硫黄泉に関する研究 (第1報)

硫黄泉の吸収スペクトルについて

抄録

The relationship between absorption spectra and sulfur compounds, such as hydrosulfide, polysulfide, and thiosulfate ions, contained in sulfur springs were examined.
(1) The maximum absorption at 230mμ, which is due to hydrosulfide ion, is observed in neutral and weak alkaline sulfur springs. The absorption curve changes its shape markedly on exposure to the air. The change is caused by the oxidation of hydrosulfide ion to polysulfide and thiosulfate ions. The absorption in the region of 220-260mμ, which is due to hydrosulfide ion, decreases with time, but when hydrosulfide ion is oxidized to polysulfide ion, the absorption at wave length longer than 260mμ, which is due to polysulfide ion, increases for a short time and then it decreases.
(2) The absorption of hydrosulfide ion changes with deviation of pH value and the relationship between absorbance, D, and concentration of hydrogen ion is given by the following equation:
1/D=1/ε₁⋅CH₂S+[H⁺]/ε₁⋅CH₂S⋅KH₂S
where ε₁ is the absorption coefficient of HS^-, CH₂S is the total concentration of H₂S, and KH₂S=[H⁺][HS^-]/[H₂S]. Plots of the reciprocal of absorbance against concentration of hydrogen ion is experimentally linear under constant total concentration of H₂S. Formal dissociation constant, KH₂S, is calculated from the equation.