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.

    509/562 (page 485)
    ELECTROLYSIS: INTERPOSED PLATES, 485 its decomposition, but likewise the resistance arising from the affinity of the electro-positive metal of the second battery for the anions of the liquid. Unless therefore the intensity of one of the currents far exceeds that of the other, little or no electric force appears to result from such combinations. In every case, it is not the quantity but the intensity of the individual currents that determines the result. | When a battery of four pairs of zine and copper in salt water, which by itself produces a deflection of 30°, is oppositely connected with a bat- tery of four zinc and copper pairs in water, which gives a deflection of only 6°, the deflection is reduced to nothing. (Marianini.) [The salt water increases the quantity, but not the intensity of the current; hence the result. | If five zinc and copper pairs A in cells are oppositely connected with five other pairs B, no current shows itself, even though the plates in A are Immersed in spring water six times as deep as those in B. If hydro- chloric acid be then added to the water in A, no current is at first apparent; but after a time, a current is produced and gradually increases till it pro- duces a deflection of 045°, its direction indicating that the pairs in B which are immersed in only a small quantity of water, are more than a match for the pairs in A, although the five pairs A in water acidulated with hydrochloric acid, produce by themselves a deflection of 44°7°, and the five pairs B in spring water, a deflection of only 1:4°. (Fechner.) If two batteries of equal numbers of plates, A zinc and copper, B zine and tin, are oppositely connected—spring water being used in both, A is found to have the advantage: the current even becomes stronger the higher the cells in B are filled with water, a still further increase taking place when hydrochloric acid is added to the water in the cells B, (Fechner.) ['The tension of zinc and copper exceeds that of zinc and tin; the cells B are therefore decomposing cells. | Two series of cups A and B, each consisting of five equal pairs of zinc and copper, are oppositely connected. Ifthe cups in A and B are filled with spring water, a slight deflection is at first produced, but soon ceases. On withdrawing a pair from one series, the needle deviates 20°, but soon returns to 0° [in consequence of polarization ?] if the circuit be kept closed. The number of pairs in A and B being still five, but the water in A being mixed with 1, of oil of vitriol, A shows a prepon- derance of 180°,—but this is soon reduced to nothing if the circuit remain closed. Ifa pair be then withdrawn from apparatus B, and again immersed, a deflection of 50° [from cessation of polarization?| is produced in favour of apparatus A (sometimes no deflection takes place). Even the mere raising and sinking of a pair of plates in B is sufficient to pro- duce this effect, though in a less degree; but the current always ceases after a time, when the circuit is kept closed. If the cells of B contain spring water, and those of A contain water mixed with ;}> oil of vitriol, a deviation of 90° is produced at the moment of closing the circuit, but it is soon reduced to nothing. With 1} or 2 parts of oil of vitriol to 100 of water in A, no deflection is produced. With 2 oil of vitriol in A,a slight deflection is produced in favour of B. If, however, in this experiment the water of the cells B be renewed, a deflection of 90° in favour of A is produced on closing the circuit, but it sinks to 0 after a minute. Like- wise when from 3 to 20 parts of oil of vitriol are mixed with 100 parts of water in A, there is sometimes no current, sometimes a feeble one which soon ceases, the direction being sometimes in favour of the acid cells, sometimes of the water cells.—If the five cells of B contain spring-