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.

    119/768 (page 107)
    expelling the carbonic acid. With the hydrates ^f po- tash or soda, it even explodes at a temperature much be- low redness, hydrogen being disengaged, and the silica produced uniting with the alkali. Heated with nitrate of potash, no action happens till the heat decomposes the acid, and liberates the potash. In these respects Silicium differs strikingly from the bases of the alkalis and other earths. Its other proper- ties are equally anomalous. Thus, all these bases are ei- ther metallic or approach very closely in characters to metals ; but silicium has not the slightest metallic lustre, and is a non-conductor of electricity. In these characters is is conceived to resemble some of the inflammables, and to bear indeed a greater analogy to carbon and boron than to perhaps any other substances. Accordingly, it has been considered by Sir H. Davy and Dr Thomson, rather as an inflammable than a metal; and its oxide, silica, having little or no tendency to unite with acids, while it has considerable affinity to various salifiable bases, has been regarded as an acid, and its compounds have been termed Silicates. For this opinion there appears to be little foundation. The mere fact of a substance uniting with alkalis and earths, which is the only title that a number of substances at present termed acids have to that character, is no decisive proof of acidity, as the alkalis and earths enter into union with each other, and with metallic oxides, and might hence be themselves denominated acids. Silica, moreover, in its inertness, insolubility and other properties, is closely connected with the other earths; and with regard to its base, if the substance which has been described be really its base, which from its singular cha- racters is in some measure doubtful, it matters little whe- ther it be placed among the inflammables or metals, as it has little analogy to either of them. The atomic weight