82 MILK PRODUCTS 



The official methods of the A.O.A.C. for the 

 analysis of butter are as follows: 



Preparation of the Sample. — If large quantities 

 of butter are to be sampled, a butter trier or 

 sampler may be used. The portions thus drawn, 

 about 500 grams, are to be perfectly melted in a 

 closed vessel at as low a temperature as possible, 

 and when melted the whole is to be shaken vio- 

 lently for some minutes until the mass is homo- 

 geneous and sufficiently solidified to prevent 

 the separation of the water and fat. A portion 

 is then poured into the vessel from which it is 

 to be weighed for analysis, and should nearly or 

 quite fill it. This sample should be kept in a 

 cold place until analyzed. 



Water. — From 1.5 to 2.5 grams are dried to 

 constant weight at the temperature of boiling 

 water, in a dish with flat bottom, having a surface 

 of at least 20 sq. cm. The use of clean dry sand 

 or asbestos with the butter is admissible, and 

 is necessary if a dish with round bottom be 

 employed. 



Fat. — The dry butter from the water deter- 

 mination is dissolved in the dish with absolute 

 ether. The contents of the dish are then trans- 

 ferred to a weighed Gooch crucible with the aid 

 of a wash-bottle filled with the solvent, and are 

 washed until free from fat. The crucible and 



