On a difficulty in isomorphism and in the received constitution of the oxygen-salts, in a letter to Professor Mitscherlich of the University of Berlin / from Thomas Clark.

  • Clark, Thomas
Date:
[1836]
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Licence: Public Domain Mark

Credit: On a difficulty in isomorphism and in the received constitution of the oxygen-salts, in a letter to Professor Mitscherlich of the University of Berlin / from Thomas Clark. Source: Wellcome Collection.

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    Instances. I. AS j II. » • • • A A S III. • • • •« A IV. • •• i A A S3 ] Protosulphate of Tin—of Iron—of Manganese. Persulphate of Mercury—of Copper. Protosulphate of Mercury—of Copper. Persulphate of Tin. Persulphate of Iron—corresponding Sulphate of Manganese—Sulphate of Alumina— of Chrome. These four descriptions of Sulphates contain each one atom of oxide. The first and second contain each one atom of acid ; but—what demands most attention—the third con¬ tains two atoms of acid, and the fourth, three atoms of acid. But, admitting* that each of these four descriptions of Sul¬ phates contains one atom of oxide, and that the first and se¬ cond contain each one atom of acid, analogy would lead us to expect that the third and fourth sorts would also contain one atom of acid in each. Sulphurous acid, on being farther ox¬ idized, so as to become Sulphuric acid, does not, in conse¬ quence of having acquired more Oxygen, combine with more Potash, in order to form a neutral salt, and, indeed, Hyposulphuric aeid, which is undoubtedly more oxidized than the Sulphurous, combines, for the same Sulphur, with only half as much Potash. Chemists, guided, as they may conceive, only by the result of analysis, may, it is true, choose to regard, as a rule of combination, that any oxide, the basis of a salt, requires, for neutral¬ ization, as many atoms of acid, as itself contains of atoms of Oxygen. But we are too apt to regard, as the result of analysis, what is merely our own arbitrary expression of that result. The objection to our admitting, as a law* of Nature, that oxides combine with acids according to such a rule, lies in this—that not only does such a rule imply that oxides, in their combinations, observe a law different from what bodies not oxides observe, but it im¬ plies that one class of oxides observe a rule of combina¬ tion, different from another class of oxides. This will at once appear on considering the following Table, where A and X stand for any two oxidizable metals, and where the combination of the oxides of each metal is represented as taking place, reciprocally in the same number of atoms of each oxide as the other combining oxide contains of atoms
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