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PROCEEDINGS OF THE AMERICAN ACADEMY 



by a rubber hose with a large glass bottle, in which a partial vacuum 

 is maintained by a Buusen pump, but this connection can be closed by 



Fig. 2. 



a compression cock. The third stem, which makes a connection with 

 the atmosphere, is closed by a rubber connector and nipper tap, and 

 serves to suddenly relieve the pressure in case the filter slips or breaks. 

 From the first and vertical stem of the three-way tube below the 

 clamp is suspended the glass tube, having the rose at its end. The 

 suspension consists of a rubber connector, so long that it can be bent 

 double and the rose inverted, and so stout that when thus bent the 

 connection with the bottle is completely closed. When inverted, the 

 tube of the rose rests against the thumbscrew of the pinion, and is 

 thus confined. 



In order that we may make clear the mode of using the apparatus, 

 let us assume that five grammes of antimonious sulphide have been 

 precipitated in a glass beaker, holding two litres of liquid, and that the 

 precipitate has settled, — as it will after boihog, — leaving the super- 

 natant liquid perfectly clear. A partial vacuum having been formed 



