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.

    496/562 (page 472)
    5. Instead of potash, the middle vessel may contain ammonia, soda, or lime-water; the sulphuric acid will still go through. When the alkaline solutions are dilute, sulphuric acid shows itself in the water in five minutes (with a battery of 150 pairs); but through concentrated potash or soda it passes but slowly. Similar effects are produced when nitre or common salt is substituted for sulphate of potash. In the same manner, hydrochloric and nitric’ acids pass through baryta or strontian- water in the middle cup. But if the negative cup contains a soluble sulphate, e.g. sulphate of potash, and the middle one baryta-water, the whole of the sulphuric acid which passes into the latter is precipitated as sulphate of baryta, and no acid appears in the positive cup. When strontian-water is placed in the middle cup, a trace of sulphuric acid appears in the positive cup after three days [probably because sulphate of strontia is somewhat more soluble]. (H. Davy.) 6. Instead of sulphate of potash the positive cup may contain any other salt of potash, soda, lime, or magnesia, and the middle cup may be filled with hydrochloric or nitric acid instead of sulphuric; e.g. nitrate of lime and hydrochloric acid, sulphate of soda and hydrochloric acid, chloride of calcium and sulphuric acid, chloride of magnesium and sulphuric acid ; similarly, salts of baryta or strontia with hydrochloric or nitric acid, The base always goes through the acid in the middle cup to the water in the negative cup; the stronger the acid in the middle cup, the slower is the passage; but with a battery of 150 pairs, decisive results are always ob- tained ir less-than forty-eight hours. If however the base should form an insoluble salt with the acid in the middle cup,—e.g. when a baryta or strontia . salt is contained in the positive cup and sulphuric acid in the middle,—the base never reaches the negative cup.—If the positive cup contains proto- sulphate of iron, the middle hydrochloric acid, and the negative cup water, green hydrate of protoxide of iron appears after ten hours in the asbestus between the middle and negative cup, and in three days a large quantity of hydrate is deposited in the negative cup. Sulphate of copper, nitrate of lead, and chloride of zinc, behave in a similar manner. (H. Davy.) The following experiments were made with a U-tube; the heaviest liquid filled the curved part, the two others the arms. The current of a ten-pair battery was passed through the apparatus for twenty-four hours. It follows from these experiments that, with currents of small tension, liquids do not transmit their constituents very quickly to the electrodes farthest removed from them. (Gm.) Liquids. There is found, in + in the middle. in — in + liquid. in — liquid. N Ht Cl NaCl Na O, S O? || no S O° no NH? Na Cl Ca Cl N H?,N O° || no N O8 (but Cl 05) N H*Cl HO, SO? | 2Na0O, PO5) no P O5 no N H CaO,N O°} NaO,NO® | NH‘Cl no Cl no CaO PbO,NO’| KO,NO® |NH¢Cl Pb O2, no Cl no Pb on — wire CuO,N O°} CaO, NO5 | N HCl no Cl no Cu on — wire AgO,NO*| KO,NO® | KO,SO# || Ag 02, no SO? no Ag on — wire 1. No copper or oxide of copper is deposited on any part of the apparatus. (Gm.) If the positive cup (App. 2) contains nitrate of baryta, the negative cup sulphate of copper, and the asbestus 4 is saturated with solution of common salt, no turbidity is produced in the nitrate of baryta by the action of the current, because the sulphuric acid which is carried in the