3879. Nitro-Muriatic Acid

3879. Nitro-Muriatic Acid. Aqua regia. This is used in the arts, chiefly as a solvent for gold. By the mutual action of nitric and muriatic acids a compound of chlorine, nitrogen, and oxygen is formed. The best proportions and strength of the acids are variously stated. Colorless nitric acid must be used. Elkington employs 21 parts of nitric acid, specific gravity 1.45; 17 parts of muriatic acid 1.15 specific gravity; and 14 parts of water. This dissolves 5 parts of gold. (See No. 3588 (Elkington's Patent Gilding Liquid).) According to Cooley this acid is prepared by mixing 1 part by measure nitric acid and 2 parts hydrochloric acid. The mixture should be kept in a bottle in a cold and dark place. (See No. 3193 (To Obtain Gold Chemically Pure).)

3880. Dyer's Aqua-Fortis

3880.    Dyer's Aqua-Fortis. Another mixture of nitric and hydrochloric acids, known as Dyer's aqua-fortis, is used by dyers, as it dissolves tin without oxidizing it. Mix 10 pounds colorless nitric acid, specific gravity 1.17, with 1 pound hydrochloric acid 1.19.

3881. Dilute Nitro-Muriatic Acid

3881.     Dilute Nitro-Muriatic Acid. Mix 11/2 troy ounces nitric acid, and 21/2 troy ounces muriatic acid in a pint bottle. Shake occasionally during 24 hours, and add distilled water to make up to 1 pint. Keep in a cool place, protected from the light. (U. S. Ph.)

3882. Muriatic or Hydrochloric Acid

3882.   Muriatic or Hydrochloric Acid. Pure muriatic acid is a colorless invisible gas, having a pungent odor and an acid taste, and fuming on coming into contact with air. It is irrespirable and uninflammable. Its specific gravity is 1.2695. Under a pressure of 40 atmospheres it is liquid. Water at 40° Fahr. absorbs 480 times its volume of this gas, and acquires the specific gravity 1.2109. One cubic inch of water at 69° Fahr. absorbs 418 cubic inches, and the specific gravity becomes 1.1958. The aqueous solution of the gas constitutes the liquid form of the acid. The combinations of muriatic acid with a base are

3883. To Obtain Muriatic Acid

3883.    To Obtain Muriatic Acid. The acid solution in water is thus obtained: Introduce 48 ounces (avoirdupois) dried chloride of sodium into a flask capable of containing an imperial gallon. Pour 44 fluid ounces sulphuric acid slowly into 32 fluid ounces water; and, when cool, add the mixture to the chloride of sodium in the flask. Connect the flask, by corks and a glass tube, with a three-necked wash-bottle, furnished with a safety tube, and containing 4 ounces water, Apply heat to the flask, conduct the disengaged gas through the wash-bottle, and thence, by means of a glass tube, into another bottle containing 50 fluid ounces distilled water, the end of the tube dipping about 1/2 inch below the surface. Continue the process until the product measures 66 fluid ounces, or till the liquid has acquired a specific gravity of 1.16. The bottle must be kept cool during the process.

The muriatic acid of commerce is now chiefly obtained from the manufacturers of carbonate of soda, who procure it as a secondary product. "When, however, it is directly prepared from sea-salt, an iron or stoneware boiler, set in brickwork over an open fire, furnished with a stoneware head, and connected with a series of capacious double-necked stoneware bottles, usually constitutes the distillatory and condensing apparatus.