44 QUESTIONS AND ANSWERS 



2. To destroy the viscosity of the fluid and to 

 free the fat-globules. 



What should be the color of the sulphuric acid? 



It should be clear and almost colorless. Organic 

 matter falling into the acid becomes charred and 

 darkens the color. This does not spoil the useful- 

 ness of the acid, unless undissolved particles are 

 present which would spoil readings. 



What are the advantages of using sulphuric acid in 

 the Babcock test? 



1. It quickly dis^lves milk solids other than 

 fat and destroys viscosity, thus liberating the fat. 



2. In combining with the water and solids of the 

 serum, it generates much heat, which melts the fat. 



3. It increases the specific gravity of the liquid 

 surrounding the. fat, thus making it easy for the 

 fat to separate. 



4. It IS comparatively cheap and easy to obtain. 



5. It is non-volatile when hot, and so produces 

 no injurious gases. 



How may one determine if the acid is of proper 

 strength? 



By using a form of hydrometer called an acid- 

 meter. This instrument, when placed in the acid, 

 should come to rest with the surface of the liquid, 

 between the graduations 1.82 and 1.83. A little 

 experience will enable one to judge by the appear- 

 ance of the fat at the end of the test if the acid is of 

 proper strength. 



