To Prepare Bouillon from Meat Extract 



191 



by steam three successive days for fifteen to twenty minutes each, 

 according to the directions already given for intermittent steriliza- 

 tion, or superheated in the autoclave. 



The loss of water during boiling is an important matter to bear 

 in mind, as unless properly replaced it is the cause of disproportion 

 between the fluids and solids of the media. The quantity must 

 therefore be measured before filtration and enough water added to 

 replace what has been lost. Measuring before filtration is compara- 

 tively easy with bouillon, but diflScult with heavy liquids, like the 

 gelatin and agar-agar solutions. To overcome this difficulty it is 



Fig. 44. — Funnel for filling tubes with culture media (Warren): a, Funnel 

 containing the culture media in liquid condition; b, pinch-cock by which the flow 

 of fluid into the test-tube is regulated; c, rubber tubing. 



best to make the entire preparation by weight and not by volume. 

 A pair of platform scales with sliding indicators will first balance 

 the empty kettle and then show the correct quantity of each added 

 ingredient. After boiling, the kettle can be returned to the scale 

 and the exact quantity of water to be added determined. 



n. To Prepare Bouillon from Meat Extract. — When desirable, the 

 bouillon may also be prepared from beef-extract, the method being 

 very simple: To 1000 cc. of clean water 10 grams of Witte's dried 

 beef-peptone, 5 grams of sodium chlorid, and about 2 grams of beef- 



