Warm the steel, and rub on a coating of white-was or hard tallow. When hard, mark the device through the wax with a sharp-pointed tool; apply nitric acid, and allow it to stand for a few minutes; then wash oil the acid thoroughly with water, heat the steel, and rub off the wax with a rag. The device will be found etched on the steel. Gold And Silver, Test for A. good test for gold or silver is a piece of lunar caustic, fixed with a pointed stick of wood.

Slightly wet the metal to be tested, and rub it gently with the caustic, If gold or silver, the mark will be faint; but if an inferior metal, it will be quite black.