Abstract
Investigated the size of clay particles of Kasuya (Fukuoka Prefecture) and Goto (Nagasaki Prefecture). The testing method applied the falling time of the particles by Stoke's law, which calculated from the fallng velocity of the fine clay particles and obtained 1∼200 micron size in clay particles.
It filled up to the constant hight with the constant volume of clay water in vessel, and agitated it, then outflawed by syphon in every desired time. And then investigated the separated particle size by microscopic examination in the purpose of inspecting of it which separated particles by Stoke's law, with the scale of micrometer, whether shows the same result or not.
