134 H. J. CONN 



were obtained with all the samples except those from dealers 

 A and C. These two, it will be noticed, are the two poorest 

 samples when used as stains. It has been found that even the 

 Griibler product shows up no better in such tests, the Coleman 

 and Bell sample being even more satisfactory than the German 

 fuchstn. 



For these reasons our present recommendation in regard to 

 fuchsin is in favor of the product of the Coleman and Bell Com- 

 pany. Although this does not show up qviite as weU in the 

 staining tests as that of the Pro\ddence Chemical Company its 

 rank is good, and its superiority as an indicator in the endo 

 medium puts it almost m a class by itself. It is plain, however, 

 that good results can be obtained with any of the samples except 

 the three that vstand lowest in table 2. 



METHYLEN BLUE 



Synonyms 

 Ethylene blue 

 Swiss blue 



The chief confusion ui regard to methylen blue lies in the 

 fact that there are really two dyes on the market, one a pure 

 chloride of methylen blue, the other a double salt, zinc and 

 methylen blue chloride. The pure chloride has the formula: 



(CH3)2N-C6H3<^ ■^CeHsNCCHs). 

 ^-Cl 



The methylen blues which are not zinc-free are generallj^ known 

 as "methylen blue" or "methylen blue for bacilli." The free 

 chloride, on the other hand, is specified in one of the following 

 maimers : 



Methylen blue, medicinal (pure, zinc-free). 

 Methylen blue, U. S. P. 

 Methylen blue, BG. 



The free chloride is soluble in both water and alcohol, the zinc 

 salt is insoluble in alcohol. 



