First outlines of a dictionary of solubilities of chemical substances / by Frank H. Storer.

  • Francis Humphreys Storer
Date:
1864
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Licence: Public Domain Mark

Credit: First outlines of a dictionary of solubilities of chemical substances / by Frank H. Storer. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    It need only be remarked, that I am accustomed to class among phenomena of solubility all those reactions of liquids upon solids or gases, and those combinations of liquids with liquids, — excluding for the present molten metals and other substances in a state of igneous fusion, — in which the chemical force, as understood by Berzelius, for in- stance, is not the principal and as it were overwhelming force in action ; we may have, perhaps, solution depending upon merely physical forces, like adhesion or cohesion, and also upon these forces plus a certain amount of chemical force. It can indeed hardly admit of a doubt that the chemical force is exerted in many cases of solution, while at the same time other forces unquestionably come into play ; in which connection the old adage, that like dissolves like, should be borne in mind. Hence, while the manifestations of chemical affinity proper, as evinced by the combination of bodies in simple and definite proportions, constitute the main subject of chemical text-books, many of the less clearly defined phenomena of chemical science may fairly come within the scope of a treatise on solubilities. Thus, though in the term solubility of a sub- stance, we ordinarily include only the comportment of the substance towards water, alcohol, wood-spirit, ether, oil of turpentine, benzin, and analogous hydrocarbons, and the other neutral solvents, it is obviously sometimes proper to add observations on the action of acids and alkalies ; for example, any account of the solubility of nitrate of baryta would be manifestly incomplete without a statement of the fact that this salt is taken up but sparingly by nitric acid. Again, in the solution of chloride of silver in ammonia-water, and that of various salts, as sulphate of lime, for example, in acids, there are probably at work other forces than the usual solvent power; but until the whole theory of solution is better understood, we must be content to treat of these allied phenomena under the same general head of solubilities. Pains have also been taken to bring forward facts known respecting those cases in which two or more salts acting upon each other in presence of water, or the like, are, to a certain extent, mutually de- composed and dissolved, as in the familiar instance of nitrate of potash and chloride of sodium, which promote each other's solubility ; or that of the reciprocal decomposition which ensues when sulphate of baryta is treated with a solution of an alkaline car- bonate. Any extended discussion of the methods ordinarily employed in determining solubili- ties, and the precautions necessary to insure accuracy, would perhaps hardly be in place in a mere compilation of results like the present work. Directions for making such experiments may be found in several chemical hand-books; — for example, in Frese- nius's System of Instruction in Quantitative Chemical Analysis, or, better, in the origi- nal memoirs of those chemists who have occupied themselves with the experimental determination of solubilities, references to which may be found in the body of this work. It may, nevertheless, be well to remark here, that the text-books do not usually lay suf- ficient stress upon the preparation of the solution of the substance under examination ; and yet this is the single fundamental point of a correct determination, the other steps of the process being altogether subsidiary, and in general easy of execution as well as comparatively free from sources of error. It is commonly stated that an exactly satu- rated solution of a salt may be prepared either by exposing a large excess of the salt to the action of the solvent during several hours at the desired temperature [method by digestion'], or by heating a mixture of the salt and solvent until a strong solution has been obtained at a temperature higher than that at which the determination is to be made, and then cooling this solution to the desired degree, and maintaining it at this point for some time in contact with crystals of the salt, the whole being frequently agi- tated [method of cooling']. Now the latter method, though theoretically correct, is in