Xanthene Dyes 195 



R30 phloxine 



c. I. NO. 774 



Synonyms : Erythrosin BB, or B extra. New pink. 



C2oH405Br4Cl2Na2; Mol. TT7. .760.804 



(An acid dye; absorption maxima about 535.7, 14-97. 1]) 

 Solubility at 26°C: in water 50.9%; in alcohol 9.02% 



This dye and the following are often denoted interchangeably 

 phloxine or phloxine B, and there is some question as to whether 

 biologists have always been furnished the same type. The phlox- 

 ines of American manufacture at present on the market are the 

 following type. 



RSI PHLOXINE B C. I. NO. 778 



Synonyms: Phloxine TA, iV, BP super, RB, TB, or BB. 



Cyanosine. Eosin 10 B. 



C2oH205Br4Cl4Na2; Mol. Wt. 829.702 

 (An acid dye; absorption maxima 54-6-54-8) 



This dye differs from C. I. No. 774 in having four instead of 

 two chlorine atoms in the phthalic acid residue of the molecule, 

 Samples of phloxine recently submitted to the Commission for 

 certification seem to vary in degree of bromination or chlorination, 

 but correspond to this C. I. number rather than to the preceding. 

 Although some of the procedures given below may have been 

 worked out originally with the other type of phloxine, this type 

 has been found to give satisfactory results. 



A spectral curve of this dye, in comparison with erythrosin B 

 and rose Bengal, is given in Fig. 25. 



Unna (1921) used phloxine in combination with several other 

 acid dyes in studying the process of chromolysis. The dye was 

 seldom specified for biological work until about 1925, but has re- 

 cently been applied to staining bacteria, Negri bodies, and to 

 various histological procedures. It has, moreover, frequently been 

 used under other names. 



