3887. Tests for Muriatic Acid

3887. Tests for Muriatic Acid. When a glass rod, dipped in liquor of ammonia, is held near it, it gives off white fumes. "With nitrate of silver it gives a white, cloudy precipitate, insoluble in nitric acid, freely soluble in liquor of ammonia, and blackened by exposure to the light.

3888. To Purify Muriatic Acid

3888. To Purify Muriatic Acid. Commercial muriatic acid may be purified by diluting it with an equal weight of water, gently heating it in a retort, and receiving the evolved gas into a fresh quantity of pure water. Iodine and arsenic may be removed by agitating it for a few minutes with some small pieces of bright copper foil previously to rectification.

3889. Acetic Acid

3889. Acetic Acid. This is the well-known acid principle of vinegar. It is one of the common products of fermentation, of the oxygenation of alcohol, and of the destructive distillation of wood and other vegetable matter. The officinal strength of acetic acid adopted by the U. S. Pharmacopoeia has a specific gravity of 1.047. Special methods for testing the strength of acetic acid are given under Acetimetry, No 69. "With bases this acid forms acetates.

Commercial acetic acid is principally manufactured on the large scale from acetate of soda, which yields a sufficiently strong and pure acid for commercial purposes, without the trouble of rectification. In this process, shallow copper vessels formed without rivets or solder in those parts exposed to the action of the acid, are employed for the purpose of the distillation. A coil of drawn copper pipe, heated by steam, having a pressure of 30 to 35 pounds to the inch, traverses the bottom of the apparatus. The refrigeratory consists of well cooled earthenware vessels, and the adopter or pipe connecting the still 'with the receivers is also of the same materials. Stills of earthenware are also frequently employed, and even worms and condensers of silver are sometimes used. The crystalline acetate of soda is placed in the still, and 35 to 36 parts of strong oil of vitriol are added to every 100 parts or the acetate of soda, and the -whole stirred together with a wooden spatula. The head of the still is then luted on and the distillation commenced. This produces an acid of a specific gravity of about 1.050, and, after being agitated with a little animal charcoal, and passed through a prepared muslin filter, is ready for sale. Some manufacturers add a little acetic ether to it. By this process 4 pounds of acetic acid of the strength above mentioned is obtained for every 3 pounds of the acetate of soda employed. (See No. 1741 (To Make Alcohol Vinegar).)

3890. Dilute Acetic Acid

3890.    Dilute Acetic Acid. The U S. Pharmacopaeia directs 1 pint acetic acid to be mixed with 7 pints distilled water, producing an acid of specific gravity 1.00b'; 100 grains of dilute acetic acid saturate 7.6 grains bicarbonate of potassa.