Section III, 1919 [47] Trans. R.S.C. 



A Continuous Flow Apparatus for the Purification of Impure Helium 



Mixtures} 



By E. Edwards, M.A., B.Sc, and R. T. Elworthy, B.Sc. 



Presented by Professor J. C. McLennan, F. R. S. 

 (Read May Meeting, 1919.) 



Introduction 



The utilization of the absorbent property of cocoanut charcoal, 

 cooled to a low temperature, introduced by Dewar^ primarily for the 

 production of high vacua and later for the separation of gases, has 

 been practically the only laboratory method adopted for the isolation 

 and purification of helium. 



The usual practice is to admit impure gas gradually at low 

 pressures to the charcoal contained in vessels immersed in liquid air 

 and as soon as equilibrium is attained the unabsorbed helium is pumped 

 ofï. 



Ramsay^ made use of this method for the final purification of 

 helium obtained by fractional distillation of liquid air and in his 

 examination of the rare gases evolved from the mineral springs at 

 Bath. It was used by Moureau and Lepape^ in their analyses of rare 

 gases given off from French mineral springs, by Cady and McFarlane^ 

 in work on the helium content of natural gases in Kansas, U.S.A., and 

 by Professor J. C. McLennan and others in an investigation of the 

 helium resources of the British Empire.^ 



Two hundred litres of helium prepared from monazite with which 

 Professor Kammerling Onnes'' carried out determinations of isother- 

 mals — ^work which culminated in the liquefaction of helium — was 

 purified by charcoal cooled in liquid hydrogen. Until recently the 

 gas at Leiden constituted the greatest supply of pure helium existent, 



^ Communicated by Professor J. C. McLennan, F.R.S., by permission of the 

 Admiralty. 



2 Dewar. Proc. Roy. Soc, 1904. A 74, 122. 

 'Ramsay. Proc. Roy. Soc, 1905. A 76, 111. 

 Proc. Roy. Soc, 1908. A 80, 599. 

 Chem. News, 1912-105-134. 



* Moureau and Lepape. Comp. Rend., 155, p. 197-1912. 



^ Cady and McFarlane. Jour. Amer. Chem. Soc. 1907-29-1523. 



• Vide this Journal. 



' K. Onnes. Proc K. Akad. Wetensch Amsterdam, 1908-11-168. 



