g6 Analysis of Feeding Materials [142 



proceed until the ether has passed over ten times. This should 

 take one and a-half hour. 



The extracted fat has now to be weighed. This is sometimes 

 done in the extraction flask, but such a proceeding is not ad- 

 visable, as the oil takes a much longer time to dry in a flask 

 than in a more open vessel. 



Whilst the extraction is going on, a small beaker, \\ inch 

 high by i inch diameter, is cleaned, dried, and weighed. When 

 the extraction is finished the extractor is removed from the 

 condenser and the cartridge case withdrawn. This is placed 

 on a clock glass in the steam oven to dry. The extractor is 

 replaced on the condenser, and the ether in the flask allowed 

 to distil over until the large tube (e, fig. 37) is filled to within 

 half-an-inch of the top of the syphon ; it is then removed from 

 the condenser. The flask is taken off from below, and the 

 ether poured out of the extractor into the ether bottle. The 

 whole apparatus is replaced, and the rest of the ether distilled 

 off from the flask to the extractor. The flask may now be 

 finally removed. 



A small quantity of oil may have got on to the cork of the 

 flask by the too rapid boiling of the ethereal solution. The 

 cork and tip of the extractor should be washed with a fine 

 spray of ether, allowing the washings to flow into the flask. 



142. The next operation is to remove the oil into the 

 weighed beaker. The sides of the flask are washed down with 

 a fine spray of ether delivered from the jet of a wash bottle 

 until about 1 c.c. of liquid has collected in the flask. The 

 liquid is poured into the beaker. This operation is repeated 

 four or five times, when all the oil will have been washed away. 

 Some, however, will have crept over the lip of the flask, there- 

 fore the outside of the neck should be sprayed, allowing the 

 ether to drip into the beaker. 



The ether is allowed to evaporate by placing the beaker on 



