1913] Walter Lewis Croll S^i 



protein and fat. The precipitate is collected quantitatively on filter 

 paper, dried, and extracted with absolute ether. 



"Rapid" methods. Nearly all the so-called rapid methods 

 depend upon centrifugation. In these methods accuracy is sacri- 

 ficed for speed and the results obtained are, at best, only approxi- 

 mate. For commercial and pediatric uses they are of sufficient 

 precision to answer most requirements. An example of these meth- 

 ods is the widely used Babcock process, with the special scale for 

 reading off the contained fat, and various other modifications dif- 

 fering only in the shape of the tube or the scale. Another rapid 

 but cruder method is the well known Feser lactoscope process. 



Woosnam,^ following the idea of Schmid, suggests the follow- 

 ing method : 25 c.c. of milk and 28 c.c. of conc. hydrochloric acid 

 sol. are placed in a special apparatus and heated on a water-bath 

 until a slight browning occurs, when the flask and contents are 

 cooled, an ether extraction made, and the volume of fat-ether 

 mixture is read. A definite portion of this mixture is then taken, 

 evaporated to dryness in a weighed glass dish and the dry fat 

 weighed. 



Following the method of Krug and Hampe^ as a basis, Arndt'^ 

 describes a process involving special extraction apparatus. The 

 milk is desiccated with kaolin and dry sodium sulfate, and then 

 extracted with ether in the apparatus. 



As a modification of the usual butyrometer method, Gerber and 

 Craandijk^ recommend the following: Into a beaker of 5.5 c.c. 

 capacity place 4-5 gm. of previously weighed, well mixed milk, 

 introduce the beaker and contents into the butyrometer, add 10 c.c. 

 of warm water, place the butyrometer in a water-bath at 6o°-'jo° 

 C. until complete Solution has occurred. To the liquid add i c.c. of 

 amyl alcohol, 10 c.c. of sulfuric acid sol, (sp. gr., 1520-1525), close 

 the butyrometer, shake until the contents are well mixed, and then 

 place it in a water-bath until the greater part of the fat separates. 

 Finally, centrifuge twice and read the scale. 



^Woosnam: Analyst, 1897, xxii, p. 91. 



6 Krug and Hampe : Ztschr. f. angew Chemie, 1894, p. 683. 

 ''Arndt: Chem. Centr., 1897, "> P- 636 (Forsch.-Ber. üb. Lebensm. u. ihre 

 Gez. 2. Hyg., etc., iv, p. 231). 



* Gerber and Craandijk: Milch-Ztg., 1898, xxvii, pp. 35 and 273. 



