98 MODERN METHODS OF TESTING MILK 



only one or two tests are made, one pipetteful of water 

 and one acid measure full of acid answer the purpose.) 

 The bottles are then whirled for 2 minutes, filled with 

 hot water to about the 8 per cent, mark, and whirled 

 again for i minute; the reading is made at 140 F. 

 from the bottom of the lower meniscus to the extreme 

 top of the upper meniscus. The result is multiplied 

 by 4. 



For accurate results, weighing the sample is indis- 

 pensable. Approximate results can be obtained by 

 diluting a measured .amount of condensed milk with 

 three volumes of water and agitating until the mixture 

 is uniform. A 17.6 cc. sample of this is taken and the 

 process above described followed. 



For condensed milk containing added sugar, 

 Many brands of condensed milk contain added cane 

 sugar, which in testing is so blackened by the acid as 

 to make the results unreliable. This trouble can be 

 overcome by special treatment devised by Farrington. 

 Dissolve 40 grams of condensed milk in enough 

 water to make 100 cc. of solution. With a 17.6 cc. 

 pipette, measure the same amount as for a milk 

 test into a milk-testing bottle. Add about 3 cc. 

 of the sulphuric acid used in the test and mix the acid 

 and milk by shaking vigorously. The acid is added 

 to coagulate the curd and enclose the fat, allowing 

 the sugar to separate in the surrounding liquid. The 

 curd is compacted into a lump by whirling the test- 

 bottles in a steam-turbine tester at high speed and at 

 a temperature of 200 F. After this whirling, the 

 bottles are taken from the tester and the liquid portion, 

 containing much of the sugar, is carefully poured 



