78 ELEMENTS OF WATER BACTERIOLOGY 



Dr. Chas. Krumwiede of the Research Laboratories 

 of the N. Y. City Department of Health has very 

 courteously furnished us with the following description 

 of the use of the brilliant green agar, which should 

 prove of value in practical water work. 



The medium is made up as follows: 



Composition of medium : 



Agar 1.5% 



Liebig's extract of beef . . . o . 3% 



Witte's peptone i . 0% 



Sodium chloride o . 5% 



Lactose i . 0% 



Glucose o. 1% 



Andrade indicator 3 . 0% 



Brilliant green (in 0.1% sol.)o. 2 cc. to each 100 c.c. 



(1-500,000). 



Andrade indicator: 



100 c.c. . 5% watery solution of acid fuchsin, 

 16 c.c. normal NaOH solution. 



The solution, after the addition of the alkali should 

 turn slowly to a salmon yellow; if it does not, a little 

 more alkali may be added. 



Dr. Krumwiede describes the use of the medium 

 as follows : 



" The reaction should be set to the indicator, so 

 that the agar when hot is pinkish to red, but not deep 



