43 



fr^" 



Ordinary Meeting, January 21st, 1873. 



E. W. BiNNEY, F.RS, F.G.S., Vice-Presi- 

 dent, in the Chair. 



The Peesident explained a simple ap- 

 paratus by means of which a very high 

 deoTee of rarefaction of air could be 

 produced with much facility, and which 

 mio'ht in some circumstances be found 

 preferable to the common air-pump or 

 even the Sprengel. It consists of a glass 

 funnel a surmounting a globe h, from 

 the lower part of which a tube c descends 

 to a jar of mercury d. The tube e, in 

 connexion with the receiver to be ex- 

 hausted, is furnished with a vulcanised 

 indiarubber plug which fits into the neck 

 of the funnel. In using the apparatus 

 the stopcock / is shut and the funnel 

 filled w^ith mercury. Then by lifting 

 the tube e with its plug, the mercury 

 fills the globe h and the pipe c. The 

 tube e is then replaced, and the stopcock 

 being opened, the mercury descends in c 

 emptying the globe. By returning the 

 mercury into the funnel by means of a 

 pump, or more simply, by lifting the jar 

 d, the process is repeated until the requi- 

 site degree of rarefaction is produced. 



Scale -k 



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^ 



d 



