94 MODERN METHODS OF TESTING MILK 



add 17.5 cc. of water, dissolve the powder as com- 

 pletely as possible, and proceed as above. Multiply 

 the reading by 3. 



METHOD OF TESTING DRIED MILK OR MILK 

 POWDER 



Successful means of drying milk have recently been 

 devised, and products are appearing on the market in 

 the form of dried skim-milk and dried milk. These 

 materials are in the form of fine flaky or powdery 

 substances. Owing to the great advantages of hand- 

 ling milk in such forms, these products are destined 

 to find extensive use, and the desirability of testing 

 them is obvious. 



The Babcock test, when applied to these materials, 

 gives results much below the truth. The writer has 

 obtained quite satisfactory results by a combination of 

 the Gottlieb and Babcock methods of determining fat. 

 The process used is as follows : Dissolve 10 grams of 

 milk powder in 100 cc. of water. Take 10 cc. of this 

 solution in a 100 cc. glass cylinder (Fig. 38, p. 104). 

 Add i cc. of strong ammonia and shake until thor- 

 oughly mixed with the solution. Then add the fol- 

 lowing reagents, one after the other, shaking vigorously 

 after each addition before adding the next material: 

 10 cc. of 92 per cent, alcohol, 25 cc. of washed ether, 

 and 25 cc. of gasoline or, better, petroleum ether 

 (boiling point below 80 C.). The cylinder is closed 

 with a tightly-fitting, moistened cork stopper. The 

 contents of the cylinder, after thorough shaking, are 

 poured into a 200 cc. beaker, the cylinder being rinsed 

 with a little gasoline, and this being added to the 



