84 MODERN METHODS OF TESTING MILK 



complete the test as usual. Multiply the fat-reading 

 by 18 and divide by 7 to find the correct per cent, of 

 fat in the sample. 



(3) Approximate results may be obtained by di- 

 luting a measured amount of condensed milk with an 

 equal volume of water, agitating the mixture until 

 uniform. Then take sample for testing with a 17.6 

 cc. pipette and proceed as usual. The per cent, of fat 

 read is multiplied by 2. 



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 over- 

 come by special treatment devised by Farrington. 

 ]\Iake a solution of 40 grams of condensed milk in 

 TOO cc. of water, as directed above in (2). 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 

 from the neck without breaking the lump of curd. 

 Then an addition of 10 cc. of water is made to the 

 test-bottles, the curd is shaken up to w^ash out more 

 sugar, and again 3 cc. of sulphuric acid added. The 

 bottles are again whirled and the liquid portion de- 



