BUTTER 83 



contents are heated at the temperature of boiling 

 water till the weight is constant. 



The fat may also be determined by drying the 

 butter on asbestos or sand, and extracting by 

 anhydrous alcohol-free ether. After evaporation 

 of the ether the extract is heated to constant 

 weight at the temperature of boiling water and 

 weighed. 



Casein, Ash, Chlorin. — The crucible con- 

 taining the residue from the fat determination is 

 covered and heated, gently at first, gradually 

 raising the temperature to just below redness. 

 The cover is removed and the heat continued until 

 the material is white. The loss in weight rep- 

 resents casein, and the residue mineral matter. 

 In this mineral matter dissolved in water slightly 

 acidulated with nitric acid, chlorin may be 

 determined gravimetrically with silver nitrate, 

 or, after neutralization with calcium carbonate, 

 volumetrically, using potassium chromate as 

 indicator. 



Salt. — ^About 10 grams are weighed in a beaker 

 in portions of about i gram at a time taken from 

 different parts of the sample. Hot water (about 

 20 c.c.) is now added to the beaker, and after 

 the butter has melted, the mass is poured into 

 the bulb of a separating funnel, which is then 

 closed and shaken for a few moments. After 

 standing until the fat has all collected, the water 



