MILK INSPECTION 175 



tion are sterilized by 20 minutes boiling or by sterilizing in a ster- 

 ilizer. 



The corks should be sterilized in the same manner. The bottle 

 must be filled to the cork and packed in a vessel with enough ice 

 to last till the examination is made. 



If a sample of milk is taken for chemical examination only, 

 the milk is mixed by pouring it from one bottle or can to another. 



In some cities the original bottle is taken for chemical exam- 

 ination (this is best in testing certified milk), but this is expen- 

 sive because the inspector is encumbered with unnecessary weight 

 and there is loss of milk and bottle to the owner, or to the city, 

 in case the milk is paid for. The two chief reasons for agitating 

 the milk are to thoroughly mix the cream for determining the fat, 

 and, again, to estimate by a bacteriological test the number of germs. 

 In the latter case it is especially important, as ninety-nine per cent, 

 of the germs in milk become entangled in the cream. Two ounces 

 of milk are sufficient for a fat or bacteriological test, and four 

 ounces for a test for preservatives. The inspector seals the corks 

 of the bottle, and, also, should place some sealing wax on the 

 edge of the label, as the labels are often soaked off and placed 

 on a similar sealed bottle. This happens where the inspector 

 is required to give a duplicate sealed sample to the milkman; and 

 the milkman, when he knows his sample is adulterated, may get a 

 sealed bottle given to another milkman (which contains pure milk) 

 and take the label from the adulterated sample and place it on the 

 pure sample. He then brings the pure sample into court with the 

 label number the inspector placed on his adulterated sample and in 

 a bottle with an unbroken official seal on the cork. For full direc- 

 tions for taking samples for bacterial analysis, see p. 251. 



Milk may be condemned on account of visible dirt. This is 

 ascertained by straining milk from one can to another through 

 •cheesecloth, or by straining only the bottom portions of several 



