STAINS. 37 



STAINS. 



The following stains are all that is really necessary 

 for the vast majority of purposes: methylene blue, 

 basic fuchsin, gentian violet, thionin, and water-soluble 

 eosin. Bismarck brown may also be obtained. Ten 

 grammes will last the practitioner for A long time, and 

 this amount costs from yd. to is. They should be of 

 Grubler's make, and can be obtained from R. Kanthack, 

 Berners St., W. ; Messrs. Baird and Tatlock, Hatton 

 Garden and Renfrew St., Glasgow ; A. Frazer, Teviot 

 Place, Edinburgh ; and from Messrs. Southall or Philip 

 Harris, Birmingham. Other firms will also supply 

 stains, but Grubler's should always be specified. 



They are conveniently kept in a saturated solution of 

 absolute alcohol. The following formulae are the most 

 useful : 



1. A saturated watery solution of methylene blue. This 

 does not keep very well, and a fresh amount should be 

 prepared after a month. It is mostly used for staining 

 blood-films. Loffler's blue will serve every purpose in 

 bacteriological work. 



2. Loffler's methylene blue is prepared by adding 30 c.c. 

 of saturated solution of methylene blue (alcoholic) to 

 100 c.c. of a i in 10,000 solution of caustic potash. 



The potash solution is prepared thus : Take i c.c. of 

 a 10 per cent, solution of caustic potash and make up to 

 100 c.c. with water ; shake thoroughly and pour away 

 90 c.c; make up to 100 c.c. with water, and again shake. 

 A sufficiently close approximation is made by adding i 

 minim of the 10 per cent, solution to 2 oz. of water. 



This stain keeps fairly well. 



