Using Na(2)SO(4) labeled with S(85) transition of sulfate ion into the body across the skin was investigated soon after the bath in sodium sulfate solution(one gram per liter) at varying conditions. Mice were used as test animal. Percutaneous absorption of sulfate ion was promoted at indifferent bath temperature (37℃) than at lower bath temperature (25℃), became less by the addition of sodium chloride (one gram per liter) to the bath water, proved stronger at lower pH (2.0) than at higher pH (7.0
or 9.0). One of the characteristic types of mineral waters in Japan is "acid spring". And many of the Japanese acid springs contain free sulfuric acid in considerable quantity.It is known that their bath cure often causes dermatitis, socalled "Yutadare". Misawa and Oshima had proved that the level of immune bodies in blood is increased by the bath cure with dermatitis in acid springs of "KUSATSU". And the author's experiment seems to give a new significance to the ro1e of sulfate ion in the action of acid spring bath in Japan.