Intelligence and Miscellaneous Articles. 459 
the inductive force is 
Here p, p' are the exterior and interior radii of the system ; \ is the 
constant distance which separates two consecutive surfaces. — 
Comptes Rendus de VAcademie des Sciences, Oct. 8, 1883, pp. 800- 
802. 
ON THE RELATION BETWEEN THE INTERNAL FRICTION AND 
RESISTANCE OF SOLUTIONS OF SALTS IN VARIOUS SOLVENTS. 
BY E1LHARD WIEDEMANN. 
In connexion with a remark of Gr. Wiedinann* attempts have in 
recent times been frequently made to establish strict numerical 
relations between the coefficients of friction and the conductivity 
for voltaic electricity, against the universality of which, however, 
he raises theoretical objections. Experimenters on this subject 
have either followed the change in the above magnitudes with the 
temperature in the same solution, or with the concentration in 
various solutions ; and a certain analogy has been ascertained to 
exist between the two processes. Tor a strict investigation, solu- 
tions of the same salt should be investigated which have as differ- 
ent coefficients of friction as possible. I have therefore made some 
experiments with solution of zinc sulphate in water and in aqueous 
glycerine. A special investigation showed that the glycerine was 
quite free from acid, and conducted the current very badly. 
The resistances to friction were determined with the apparatus 
described by Sprung t ; the electrical resistances were determined 
by Wheatstone's bridge. Solutions of zinc sulphate in water and in 
glycerine of the same strengths were placed in two troughs of equal 
dimensions, and two equal amalgamated zinc plates were dipped in 
them. Both troughs were simultaneously introduced into the two 
arms of the bridge. 
In the first series of experiments the solutions were prepared 
by dissolving 10 parts of ZnS0 4 + 7H 2 in 100 parts of water, and 
then making this solution up to 500 c. c. by the addition of 50 c. c, 
100 c. c, or 250 c. c. of water or of glycerine. Hence the solu- 
tions always contained an equal number of molecules of the salt 
in equal volumes. 
For the solutions in water and glycerine the following ratios 
were obtained : — 
Internal 
Friction. Resistance. 
50 Zn S0 4 . . . . 1 : 687 1 : 12-1 
100 Zn S0 4 . . . . 1 : 29-8 1 : 9-52 
250 Zn S0 4 . . . . 1 : 6-15 1 : 3-68 
* G-. Wiedmann, Galvan. 2 ed. i. p. 631 et seqq. ; 3 ed. i. p. 952. 
t Pogg. Ann. clix. p. 1, 1876. 
