Abstract
To study the relative catalytic ability of some colloidal constituents of ordinary soils on the conversion of cyanamide, the following substances were added to aquoues solutions of cyanamide at 50℃, viz., iron oxide, iron hydroxide, manganese-hydroxide, manganese dioxide, manganese dioxide hydrate, aluminium hydroxide, colloidal silica gel, fuller's earth (Japanese acid clay), humic acid and activated charcoal. At the end of various periods of time the content of cyanamide-, urea- and dicyandiamide-nitrogen was determined. The results may be summarized as follows : - Of the greatest catalytic activity to form urea was manganese dioxide hydrate; second, manganese dioxide and iron hydroxide. Manganese hydroxide showed catalytic ability to form dicyandiamide. Iron oxide, aluminium hydroxide, colloidal silica gel, fuller's earth, humic acid, and activated charcoal had a very slight ability to convert cyanamide. As previous investigators showed, most of cyanamide was transformed to dicyandiamide in the alkaline solution of pH 9.2,but this reaction was modified to form urea and dicyandiamide simultaneously, when iron hydroxide or manganese dioxide hydrate was added to this solution.
