The completely unmixing of the liquid on the plates was assumed by Lewis to derive the theoretical relation between the plate efficiency and local efficiency. This assumption is not true for the actual cases. In the present paper

introducing a conception of the liquid pool

suggested early by Kirschbaum

to express the mixibility of the liquid on the plates. Using this conception the three equations were derived for three cases as in the Lewiss paper. It is interested to note that the first two cases

as k approaches infinity

can be reduced to the Lewiss form

and as k=l

equal to the Murphrees plate efficiency. These derived equations are the intermediate between the Lewis and Murphree equation

which represent the extremes of actual condition. In this paper

a method for estimating the point efficiency is also given

which is resonablly shown by the two examples. However

no further experimental data are available to demonstrate the utility.