Activity of Water in Sucrose Solutions. 



485 



water. It has already been pointed out by Miiller (Zeit. 

 pJiys. Chem. 1912, lxxxi. pp. 483-503 ; see also J. C. Philip, 

 Trans. Faraday Soc. 1907, iii. pp. 140-146) that other gases 

 are quantitatively similar to hydrogen in this respect. 



Lewis 



§ Jones. 





Berkeley $ Ha 



riley 



Morse 



§■ Frazer. 



H 2 aq. 



H 2 sucr. 



Sucrose, 

 nols./litre. 



(H- 



suor. 



)aq. 





P obs 



./Peal. 







20°. 



40°. 



0°. 





20°. 



40°. 



15°. 



•292 



1-13 



1-12 



1-11 





1-13 



1-09 



1-11 



•585 



1-30 



1-24 



1-20 





1-23 



1-21 



1-23 



•877 



1-49 



1-56 



1-36 





(1-38) 



(1-33) 



1-39 



1-169 



1-75 



1-82 



1-56 









1-61 



1-460 



1-97 



2-18 



1-80 





... 





1-87 



1-755 



2-32 



260 



2-11 









2-17 



2-047 



2-70 



304 



2-49 











There is a very clear parallelism between these ratios, 

 which is well shown when the data are plotted as curves. 



The general agreement shown by these figures indicates 

 that the causes which are operative in increasing the activity 

 of the hydrogen ion are substantially the same as those which 

 cause the deviations of the osmotic pressure from van't Hoff's 

 law and the decrease in the solubility of gases in sugar 

 solutions. These causes would appear to be at work inde- 

 pendently of the presence of hydrogen ions. 



Jones and Lewis have further shown, from their expe- 

 riments on inversion velocities, that " the environmental 

 catalytic influence of a molecule of sucrose is identical in 

 magnitude with that exerted by one molecule of dextrose 

 together with one molecule of lsevulose/' Osmotic data 

 are available for glucose (Berkeley and Hartley) as well as 

 for sucrose ; and assuming that a molecule of lseyulose is 

 identical in its behaviour with a molecule of glucose, we 

 can again tabulate the ratios of observed to calculated 

 osmotic pressures. 



J. & L., Sucrose con- 

 centration. 



■202 



■585 



■877 1-169 1-460 



04' 



~ h *- ; Sucrose, B. & H., Ml 120 1-36 1'56 180 211 



obs. 



cal. 



o°c. 



B. &H., 0°C 



•49 



'• ; Glucose + la3vulose, 107 119 1*34 152 1*72 (20) (2*3) 



(H')sucr. j & L 2QO 1>13 j.gQ i^g v75 1 - 97 2 32 



(H')aq. 



Phil. Mag. S. 6. Vol. 41. No. 243. March 1921. 2 K 



