30 Condensed Milk and Milk Powder 



this method, tell with much accuracy, whether the milk should pass 

 or not, 



Inspection of Milk According to its Temperature. — The 

 temperature is also noted. This need not be done with the ther- 

 mometer in each case. By placing his hand on the body of the. can, 

 or by noting the warmth of the air and odor in the cover immediate- 

 ly after removing it, or by the presence or absence of small par- 

 ticles of butter floating on the surface of the milk, the inspector 

 can readily tell if the milk has or has not been properly cooled. A 

 correct thermometer should always be on the platform for guidance. 



Inspection of Milk by the Use of Acid Tests. — Since the 

 degree of acidity, or the sweetness of the milk, is one of the chief 

 factors that determines its fitness for condensing purposes, tests 

 that rapidly and accurately determine the per cent, of lactic acid in 

 the fresh milk, are of great service. 



Some concerns have adopted a definite standard of milk, re- 

 jecting all milk containing more than the maximum per cent, of 

 acid of their standard, and they test every can of milk' received with 

 an acid test. This method insures sweet milk in the factory, pro- 

 vided that the alkaline solutions used are correct. This work in- 

 volves considerable expense, however, and unless the solution is 

 carefully prepared and made up fresh often, its use may yield mis- 

 leading results. Again, when the acid test is performed on the milk 

 of each can, the acceptance or rejection of the milk depends alto- 

 gether on the per cent, of acid it contains. Although milk may be 

 otherwise unfit for use, it will pass, as long as it is low in acidity. 

 Experience has shown that, while it is necessary for the condensery 

 to decide on a maximum acidity of milk above which all milk be re- 

 jected, the nose and the palate of the experienced inspector are 

 better criterions than the acid tests alone, as to the fitness of milk for 

 condensing. Acid tests are valuable in the case of uncertainty and 

 suspicion as to the quality of any given can of milk. All milk con- 

 taining .2 per cent, lactic acid or more is dangerous for condensing 

 purposes and should be rejected. 



Acid Test for Daily Use, Where Bach Can of Milk is Tested. — 

 Stock Solution. — Weigh out two hundred grams of sodium hydrate 

 C. P. and add distilled water to make up one liter. Keep tightly 

 stoppered. 



