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PROCEEDINGS OF THE AMERICAN ACADEMY 



an apparatus can readily be arranged to work satisfactorily from 

 material always at hand in the laboratory. Hill's * application of 

 the Hempel device, which consists in supporting glass beads in the 

 neck of the distillation flask on a piece of glass rod with one end 



enlarged, is a means of saving much time in a long series of separa- 

 tions. The receiver is simply a second distillation flask. This form 

 of manometer was most convenient, since hydric sulphide was evolved 

 to a certain extent, and, the manometer tube becoming discolored by 

 mercuric sulphide, occasionally it had to be cleaned. In exhausting 

 the apparatus we used an ordinary glass water-pump, and to avoid 

 loss of time in disconnecting the flask, a ten-litre bottle was inserted 

 as a reservoir with stopcocks necessary for continuous action, and a 

 nipper tap with an enlarged thumbscrew was also attached for closely 

 adjusting the pressure. f With this apparatus there is scarcely more 



* Tliese Proceedings, xxiv. 342. 



t We were unable to use the convenient device of Anschiitz for maintaining 

 constant tensions, since the current of air produced considerable decomposition 

 of the oils. 



