ラジウム北光泉、鉄湯1号、苦湯3号、姥湯 混合泉
Radium Hokkosen, Tetsuyu No. 1, Nigayu No. 3 and Ubayu Blended SpringOperated by · 万座温泉 日進舘
Mixed source
- Skin conditionsatopic skin, eczema
- Circulationtired legs
- Aches & jointsstiff shoulders
- Sensitive-skin cautionbroken or dry skin
A blended source that pools four Manza wells — Radium Hokkosen, Tetsuyu No. 1, Nigayu No. 3 and Ubayu — into an acidic, sulfur-bearing magnesium-sodium sulfate spring of the hydrogen-sulfide type. At 3.4 mg/kg of free hydrogen ion the water is sharply acidic, 45.8 mg/kg of dissolved H₂S gives it the unmistakable rotten-egg note, and 615.8 mg/kg of sulfate carries the body. The source emerges at 69.2 °C, among Japan's hotter natural waters, so the tubs are cut with spring water to make them bearable — the posted bath guide notes that only the Ubayu tub runs at 100 % onsen, and that a plain non-thermal tub is kept for guests with sensitive skin. There is no reheating, no recirculation and no chlorine. A generous 160.4 mg/kg of metasilicic acid rounds off what would otherwise be a purely astringent water, leaving a fine silica film on the skin.
Analyzed Nov 16, 2015·公益財団法人 中央温泉研究所
