1 9 6 D O C . 4 2 C O M M E N T O N P A P E R B Y H E S S

44. “Comment on the Paper by W. R. Heß,

‘Contribution to the Theory of the

Viscosity of Heterogeneous Systems’”

[Einstein 1920g]

Received 3 August 1920

Published September 1920

In: Kolloid-Zeitschrift 27 (1920): 137.

In my 1906 dissertation I derived by a theoretical method the formula

(1)

for the viscosity of a suspension of rigid spheres in a fluid of viscosity

where is the total volume of the suspended spheres per unit volume of suspen-

sion.

Motivated by J. Perrin’s experiments, I revised my calculations a few years

later and found an error in my calculation.—The correct formula is (Ann. d. Phys.

4, 34, 1911):

(2)

It appears that none of the people working in this field has noticed this correc-

tion. It should be noted that the factor 2.5 in this formula (for a diluted suspension

of rigid spheres) is rigorously derived from the hydrodynamic equations of

motion.

[1]

[2]

[3]

η′ η( 1 ϕ) + =

η′ η,

ϕ

[4]

[5]

η′ η( 1 2.5ϕ). + =