Contamination of Milk. 31 



be well cleaned by washing unless the facilities for such 

 purposes are much better than on the ordinary farm. 



All tin-ware should have a smooth and unbroken sur- 

 face. Even the roughness due to the accumulation of 

 the white layer (milk stone) on the pails and cans ren- 

 ders them much more difficult to wash and hence in- 

 creases the contamination from them. Pressed tin- 

 ware is preferable but if the utensils are made with 

 seams the depressions should be thoroughly flushed with 

 solder. 



The farm cream-separator is a utensil that needs 

 especial care. Often it is not the custom to take the 

 machine apart after each period of use and wash it thor- 

 oughly. When used for the evening milk it is often 

 only rinsed out by passing water through the bowl. 

 The slime that accumulates on the wall of the bowl can 

 not be removed in this way, and between the periods of 

 use, especially during warm weather, the bacteria grow 

 rapidly in the slime. When milk is passed through the 

 separator in the morning, a large part of these bacteria 

 find their way into the milk and cream and may cause 

 undesirable fermentation changes in them. The sepa- 

 rator should be taken apart, well washed and scalded 

 after each period of use. Much loss is caused to the 

 farmers of the country due to the diminished returns 

 received from butter made from cream separated in 

 dirty farm separators. In fact, it is well recognized 

 that the general introduction of the farm separator has 

 led to a deterioration in the quality of butter. 



Contamination from factory by-products. The 

 farmer is accustomed to return to the farm the skim 

 milk or whey from creamery or factory in the milk can. 

 If the can is at once emptied and thoroughly washed, no 



