SUGAR BOUILLONS 23 



sodium chloride in the outer compartment of the rice cooker enables us to secure 

 a boiling temperature for the contents of the inner compartment. Do not stir the 

 bouillon that is being heated, as the pultaceous membranous mass of coagulated 

 albumin makes filtration easy. Filter. The filter-paper in the funnel should be 

 thoroughly wet with water before pouring on the bouillon. This is to prevent 

 clogging of the pores of the filter-paper. Make up the quantity of filtrate to 1000 

 c.c. by adding water. 



If greater exactness is demanded than answers for ordinary, clinical work, it is 

 advisable to again titrate and again adjust the reaction or to simply record the exact 

 reaction. It is more convenient to have a counterpoise to balance the inner com- 

 partment and then to add water to the medium until a kilo weight, in addition to the 

 weight balancing the container, is just balanced. Then titrate, adjust the reaction 

 (if so desired), and filter. Sterilize in the autoclave at i i5C. for fifteen minutes or in 

 the Arnold on three successive days. The use of a balance is preferable in the 

 preparation of bouillon, necessary in making gelatin and imperative in making 

 agar media. 



BOUILLON MADE FROM LIEBIG'S MEAT EXTRACT 



Place in a mortar 3 grams of Liebig's extract, 10 grams of peptone and 5 grams 

 of sodium chloride. Dissolve the whites of one or two eggs in 1000 c.c. of water. 

 Then add this egg-white water, little by little, to the extract, peptone, and salt in the 

 mortar until a brownish solution is obtained. Pour this into the inner compartment 

 of a rice cooker; apply heat to the outer compartment containing the salt or calcium 

 chloride solution, allow to come to a boil and to continue boiling for fifteen to twenty 

 minutes. Do not stir. Place inner compartment on the scales and its counterpoise 

 and a one-kilo weight on the other side. Add water until the two arms balance. 

 Filter and sterilize. 



The reactions of media made with Leibig's meat extract rarely exceeds +0.75 

 (from -f 0.6 to +0.9). Consequently for growing bacteria it is unnecessary to 

 titrate and adjust reactions unless precision is demanded. 



SUGAR-FREE BOUILLON 



Inoculate nutrient bouillon in a flask with the colon bacillus. Allow to incubate 

 at'37C. over night. Pour the contents into a sauce-pan and bring to a boil to kill 

 the colon bacilli. Put about 15 grams of purified talc (Talcum purificatum, U. S. P.) 

 in a mortar. Add the dead colon culture, stirring constantly. Then filter through 

 filter-paper. It may be necessary to again pass the filtrate through the same filter 

 until the sugar-free bouillon is perfectly clear. 



For ordinary purposes the very small amount of sugar in bouillon made from 

 Liebig's meat extract may be neglected in determining gas production; so that under 

 such conditions the various sugars could be added directly to the meat-extract bouil- 

 lon. Dunham's peptone solution may be used as a substitute for sugar-free bouillon, 

 the sugars being added to it. We prefer the serum water medium of Hiss. 



