At the bottom of the crater and the slope of the central cone Myokogatake of Mt. Iwate many fumaroles are found, from which an enormous amount of volcanic gases containing H
2O, H
2S, SO
2, CO
2, HCl, HF, HBr etc. flow out. The authors examined those fumarole gases on July 27 and September 29~30, 1960. We found sublimates of alunogen, halotrichite, sulfur etc. at such fumaroles that show the temperature near to 100℃ and ammonium chloride at the fumaroles showing 144~205℃. As to the chemical compositions of ammonium chloride, condensed waters and fumarole gases, the following results were obtained : 1) Ammonium chloride No.1. Temp. 205℃, NH
4 33.5, Cl 65.9, SO
4 0.0, Br 0.15, B 0.000 (wt. %) (Theoretical value: NH
4 33.7, Cl 66.3) No.2. Temp. 183℃, NH
4 33.4, Cl 66.1, SO
4 0.0, Br 0.21, I 0.0003, B 0.000 (wt. %) No.3. Temp. 144℃, NH
4 33.6, Cl 66.3, SO
4 0.0, Br 0.14, I 0.0003, B 0.000 (wt. %) 2) Condensed water . No.2. Temp. 183℃, pH 1.4, H
2S 104, SO
2 143, SO
4 5.4, Cl 2876, Br 1.0, I 1.8, B 0.0, Na 2.38, K 0.16, NH_4 16.2, Fe 0.10 (mg/l.) No.3. Temp. 144℃, pH 1.8, H
2S 241. SO
2 297, SO
4 1.0. Cl 784, Br 0.2, I 0.3, B 0.0, Na 6.21, K 0.43, NH
4 18.4 (mg/l.) 3) Fumarole gas No.2. Temp. 183℃, H
2O 98.3, CO
2 1.46, H
2S 0.109, SO
2 0.0817, HCl 0.0376, NH
4Cl 0.00181 (vol. %) No.3 Temp 144℃ H
2O 98.2, CO
2 1.84, H
2S 0.117, SO
2 0.152, HCl 0.0185, NH
4Cl 0.00167 (vol. %) The temperature above mentioned was measured at the orifice of fumaroles.
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