Nitro and Azo Dyes 93 



useful as a negative stain for bacteria (Benians, 1916, Cumley, 

 1935, Maneval, 1934) and for staining protozoa (Merton, 1932) 

 and yeasts (Gutstein, 1932). 



A spectrophotometric curve of this dye is given in graph 2, Fig. 

 8, page 79. 



For use of Congo red with Mayer's hemalum, see Staining Procedures, IA4-I3. 

 For use in Bennhold's stain for amyloid, see p. IA4-IO. 



d31 ERIE GARNET B C. I. NO. 375 



Synonyms: Congo corinth G or GW. Corinth brown G. Cotton 



corinth G. Amanil garnet H. Direct garnet R. Buffalo garnet R. 



Direct violet C. Diamine Bordeaux CGN. 



NH. OH 



I I 



/\/V_N=N_/-X_/'^V_N=N _/\/\ 



'xa; ^/ ^/ yx; 



NaSOj XaSOj 



C32H2iN507S2Na2; Mol Wt. 697.642 



{An acid dye) 



This dye has been employed by Geschickter (1930b), mixed with 

 azure A, for staining frozen fresh tissue. 



d35 trypan red C. I. NO. 438 



SOaNa 



NaSOj 



NaSOi SOiNa 



C32Hi9N60i5S5Na5; Mol. Wt. 1002.805 

 {An acid dye) 



The chief use of this dye is as a vital stain. Varco and Vischer 

 (1941), for instance, thus use it in studies of gastric secretion. As 

 pointed out by AYhitby (1942) this dye has an interesting history 

 because it had very early application as a chemotherapeutic agent, 

 and led ultimately to the discovery of the arsenicals. 



d38 BENZOPURPURIN 4B C. I. NO. 448 



Synonyms: Cotton red Jf-B. Dianil red J^B. Diamin red J^B. 



Sultan Jt.B. Direct red J^B. 



