Precautions in Sampling Milk. 57 
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 the milk.—The aecuracy 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 drawn 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 
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