抄録
For the purpose of looking into the nature of the humic acid components, made clear in the 1st report, A-type humic acids free from bitumen, were separated into three or four fractions by means of Al_2O_3 column, and an absorption spectrum was formed for each of these fractions. Then comparision was made of the shape and characteristic of the curves thus formed, and the curves, on the other hand, were compared with those of the artificial humic acid obtained from lignin. As the result, those components of different A-type humic acids which are in the same order seemed to be identical regardless of the kind of humic acid when the A-type humic acids are extracted from the same soil. However, when they are extracted from different soils, there is a considerable difference between their components even in the same order. Judging from the forms of the absorption curves of the fractions l, 2,3,and 4,the writers could assume the inclination that these components are getting into the process of their humification. In the case of black and humus volcanic ash soil, both similarity and dissimilarity were observed in the absorption curve of these components.
