_Prop., &c._ All the neutral acetates, except those of molybdenum and tungsten, are more or less soluble in water, several so much so as to be uncrystallizable; many dissolve in alcohol; they suffer decomposition at a dull red heat, and by distillation, at that temperature, yield acetone and water, or acetone and acetic acid, and leave a carbonaceous residuum; at a full red-heat, those of potassium, sodium, barium, strontium, calcium, and magnesium, are converted into carbonates, whilst the other metallic acetates leave behind the pure metal, or its oxide. The aqueous solutions of the alkaline acetates soon turn mouldy and suffer decomposition. No more of them should, therefore, be dissolved at once than is required for immediate use. _Char., tests, &c._ The acetates are known——1. By evolving fumes of acetic acid, recognisable by its peculiar and characteristic odour, on the addition of strong sulphuric acid:——2. By evolving the vapour of acetic ether (known by its peculiar and agreeable odour) when heated with a mixture of about equal parts of concentrated sulphuric acid and alcohol. =AC′ETATED= (ăs′-). In _chemistry_ and _pharmacy_, combined or impregnated with acetic acid or vinegar. =ACE′TIC.= _Syn._ ACE′TICUS, L.; ACÉTIQUE, Fr. Of or relating to vinegar; made with acetic acid, as perfumes, &c. (See _below_.) =ACETIC ACID.= HC_{2}H_{3}O_{2}. _Syn._ PYROLIG′NEOUS ACID (_pure_); ACID OF VINEGAR; ACIDUM ACE′TICUM, L.; ACIDE ACETIQUE, Fr.; ACIDO ACETICO, It.; ESSIGSÄURE, Ger.; AZYNZUUR, Dut.; EISEL, Sax. When free from water it crystallises on cooling, and is distinguished as——ACETIC HYDRATE, HY′DRATED ACETIC ACID, MONOHY′DRATED A. A., GLA′CIAL A. A., MONOHYDRATED A. A., ACE′TUM GLACIA′LE, ACIDUM ACE′TICUM G., L., &c. the sour principle of vinegar. _Var._ Commercial acetic acid is found under the form of the pure acid of the chemist and pharmaceutist (glacial and dilute), and of vinegar, of which there are several varieties, which are noticed under their respective heads. _Sources._ Fermented liquors; the vinegars of commerce; alcoholic liquors; wood, from which it is obtained, as pyroligneous acid, by distillation; the commercial acetates of soda, potassa, lime, lead, copper, &c. The pure acetic acid of the chemist and of commerce is almost wholly obtained from the acetates, either by the action of a strong acid, which seizes on the base, setting the acid free; or, by dry distillation, in which the high degree of heat employed separates the acetic acid from the base in the form of vapour. It is also obtained by the oxidation of alcohol. _Prep._ The following are the principal processes at present adopted to obtain pure acetic acid:—— 1. From the _Acetates_ in the moist way:—— _a._ From ACETATE OF SODA:——