38 



minute's delay in the barn may mean an hour's quicker souring. 

 Milk always ought to be strained in a room separate from the 

 stable, where the air is pure and fresh, and where cleanliness is 

 most carefully observed. 



Several thicknesses of strainer cloth through which the milk is 

 allowed to trickle slowly will filter out many bacteria as well as 

 much filth. It is therefore important, in a herd of any consider- 

 able size, to change the strainer cloth often, as it soon becomes 

 impregnated with bacteria which have been entangled in its 

 meshes, and some of these are liable to wash through into the 

 milk if the same cloth is continually used. The more unclean the 

 milk the more frequently the change of strainer cloths should take 

 place. The more violently the milk is poured into the strainer the 

 greater the chance of the force of the stream driving some bacteria, 

 which had become entangled in the strainer, through into the 

 strained milk. 



A third cause of infection is unclean utensils and cans. If these 

 are not washed with the greatest care and thoroughly scalded and 

 aired there is an opportunity for impurities to be left in the seams 

 of the tin where joints occur. In this residue there is a fine oppor- 

 tunity for bacteria to increase and multiply in large quantities, and 

 then spread the contamination through the milk itself. The word 

 cleanliness, when carried to its extreme import, nowadays, means 

 sterilization, — freedom from bacteria. Wooden pails should 

 never be used for milking as it is almost impossible to keep them 

 clean. Tin utensils should be used. In cleaning them the milk 

 remaining should be rinsed out with lukewarm water. Then boil- 

 ing hot water or steam should be applied, as these are among the 

 strongest foes to bacteria. Live steam is best but not always 

 practicable. After scalding, exposure to bright sunlight is advis- 

 able and ought to be given. It is common to see inverted cans 

 standing by farmers' doors, sunning the outside of the cans. If 

 the location is one where the air is pure the cans should be set so 

 that the direct rays of the hot sun may get into them. 



Finally, having done all that is possible in way of care and 

 cleanliness, you have not kept all the bacteria out of the milk. 

 The ravages of the few remaining ones must be reduced as much 

 as possible. This is done by chilling the milk at the earliest possi- 

 ble moment. Bacteria increase most rapidly in warm milk. One 

 experimenter found that at 93° the bacteria in milk multipled 

 3,600 times in six hours. At 55° they multiplied only 435 times. 

 Don't let the milk stand a moment longer than is necessary with- 

 out chilling it. Delay is dangerous and may be costly. This 

 cooling of milk is beneficial in removing the last traces of animal 



