SHIPPING 273 



against this surface during cooling, otherwise precautions taken 

 during milking may be largely nullified. 



Cold water tanks of some form are necessary on practically 

 all milk-producing farms. The efficiency of cold water over 

 air of the same temperature as cooling agent can hardly be over- 

 estimated. A cold water tank will be found necessary during 

 the summer and even all winter in some sections. The ideal tank 

 would be one made of cement placed low in the milk room, thus 

 obviating the necessity of lifting the cans high. If it is not 

 possible to pump water through this tank for the stock, even 

 greater efficiency in cooling may be got by placing in the tank- 

 water a few chunks of ice. A well insulated tank filled with 

 water in which are floating several cakes of ice forms the most 





PROGENY OF A 



SINGLE GERM 



N TWELVE HOURS WPf; 



Fig. 90. — Showing the effect of prompt cooling on the number of bacteria in milk. 



economical and efficient method known for keeping milk sweet. 

 Shipping. — Much remains to be accomplished in the matter 

 of shipping milk. ]NTo matter how much care has been bestowed 

 during the milking process some dirt, which means some germs, 

 is sure to find its way into the milk, though germs are held 

 down or prevented from growing by the cold temperature imme- 

 diately given. They are present, however, to grow the moment 

 the milk becomes warm enough and this point is reached at about 

 50 degrees. At 60 degrees the lactic acid germ grows rapidly. 

 Cans of milk delivered to the railroad station and there allowed 

 to stand in the sun very soon warm to such a point that the 

 bacteria within commence growing rapidly. Insulating jackets 

 are on the market which aid considerably, but these are 

 18 



