32 METHODS OF QUANTITATIVE ANALYSIS. 



ferred, aided by a folded piece of paper, to the extractor. 

 The dish as well as the glass rod and the paper used are 

 finally rinsed with ether into the extraction apparatus. 

 The Soxhlet extraction apparatus is composed of the fol- 

 lowing parts : see figure 2. The large tube (a) is 

 sealed across at the bottom and is intended to hold the 

 material to be extracted. Into the lower end a narrow 

 tube (b) is sealed and bent upward parallel to tube (a). 

 At the point opposite about the middle of (a), this small 

 tube is curved downward and the end sealed into the 

 stem (d) of the extractor. The tube (e) connects the 

 stem (d) with the upper part of the extractor (a). In the 

 lower end of a tube (a) is placed in a tuft of fat-free 

 cotton (about 2 cm. high). Upon this the substance to be 

 analyzed is placed and the apparatus is connected by 

 means of a tightly fitting cork with a wide necked flask 

 of about 150 c.c. capacity in which is contained about 75 

 or 80 c. c. of ether. The upper end of the extractor is con- 

 nected with a Liebig condenser (g). The flask is now 

 warmed on the water bath. The ether vapor passes' 

 through the tubes (d) and (e) into the condenser (g). The 

 condensed ether drops back into the tube (a) containing 

 the substance to be extracted. Because of the connec- 

 tion of the tube (b) with (a); the ether is always equally 

 high in both tubes. When the ether reaches the highest 

 point at (h) the tube (b) acts as a siphon and draws the 

 ether, containing the fat in solution, into the flask below. 

 The ether again vaporizes and fills the extractor and 

 siphons ofl. Thus the process may be continued in- 

 definitely. 



The temperature of the water bath is so regulated that 

 within one hour the tube (a) is filled and emptied about 

 twelve times. At the end of this time the extraction may 

 be considered completed. The temperature of the water 

 bath should not be too high, because,. if the ether boils 



