The solubility and rate of solution of oxygen in silver

A large number of investigations have been made on the solubility of gases in metals, and on the rate of diffusion of gases through metals. Hydrogen-platinum and hydrogen-palladium are, however, the only systems which have been thoroughly investigated. The behaviour of these systems is such that they can by no means be regarded as typical. The system oxygen-silver was chosen as a more typical one which was suitable for purposes of investigation. The rate of diffusion of oxygen through silver has been measured by Johnson and Larose. This paper deals with solubility and rate of solution of oxygen in silver. It has been known for a long time that molten silver will absorb oxygen from the air and will "spit" on solidification. Sieverts and Hagenacker found an absorption of 20 volumes of gas per volume of silver at the melting point. The solubility decreases as the temperature increases beyond the melting point The absorption is proportional to the square root of the pressure. Dumas showed that a portion of the oxygen is retained by silver on solidification. He obtained 57 c. c. of oxygen from 1 kilogram of silver. Brauner found that 0·04 volumes of gas were retained on solidification. Richards and Wells found 0·6-1·8 volumes. Graham found that silver takes up oxygen at a red heat. He obtained an absorption of 0·7 volumes. Neumann found a some-what larger absorption, while Berthelot obtained a smaller value. More recently Sieverts obtained an absorption of 0·3 volumes of gas per volume of silver. His results, however, do not check closely and he does not place much confidence in them himself.