INVESTIGATION OF AMERICAN GENTIAN VIOLETS 535 



Griibler, the methyl violet GB of Providence, and the gentian 

 violet of Harmer. With the exception of these few samples 

 there seems no question but that the rest are entirely satisfac- 

 tory for the Gram stain, and the American samples have ranked 

 practically as well as the Griibler samples. In fact, the Griibler 

 crystal violet ranks the lowest of any of the samples tested. 



The chief conclusion from this work seems to be that samples 

 of these three dyes are now produced in this country which are 

 perfectly satisfactory for the Gram stain, apparently just as 

 good as the Griibler samples, and that either crystal violet or 

 methyl violet 6B can be substituted for gentian violet in the 

 gram stain. The committee especially recommends the use of 

 crystal violet for this purpose as it is the one dye of this series 

 for which a definite chemical formula can be indicated, although 

 commercial samples of it are not necessarily pure and may vary 

 in their composition. This variation is probably less than in 

 the case of methyl violet 6B, where the name denotes merely a 

 certain shade of violet, and in the case of gentian violet, where 

 the name is not used in the dye industry and is not mentioned 

 in Schultz's index of dyes. For this reason the committee 

 recommends that those ordering stains to be used in the Gram 

 technic should specify crystal violet instead of gentian violet. 



Turning to the results with the different samples of crystal 

 violet, it will be seen that only one of those investigated was 

 from a basic manufacturer, namely the Du Pont sample. 

 This sample and the Goldin sample have given the highest 

 average grade of any of the crystal violets tested. All of 

 the other crystal violets seem to fall slightly below the Du Pont 

 sample which is rather surprising because there are indica- 

 tions to suggest that nearly all of these dealers in biological 

 stains merely rebottle the Du Pont crystal violet and sell it 

 under their own name. If this is the case, the sUghtly higher 

 rank of the Du Pont sample may be considered to be pure 

 accident. 



The only other actual manufacturer of crystal violet in this 

 country of which we have knowledge is the National Anilin 

 and Chemical Company. Their product was not included in 



