An ethereal solution of gold is made thus: Dissolve 1 dwt. of pure gold in 1 fluid oz. of warm aqua regia (3 parts hydrochloric acid, 1 part nitric acid, and 1 part water), evaporate the liquid until it appears like red syrup, then make up to 1/2pt. with hot distilled water. Pour this into a pint glass-stoppered bottle, add a fluid ounce of sulphuric ether, and well shake. The ether will take up the gold from the acid, and float above it when at rest. This solution is applied with a camel-hair pencil, and on bright iron and steel it forms a fairly adherent coat, which may be lightly burnished. It will also deposit its gold on other metals as the ether evaporates; but it must always be regarded as a kind of gold paint. As it is highly volatile, and is affected by light, it should be kept in a closely stoppered bottle in a dark place when not in use.