26 



ATLAS OF ABSORPTION SPECTRA. 



33. Naphtliylamine Brown Continued. 



the latter wave-length the absorption 

 decreased very gradually to a maxi- 

 mum of semi-transparency at about 

 o.43/t. The apparent absorption at 

 o.52yti is much exaggerated by the 

 lack of relative sensitiveness of the 

 photographic film at this spot. Very 

 slight absorption from o.55yti to 0.63/*. 

 A weaker solution presented only 

 ultra-violet absorption. 



34. Fast Red A. (A.) New Coccine O. 



(M.) Sodium salt of /i-sulphonaph- 

 thalene-azo-y8-naphthol. 



Fig. 27, pi. 7; No. 102, S. & J. 



Brownish-red powder. In solution red, 

 pink. 



5 g. per liter (heated). 



Angle 27.3'. Depth o to 0.25 mm. 



Hazy absorption in blue-green and 

 general absorption in blue. Muddy- 

 looking solution. Two partially re- 

 solved bands extend from 0.41 5/^ to 

 0.54/t with maxima of absorption at 

 about 0.45/x and 0.50S/X. The less 

 refrangible band is the more intense. 

 Orange and red are transmitted, but 

 the sloping end of the photograph 

 shows that slight, general absorption 

 is present in orange. Nos. 33 and 34 

 have the same empirical formula. 

 They differ by a and (3 naphthol. 



35. Azo Rubine S. (A.) Sodium salt of 



/"-sulphonaphthalene - azo-a-naphthol- 

 /'-sulphonic acid. 



Similar to fig. 55, pi. 14; No. 103, 

 S.&J. 



Brown powder. In solution red, pink. 



10 g. per liter. 



Angle 19.5'. Depth o to 0.18 mm. 



Absorption in green. Much like solu- 

 tion No. 17 with slight differences in 

 the ultra-violet. Absorption decreases 

 from o.20fi to 0.27/1. The strong lines 

 at 0.255/X and 0.275/x are transmitted 

 by the deepest layer. Absorption in- 

 creases from o.27;u to a maximum at 

 0.315/i. Then the absorption de- 

 creases to approximate transparency 

 at o.36ja. Transparent from 0.36/^ to 

 o.465;it. Strong band from 0.465/a to 

 0-55.S/^ with maximum at 0.51/11. The 

 visible band is in the same place as 

 the like band of No. 20, but the 

 ultra-violet is different. Transparent 

 to orange and red. 



36. Fast Red, extra. (A.) Sodium salt of 

 />-sulphonaphthalene-azo-^-naphthol- 

 monosulphonic acid. 



Similar to fig. 55, pi. 14; No. 105, 

 S.&J. 



Reddish-brown powder. In solution 

 red, pink. 



7 g. per liter. 



Angle 27.3'. Depth o to 0.25 mm. 



Absorption in blue-green and green. 

 Absorption the same throughout as 

 for No. 35 except the position of 

 the visible band. No. 36 absorbs 

 from 0.460/t to o.545;a with the max- 

 imum at 0.505^1. Same empirical 

 formula as for No. 35. 



^y. New Coccine. (A.) Sodium salt of 

 /'-sulphonaphthalene-azo-;8-naphthol- 

 disulphonic acid. 



Similar to fig. 52, pi. 13 ; No. 106, 

 S.&J. 



Scarlet-red powder. In solution yel- 

 lowish red, pink. 



10 g. per liter. 



Angle 23.4'. Depth o to 0.21 mm. 



Absorption in blue-green and green. 

 Similar absorption to that of solu- 

 tion No. 21. The ultra-violet absorp- 

 tion of solution No. 37 seems to con- 

 sist only of one band whereas that 

 of solution No. 21 seems to be separ- 

 ated into two bands by a minimum of 

 absorption near 0.274/11. Absorption 

 decreases from o.20;u, to transparency 

 about 0.37^. A strong, round band 

 from 0.445/i to 0.56/11 has its maxi- 

 mum at 0.5 i/u. Transparent from 

 0.56/a to 0.63/u. 



38. Fast Brown 3 B. (A.) Sodium salt of 

 sulphonaphthalene-azo-a-naphthol. 



Similar to fig. 23, pi. 6 ; No. 1 1 1, S. & J. 



Dark-brown, glistening powder. In so- 

 lution reddish brown, faint brown. 



15 g. per liter. 



Angle 2^.^'. Depth o to 0.25 mm. 



Absorption most intense in blue-green 

 and green with slight general absorp- 

 tion on both sides. Similar absorp- 

 tion to that of solution No. 60. A 

 fairly strong band from 0.46/u to 

 0.54/u, has its maximum at 0.51/1. No 

 definite band from 0.54/n to 0.63/u, but 

 general absorption is made evident 

 by the slope of the end of the nega- 

 tive. 



