Abstract
In the case of dispersing the so-called volcanic ash soils, the acid reaction of the liquid has been observed to be prefered to the alkaline reaction, which has been hitherto accepted as a suitable reaction for ordinary soils. Of four soils of various parent materials, including of volcanic ash, mechanical analyses were made after British Pipette Method, the soils being dispersed in both reactions acid and alkaline. The acid reaction was obtained by an addition of acetic acid to the extent of pH 4.0 as well as of pH 5.0 the alkaline reaction by ammonium hydroxide in an ordinary way as much as pH 11.0. From the results of analyses, volcanic ash soils were suitably dispersed in the case of the liquid being acidified as much as pH 5.0 by acetic acid (see Table). For the tentative device, especially for the routine work of soil survey, the aforementioned acidification was concluded to be convenient by the authors.
