30 CLINICAL BACTERIOLOGY AND 



can be dissolved. Allow this to settle, and then filter 

 through a double thickness of filter-paper. To 9 parts of 

 this solution add 1 part of a saturated alcoholic solution of 

 gentian violet. 



This stain keeps much better if carbolic lotion 1 in 40 is 

 added. 



Loffler's Methylene Blue. 



This stain is made by adding 30 c.c. of a saturated alco- 

 holic solution of methylene blue to 100 c.c. of a 1 in 10,000 

 solution of caustic potash. The potash solution is made by 

 taking 1 c.c. of a 10 per cent, solution of caustic potash and 

 making up to 100 c.c. with water; shake well, and pour 

 away 90 c.c, making up the remainder to 100 c.c. with 

 water, and shaking thoroughly. Now add 1 minim of the 

 10 per cent, solution to 2 ounces of water. 



This stain keeps well. 



Carbol-Fuchsin (Ziehl-Neelsen). 



This stain is prepared by adding a saturated alcoholic 

 solution of fuchsin to carbolic lotion (1 in 20) until the 

 fluid has lost its transparency, the preparation usually 

 being about 1 in 9 strength. 



The above makes a very powerful stain, and should be 

 diluted, when required, with five times its volume of distilled 

 water. 



Carbol-Thionin. 



This stain can be used instead of methylene blue. It 

 is made by adding 1 gramme of thionin to 100 c.c. of 

 1 in 40 solution of carbolic acid in distilled water. 



Particular care should be taken to always filter this 

 stain, as it crystallizes very readily ; in fact, it is a good 

 axiom to filter all stains before using as a matter of 

 routine. Before use dilute with equal quantities of distilled 

 water. 



