166 Lloyd, Extraction of Fat from Bird-Skins. [April 



subterfuge and, as all the fat is not removed, the decomposition 

 still continues. 



The method which I have found successful consists in washing, 

 soaking and extracting the specimen with automatically repeated 

 doses of the freshly distilled fat solvent. It is an adaptation of the 

 Soxhlet extraction apparatus of the chemist. By this method the 

 entire bird-skin, including the skin, feathers, beak, feet and label, 

 is rendered chemically free from fat, the decomposition due to fat 

 is checked completely, and the future existence of the specimen is 

 probably assured. 



The apparatus used is shown in the figure. The one represented 

 is made of glass connected by ground in joints. Cold water is 

 supplied to the invert condenser and heat is supplied to the flask 

 of solvent by an electric light bulb or by an electric hot plate pro- 

 vided with a rheostat so that the temperature can be adjusted. Do 

 not use a flame to heat the flask, as the solvent, ethyl-ether, (C^H^O 

 is inflammable and explosive when mixed with air; it boils at 35° C. 



The specimen to be cleaned is placed in the extraction chamber, 

 the apparatus is closed, enough ether is poured in the opening in 

 the top of the condenser to charge the syphon twice, and the opening 

 covered with a funnel or loose cap. It must not be closed tight. 

 Then the water is turned into the condenser and the current for 

 the heating apparatus is turned on. Sufficient heat is being sup- 

 plied when the liquid boils gently. 



The ether vapor goes around by way of the by-pass into the 

 condenser, is condensed and falls on the specimen. When the 

 extraction chamber is full of solvent, the first extracting charge 

 syphons automatically into the flask below and carries with it all 

 the fat which it has dissolved. As the operation continues, the 

 specimen is repeatedly washed with freshly distilled ether until 

 not a vestige of fat remains. Two or three hours should complete 

 the operation, but the apparatus can safely be left in operation all 

 night, if it is carefully set up and if the heating apparatus is cor- 

 rectly adjusted. 



The operation is completed when the solvent, after passing over 

 the specimen, remains perfectly colorless. 



Before opening the apparatus, turn off the heating unit and allow 

 the ether to cool thoroughly. This can be hastened by immersing 



