30 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



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, and for staining 

 wet specimens of cells from the pleura, pericardium, etc. ; borax 

 methylene blue will serve every purpose in bacteriological work. 

 Instead of this I now employ acid methylene blue (No. 9). 



2. Loffler's methylene hkie is prepared by adding 30 c.c. of a 

 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 ap- 

 proximation is made by adding i minim of the 10 per cent, 

 solution to 2 ounces of water. 



This stain keeps fairly well. 



3. Manson's borax methylene blue, which I now use in place of 

 Loffler's blue and find much preferable. A stock solution (which 

 keeps well) is prepared by dissolving 2 grammes of methylene 

 blue and 5 grammes of borax in 100 c.c. of water. It is to be 

 diluted with five to ten times its volume of water for use. It 

 may be used whenever Loffler's blue is recommended. In 

 English measures it is methylene blue, grs. xxx. ; borax, grs. Ixxv. ; 

 aq., giii.ss. 



4. Cavbol fuchsin is made by adding a saturated alcoholic solution 

 of fuchsin to carbolic acid lotion (i in 20) until the fluid has lost 

 its transparency, or i part of the saturated solution to g of the 

 carbolic acid. This keeps well. 



The following is another formula : 



Fuchsin, i gramme, or grs. xv. 

 I in 20 carbolic, 100 c.c, or giii.ss. 

 Glycerin, 50 c.c, or 3xiv. 



5. The above stain diluted with four or five times its volume of 

 water. Label " Dilute Carbol Fuchsin." It is usually prepared 

 by diluting a little strong carbol fuchsin when required. 



6. Aniline gentian violet, which is prepared as follows : 



First prepare aniline oil water by shaking water (preferably 

 distilled) with more aniline oil than it will dissolve; a milky 



