yUro and Azo Dyes 77 



Lillie (1944c) has tried both dyes in his supersaturated isopropanol 

 technic, and finds Sudan II satisfactory, better in fact than Sudan 

 III, although not so intense or yielding such |a stable solution as oil 

 red O, oil red 4B or Sudan red 4B, it is especially good as a fat stain 

 for central nervous tissue, in combination with Weigert's technic 

 for myehn. (See p. 88.) 



For Lillie's supersaturated isopropanol technic, see Staining Procedures, p. 

 ID3-20. 



c35 PONCEAU 2.R C. I. NO. 79 



Synonyms: Ponceau R, RG, G, 4^R, 2RE, XR, J, FR, GR. 



Scarlet R. Xylidine ponceau 3RS. Lake ponceau. Brilliant 



ponceau G. Sew ponceau Ji-R. 



CH3 OH SOsNa 



/ I / 



H3C_/~\_N_N_/~\ 



/ \ 



~~SOgXa 

 Ci8Hi4N207S2Xa2; Mol. Wt. 480.422 

 {An acid dye; absorption maxima about \538\ 4-99) 



A dye called xylidine ponceau, possibly this one, has been used 

 as an histological counterstain in the Masson technic (see Foot, 

 1933), and by others who have followed Masson's methods with 

 certain modifications. Lillie (1940), however, suggests other dyes 

 for this purpose which give better results. The exact identity of 

 the French "ponceau de xylidine" employed by Masson is not 

 known. 



For the technic of Masson's trichrome stain, see Staining Procedures, p. IB3-I8. 

 c38 OIL BROWN D. C. I. NO. 8 1 



Svnonvms: Sudan brown. Sudan brown AX. Fast oil brown S. 

 Brilliant fat brown B. Fat brown III. 



N = N 



OH 

 C20H14N2O; Mol. Wt. 298.328 



Lillie (1944c) recommends Sudan brown, Sudan brown oB, and 

 oil brown D as satisfactory fat stains in the supersaturated iso- 

 propanol technic. These dyes all undoubtedly represent shades 

 of the above. 



