METHODS OF EXAMINING MILK 241 
water oven for a half hour, removed to the desiccator 
_ until cool and then weighed. After they are placed in 
the oven they should be handled with tongs or forceps 
and should not be touched with the fingers. As each 
dish is weighed the weight is recorded. The milk sample 
is mixed thoroughly and some of the milk (8 to 5 ¢.c.) is 
transferred to the dish, which is again weighed, the 
weight being recorded. The dish is placed on a water 
bath where it remains until the milk is evaporated to 
dryness. It is then removed to the desiccator and when 
cool it is weighed. Following this it is placed in the 
hot-water oven for 30 minutes, after which it is again 
cooled in the desiccator and weighed. If the two weigh- 
ings agree, or are within 0.2 milligramme of each other, 
the water has all been driven off. If the weighings do 
not agree to this extent, the dish must be returned to 
the hot-water oven for another period, then placed in the 
desiccator until cool and again weighed, and this must 
be continued until the weight is constant, or within 0.2 
milligramme of being the same. The last weight minus 
the weight of the dish represents the weight of the dry 
matter or total solids in the charge of milk. Multiplying 
the weight of the dry matter by 100 and dividing by the 
weight of the charge will give the per cent. of dry matter 
in milk. The per cent. of ash may be determined by 
heating the dry matter until the ash is free from carbon, 
placing the dish in the desiccator until cool, weighing, 
subtracting the weight of the dish, multiplying the re- 
mainder by 100 and dividing by the weight of the charge. 
By Calculation—There are several formulas for 
calculating the total solids and solids not fat from the 
specific gravity and per cent. of fat. Of these Babcock’s 
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