. Depth o to 0.18 mm. 



Absorption in violet, blue, and green. 

 Similar absorption to that of solu- 

 tion No. 15. Rather strong absorp- 

 tion continues from 0.20/1 to about 

 0.33/1 and then decreases rapidly to 

 semi-transparency. A tolerably trans- 

 parent region is from 0.35/1 to 0.37/1. 

 Three unresolved bands with maxima 

 at about 0.41/1, 0.48/1, and 0.52/1 fol- 

 low. The intermediate points of less 

 intensity of absi.irption are 0.435/t 

 and 0.450/1. At 0.545/1 the absorption 

 cea.ses. Transparent from 0.545/1 to 

 0.63/1. 



