THE ANALYSIS OF BUTTER 65 



Estimation of Casein. Extract another portion of 

 curd with dilute ammonia till no lumps are left ; filter and 

 wash the residue ; add dilute acetic acid till a white preci- 

 pitate falls, and collect this in a weighed Gooch crucible 



FIG. 33. Water Estimation. 



or on tared filter-papers, as on p. 35. Extraction and 

 ignition may be omitted. The precipitate is casein. 



Tests for Preservatives. Boric acid may be 

 detected by melting the butter at a low temperature, 

 and testing the aqueous portion with turmeric paper as 

 directed on p. 53. 



E 



