408 COMPARISON OF RESISTANCES. 



the tube, L its length, p the difference of pressures at the two ends, 

 and / the temperature, the quantity Q of liquid which flows in 

 unit time is 



The factor K, which depends on the nature of the liquid, is 

 inversely as rj ; it only varies with the temperature /, and may be 

 represented by 



we deduce from it, for the coefficient r;, an expression of the form 



1 



i+a 



We may also, as Meyer* has shown, deduce the coefficient rj from 

 the method used by Coulomb in determining the cohesion of a fluid, 

 and which consists in investigating the oscillations of a body im- 

 mersed in a mass of liquid. If A, is the logarithmic decrement of 

 the oscillations, R the radius of the oscillating disc, M the moment 

 of inertia of the system, and T the time of the oscillations in a 

 vacuum, Mayer obtains the formula 



x^ 



Grossmann,f applying this latter formula, suitably corrected, to the 

 experiments of Kohlrausch and Grotrian, finds that the product of 

 the electrical conductivity by the coefficient of internal friction is 

 independent of the temperature for the same salt, and the same 

 condition of solution ; it follows from this that the two coefficients 

 a and /?, for the variation of conductivity, are respectively equal to 

 the coefficients a and b relative to the variation of friction. 



Bouty confirms this law for very weak solutions ; he found that 

 the molecular conductivity of any salt varies as the binomial 



i + 0-033695 /. 



* Pogg. Ann., Vol. cxin., pp. 55, 193, 383. 1861. 

 t Wiedemann's Annalen, Vol. xvni., p. 119. 1883. 



