Manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

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    which is completely volatilized when the temperature is increased, the only basic substances which can be present are ammonia, mercury, arsenic, and antimony. If the residue is not volatile, or at least not completely so, other substances besides these must be present. In both cases it is requisite to perform the next experiment. 541. 2nd. The solution is examined by well-prepared test-papers, as to its neutrality, &c. Each of the three cases which may occur, and the conclusions to which they lead, are considered in the paragraphs 542, 543, and 544. 542. The solution is neutral. A large number of sub- stances must therefore be absent, because the neutral salts of the greater proportion of the metals possess an acid reaction. The only salts which are neutral to test-papers are the salts of silver and manganese, and some of the salts of the alkalies and alkaline earths. The alkalies, alkaline earths, silver, and manganese are the only basic substances, therefore, which can be present; but to distinguish still further, add to a portion of the solution carbonate of soda. If no precipitate ensue, the alkaline earths and the oxides of silver and manganese must be absent; but should a precipitate be formed, all these substances may be pre- sent. 543. The solution is acid. The acidity may proceed’ from the presence of a free acid, an acid salt, or a neutral salt having an acid reaction. To ascertain to which of these causes the acidity is due, place the end of a glass rod moistened with a solution of carbonate of soda, into a por- tion of the fluid in a watch-glass. If the solution becomes turbid and remains so, it is due to the presence of a neutral salt; if it becomes clear again, the reaction is due either to an acid galt or a free acid. Carbonates and sulphides can- not be present in an acid solution.