RECEIVING, SAMPLING, AND GRADING. 87 
the reading may be facilitated. The temperature at the time of 
reading should be between 120° and 140° F. 
There are three very common defects in the clearness of fat 
reading: (1) The fat contains black, charred, flocculent matter 
at the bottom of the fat column. This is commonly caused by 
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Wagner’s skim- Ohison’s skim- Butter test-bottle, and Russian Babcock 
milk bottle. milk bottle. funnel which holds test-bottle and 
(Both with pneumatic fat- about 9 grams of reading-tube. 
indicator (pat.).) butter. 
using too much or too strong acid or mixing milk and acid at too 
high a temperature. The remedy is to use less acid or to 
cool milk and acid before mixing. The black charred matter 
may also be due to allowing the acid to stand in contact with 
the milk too long a time before mixing or by pouring acid 
through the center of the milk. (2) There may be a layer of 
white flocculent matter at the bottom of the fat column. This 
is due to not having used enough acid or to the temperature of 
milk and acid being too low or to not mixing the acid and milk 
