COLORING MATTERS. 



23 



13. Chromotrope 6 B Continued. 



imum until it joins the associated 

 band. More concentrated solutions 

 show very distinctly the weaker 

 band in the orange-red. 



14. Azo Coccine 2 R. (A.) Sodium salt 



o f xy lene-azo-a-naphthol-/'-sulphonic 



acid. 

 Fig. 9, pi. 2 ; No. 50, S. & J. 

 Reddish-brown powder. In solution 



salmon pink, salmon pink. 

 Saturated (heated). 

 Angle 27.3'. Depth o to 0.25 mm. 

 Narrow band in the blue-green. An 



absorption band of very indefinite 



edges extends from about 0.48/* to 



o.53ft with its maximum at 0.505^. 



Transparent from o.^^/x to 0.63/i. 



15. Brilliant Orange G. (M.) Sodium salt 



of xylene-azo-/8-naphthol-mono - sul- 

 plionic acid. 



Fig. 31, pi. 8;No. 54, S. & J. 



Cinnabar-red powder. In solution 

 yellowish red, deep yellow. 



7 g. per liter. 



Angle 23.4'. Depth o to 0.21 mm. 



Intense absorption in blue-green and 

 blue. Very sharp on the yellow side. 

 Absorption decreases from 0.20/i, to 

 weak absorption at 0.295/*, then in- 

 creases to maximum absorption at 

 0.32/1. At o.355/t semi-transparency 

 obtains. A definite band has its 

 maximum at 0.395/1 and joins the 

 next band at 0.43/*. The next band 

 has its maximum at 0.48/1 and joins 

 the adjacent band at 0.505/1. The 

 final band" has a maximum at 0.52/1. 

 Absorption ends at 0.545/1. Com- 

 plete transparency to 0.63/1. The 

 band at 0.395/1 disappears rapidly 

 with dilution. Same empirical 

 formula as solution No. 14. 



16. Ponceau 2 R. (A.), (M.) Sodium salt 



of xylene-azo-/?-naphthol-disulphonic 

 acid. 



Similar to fig 55, pi. 14 ; No. 55, S. & J. 



Brownish-red powder. In solution red, 

 pink. 



5 g. per liter (heated). 



Angle 27.3'. Depth o to 0.25 mm. 



Hazy-edged band in the blue-green. 

 Similar absorption to that of solu- 

 tion No. 17 in the ultra-violet and 

 identical with it in the visible region. 



17. Ponceau 3 R. (A.), (M.) Sodium salt 



of i/i-cumene-azo - j3 - naphthol-disul- 

 phonic acid. 



17. Ponceau 3 R Continued. 



Fig. 55, pi. 14; No. 56, S. & J. 



Dark-red powder. In solution red, pink. 



5 g. per liter (heated). 



Angle 29.3'. Depth o to 0.27 mm. 



An absorption band is in the blue- 

 green. It has its maximum at 0.50/1 

 and extends from about 0.47/1 to 

 0.54/1. Transparent from 0.54/1 to 

 0.63/1. 



18. Crystal Ponceau 6 R. (A.), (M.) 



Sodium salt of a-naphthalene-azo- 

 /3-naphthol-disulphonic acid. 



Similar to fig. 55, pi. 14; No. 64, S. & J. 



Brownish-red crystals with golden re- 

 flex. In solution light red, pink. 



5 g. per liter (heated). 



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. 17. The ultra-violet ab- 

 sorption, however, is somewhat more 

 intense and extends to greater wave- 

 lengths for solution No. 18 than for 

 solution No. 17. The visible band 

 extends from 0.465/1 to 0.56/1 with 

 its maximum at 0.5 i/i. 



19. Bordeaux B. (M.) Sodium salt of o- 



naphthalene-azo - /3 - naphthol-disul- 

 phonic acid. 



Similar to fig. 19, pi. 5 ; No. 65, S. & J. 



Brown powder. In solution red, red. 



4.18 g. per liter. 



Angle 42.5'. Depth o to 0.36 mm. 



Hazy-edged band in the green. The 

 sides of the band in the green and 

 the orange end of the spectrogram 

 slope a little more for solution No. 

 19 than for No. 106. Band from 

 0.485/1 to 0.545/1, with maximum at 

 0.515/1. The least refrangible ends 

 for all the spectrograms slope, thus 

 showing that there is some general 

 absorption in the orange. More con- 

 centrated solutions show that the 

 greatest transparency occurs at 

 0.414/1. Same empirical formula as 

 No. 18. 



20. Coccinine B. (M.) Sodium salt of p- 



methoxy- toluene - azo - p - naphthol- 

 disulphonic acid. 



Similar to fig. 55, pi. 14; No. y^, S. & J. 



Dark-red powder. In solution bright- 

 red, red. 



13.64 g. per liter. 



Angle 12.8'. Depth o to o.ii mm. 



.Strong absorption in green-yellow. 

 Similar to solution No. 17, save that 



