170 BACTERIOLOGICAL CHEMISTRY LESSON 



Ammonium phosphate . 10 grammes. 



Bi-potassium phosphate . 1 gramme. 



Magnesium sulphate . '2 gramme. 



Glycerine. . . . 40-50 cc. 



Distilled water . . . 1000 cc. 



(2) Two to three litres should be prepared and dis- 

 tributed in twenty to thirty small flasks. 



(3) Allow the inoculated flasks to stand at 30 C. for a 

 week. 



(4) Filter the cultures through a Berkefeld filter. 



(5) Evaporate the filtrate to a small bulk in a vacuum 

 pan. 



(6) Pour this concentrated solution into eight to ten 

 times its volume of absolute alcohol : a precipitate appears. 



(7) Filter through a paper filter, and thoroughly wash 

 the residue on the paper with absolute alcohol. 



(8) Redissolve the washed residue in the least possible 

 quantity of distilled water. 



(9) Dialyse against distilled water or running water 

 for twelve to twenty-four hours. 



(10) Now evaporate the dialysed solution to a small 

 bulk in a vacuum pan. 



(11) Pour the concentrated solution into eight to ten 

 times its volume of absolute alcohol as before. 



(12) Filter through a paper filter, and wash the residue 

 with absolute alcohol. 



(13) Collect the washed residue in a small glass dish, 

 and drive off the alcohol by heating it to 45 C. 



