depth according to the amount of rosanilin present. These mix- 

 tures are the various fuchsins known to commerce. In the course 

 of the recent investigation of fuchsins, no basic fuchsin of this type 

 has been found offered to biologists as a stain. Whether it would 

 prove satisfactory for staining purposes still remains to be deter- 

 mined. 



NEW FUCHSIN C. I. NO. 678 



Synonyms: Isonihin. Fuchsin NB. 



This compound is tri-methyl fuchsin, or triamino tritolyl 



methane chloride: 



CH3 



H CI /~\_NH. 



N_/^_C 



_ "\_NH. 



H 



CH3 ! 



CH3 



{A basic dye; absorption maximum about 5^4, 5J^5.) 



This dye is sometimes sold for a stain under the name of basic 

 fuchsin, altho the most reliable companies sell it under its correct 

 name. Recent investigations show that it may be admirable for 

 all the staining purposes for which basic fuchsin is used. 



ACID FUCHSIN C. I. NO. 692 



Synonyms: Fuchsin 8, S.Y, SS, ST, or S III. Acid magenta. 



Acid rubin. 



{An acid dye; absorption maximum about 5^5.) 



This dye owes its acid character to the fact that it is a sulfonated 

 derivative of basic fuchsin. Acid fuchsins are ordinarily rather 

 complex mixtures. As there are four primary basic fuchsins pos- 

 sible, according to the degree of methyl substitution, and as each 

 may yield at least three different compounds on sulfonation, fully 

 a dozen acid fuchsins are theoretically possible, and samples are 

 hardly to be expected which are not mixtures of several. 



The generally accepted formula of one of the homologs present 



in acid fuchsin, namely the di-sodium salt of rosanilin trisulphonic 



acid, is: 



SOj-Na 



/ 

 CH3 /— \_NH. 



\ IIV_/ / 



H2N_/^_C SO3 



NaSO, 



NH2 



64 



