EBBULIOSCOPES. 



155 



11.— NEW TYPES OF EBBULIOSCOPES. 



By Prof. T. H. EASTERFIELD, M.A., Ph.D., F.I.C., Victoria University 

 College, Wellington, N.Z. 



[Abstract.] 

 The apparatus, at present in use for determining molecular 

 weights by obsei-vation of the elevation of the boiling point of a 

 solution, belong as is well known to two types. In one of these, 

 due primarily to Beckmann, super-heating is prevented as far as 

 possible by means of a number of balls of suitable material which act 

 as buffles, and lead to unifomi heating of the liquid. In the second 

 type, first put into practical form by Landsberger and improved by 

 Walker and Lunsden, equilibrium between the solvent and its vapour 

 is maintained by passing the vapour of the boiling solvent through 

 the solution, which rapidly rises to its boiling point. The convenience 

 of the second method has led to its general adoption in the laboratory 

 of the organic chemist. 



It is evident that an intermediate 

 type of ebbulioscope is possible; one in 

 which the boiling liquid has two free 

 surfaces, an upper and a lower. If after 

 the bubbles of steam have broken at the 

 lower surface the vapour pass through 

 the upper portion of liquid, the upper 

 portion should arrive at its true 

 boiling point, superheating being entirely 

 obviated. 



To test the workableness of the idea 

 the (Simple apparatus here figured was 

 constructed. Upon the tube A a small 

 bulb was blown, so that it would not 

 pass into the boiling tube B, and the two 

 tubes were fixed in position by means of 

 a rubber band. The lower end of A was 

 drawn out and cut off, as shown, and a 

 hole blown at the point C. D is a side 

 tube adapted to a condenser, F a ther- 

 mometer graduated in 20ths, and held in 

 position by an ordinary cork. 



To use the apparatus it was mounted 

 over a hole in a tile of compressed 

 asbestos, protected from draughts by a 

 small cylinder of tinplate, a measured 

 quantity of solvent introduced, and 

 heated by a small luminous flame. To 

 prevent bumping a fragment of clay 

 tobacco-pipe was introduced before each 

 heating; the construction of the tube A 

 allows the piece of pipe clay to fall to 

 the bottom of the boiling tube. 

 The working of the apparatus is obvious. The bubbles which 

 form in the lower portion of the boiling liquid break upon the free 



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