64 Testing Milk and Its Products. 



3. SULFURIC ACID. 



72. The sulfuric acid to be used in the Babcoek test 

 should have a specific gravity of 1.82-1.83. 1 The com- 

 mercial sulfuric acid (sometimes called oil of vitriol) 

 is commonly used ; it can be bought for about 2 cents a 

 pound in carboy lots and 25 cents or less a quart at re- 

 tail. One quart of acid is sufficient for fifty tests. The 

 acid should be kept in stoppered glass bottles, prefer- 

 ably glass or rubber stoppered ones, since a cork stop- 

 per is soon dissolved by the acid and rendered useless. 

 If the bottle is left uncorked, the acid will absorb 

 moisture from the air and after a time will become too 

 weak for use in this test. 



Lead is the only common metal which is not dissolved 

 by strong sulfuric acid ; where considerable milk testing 

 is done, it is therefore desirable to provide a table cov- 

 ered with sheet lead on which the acid may be handled. 

 The acid dissolves iron, tin, wood and cloth, and 

 burns the skin. If acid is accidently spilled, plenty of 

 water should be used at once to wash it off. Ashes, 

 potash, soda, and ammonia neutralize the action of the 

 acid, and a weak solution of any one of these alkalies 

 can be used after the acid has been washed off with 

 water. The red color caused by the action of the acid 

 en clothing can be removed by wetting the spot with 

 weak ammonia water; the ammonia must, however, bo 

 applied while the stain is fresh, and is in its turn 

 washed off with water. 



1 A specific gravity of 1.82 means that a given volume of the arid 

 weighs 1.82 times as much as the same volume of water at the same 

 temporal un- (see also under Lactometer, 109). 



