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LXVII. Intelligence and Miscellaneous Articles, 



MOLECULAK THEOKY OF DIFFUSION AND ELECTROLYSIS. 

 BY E. EIECKE. 



FOE a dilute solution of a body which is not an electrolyte, the 

 concentration of which is constant in all plane layers which are 

 at right angles to an axis (z- Axis), but is variable in the direction of 

 this axis, the author finds that the excess of the molecules moving 

 downwards (that is, the strength of the diffusion-current) is 



S= ~ 



lu dN 



in which I is the mean path of the dissolved molecules, u the 

 molecular velocity, N the number of gramme-molecules in unit 

 volume of the solvent ; then S is the number of gramme-molecules 

 which move through unit section in a second in the direction of 

 decreasing concentration. The coefficient of diffusion Tc for the 

 time of a day is therefore 



£=86400. lu/3. 



Thus the author calculates : — 





Tc. 



Molecular 

 "weight. 



I in cm. 10-8. 



Urea 



0-81 

 0-55 

 0-38 

 0-31 



60 

 165 



182 

 342 



0-086 

 0-094 

 0-068 

 0077 



Chloral hydrate ... 







For electrolysis Prof. Biecke finds for the number Q^ of positive 

 ions which pass in a second through unit section, 



N 



Q„=- 



T p flpUp 



Z; 



in which N is the number of molecules in unit volume, e the quan- 

 tity of positive electricity united to each molecule, I the mean path, 

 u the molecular velocity, fx the molecular weight, r the time between 

 two successive impacts of a molecule of the ion against a molecule 

 of the solvent, and Z the E.M.F. in electrostatic measure. The suffix 

 p signifies that the numbers refer to the positive ion ; n in like 



