1916-17.] The Adsorption of Sulphur Dioxide by Charcoal. 161 
XI.— The Adsorption of Sulphur Dioxide by Charcoal at -10° 0. 
By A. M. Williams, M.A., B.Sc., 1851 Exhibition Scholar of the 
University of Edinburgh, 1911-14. Communicated by Professor 
James Walker, F.R.S, 
(MS. received December 2, 1916. Read February 5, 1917.) 
The object of this research was to find how the heat evolved on the 
adsorption of a vapour varied with the amount adsorbed. Work in this 
direction had already been done by Chappuis,* and more recently by TitofF.j* 
Neither of these experimenters carried out the adsorption till the adsorbent 
was even approximately “ saturated,” with simultaneous measurement of 
the heat effect. To do this, then, was the aim of the author. 
The adsorbent selected was blood charcoal (puriss. Merck). Similar 
charcoal had been employed before by the author and no further purifica- 
tion by means of acids, etc., was attempted. Its relative density had been 
found to be 1*628. The adsorbate selected was a vapour whose liquid boiled 
not far from room temperature, namely, sulphur dioxide with boiling-point 
at —101° C. The sulphur dioxide was prepared by redistillation of the 
liquid from a siphon. The gas was passed through sodium sulphite 
solution to free it from traces of sulphur trioxide, and through bulbs 
containing concentrated sulphuric acid to dry it thoroughly. It then 
passed into a spiral glass worm surrounded by a freezing mixture. The 
exit from the condensing flask led to another sulphuric acid bubbler and 
finally to a caustic alkali solution which prevented the gas escaping into 
the air. 
Instead of a Bunsen ice calorimeter such as was employed by Chappuis 
and by Titoff, the author used a gas calorimeter after the manner of Dewar J 
and of Estreicher.§ The dimensions of the calorimeter were determined with 
reference to a large vacuum vessel possessed by the University College, 
London, Chemical Laboratory. This vessel was used to contain the freezing 
mixture in which the calorimeter was immersed. The calorimeter is shown 
in fig. 1. It consists of a Dewar’s vessel, silvered save for a narrow 
* JVied. Ann., xix (1883), p. 21. 
t Zeits. f. physik. Chem., lxxiv (1910), p. 641. See also Joulin, Ann. Ghim. phys. (5), 
xxii (1881), p. 398 ; and Favre, Ann. Ghim. phys. (5), i (1874), p. 209. 
X Proc. Boy. Soc., lxxiv, A (1904), p. 122, and Ixxvi, A (1905), p. 325. 
§ Zeits. f. pliysik. Chem., xlix (1904), p. 602, and Anz. Akad. Wiss. Krakau, 1910 A, p. 345. 
VOL. XXXVII. 11 
