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.

    461/562 (page 437)
    altogether prevented. | When a Daniell’s constant battery, with amalgamated zinc was used, 33°6 parts of zinc were dissolved in each cell of the battery for every 9 parts of water decomposed. (Jacobi.) With batteries containing only one liquid, the loss of zine is greater. When the form of the battery and the nature of the liquid are varied, the following differences are observed,—F. denoting Faraday’s apparatus, with double copper surface (p. 424); Tg. the common trough-battery, with single copper surface; QZ. the surface of the plates in square inches, P Z. the number of pairs; 1 Tr. the number of atoms of zinc dissolved in one trough during the decomposition of one atom of water; and Tot. the number of atoms of ziuc dissolved in all the troughs taken together. In both batteries, the liquid used was a mixture of 200 measures of water, 4°5 of oil of vitriol, and 4 of strong nitric acid. aan eae lot. OZ. CP Zar. Tet AZo PZ. 1 Trios Peeir-3 40 2°25 884 4 20 ari fe 4 10s 6726. 6730 Tg.. 4 40 3:54 141°6 4 20 5°5) «110 4 10 15°95 = 155°0 When different liquids are used in a Faraday’s battery of forty pairs, the quantities of zine dissolved in each cell foroneatom of water decomposed are as follows: With 200 measures of water mixed with 8 of strong nitrie 82 nitric acid, 2°] At.; with 16 measures of strong hydrochloric acid, 3:8; with 9 measures of oil of vitriol, 4:66; with 16 measures of strong hydro- chloric and 6 of nitric acid, 2:11; with 4°5 measures of oil of vitriol and 4 of nitric acid, 2:26; with 9 measures of oil of vitriol and 4 of nitric acid, 2°79; and with 9 measures of oil of vitriol and 8 of nitric acid, 2:26 At. zinc. Nitric acid is therefore the best for this battery; and different degrees of dilution of this acid do not affect, to any considerable extent, the proportion between water decomposed and zine dissolved. (Faraday.) If the current from about four pairs of zinc and copper be made to pass into a solution of nitrate of silver, and the quantity of zinc dissolved be the same one time as another, the quantity of silver separated will likewise be constant,—whether the zinc be quickly dissolved by the use of strong and warm acid, and the galvanometer strongly deflected by the cur- rent—or the zine be slowly dissolved by cold, weak acid, and the galva- the liquid in both cases, though in different times: hence the quantity of silver precipitated is likewise the same. Similar results are obtained with a battery of copper, platinum, and nitric acid.—If a pile a be constructed of lead and platinum plates, and a pile 6 of copper and platinum, the weight of the lead plates being to that of the copper plates in the ratio of the atomic weights of the metals, viz., as 102°8 : 32,—and the currents of both batteries be passed through solution of nitrate of silver contained in separate vessels,—then, when all the copper and lead are dissolved, the quantities of silver separated in the two vessels will be found to be equal. ( Matteucci.) Lies: Since an electrical machine developes much less electricity in a given time than a galvanic battery, even with very small plates, it does not i the machine is employed for this purpose, the two electrodes are connected. with the two coatings of the electrical battery, or one with the conductors and the other with the rubber or the ground. The excessive tension of