Condensed Milk and Milk Powder 31 



Solution for Daily Use. — Mix 4 c.c. of stock solution with 991 

 c.c. of distilled water, and add 5 c.c. of phenolphthalein indicator. 

 The indicator is prepared as follows : dissolve one gram of dry 

 phenolphthalein in 100 c.c. of 50 per cent, alcohol. Each cubic 

 centimeter of the prepared alkaline solution neutralizes .01 per cent, 

 lactic acid, 20 c.c. of the prepared solution, therefore, neutralize .2 

 per cent, lactic acid, when a 17.6 c.c. pipette is used for measuring 

 out the milk. 



Making the Test. — With the Bab cock pipette, measure 17.6 c.c. 

 into a white cup. With a small dipper, holding exactly 20 c.c, pour 

 20 c.c. of the prepared solution into the cup ;• stir or shake. If the 

 mixture remains faintly pink, }t contains less than .2 per cent, acid 

 and will pass ; if it turns white, it contains more than .2 per cent, 

 acid and should be rejected. 



The stock solution should be standardized by a chemist. The 

 prepared solution should be made up daily. Both solutions should 

 be kept in glass bottles, tightly corked. The bottle containing the 

 stock solution should be glass-stoppered. 



Acid Test for Use on Suspicious Cans Only. — The Farrington 

 Alkaline Tablet Test. Use an eight ounce,- wide-mouth bottle, place 

 in it sixteen Farrington alkaline tablets, add eight ounces of distilled 

 water or rain water, or any pure water relatively free from car- 

 bonates. Stopper tightly and let stand for six hours, or until the 

 tablets are completely dissolved. This solution neutralizes .2 per 

 cent, of lactic acid in equal parts of milk. 



Making the Test. — Use small dippers of the same size for milk 

 and for test solution. Pour into a white cup one dipperful of milk 

 and one dipperful of solution. If the mixture turns white, it con- 

 tains more than .2 per cent, lactic acid and should be rejected. If 

 it remains pink, the milk contains less than .2 per cent acid. 



The Boiling Test. Inspection by Heating. — The heating 

 to the boiling point of samples of suspicious milk furnishes a most 

 reliable means to determine the fitness of such milk for condensing. 

 In many instances milk may satisfactorily pass the other tests and 

 yet it may not be in condition to stand the heat to which it will be 

 subjected in the process. If it curdles, when boiled, it is obviously 

 unfit for use. This test shows more than the acid test above. By 

 its use the operator is able to detect milk otherwise abnormal, such 



