254 



BACTERIOLOGICAL ANALYSIS OF MILK. 



important step in the whple preparation. A satisfactory 

 method of neutralization is as follows : 



Neutralization. Remove 5 c.c. of the mixture by a pipette 

 and place in an evaporating dish. Add 45 c.c. of distilled 

 water, boil for three minutes and add I c.c. of phenol- 



FIG. 39. 



Normal 

 ffCl 



Two burettes arranged for neutralizing culture media. 



phthalein solution (5 gm. phenolphthalein powder in 100 c.c. 

 of 50 per cent, alcohol). Place in a burette having a rubber 

 pinch-cock (Fig. 39), a quantity, of one tenth normal solu- 



