Nitro and Azo Dyes 95 



This dye is a very important vital stain, much used by Evans. 

 (See Dawson, Evans and Whipple, 1920.) Commercially it is 

 better known under the name of brilliant Congo R. Difficulty 

 was at first found in securing a satisfactory product; but it was 

 overcome thanks to the cooperation of the Dept. of Agriculture, 

 and a good vital red is now obtainable from stain dealers. 



d5o azo blue c. I. NO. 463 



Synonym: Benzoin blue R. Direct violet B. 



OH OH 



N=:N_ _ 



■ /\ 



SO3 Na NaSOj 



C34H24N408S2Na2; Mol. Wt. 726.678 



{An acid dye; absorption maximum 560.5) 



Monne (1935) has listed this dye among a series with which vital 

 staining of protozoa has been secured. Butt, Bonynge and Joyce 

 (1936) find that it can replace India ink in demonstrating capsules 

 of bacteria. Broda (1939) uses it in the histochemical demon- 

 stration of magnesium. 



d52 DIANIL blue ZR C. I. NO. 465 



Synonyms: Direct steel blue BB. Benzo new blue 2B. 

 Naphthamine brilliant blue 2R. 



CH3 



OH OH 



N_N I I 



NaSOj SOjNa 



SOaNa 



/ 



CH3 



C34H23N40i2S3Na3; Mol Wt. 844.727 

 {An acid dye; absorption maximum about 568) 



This has been used as a vital stain by Corner and Hurni (1918) ; 

 also by Sutter (1919), and Duran-Reynals (1937). 



