抄録
Most of potassium incorporated into precipitation is considered as originating from sea water. In general, however K/Na ratio in precipitation is higher than that of sea water. The determination of sodium, potassium and silica contents of a sequence of rain fall showed that potassium was inversely correlated with silica. This fact indicates that the excess potassium in precipitation does not originate from soil. When the mechanism of rain formation is taken into consideration, the excess potassium is concluded to be supplied in the form of aerosol which is present above the layer of rain drop formation. Potassium emitted from plents may be the ultimate origin of the excess potassium.