MARKET MILK 163 



to the dairy-farmer and the milk inspector. While the score- 

 card gives a certain value to the different factors, it must be 

 borne in mind that our present knowledge does not make it 

 possible to give these values with much accuracy because the 

 relative importance of the various factors has not yet been 

 fully established by experimental work. While it is easier to 

 produce clean milk with good equipment, the methods used are 

 much more important and if the necessary care is used, milk 

 of excellent quality can be obtained even with fairly poor 

 equipment. A number of different forms of score-cards are in 

 use, but the preceding is the form most widely used at the 

 present time. 



TREATMENT AFTER MILKING 



Straining. 



The practice of straining milk to remove dirt is a universal 

 one. Theoretically, this should not be necessary if the milk 

 has been produced under proper sanitary conditions, but the 

 natural conditions surrounding the process of milking make 

 it almost impossible to be certain that some particles of for- 

 eign matter have not fallen into it. For this reason, it is de- 

 sirable that milk should be carefully strained. This may be 

 done by pouring it through one or more layers of fine cheese- 

 cloth, linen, or wire gauze. Sometimes the milk is passed 

 through a layer of absorbent cotton or a layer of washed fine 

 sand. The latter are rather expensive and not so generally 

 used. In using any form of strainer, it should be borne in 

 mind that only the insoluble dirt can be removed, as any ma- 

 terial which is soluble will dissolve and pass through the strainer. 

 In practice, it has been found that the percentage of foreign 

 matter which is removable by straining may vary all the way 

 from 10 or 12 per cent up to 90 or more, depending on the 

 nature of the dirt. The chief purpose of straining milk is to 

 improve its appearance, because consumers do not like to see 



