484 Messrs. W. E. Garner and Irvine Masson on the 



~d' 2 A d 2 A 



-^— 2 and ^g will be obtained by cyclic interchange. 



Thus 



dx'dv'dz' 



and does not vanish. 



I am, Gentlemen, 



Yours faithfully, 



A. Lienard. 



XLIII. The Activity of Water in Sucrose Solutions. 

 By W. E. Garner and Irvine Masson *. 



Jones and Lewis (Trans. Ohem. Soc. 1920, oxvii. p. 1125), 

 in investigating the catalysis of the inversion of cane-sugar 

 by decinormal sulphuric acid, have obtained values for the 

 activities of the hydrogen ion in solutions of varying sucrose 

 content with the aid of the hydrogen electrode. These 

 activities increase markedly with increasing concentration 

 of sucrose ; thus, " when the sucrose content is 70 per cent, 

 the thermodynamic concentration [per litre of solution] 

 of the hydrogen ion is 0'162 at 20° C. and 0*152 at 40° C., 

 although the maximum actual concentration cannot exceed 

 0-10. " 



It occurred to us that this increase in the activity of 

 the hydrogen goes pari passu with the abnormalities in the 

 osmotic pressures of sucrose solutions observed by Berkeley 

 and Hartley and by Morse and Frazer. Arrhenius (Zeit. 

 phys. Chem. 1899, xxviii. p. 317) has already correlated 

 velocities of inversion with earlier measurements of osmotic 

 pressure. That such a connexion exists is best shown by 

 comparing the ratios of the activity of the hydrogen ion 

 in sucrose solution to that in pure water with the ratios 

 of the observed osmotic pressure to the osmotic pressure 

 calculated according to van't Hoff. Tiie former set of 

 ratios is denoted in the following table by (H* )sujr./(H")aq., 

 and the latter by Poba./Pcai.* 



The ratios of the solubility of hydrogen gas in pure water 

 to those in sucrose solutions are also given in the last column, 

 as a further indication of the change in the activity of the 



* Communicated by Prof. F. G. Donnan, F.R.S. 



