174 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



depended upon to protect milk from contamination. 

 They do not keep out bacteria, but hold back only the 

 larger particles of dirt. Some of these particles are sub- 

 sequently dissolved by milk and carried through the 

 strainer, while bacteria are washed off of the insoluble 

 particles remaining on the strainer. It is also difficult 

 to clean strainers of this kind thoroughly. Particles of 

 dirt become entangled in the meshes of the wire gauze, 

 especially at the periphery where it is soldered to the tin, 

 and it is difficult to remove them, while the cheese cloth 

 requires much care in cleaning. It should be rinsed in 

 cold water, washed in hot water containing two per cent, 

 of soda, again rinsed in cold water and then wrapped in 

 a clean cloth and sterilized in a steam chest. If a steam 

 chest is not available, it should be put into a thick paper 

 sack and placed in a stove oven and kept there until the 

 sack begins to scorch. A strainer composed of a thin 

 layer of absorbent cotton is much more effective and it 

 can be thrown away after being used and thus save the 

 labor of cleaning. Some of the bacteria are apparently 

 enmeshed in the cotton and kept out of the milk. The 

 use of a cotton strainer has reduced the bacterial content 

 of the milk nearly one-third in some tests. Coarse cot- 

 ton-flannel and turkish toweling are also used for strain- 

 ers, but they are no more effective than cheese cloth. 



Bacteria cannot be kept out of milk by strainers nor 

 can they be removed by these contrivances after they 

 have entered the milk. The coarse particles of dirt may 

 be strained out, but the most objectionable part of the 

 dirt the bacteria, will remain. Much more satisfactory 

 results will be obtained by cleanliness and care in milking 

 and in the subsequent handling of the milk. 



In some receiving stations and distributing plants, 



