Copy 1, Volume 1

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.

    472/562 (page 448)
    & 448 ELECTRICITY. ‘consequence of reduction of the gold previously oxidized. (De la Rive, Pogg. 46, 489; and more fully in Pogg. 54, 378.) . To subject a liquid to the action of pci alternating currents, Clarke’s magneto-electric apparatus may be used (or Daniell’s constant battery with a Commutator). To determine the quantity of the current, a Breguet’s thermometer may be interposed in the circuit. The less the current is retarded by the liquid and electrodes, the higher will be the temperature, = T. The liquids experimented upon are: 1 measure of oil of vitriol to 9 measures of water = V, and 1 measure of concentrated nitric acid to 9 measures of water = N. The quantity of mixed hydro- gen and oxygen gases evolved in the constant: interval of five minutes = G. The residue obtained after the successive detonation of all the several quantities of gas = R. The results are as follows: Two platinum wires in N give, at the beginning, 1°5 cub. in. G (in 5 minutes), T = 20°; after 20 minutes, 0°7 cub. in. G (in 5 minutes) ; T = 33°; after 40 minutes, only 0°05 cub. in. G, and soon afterwards, all evolution of gas ceases; T = 35°. The wires become completely covered with black powder, consisting of finely divided platinum. The whole quantity of gas obtained amounts to 7 cubic inches; and after explosion there remains 0°65 cub. in. R, which is a mixture of oxygen and nitrogen: the latter probably arises from air contained in the water,—the former from and hydrogen having been expended in the reduction of the oxide thus formed. Platinum wires in V: In the first 5 minutes, 1:4 cub. in. G; after 40 minutes, 0°5; T= 50°. After explosion, there remains 0°3 cub. in. R, consisting of 0°15 cub. in. of hydrogen gas and 0°15 cub. in. of nitrogen. The excess of hydrogen is due to the oxidation of the platinum. Gold wires in N: In the first 5 minutes, 1°5 cub. in. G; T = 21; after 40 minutes, 0°9 cub. in. G; T = 27°. Whenthe experiment is continued for a longer time, the evolution of gas no longer diminishes, and T no longer increases. R amounts to 0:4 cubic inches, consisting of 0-2 oxygen gas and 0-2 nitrogen; when the experiment is continued, R does not in- crease any further. Gold wires in V: At first, 1:1 cub. in. G; after 40 minutes; almost 0 G; T = 44°; 0°22 cub. in. R consisting of 0:16 hydrogen and 0°06 ni- trogen. Silver wires in V give no perceptible evolution of gas; T = 50°. Copper wires in V evolve gas at intervals, and generally in very small quantity, probably nothing but hydrogen; T varies from 43° to 46°, according as more or less gas is evolved. The wires oxidate slightly, and acquire a pulverulent surface, while a portion of oxide of copper dissolves in the acid. Gold and silver wires likewise acquire pulverulent surfaces. Lead wires in V: In the first five minutes; 0°5 cub. in. hydrogen gas, T varying from 5° to 6°. The liquid is rendered turbid by a white pow- der [sulphate of lead?], with which also the anode becomes covered and consequently isolated; hence the small rise of temperature. Iron wires which evolve 0°35 hydrogen gas from V without the aid of electricity, give in the electrie current 10 cub. in.; T = 33°. | Cadmium wires in V give scarcely any gas without the aid of the current, and no more when placed in the current. Zinc wires give about the same quantity of gas with and without the current.