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.

    72/768 (page 60)
    <30 pitate when suddenly exposed to heat, the water of crys- tallization being dissipated in vapour; the salt melts at a red heat, and at a more intense heat is volatilized. When perfectly dry, it consists of one atom of chlorine 36, and one of sodium 24, = 60. Muriate ol Soda, or Chloride of Sodium, is in common use to counteract the process of putrefaction in animal matter, and the theory of its antiseptic operation is not well understood : it is taken universally as a condiment to food, and it is employed in a number of chemical arts. The decomposition of it, so as to obtain its alkaline base, is a process of much importance, as affording a source whence soda can be abundantly procured. It has been attempted on the large scale by the intermedium of oxide of lead, of carbonate of potash, of lime and iron; but the process by which it is at present effected, is to decompose it first by sulphuric acid, obtaining muriatic acid, and then to expose this sulphate of soda, mixed with charcoal, and lime or chalk, to a violent heat for some hours. The sulphuric acid loses part of its oxygen, which passing to the charcoal, forms carbonic acid ; this unites with the soda, and the carbonate of soda is extracted from the mass by solution. Much of the carbonate of soda used by soap-makers and bleachers is now prepared in this manner. Chlorate of Soda is not so easily obtained pure as that of potash, as it is nearly of the same degree of solubility with muriate of soda, and is therefore not easily separated from it by crystallization. It crystallizes in cubes, is deliquescent, and is soluble in 3 parts of water. Flu ate of Soda is less sapid than fluate of potash, is neither deliquescent nor efflorescent, and can be obtained in minute crystals. Hydriodate of Soda is soluble and crystallizable in large flat rhomboidal prisms ; by heat it is converted into