Abstract
Studies was made on complete dispersion of "Onji" (allitic volcanogenous soil) as previous treatment for mechanical analysis by elutriation. Satisfactory result was obtained by the following procedure : 5 g of sample, taken in 1 l shaking bottle, was added with 500 ml. of 5% oxalic acid solution. The solution was heated previously at about 30℃ before the addition. The bottle with the sample was shakened for one hour by shaking machine. For "Onji" with humus, it was necessary to add 30〜50 ml. of 30% H_2O_2 to the soil on the water bath, to decompose humus before the addition of oxalic acid. Solubility of various fresh minerals by 5% oxalic acid was found almost negligible.
