CONDENSED MILK 71 
of the bottle by shaking. Raise the fat column 
to the top of the scale by means of the acid and 
water mixture, and whirl for five minutes. 
Read promptly (see page 20) from the extreme 
bottom of the fat column to the bottom of the 
upper meniscus. Multiply the reading by 2, and 
deduct 0.25; the remainder is the per cent. of 
fat. 
If an electric centrifuge without heat has been 
employed, the fat column will be somewhat cool 
and should be heated, before reading, in a water- 
bath about 60°. 
The same authors give the opinion that the 
centrifugal methods are not sufficiently accurate 
to be depended upon for determining if evapo- 
rated milk is up to standard. The Rose-Gottlieb 
method is best for this purpose. If the centrif- 
ugal methods are employed, considerable allow- 
ance must be made for inaccuracies. Results 
obtained are inaccurate unless the fat column 
is clear, with the meniscus at the bottom of the 
column perfect and not distorted by either char 
or milky appearance. 
The percentage of solids as calculated from 
the sp. gr. is not sufficiently accurate to 
determine whether the milk complies with the 
standard unless the correction factor for the for- 
mula of calculation is ascertained frequently by 
the determination of solids by drying. 
6 
