COMPOSITE SAMPLES 103 
spill as little milk as possible around the neck, inside as well 
as outside, of the bottle when the sample is put in. If the 
nulk is spilled there, it makes an unattractive appearance. 
Very often it becomes moldy, and, as more milk is added and 
the sample shaken every day, this mold gradually extends 
down the sides of the bottle. This causes the composite sample 
to be infested with undesirable growth, and to spoil sooner than 
oo Sea 
Fig. 62.—Testing-room in Model Dairy, St. Louis Exposition. 
(Chicago Dairy Produce.) 
it would if greater care were taken in keeping the milk from 
coming in contact with the sides of the bottle, before coming 
in contact with the preservative. 
It is important also that the sample jars be well covered, 
otherwise the moisture evaporates and causes the milk or cream 
to dry up. It also makes the test unreliable by increasing the 
per cent of butter-fat. A gentle rotary motion should be 
given each jar when a sample is added to it to mix the cream, 
which rises to some extent after the milk has stood a while. 
