Chemical Analysis of Milk and Its Products. 231 



1.030 and a i =9 per cent., then c==^ gives the con- 

 centration. 



C. BUTTER. 



265. Sampling. A four- to eight-ounce sample of 

 butter is melted in a tightly-clcsed pint fruit jar, 

 shaken vigorously and cooled until the butter is hard- 

 ened, the jar being shaken vigorously at short intervals 

 during the cooling so as to keep the water of the butter 

 evenly distributed in the mass (102). 



266. a. Determination of water. Small pieces of 

 butter (about 2 grams in all) are taken from % the sam- 

 ple by means of a steel spatula and placed in glass tubes, 

 seven-eighths of an inch in diameter and two and a half 

 inches long, closed at the bottom by a layer of stringy 

 asbestos, and filled two-thirds full of asbestos prepared 

 as for milk analysis (252). The tubes are dried at 

 100 C. in a steam oven, until no further loss in weight 

 takes place, and are then cooled and weighed. The loss 

 in weight shows the per cent, of water present. 



267. b. Fat. The tubes are placed in Caldwell ex- 

 tractors and extracted for four hours with anhydrous 

 ether ; the ether is then distilled off, and the flasks dried 

 in the steam bath and weighed, the increase in weight 

 giving the fat in the sample of butter weighed out. 



268. c. Casein. 10 grams of butter are weighed into 

 a small beaker provided with a lip, and treated twice 

 with about 50 cc. of gasoline each time; the solution is 

 filtered off, and the residue transferred to a filter and 

 dried; its nitrogen content is then determined by the 

 Kjeldahl method (255). The nitrogen in the filter and 



