60 QUESTIONS AND ANSWERS 



Then rehuat and whirl for a short time in the 

 machine before reading. 



2. In filling after first whirling use a mixture of 

 equal volumes of sulphuric acid and water. 



How often should the test bottles be washed? 



The bottles should be thoroughly washed after 

 each test, not only to remove the fat, but also to 

 remove other foreign matter that would become too 

 firmly attached to remove if left in while making 

 several tests. 



How should the test bottles be washed? 



1. Shake them well when emptying. 



2. Rinse with hot water containing some good 

 washing powder. 



3. Rinse thoroughly with plain hot water. 



What can be done to hasten the washing process? 



Special devices which enable the operator to 

 handle several bottles at a time may be used. 

 These consist of racks for holding bottles securely, 

 trays for submerging large numbers of bottles in 

 the washing solutions, and sprays for rinsing. 



How may unsweetened condensed milk be tested 

 by the Babcock method? 



Thoroughly mix the sample and weigh 20 grams 

 into a bottle or flask. Add 40 c. c. of water and 

 shake until thoroughly mixed. Test in duplicate, 

 weighing 18 grams into a milk test bottle and pro- 

 ceed as in testing milk. Multiply the reading of the 

 fat by three to obtain the per cent. 



