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AGRICULTURAL CHEMISTRY 



is then placed in a glass extractor connected with a small 

 weighed flask containing ether. The flask is immersed 

 in a water-bath heated by a gas 

 burner, the ether is volatilized, 

 and the vapor passes through 

 openings 2 and 4 into the con- 

 denser where it is cooled and 

 falls back in drops from point 4 

 on the substance at 5. The 

 ether percolates through the sub- 

 stance and returns to the flask. 

 The fats and ether-soluble mat- 

 ters are not volatilized but remain 

 in the flask while the ether is 

 vaporized and condensed again 

 and again. After the extraction 

 is completed, the ether is distilled 

 from the flask, the ether extract 

 dried and weighed, and the per- 

 centage amount calculated. While 

 the process appears to be simple, 

 it is a difficult operation to con- 

 trol, because even after many 

 days' extraction, some materials 

 will continue to give up ether 

 extract, and unless unusual care 

 Fig. 79. Ether extractor. is taken some of the fats are 

 oxidized. Then, too, the ether extract is liable to be 

 contaminated with impurities if ether of a high degree 

 of purity is not used. When the determinations are made 



