When acetate of soda and sulphuric acid are the ingredients employed in the production of acetic acid, sulphate of soda is formed, which, in the large way, the chemist returns to the manufacturer of acetate of soda (_i. e._ to the pyroligneous acid maker), who employs it in the decomposition of fresh acetate or pyrolignite of lime. In this way the same soda-salt is employed over and over again, acting merely as the vehicle for the separation of the crude acetic acid in the solid form, and its easy and cheap transportation from one point to another. This ingenious method of mutual assistance resulting from the application of chemical science to provide for the wants of everyday life, offers some explanation of the extraordinarily low price at which acetic acid may now be purchased. The acetic acid of commerce (pure pyroligneous acid) is almost wholly obtained from the acetates of soda and lime. The principal supply of crude acetate (pyrolignite) of soda is from America, Norway, and Sweden; but much is also obtained from our home manufactories. See ACETIFICATION, ACETIMETRY, FERMENTATION, PYROLIGNEOUS ACID, SODIUM, (Acetate of), VINEGAR, &c. More recently, acetic acid has been obtained by decomposing with hydrochloric acid the double salt of chloride of calcium and acetate of lime, mentioned by Fritzsche (‘Ann. de Poggend,’ xxviii, 123). For this purpose, solutions of acetate of lime and chloride of calcium are mixed and evaporated, the combined salts readily crystallising in large needles. These are freed from the mother-liquor and distilled with common muriatic acid. The acid furnished by this method requires redistillation, and is, moreover, contaminated with some of the fatty products always present in the crude pyrolignite. =Anhydrous Acetic Acid.= _Syn._ ACETIC ANHYDRIDE. Acetic acid deprived of the elements of water. Acetic Acid. Water. Acetic Anhydride. 2C_{2}H_{4}O_{2} - H_{2}O = C_{4}H_{6}O_{3}. =Aromat′ic Acetic Acid.= _Syn._ AROMATIC VINEGAR; A. SPIRIT OF V.; ACIDUM ACE′TICUM AROMAT′ICUM, L.——_Prep._ 1. (Ph. E. 1839.) Dried rosemary and origanum, of each 1 oz.; lavender flowers, 1/2 oz.; bruised cloves, 1/2 dr.; acetic acid (sp. gr. 1·068), 1-1/2 pint; macerate for 7 days, express, and filter. A fragrant and refreshing perfume. Omitted in Ph. E. 1841 and P. B. 1867. 2. (Ph. E. 1817.) As the last, but using distilled vinegar instead of the strong acid of the Pharmacopœia. Inferior. 3. (P. Cod. 1839) Camphor, 2 oz.; oil of lavender, 10 gr.; oil of cinnamon, 20 gr.; oil of cloves, 30 gr.; concentrated acetic acid, 1 pint. Very fragrant and refreshing. 4. (Ph. Bor. 1847; Cod. Med. Hamb. 1845.) Oil of cloves, 1 dr.; oils of lavender and citron, of each 2 scrup.; oils of bergamot and thyme, of each 1 scrup.; oil of cinnamon, 10 drops; strongest acetic acid, 1 oz.; mix. Limpid; yellow-brown; highly fragrant and refreshing. See ACETIC ACID (Camphorated), and VINEGAR (Aromatic).