CHEESE. 77 



tion may be taken for the ash. If the cheese be rich, 

 the asbestos will be saturated therewith. This mass 

 may be ignited carefully, and the fat allowed to burn 

 off, the asbestos acting as a wick. No extra heating 

 should be applied during the operation, as there is 

 danger of spurting. When the flame has died out, the 

 burning may be completed in a muffle at low redness. 

 When desired, the salt may be determined in the ash 

 by titration with silver nitrate and potassium chromate. 



Fat. — 5 to lo grams of the sample are ground in a 

 small mortar with about twice the weight of anhydrous 

 copper sulfate. The grinding should be continued 

 until the cheese is finely pulverized and evenly dis- 

 tributed throughout the mass, which will have a uni- 

 form blue color. This mixture is transferred to a glass 

 tube which has strong filter paper, supported by a 

 piece of muslin, tied over the end. A little of the 

 clean anhydrous copper sulfate is put into the tube 

 next to the filter before introducing the mixture con- 

 taining the cheese. On top of the mixture is placed 

 a tuft of ignited asbestos, and the contents of the tube 

 extracted with anyhydrous ether in the continuous ex- 

 traction apparatus, for 15 hours. The ether is re- 

 moved as usual and the fat dried at 2i2°F., to a. con- 

 stant weight. 



This fat may be used to determine the presence or ab- 

 sence of oleomargarin, by applying the Reichert test. 



Casein. — ^The nitrogen of about 2 grams of the 

 cheese is determined by the Kjeldahl-Gunning method. 



