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.

    147/768 (page 135)
    powerful than that of the other in a high state of oxida- tion. Metallic oxides, either in high or low states of oxida- tion, unite with acids as the metals do with oxygen, in a few certain and definite proportions. Their nomencla- ture is constructed on the same principle as that of the oxides, the salt which contains the protoxide of a metal has the term proto, and that which contains the peroxide the term per prefixed to it; thus we have protosulphate and persulphate of iron. The salt of a deutoxide may, in like manner, be called a deuto salt, but this term is scarcely ever required. Frequently, also, salts are distinguished by their colour; thus, we speak of the green and brown sulphates of iron. The metallic salts, like the other orders of compound salts, may exist with various proportions of their consti- tuent principles. When these are united in one propor- tion, the state of neutralization is established ; but besides this, combinations may be formed in which there is an ex- cess of acid, or an excess of oxide. In the former case, the Latin preposition super is prefixed, in the latter, the preposition sub is employed. As it sometimes happens, that in the salt containing the larger proportion of acid the quantity of that ingredient is exactly double of what ex- ists in the sub salt, the term bi is often used instead of super and sub: this is less frequently the case, however, than in alkaline and earthy salts. When, instead of two equivalents, as in bi-salts, there are two equivalents of base, Dr Thomson proposes to use the Greek syllable dis or di instead of sub; the latter, however, is the term commonly used. What are called sesqui salts, or those composed of an atom and a half of acid to an atom of base, are less unfrequent among metallic than among al- kaline and earthy salts. To reconcile them with the doc-