MILK AND ITS PRODUCTS 



179 



they will dry quickly. It is well to set them in the sun dur- 

 ing the day. 



Coldness is as important as cleanliness. Keeping milk 

 cl j an keeps most of the bacteria out. Cooling it prevents 

 tl e growth of those that 

 d' get in. Effective cool- 

 ing means bringing the 

 tr nperature of the milk, 

 n< t later than an hour 

 af :er milking, and prefer- 



FIG. 50. Brush for cleaning milk utensils. 



al ly sooner, to a temper- The brush & much bet ter than a cloth. 

 at ure of 50 F., or lower. 



In an experiment by the author a sample of fresh milk 

 w is divided into two parts, one of which was cooled at once 

 to 50 F., while the other was placed at 75 F., with the fol- 

 io ving results : 



Putting warm milk in an ordinary ice box is not an effec- 

 tive method of cooling, as can be readily determined by 

 testing it with a thermometer. The importance of the 

 statement regarding the necessity for sudden cooling and 

 the inefficiency of cold air as a means of cooling is illus- 

 trated in a striking way by an experiment conducted by 

 students under the supervision of the author. Sixteen gal- 

 lons of fresh warm milk was received from the barn, mixed, 

 and then placed in two cans. Plate cultures were made 



