Precmdions in Sampling Milk. 59 



should weigh 17.6 grams, the latter 239 grams. 

 Any bottle or pipette that varies more than 2 per 

 cent from the standard should be discarded. 



Sampling tJie milk. — The accuracy of the test 

 depends wholly upon getting an accurate sample of 

 the milk to be analyzed. A part of the fat so 

 readily separates from the milk in the form of 

 cream that milk cannot stand even for a short 

 time without the upper layer becoming richer and 

 the lower layers poorer in fat. Even in milk 

 freshly di-awn from the cow, that in the upper part 

 of the pail will be considerably richer than that 

 below. The first step, then, in sampling milk is 

 that it should be evenly and thoroughly mixed. 

 This is best brought about by pouring from one 

 vessel to another : but if the milk has stood over 

 night and a layer of tough cream formed, the par- 

 ticles of cream will not be thoroughly mixed by a 

 single pouring from one vessel to another. In 

 all such cases, the sampling must not be done 

 until all visible portions of cream have disappeared 

 in the mass of the milk. Various forms of sam- 

 pling tubes or "milk thieves" have been devised for 

 taking samples of milk. They serve the purpose 

 fairly well, but are not to be depended upon in 

 comparison with a thorough agitation of the milk. 



Where the previous night's milk is carried to the 

 factory, the agitation enroute and the stirring inci- 

 dent to pouring from the carrying can into the 

 weigh can are ordinarily sufficient to cause a pretty 

 complete mixture of the milk : but in cold weather 



