

136 Milk and Its Products. 



ize each other ; and, further, that a normal solu- 

 tion of lactic acid contains 90 grams of acid in 

 each liter, or 1,000 c. c. A decinormal solu- 

 tion would contain 1-lOth as much, or 9 grams 

 in each liter, and a cubic centimeter would con- 

 tain ^;oooth as much as a liter, or .009 grams 

 of lactic acid. Each tablet of the Farrington 

 alkali is equal in strength to 3.8 c. c. of de- 

 cinormal alkali, and if the tablet solution is 

 made by dissolving 10 tablets in 100 c. c. of 

 water, each cubic centimeter of the solution will 

 be equal to .38 c. c. of decinormal alkali, and 

 will, therefore, neutralize .38 of .009 grams, or 

 .0034 grams, of lactic acid. 

 ^M|l To determine the percentage of acid in anj- 



given sample of milk or cream, any convenient 

 amount, as 20 c. 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 c. c. of the tablet 

 solution has been added, the 20 c. c. 

 Bu-' of milk contain .0034 grams of lactic 

 acid; but 20 c. c. of milk weigh 20.64 

 grams (sp. gr. milk, 1.032), therefore the per- 

 centage of lactic acid is .0034^-20. 64=. 00017, 

 or .017 per cent. If more than 1 c. c. of f^i^J 

 the tablet solution is required to neutralize 

 the acid, or if more or less than 20 c. c. ^ 



/ 



O-i-ID 



n-ffso 



30-S.70 



of milk or cream are taken, the percentage Graiiua- 

 of acid will be found by multiplying the cylinder! 



