Section III, 1918 



[79] 



Trans. R.S.C. 



The Adsorption of Helium by Charcoal. 



By Stuart McLean, M.A. 

 University of Toronto 



Presented by Professor E. F. Burton, Ph.D., F. R.S.C. 



(Read May Meeting, 1918.) 



Sir James DewarS investigating the efficiency of the use of 

 charcoal in the production of high vacua, made an experiment with 

 helium when the charcoal was cooled to the temperature of liquid 

 hydrogen. He found that at a temperature of 20° absolute, charcoal 

 is a good adsorbent of helium. By boiling the liquid hydrogen under 

 exhaustion, he was able to obtain a temperature of 15° absolute. 

 At this temperature, charcoal is a much better adsorbent of helium. 



As the adsorption of helium at liquid air temperature is very 

 small, it was impossible to investigate its adsorption as fully as for 

 other gases. The following are the results of a series of experiments by 

 Miss Homfray:^ 



The amount of gas worked with is usually so small that measure- 

 ments of volumes by observation of pressures in a comparatively 

 large apparatus give very discordant results. The object of this 



Dewar: Proc. Roy. Soc. Lon., 74, 1904, p. 122. Chem. News, 90, 1904, p. 145. 

 Homfray: Zs.f. phys. Chem., 74, 1910, p. 129. 



