Copy 1, Volume 12

Hand-book of chemistry / Translated by Henry Watts.

  • Gmelin, Leopold, 1788-1853
Date:
1848-1872
Catalogue details

Licence: Public Domain Mark

Credit: Hand-book of chemistry / Translated by Henry Watts. Source: Wellcome Collection.

    508/594 (page 478)
    viously purified by passing through oil of vitriol and collected over water. The bottles carefully closed are placed so as to receive the sun’s rays reflected from a wall; and, as soon as the colour of the chlorine is no longer visible, they are opened under a mercury, and pieces of hydrate of potash are introduced together with a few drops of water. The volume of the gas is thereby reduced one-half, and the residual gas which contains the chloride of methyl, together with unaltered marsh-gas and sometimes hydrogen, is agitated with glacial acetic acid (250 grm. to 8 litres of the residual gas), which absorbs the chloride of methyl together with other gases. On subsequently boiling the acetic acid, the greater part of the absorbed gas escapes; and the remaining portion, which may be expelled by saturating the acid with strong soda-ley, exhibits, after being freed from vapour of acetic acid by contact with sticks of potash, the composition and properties of pure chloride of methyl.” 2. Chloride of methyl may be converted into methylic alcohol: a. By dissolving it in acetic acid and heating the solution to 200° with acetate of soda; acetate of methyl] is then formed, from which the alcohol is easily obtained. This method however is not adapted for large quantities. — 6. By heating it with aqueous potash to 100° for a week : C?7H3Cl + KO + HO = C?H40? + KCl. 2 litres of the gas thus treated, yielded 2 grammes of wood-spirit. — c. By treating the chloride with a mixture of oil of vitriol and mercuric- sulphate or sulphate of silver at 100°; methylosulphate of silver is then formed, from which the barium-salt is easily obtained, and from this, methylic alcohol, or benzoate or oxalate of methyl may be obtained. (Berthelot, Compt. rend. 45, 916; Ann. Pharm. 105, 241.) Page 271. Preparation of Formic acid. —Oxalic acid is resolved by heat into carbonic acid, carbonic oxide and water; CfH?08 -='2CO? + 2CO +°2H0. and, as first observed by Gay-Lussac (vil, 269), a small portion of the garbonic oxide unites with water, producing formic acid C*H*?O0*. Now Berthelot has shown that when this decomposition takes place in presence of glycerin, the whole of the carbonic oxide is converted into formic acid. When equal weights of commercial oxalic acid and syrupy glycerin (a kilogramme of each) and from 100 to 200 grammes of water are gently heated (scarcely above 100°) in a capacious retort, a brisk evolution of carbonic acid soon begins, and after 12 or 15 hours, the whole of the oxalic acid is decomposed, half its carbon being given off in the form of carbonic acid, while the remainder produces formic acid in the manner just mentioned. A small quantity of this formic acid distils over with the water, but the larger portion remains in the retort together with the glycerin, and may be separated by distilling the residue with half a