Volume 1

A dictionary of chemistry and the allied branches of other sciences / by Henry Watts. Assisted by eminent contributors.

  • Henry Watts
Date:
1868-1871
Catalogue details

Licence: Public Domain Mark

Credit: A dictionary of chemistry and the allied branches of other sciences / by Henry Watts. Assisted by eminent contributors. Source: Wellcome Collection.

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    acid salt is deposited in needles or laminae, or by slow evaporation in long flattened prisms, apparently belonging to the rhombic system. It is very deliquescent, melts at 148°, and decomposes at 200°, giving off erystallisable acetic acid. On this property is founded an easy method of obtaining the erystallisable acid. Diacetate of potassium is formed when the normal acetate is distilled with butyric or valerianic acid; but neither of these acids decomposes the salt thus produced. Hence, when butyric or valerianic acid is mixed with acetic acid, a separation more or less complete may be effected by half neutralising the liquid with potash, and distilling. If the acetic acid is in excess, diacetate of potassium alone remains behind, the whole of the valerianic or butyric acid passing over, together with the remainder of the acetic acid. If, on the contrary, the other acid is in excess, it passes over, unmixed with acetic acid, and the residue consists of diacetate of potassium mixed with butyrate or valerate. By repeating the process a certain number of times, either on the acid distillate or on the acid separated from the residue by distillation with sulphuric acid, complete separation may be effected. (Liebig, Ann. Ch. Pharm. lxxi. 355.) Anhydrous Diacetate of Potassium, 2C2H302K.CJH603 [ = KO. 2 C'lP O3] is pro- duced by dissolving melted acetate of potassium in acetic anhydride at the boding heat, or by the action of potassium on acetic anhydride. Forms colourless needles very soluble in water, less deliquescent than normal acetate of potassium. It is de- composed by heat, giving off acetic anhydride. (Gerhardt, Ann. Ch. Phys. [3] xxxvii. 317.) Acetate of Silver, C2H302Ag. — Obtained by precipitating nitrate of sdver with acetate of sodium. Crystallises from boiling water in thin, flexible laminae ; soluble in 100 pts. of cold water. Acetate of Sodium, C2H302Na [or CP IP 03.Ka 0.~\ Terra foliata tartari crystal- lisabilis, Terre foliee minerals.—Prepared either by dissolving carbonate of so- dium in acetic acid, or by decomposing acetate of calcium with sulphate of sodium. Forms large transparent prisms belonging to the monoclinic system. Ordinary combination: go P. [go Poo] . OP . —P; more rarely with oo Poo, + P, + 2Poo. Ratio of the axes: a: b : c = 0-8348 : 1 : 0 8407. Angle of the axes = 68° 16'. In- clination of the faces : co P: go P in the plane of the orthodiagonal and principal axis = 95°-30; - P : +P, forming the obtuse edges of the pyramid +Pin the plane of the oblique diagonal and principal axis •= 117°-32; co P: OP = 75°-35. Cleavage parallel to OP and go P. (Gerhardt, Traits i. 725.) The crystals contain 3 at. water. They effloresce slightly in dry air, completely at a moderate heat, and melt below 100°. They dissolve in 3-9 pts. of water at 6°, in 2-4 pts. at 37°, and in 1‘7 pts. at 48° (Osann). According to Berzelius, a solution saturated at the boiling heat, contains 0-48 pts. water to 1 pt. of salt, and boils at 124°-4. The s:dt is less soluble in alcohol. It has a bitter, pungent, but not disagreeable taste. Acetate of Strontium crystallises like the barium-salt in two different forms, con- taining different quantities of water. The salt deposited at 15°, contains 4-23 p. c. water (? 4C2H302Sr + H20), and that which is deposited at low temperatures con- tains C2H302Sr + H20. The latter forms prisms belonging to the monoclinic. system, oo P : co P = 124° 54'; mP . ooPoo = 107° 33'; OP : Poo = 153°T2. Cleavage indistinct, parallel to oo Poo . Acetate of Tin. — Boiling acetic acid dissolves tin slowly, with evolution of hy- drogen ; the hydrated protoxide dissolves easily in the boiling acid, and the solution evaporated to a syrup and covered with alcohol yields small colourless crystals. Hy- drated dioxide of tin also dissolves in acetic acid, and the solution yields a gummy mass when evaporated. Dichloride of tin forms a crystalline compound -with glacial acetic acid. Acetate of Uranium. — Uranous Acetate, obtained by evaporating a solution of oxide in acetic acid, crystallises in green needles grouped in warty masses. Uranic Acetate, or Acetate of Uranyl, C2H302(U20)* [ = C//304. fPO2], is ob- tained by heating uranic nitrate till it begins to evolve oxygen, dissolving the yellow- ish red mass, which still contains nitric acid, in warm concentrated acetic acid, and evaporating to the crystallising point; all the nitric acid then remains in the mother liquid. From a very concentrated, or from an acid solution slightly cooled, the salt separates in beautiful rhomboi’dal prisms, C2II302(U'-’0) + H20, belonging to the mo- noclinic system ; boiling water decomposes them with separation of uranic hydrate, but the solution yields the same crystals by evaporation. A more dilute solution cooled below 10° deposits square-based octahedrons containing C2H302(U20) + § H20, or • Uranyl, U20, Is a monatomic radicle,-supposed to exist in the uranic compounds. (See Uranium.)
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