STALLING METHODS 88 



ferrous sulphate, tannic acid, carbolic acid, etc. These chemical 

 agents seem to have great powers of penetration into the cells, 

 carrying the stains through the membranes with them. 



Aniline oil water is also used as a mordant. It is prepared by 

 shaking a small amount of aniline oil in distilled water for fifteen 

 minutes or longer and then filtering. The aniline oil water so 

 obtained is mixed with the dye to be used. It is not stable for a 

 long time. 



Exercise 58. Preparation of Simple Stains 



1. Fuchsin (basic). 



a. Saturated aqueous solution. 



Basic fuchsin 1.5 g. 



Distilled water 100.0 cc. 



b. Saturated alcoholic solution. 



Basic fuchsin 3.5 g. 



95 per cent alcohol 100.0 cc. 



Place in a stoppered bottle, shake well at frequent intervals, 

 and filter after two hours. 



c. Carbol fuchsin (Ziehl). 



Saturated alcoholic solution fuchsin ... 10 cc. 



Carbolic acid (cryst.) 5 g. 



Distilled water 100 cc. 



Filter before using. This solution improves with age. 



2. Methylene blue. 



a. Saturated aqueous solution. 



Methylene blue 1.5 g. 



Distilled water 100.0 cc. 



b. Saturated alcoholic solution. 



Methylene blue 1.5 g. 



95 per cent alcohol 100.0 cc. 



Place in a stoppered bottle, shake well at frequent intervals, 

 alid filter after two hours. 



c. Alkaline methylene blue (Lofner). 



Saturated alcoholic solution methylene blue . 30 cc. 

 0.1 per cent aqueous solution KOH . . . 100 cc. 



Filter before using. 



