130 H. J. CONN 



wanted direct from the company; but for the sake of fairness we 

 did not want to buy this one brand of stains direct, while picking 

 up the others on the open market. The jobber through whom 

 we dealt had such delays in getting the Heyl samples that they 

 were not ready at the time of our main tests. It might further 

 be remarked that Mr. Heyl himelf says that his crude dyes are 

 generally obtained from abroad, as he does not believe the 

 American products satisfactory. 



One of the troublesome factors in the stain situation is due to 

 confusion in nomenclature. It may happen that the same name 

 is given to more than one product or that the same product is 

 called by several names. Accordingly it seems worth while to 

 discuss these three stains from the standpoint of their chemical 

 composition and to list their synonyms. In the list of synonyms 

 in each case, preferred names are given in bold-faced type. 



FUCHSIN (basic) 



.S'j/nojiJ/rns 

 Rosanllln 

 Diamond fuchsin 

 Magenta 

 Rubin 

 Anilin red 



The formula of fuchsin, or rosanilin, is (NH2.C6H4)2:C:C6H4" 

 NH. Being a basic dye, this is ordinarily combined with an 

 acid, and the dye with which we are familiar is the chloride 

 (NHs -06114)2 :C:C6H4:NH:HC1. Fuchsin proves the easiest to 

 obtain in a satisfactoiy state of purity of any of the dyes we 

 have so far investigated. 



There are three chief uses of fuchsin in bacteriological work: 

 general bacterial staining; staining for acid-fast quaUties; and 

 use in the endo medium for colon-typhoid differentiation. A 

 satisfactory stain should give good results for all three purposes. 

 In the present investigation, the acid-fast test has been most 

 frequently used, but enough tests have been made for the other 

 purposes to indicate the general utility of the different samples. 

 Only two investigators have used the stains in the endo medium, 



