66 Testing Milk and Its Products. 



ceriu protects the milk to some extent from the acid be- 

 fore the two are mixed, and a clear fat may thus often 

 be secured under otherwise unfavorable conditions. The 

 results appear not to be influenced by the addition of 

 the glycerin. 



75. If the acid is a little too weak, correct results 

 may be obtained by using more than the specified quan- 

 tity, say 20 cc. If a good test is not obtained with this 

 quantity of acid, a new lot must be secured, as its spe- 

 cific gravity in such a case is below 1.82. The observing 

 operator will soon be able to judge of the strength of 

 the acid by its action on milk in mixing the two liquids 

 in the Babcock test bottles; it is indeed remarkable 

 what slight differences in the specific gravity of the 

 acid will make themselves apparent in working the test, 

 as regards the rapidity with which both the curdled 

 milk is dissolved and the mixture of acid and milk turns 

 black. 



76. Strength of sulfuric acid. The relation between 

 the strength of sulfuric acid and its specific gravity 

 will be seen from the following table: 



Specific Gravity of Sulfuric Acid of Different Strength. 



Spectflc Gravity Sulfuric Acid 



(15°C., water i'C). (H^SO,) ' 



1.841 97 per cent. 



1.840 96 



1.839 il5 



1.837 94 



1.834 93 



1,830 92 



1.825 91 



1.820 - 90 



1.815 89 



1.808 88 



