Permeation rate of hydrogen through a gold cell made as a reaction vessel for a Dickson-type hydrothermal apparatus was measured at 50°intervals from 300°to 450℃ under a hydrothermal condition. The gold cell chosen for the measurement had a shape and size illustrated in Fig. 1 when it was fully expanded, and was a typical one in the meaning that it had been used several times for hydrothermal experiments (its total history may be equivalent to one month at 490℃) and that it had a body enlarged by about 8% in diameter from the original size as a result of pinhole check made by applying a gas pressure to the inside. The cell was filled with an appropriate amount of pure water, placed in a pressure vessel made of Ni-base alloy, pressurized by injecting water to the outside of the cell and kept under predetermined temperatures and pressure (=1 kbar). Meanwhile, small fractions of the waters inside and outside the cell were sampled at times and analyzed for H(2) gas-chromatographically as described in ref. (5). H(2) concentrations in the samples (CH(2)) were converted to H(2) fugacity values by using the conversion factors (Y) given in ref. (6). At each temperature, the permeation rate (k) of H(2) through the cell is evaluated by correlating the measured fH(2) values with time (t) according to eq. (2), where fo is the fH(2) in the outer water and is a constant, and fi and m are the fH(2) in and the mass of the inner water, respectively. The relevant data and results are shown in Table 1. The present data for the permeation rate φ, expressed in c㎥ H(2) at STP per 1c㎡ surface area, 1 mm wall thickness, 1 (bar)(1/2) of (fH(2))(1/2) difference and 1 hour, are plotted in Fig. 2 in relation to 1/T (K) and compared with one available data, which is a combination of reported solubility and diffusion coefficient data for hydrogen into gold at higher temperatures. The present data can be fitted into eq. (3). The present result may be of importance for
hydrothermal experimental studies of geochemical redox reactions and of hydrogen isotope exchange reactions, and the technique used may also be important as a new, simple method of measuring hydrogen permeability through noble
metals.
