Elements of chemistry, in two volumes / by John Murray.

  • Murray, John.
Date:
1828
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry, in two volumes / by John Murray. Source: Wellcome Collection.

    66/768 (page 54)
    to ail* or water, the sodium by absorption of oxygen be- ing converted into soda. Soda is usually obtained from the combustion of marine vegetables, of which different species afford it in different quantities and states of purity. The various kinds of fiici or sea-weed afford in this country the impure alkaline product, known by the name of Kelp; on the shores of the Mediterranean, the salsola, salicornia, and others, af- ford the purer Barilla. Even it contains much foreign matter : the soda is combined with the carbonic acid, and with this are associated muriate and sulphate of soda, a small portion of hydriodate of potash or soda, charcoal, lime, magnesia, silica and alumina. The origin of the soda afforded by the process is not altogether determined, but it is most probable that it is ultimately derived from the muriate of soda with which these plants are from their situation supplied; as when they are transplanted to an inland situation, it is established by the experiments of Du Hamel and Cadet, that the quantity they afford di- minishes progressively, and after some years they afford only potash. Vauquelin’s experiments prove, that in the salsola soda, carbonate as well as muriate of soda exists previous to the combustion. It is usually from barilla that soda is procured. The barilla in powder being lixiviated with boiling water, the solution on evaporation affords crystals of carbonate of soda. To remove the acid, the same process is employ- ed as in procuring potash. The salt is dissolved in twice its weight of water, and filtered through slaked lime. The lime abstracts the carbonic acid, its affinity to it be- ing aided by the large quantity of it used, and the slow- ness with which the solution passes through it. Still the soda has a small quantity of carbonic acid combined with it: to obtain it pure, therefore, it requires, like potash, to