Oshima proved that blood catalase level tends to decrease after the internal use of the vitriol waters of Yanahara and Fujino and explained his data by the promotion of oxidative process in the body by the waters. Consumption of iodate by proteinfree serum filtrate is an index of total reductive substances in serum. After the internal use of these two mineral waters, this index increased temporarily, but there was no significant difference between the effects of the two mineral waters and of plain
water. In anaemic patients this index tends to decrease after successive daily intake of Yanahara vitriol water in accordance with the recovery of anaemia.