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The acidemeter
Acidity Test.[1]—The acidity, or sourness, of milk or cream, which depends upon the amount of lactic acid developed in it, may be tested by a liquid normal alkali or by the Farrington Alkaline Tablets, a solution of which added to sour milk neutralizes the acid. A few drops of an indicator, Phenolpthalein, added to the milk, turns it pink when all the acid has been neutralized, and the amount of alkali solution used shows the percentage of acid in the milk. This is quite important in preparing "starters" for ripening the cream in butter making or milk in cheese making, and in the manufacture of "Commercial Butter-*milk," etc.*
- ↑ The Acid Test depends upon what in the laboratory is called "titration" and makes use of a "burette," a long, graduated measuring tube provided with a pinch-cock. This burette is filled with an alkali solution of known strength, usually a "tenth normal" solution of caustic soda. A certain amount of the milk to be tested is measured off into a glass or a white porcelain cup. As a 17.6 c.c. pipette belonging to the Babcock test usually is at hand, that may be used for this purpose. A few drops of an Indicator is added to the milk and under constant stirring the soda solution is allowed to drip into it until suddenly it turns
