130 
ize 
grams (sp. er. milk, 1.032), therefore the per- 
cent 
or 
the 
the 
of 
Milk and Its Products. 
each other; and, further, that a normal solu- 
tion of lactic acid contains 90 grams of acid in 
each liter, or 1,000 c.¢. A decinormal solu- 
tion would contain 1-10th as much, or 9 grams 
in each liter, and a cubie centimeter would con- 
tain sth as much as a liter, or .009 grams 
of lactic acid. Each tablet of the Farrington 
alkali is equal in strength to 3.8 ¢.¢. of de- 
cinormal alkali, and if the tablet solution is 
made by dissolving 10 tablets in 100 c. ¢. of 
water, each cubie centimeter of the solution will 
be equal to .388 ¢. ¢. of decinormal alkali, and 
will, therefore, neutralize .388 of .009 grams, or 
.0034 grams, of lactic acid. 
To determine the percentage of acid in any 
given sample of milk or cream, a_ certain 
amount, as 20 v.c., of the sample to be tested 
is measured out, and the tablet solution is ad- 
ded from a burette or graduated cylin- 
der till the milk retains a pinkish tinge. 
If this occurs when 1 ¢. ¢. of the tablet 
solution has been added, the 20 e. e. 
“of milk contain .0034 grams of lactic 
“acid; but 20 e.c¢. of milk weigh 20.64 
age of lactic acid is .0034-'-20.64=.00017, 
O17 per cent. If more than 1 ¢. ©. of 
tablet solution is required to neutralize 
acid, or if more or less than 20 «¢. @. 
, : 2 Fig. 15. 
of milk or cream are taken, the pereentage ‘Gradua. 
ted glass 
the 3 
avid will be found by multiplying cylinder. 
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