70 MILK ANALYSIS 



some respects. The determination of water may be made by 

 the extraction of the cheese with alcohol and ether and drying 

 of the alcohol-ether extract and fat-free solids separately. 

 Blyth recommends this method as more accurate and less 

 tedious than the direct drying. In the determination of ash 

 it will be better to extract the charred mass with water and 

 proceed as described in the determination of the ash of milk. 



The fat extracted by ether may be examined for other than 

 butter-fat by the distillation method in the usual way. When 

 the composition of the fat is alone desired, it may often be ex- 

 tracted by simple methods. Pearmain & Moor recommend 

 that 50 grams be chopped fine and tied up in a muslin bag, 

 which is placed in a water-bath. When the water is heated, the 

 fat will generally run out clear. If not clear, it can be filtered 

 through paper. 



Henzold suggests the following : 300 grams of the powdered 

 cheese are agitated in a wide-neck flask with 700 c.c. of 5 per 

 cent, solution of potassium hydroxid previously warmed to 20. 

 In about 10 minutes the cheese dissolves, the fat floats, and by 

 cautious shaking may be collected in lumps. The liquid is 

 diluted, the fat removed, washed in very cold water, kneaded 

 as dry as possible, melted, and filtered. It is claimed that the 

 fat is not altered in composition by the process. 



The fat of cheese may be estimated by the centrifugal method, 

 as follows: 



About 3 grams of the mixed cheese in small fragments are 

 weighed and transferred to the bottle, the last portions being 

 washed in with the acid of water. A few drops of ammonium 

 hydroxid are added, and sufficient water to make the liquid 

 about 15 c.c. The liquid is warmed with occasional shaking 

 until the cheese is well disintegrated, and then treated as a 

 sample of milk. The percentage of fat is found by multiply- 

 ing the percentage reading by 15.45 and dividing by the num- 

 ber of grams of cheese taken for analysis. 



