THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 

 JANUARY 1887. 



I. On Liquid Diffusion. 

 By J. J. Coleman, F.I.C., F.C.S., F.R.S.E* 



[Plate L] 



OUR knowledge upon this subject is chiefly derived from 

 Graham's classical researches. His first paper was 

 communicated to the Royal Society in 1849, and further 

 papers in 1850 and 1851. 



About the year 1855, Fickf, commenting upon these in- 

 vestigations, remarked that it was a matter of regret that in 

 such an exceedingly valuable and extensive investigation the 

 development of a fundamental law for diffusion in a single 

 element of space was neglected, which (he added) it w r as quite 

 natural to suppose would be identical with the law according 

 to which diffusion of heat takes place in a conducting body, 

 and upon which Fourier founded his theory of heat, and Ohm 

 his theory of diffusion of electricity in conductors. Fick 

 endeavoured to supply this omission so far as common salt is 

 concerned, and Voit calculated the coefficient of diffusion of 

 sugar. Professor Mach, of Prague, has also worked with 

 these substances. Other experimenters have calculated the 

 coefficients of diffusion of salts, or, rather, of a limited number 

 of them, with not very concordant results, as may be seen by 

 consulting the tables of Schumeister attached to the article 

 " Heat," by Sir W. Thomson, in the ninth edition of the 

 Encyclopaedia Britannica, and comparing them with the results 

 of Beilstein, who employed Jolly's method, described in 



* Communicated by the Author, 

 t Phil. Mag. [4] x. 1855. 



Phil. Mag. S. 5. Vol. 23. No. 140. Jan. 1887. B 



