MAKING COVER-GLASS PREPARATIONS 2^ 



If the mixture is not clear, add more of the saturated alco- 

 holic solution of fuchsin drop by drop until when viewed 

 through the pipette by transmitted light the liquid is perfectly 

 clear. 



ANILINE GENTIAN VIOLET (EHRLICH-WEIGERT) 



Saturated alcoholic solution of gentian violet . n cc. 



Absolute alcohol 10 cc. 



Aniline water loocc. 



It is more convenient for each student to prepare one fifth 

 of this quantity. 



CARBOLIC THIONINE BLUE (NICOLLE) 



Thionine blue I gram 



Carbolic acid 2.5 grams 



Distilled water 100 cc. 



Filter. Before using, dilute with an equal quantity of distilled 

 water and filter again. 



CARBOLIC GENTIAN VIOLET (NICOLLE") 



Gentian violet (saturated alcoholic solution) . 10 cc. 

 Carbolic acid (i % solution) loocc. 



Mix and filter before storing. 



38. Aqueous solutions. Aqueous solutions of methyl violet, 

 gentian violet, fuchsin, and the other aniline dyes are prepared 

 by adding i cc. of the saturated alcoholic solution of the 

 desired dye to 20 cc. of distilled water. This will impart a 

 decided color to the liquid, so that in a pipette it will be barely 

 transparent. 



The true aqueous solutions are made by dissolving the dyes 

 in water, but these are weak and not so effective as those pre- 

 pared from the alcoholic solutions. These solutions deteriorate 

 in a short time. The carbol fuchsin and alkaline methylene 

 blue will keep a little longer, but they require filtering occa- 

 sionally. 



