The exchange of silver ions with a drop of mercury was studied systematically. Under defined conditions, the redox exchange is quantitative (complexation of Hg²⁺) very rapid and selective; most other ions remain in solution. The reoxidation of amalgamated silver is proposed; this increases the selectivity and makes possible the chemical or the physico-chemical determination of this element. The method was applied to the determination of silver in gold, blende and pyrite.