Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopœia / by John Attfield.

  • John Attfield
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopœia / by John Attfield. Source: Wellcome Collection.

    71/650 (page 55)
    grooved cork) with fragments of marble, insert a cork and de- livery-tube, and connect the latter with the similar tube of the vessel containing the carbonate of sodium by a piece of india- rubber tubing. N^ow plunge the tube of marble into a test-glass, or other vessel, containing a mixture of one part hydrochloric acid and 2 parts water, and loosen the cork of the carbonate-of- sodium tube until carbonic acid gas, generated in the marble tube, may be considered to fill the whole arrangement; then replace the cork tightly and set the apparatus aside. As the gas is absorbed by the carbonate of sodium, hydrochloric acid rises into the marble tube, generates fresh gas, which, in its turn, drives back the acid liquid, and thus prevents the production of any more gas until further absorption has occurred. When the salt is wholly converted into bicarbonate (JSTaHCOg), it will be found to have become damp through the liberation of water from the crystallized carbonate (I^a^COg, lOH^O). (It would be incon- veniently moist, even semifluid, if a part of the carbonate had not previously been rendered anhydrous.) To purify the resulting bicarbonate from any carbonate or traces of other salts, add half its bulk of cold distilled water, set aside for about half an hour, shaking occasionally, drain the undissolved portion, and dry it by exposure on filtering paper. This is the official process for Sodm Bicarhonas, B. P. The ar- rangement of apparatus is also that adopted in the Pharmacopoeia for Potassce Bicarhonas, one part of carbonate dissolved in two- and-a-half parts of water being subjected to the action of the gas, and not the solid carbonate as in the case of the sodium salt. A crystal of carbonate of sodium is carbonate of sodium plus water; on heating it, more or less of the water is evolved, and anhydrous carbonate of sodium is partially or wholly produced (Sodce Carhonas Exsiccata, B. P.). ]Sra,CO3,10H,O - lOH^O = m,co^ Crystallized carbonate Water. Dried carbonate of sodium. of sodium.