COLORING MATTERS. 



39 



107. Uranine Continued. 



Fig. 16 resulted from a solution of 2 g. 

 per liter. 



Angle 23.4'. Depth o to 0.21 mm. Only 

 the stronger band shows. Here it 

 extends from 0.480/n to 0.504/* with 

 its maximum at 0.493/x. 



Fig. 15 corresponds to 2.67 g. per liter. 

 The angle 31.2' gives a maximum 

 depth of 0.49 mm. Complete trans- 

 parency from 0.330/* to 0.443/*. The 

 spectrogram shows that the visible 

 region of absorption has roughly 

 parallel sides which are very definite. 

 The visible maximum is at 0.493/i 

 as before. At the outer edge of the 

 fifth strip the absorption covers the 

 interval from 0.443/* to 0.515/*. 



A solution of 5 g. per liter, of angle 

 42.5', and of depth o to 0.36 mm., 

 absorbed from 0.432/* to 0.518/* with 

 the maximum at 0.493/1. 



A solution of 20 g. per liter with an 

 angle of 42.5' caused the ultra-violet 

 and visible absorption bands to 

 coalesce, on the third photographic 

 strip, in a semi-transparent region 

 extending roughly from 0.355/1 to 

 0.395/*. Intense absorption from 

 0.395/1 to 0.533/*. The short wave- 

 length boundary is indefinite, but the 

 opposite limit is very sharply de- 

 fined and steep. Maximum absorp- 

 tion at 0.493/t. 



Tests were made to ascertain whether 

 or not the conditions were favor- 

 able to c'Dntamination of the absorp- 

 tion spectra by the fluorescent light. 

 The most dilute solution was illu- 

 minated with intense ultra-violet 

 light and an exposure of five min- 

 utes was given to the photographic 

 film. Full development of the film 

 brought out no trace of previously 

 incident light. Therefore, since the 

 Nernst glower alone was used in 

 making the records of the visible 

 bands and because, in all cases ex- 

 cept one, more concentrated solutions 

 were used, it follows that the spec- 

 trograms are correct representations 

 of the absorption, at least so far 

 as the fluorescent light is concerned. 

 108. Eosine, yellowish. (A.) Alkali salts 

 of tetrabromo-fluoresceine. 

 Fig. 58, pi. 15; No. 512, S. & J. 



108. Eosine, yellowish Continued. 



Deep red powder. In solution yellow- 

 ish red, pink. 



20 g. per Hter. 



Angle 21.3'. Depth o to 0.18 mm. 



Very strong absorption in blue and 

 green. Faint green fluorescence in- 

 creasing with dilution. Intense ab- 

 sorption from 0.20/1 to 0.33/*. The 

 absorption then decreases, first gradu- 

 ally and then steeply, to partial trans- 

 parency at 0.37/1. This transparent 

 region continues as far as 0.434/*. 

 Intense absorption from 0.434/* to 

 0.56/*. From 0.515/1 to 0.525/1 the 

 solution is almost opaque. Two un- 

 resolved bands seem to be present. 

 The more refrangible boundary of 

 the visible absorption is less definite 

 than the opposite side. The latter 

 limit is steep and sharp. Transpar- 

 ent from 0.56/1 to 0.63/1. 



109. Eosine a I'alcool. (B.) Potassium 



salt of tetrabromo-fluoresceine-ethyl- 

 ether. 



Fig"- 17. Pl- 5; No. 514, S. & J. 



Brown powder mixed with small, 

 green crystals. In solution red, pink. 



4.29 g. per liter (heated). 



Angle 46.8'. Depth o to 0.43 mm. 



Sharp, narrow band in green, abrupt 

 on yellow side and diffuse on the 

 blue side due to a faint companion 

 band. Slight greenish-yellow fluo- 

 rescence. Very weak absorption in 

 extreme ultra-violet. Absorption be- 

 gins at 0.495/* ^nd ends at 0.540/*. 

 The chief maximum is at 0.525/1. 

 Transparent from 0.540/* to 0.63/t. 



1 10. Methyl Eosine. (A.) Potassium salt 



of dibromodinitro-fluoresceine. 



Similar to fig. 58, pi. 15; No. 515, 

 S. & J. 



Brown, crystalline powder. In solution 

 red, orange. 



10 g. per liter. 



Angle 15.6'. Depth o to 0.14 mm. 



Intense band in blue and green. Ap- 

 parently two unresolved bands. Sim- 

 ilar absorption to that of solution 

 No. 108. Absorption is rather com- 

 plete from o.20/t to 0.30/1 and then 

 decreases to about 0.36/*. Strong 

 absorption from 0.46/* to 0.56/1. The 

 principal maximum is at 0.52/1. Very 

 transparent from 0.56/* to 0.63/1. 



