Phenyl Methane Dyes 159 



violet is a component of all the deeper shades of methyl violet. 

 It is possible that before 1914 gentian violet did represent a fairly 

 constant mixture, but there seems to be some doubt even on this 

 point. It is certain that immediately following the first World 

 War each company used its own judgment as to what to furnish 

 when gentian violet was ordered. As a result there were placed 

 on the market under this name various methyl violets, with or 

 without dextrin, and also crystal violet; of course the purchaser had 

 no knowledge as to what he was obtaining in any given instance. 



Under the circumstances the Commission faced a difficult 

 problem in trying to standardize gentian violet. The question 

 was whether to recognize the name at all, or to approve some 

 particular dye or mixture of dyes of this group as gentian violet. 

 The former course was almost impossible because of the wide 

 demand among biologists for a stain labeled gentian violet; it was 

 plain that the stain companies would meet this demand in some 

 way. The second course (unless considerable latitude were recog- 

 nized) would be entirely arbitrary, inasmuch as no information 

 was available to show which members of this group of dyes were 

 especially needed in histology or bacteriology. Accordingly in 

 the first edition of this book gentian violet was defined as either 

 penta-methyl or hexa-methyl pararosanilin, or else a mixture of 

 methylated pararosanilins composed primarily of the two com- 

 pounds just named and having a shade at least as deep as that 

 recognized in the trade as methyl violet 2B. 



This definition was quite broad and did not exclude anything 

 sold at that time as gentian violet. As a result there are still 

 various different products sold under this name. The nature of the 

 imported gentian violet has not been recently investigated ; but it is 

 known that there are at least three types of gentian violet on the 

 market, prepared by American concerns. They are as follows: 

 1) crystal violet, as sold under the labels of the National Aniline 

 and Chemical Co. and of the Hartman-Leddon Co., each of these 

 products being plainly marked '^crystal violet" in small letters 

 following the name "gentian violet;" 2) one of the higher methyl 

 violets prepared by Coleman and Bell and labeled "gentian violet 

 improved;" 3) a product manufactured by the National Aniline 

 and Chemical Co. and labeled "gentian violet. Churchman," 

 which is claimed to be a mixture in equal parts of crystal violet 

 and methyl violet 2B. 



The situation is not yet regarded as entirely satisfactory. Users 

 should specify crystal violet, for bacteriological work and for* 

 histological purposes where a deep blue-violet is required; but 

 should order methyl violet 2B in histological procedures where a 

 reddish shade is called for. With this knowledge at hand, gentian 

 violet, as such, is not necessary. 



