Isothermal etching of calomel crystals

The process of isothermal etching of calomel (mercurous chloride) crystals in vacuo in the temperature range 80–180°C was studied. The sublimation rate depends not only on temperature but also on the crystallographic orientation. The ratio of the sublimation rate from (001) to that from (110) being roughly 5:1. The relation between chemical bonding and sublimation rate was discussed and the experimental values compared with the Langmuir relationship.