CONDENSED MILK 47 



leum spirit or a mixture of this with anhydrous ether, extracting 

 for five hours. Bryant has obtained better results with carbon 

 tetrachlorid, which is, moreover, safer. 



Some analysts have advised the extraction of the fat from 

 the precipitate obtained with copper sulfate (see page 23). 

 This is collected on fat-free filter paper (hardened paper will 

 answer), washed and dried. The folded filter is placed on a 

 fat- free thimble and extracted with carbon tetrachlorid for 

 several hours. 



The Werner-Schmid method may be employed, but the fat 

 is apt to be contaminated with caramel. It should be dissolved 

 in anhydrous ether, by which the caramel will be left adher- 

 ing to the glass; and after washing this with a little more ether, 

 it should be dried and weighed and the fat determined by dif- 

 ference. 



The estimation of fat by centrifugal method is seriously 

 impeded by the carbonization of the sucrose, and various 

 methods have been proposed for overcoming this difficulty. 

 Leach devised the following method, which he finds to be more 

 trustworthy than ordinary extractions with solvents. Leach 

 applied the process to a centrifugal method not identical with 

 the one described on page 16, but this is not important: 



25 c.c. of diluted material are measured into the test-bottle, 

 water added sufficient to fill it to the beginning of the stem, 

 and then 4 c.c. of the copper sulfate solution used for sugar 

 determination, the mixture allowed to stand for a few minutes, 

 then shaken well, and the precipitate settled by whirling the 

 bottle in the machine. The supernatant liquid is drawn off. 

 The precipitate is washed twice with water by the same method, 

 settling the precipitate in each case by the use of the centrifuge, 

 taking care that the mass is well stirred with the water before 

 each whirling. After the second washing, about 15 c.c. of 

 water are put in, the precipitate stirred up, the amyl alcohol 

 mixture added, then the sulfuric acid, as directed on page 16, 



