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.

    493/562 (page 469)
    ad ELECTROLYSIS: TWO LIQUIDS. 469 water, is precipitated.] So likewise it was found by Sir H. Davy that when the positive cup (App. 2) contains nitrate of silver, and the nega- tive cup water, metallic silver is deposited along the whole length of the asbestus fibres. 8. Hisinger & Berzelius employed in their experiments the U-tube, the open ends of which were turned downwards and closed with stoppers through which the polar wires passed; the bend of the tube had an opening for the purpose of collecting the gas which arose. But this evo- lution of gas must have caused the liquids to mix. 9. No copper reaches the negative wire, because it is not soluble in water. (Becquerel.) 10. At the beginning, crystals of sulphate of copper and potash are deposited in the negative tube, because potash gets into it: these, however, are destroyed as soon as the nitrate of potash is completely decomposed, and then sulphuric acid collects in the positive tube. (Bec- querel. 11. The heavier copper solution likewise filled a portion of the nega- tive arm; after twenty-four hours action of a twelve-pair battery, not a trace of chlorine was found in the liquid of the positive arm, and but a slight tinge of copper at the negative wire. (Gim.) 12. On the lower surface of the bladder which closes the negative tube containing potash, a deposit of metallic copper is formed, mixed with black oxide and blue hydrated oxide, the latter possibly arising from the ordinary chemical action of the potash on the copper-salt. Similar rela- tions are likewise exhibited by nitrate of lead, subnitrate of mercury, and nitrate of silver, and by the protosulphates of iron and palladium. Sul- phate of magnesia, on the other hand, merely deposits magnesia on the bladder. (Daniell.) 13. In this and the following experiments of Becquerel, the solutions must be very concentrated, otherwise nothing but water will be decom- posed; the battery must also contain from thirty to one hundred pairs of plates. Nota trace of hydrogen is evolved. (Becquerel.) 14. The solution of chloride of glucinum, and that of chloride of zir- conium must be mixed with a small quantity of chloride of iron,—other- wise no glucinum or zirconium will be separated. The first portions of these metals deposited on the negative wire contain iron,—the subsequent portions are pure. (Becquerel.) 15. Sulphuric acid always collected in the positive arm, but the occurrence of ammonia in the negative arm was not constant. When the positive arm and the lower part of the negative arm of the U-tube contain nitrate of lead,—the solution in the negative arm being covered with a layer of cotton an inch high, moistened with solution of nitre, and a portion of the same solution being placed above the cotton,—a large quantity of peroxide of lead is deposited on the positive wire after twenty- four hours action of a small fifty-pair battery, but no lead on the negative wire. (Gm.) Two Liquids in three Divisions, one Liquid in the middle, and the other in the two eatertor Divisions. All the experiments of Davy and Connell, enumerated in the following table, were made with App. 9; De la Rive, on the other hand, formed his three divisions by means of two upright sheets of bladder.