FAT IN CHEESE. 231 



It is advisable to make a separate estimation of the fat. This 

 may be done by Short's method, which consists in grinding up 

 a few grammes of cheese with twice its weight of anhydrous 

 copper sulphate, and extracting the mixture with ether in a 

 Soxhlet extractor. Filter paper thimbles are very convenient 

 for holding the mixture. The Werner-Schmid method is also 

 applicable. To 2 or 3 grammes of cheese 5 c.c. of water and 

 10 c.c. of strong hydrochloric acid are added, and the whole 

 boiled with constant shaking till all, except fat, is dissolved. 

 The solution is cooled, about 25 c.c. of ether added, and the tube 

 shaken well. After complete separation, as much as possible 

 of the ether is drawn off, and a fresh portion added. After 

 four or five repetitions of the same process, the extraction of fat 

 is complete. The combined ether extracts are then evaporated, 

 and the fat weighed. 



M. Weibull uses the Gottlieb method as follows*: 2 to 3 

 grammes of cheese are placed in a graduated tube, heated with 

 10 c.c. of ammonia to 75 C. with frequent shaking ; if the cheese 

 is not all dissolved by this treatment 10 c.c. of alcohol are added, 

 and the heating and shaking continued till solution is effected. 

 The solution is cooled, 25 c.c. of ether are added, and the contents 

 of the tube mixed, and 25 c.c. of petroleum ether poured in, 

 the solutions mixed, and the fat estimated in the usual manner. 



The Schmid-Bondyzynski method is carried out by heating 



1 to 2 grammes of cheese in a small flask with 5 c.c. of hydro- 

 chloric acid and a little powdered sulphur. When dissolved 

 the contents are poured into a cylinder and washed in with 



2 portions of 2-5 c.c. of alcohol and ether in small quantities 

 till 12-5 c.c. are added. The tube is well shaken, and 12-5 c.c. 

 of petroleum ether added, and the contents mixed well ; the 

 method is then conducted as the Gottlieb method. 



Proteins and the Products of Ripening. About 10 grammes 

 of cheese are ground up well in a mortar with ten successive 

 portions of 20 c.c. each of hot water, the aqueous portions 

 being poured off into a 250 c.c. flask. The grinding should 

 be as thorough as possible, every lump of cheese being crushed 

 well. After cooling, the solution should be made up to 250 c.c. 

 and filtered. 



Twenty-five c.c. of the filtrate should be evaporated in a 

 platinum basin on the water-bath, and the residue dried in the 

 water-oven to constant weight. This may be termed the 

 " total soluble extract." The residue may be incinerated at 

 a low red heat, and the ash of the soluble extract weighed. 



Twenty-five c.c. of the filtrate are diluted to about 100 c.c., 

 5 c.c. of the solution of copper sulphate solution added (34-64 

 grammes to 500 c.c.), and caustic soda solution added, drop by 



