R = [kappa]´[omega](nV). (2)

But equations (1) and (2) may both be expressed in one equation if

[kappa] and [kappa]´ are replaced by a constant varying inversely as

the thickness of the layer. Putting [kappa] = [mu]/T, [kappa]´ =

[mu]/nT,

R = [mu][omega]V/T;

or, for an indefinitely thin layer,