Note 126 — Appendix. Cement for Earthenware. Restorations.

A number of modifications in the metals employed and the composition of the bath have been suggested. Setlik (“Chemiker Zeitung,” XXVII. 1903, p. 454) imbeds iron objects which have a very weak core in a zinc-wire basket immersed in a magma of zinc dust and caustic soda. Personally I should prefer not to attempt a reduction process in such cases, but should rely rather upon mechanical removal of the rust, soaking and impregnation. For the treatment of bronzes this observer prefers the Finkener method (q. v.) and suggests caustic soda, sodium chloride, or ammonia chloride, instead of potassium cyanide as the electrolyte. Rhousopulos (“Chemische Zeitschrift,” II. 1903, pp. 202 and 364) uses zinc and hydrochloric acid, and when dry gives to the bronze a coating of wax. I should deprecate the use of either of these substances, the hydrochloric acid because of the difficulty of completely removing it by steeping and the danger of subsequent decomposition of the bronze, the wax because the contained fatty acids may act upon the metal.