92 Testing Milk and Its Products. 



In order to make this separation complete and to com- 

 pact the curd into a firm lump, the test bottle is whirled 

 for about six minutes at a rather high speed (1,000 rev.) 

 in a steam-heated turbine centrifuge. 



The chamber in which the bottles are whirled ought 

 to be heated to about 200 F. This can be done either 

 by the turbine exhaust steam which leaks into the test- 

 bottle chamber of some machines, or by means of a 

 valve and pipe which will allow steam to be turned 

 directly into the test bottle chamber. After this first 

 whirling the test bottles are taken from the centrifuge 

 and by being careful not to break the lump of curd 

 nearly all the whey or sugar solution can be poured out 

 of the neck. Ten cc. of water are then poured into 

 the test bottle and the curd is shaken up with it so as to 

 wash out more of the sugar. Three cc. of acid are 

 now added as before and the test bottle whirled a second 

 time in the centrifuge. The whey is decanted again and 

 this second washing removes so much of the sugar that 

 what remains will not interfere with testing in the usual 

 way. The curd remaining in the test bottle after the 

 second washing is shaken up with ten cc. of water and 

 to this water emulsion of the curd the usual amount, 

 17.5 cc. of sulfuric acid is added and the test completed 

 in the same way as milk is tested. The amount of fat 

 finally obtained in the neck of the test bottle is calcula- 

 ted to the weight of condensed milk taken. 



Five brands of sweetened condensed milk were exam- 

 ined by this process, at least four determinations being 

 made of each sample. The fat separated was clear and 

 the final results satisfactory. 



