MAKING COVER-GLASS PREPARATIONS 27 
If the mixture is not clear, add more of the saturated alco- 
olic solution of fuchsin drop by drop until when viewed 
hrough the pipette by transmitted light the liquid is perfectly 
lear. 
ANILINE GENTIAN VIOLET (EHRLICH-WEIGERT) 
Saturated alcoholic solution of gentian violet . I! cc. 
Absolute alcohol . . . . . 1. 1. ww. «60 e. 
Aniline waters 2 4 eo BAe 2 a & & TOOCR 
It is more convenient for each student to prepare one fifth 
f this quantity. 
CARBOLIC THIONINE BLUE (NICOLLE) 
Thionine blue. . . . . . 1... |. FT gram 
Carbolic acid . . . . . . . ws we.) 25 grams 
Distilled water. . . . . . +... . « «100 CC. 
Filter. Before using, dilute with an equal quantity of distilled 
vater and filter again. 
CARBOLIC GENTIAN VIOLET (NICOLLE) 
Gentian violet (saturated alcoholic solution) . tocc. 
Carbolic acid (1% solution) . . . . . . . Iooce, 
Mix and filter before storing. “ 
38. Aqueous solutions. Aqueous solutions of methyl violet, 
entian violet, fuchsin, and the other aniline dyes are prepared 
y adding 1 cc. of the saturated alcoholic solution of the 
sired dye to 20 cc. of distilled water. This will impart a 
ecided color to the liquid, so that in a pipette it will be barely 
ransparent. 
The true aqueous solutions are made by dissolving the dyes 
1 water, but these are weak and not so effective as those pre- 
iared from the alcoholic solutions. These solutions deteriorate 
1a short time.' The carbol fuchsin and alkaline methylene 
lue will keep a little longer, but they require filtering occa- 
ionally. 
