Elements of chemistry : including the applications of the science in the arts . rofluoric acid and fluoride of silicon, in solu-tion, were supposed to be in combination by Berzelius, forming 3HF + 2SiF3, whichwas termed by him hydrojluosilicic acid. When this liquid is placed in a mode-rately warm situation, the whole of it gradually evaporates j the free hydrofluoricacid reacting upon the deposited silica, with formation of water, and fluoride of sili-con being revived. The most remarkable property of the fluoride of silicon is to produce, with neutralsalts of potassa, soda and lithia, precip
Elements of chemistry : including the applications of the science in the arts . rofluoric acid and fluoride of silicon, in solu-tion, were supposed to be in combination by Berzelius, forming 3HF + 2SiF3, whichwas termed by him hydrojluosilicic acid. When this liquid is placed in a mode-rately warm situation, the whole of it gradually evaporates j the free hydrofluoricacid reacting upon the deposited silica, with formation of water, and fluoride of sili-con being revived. The most remarkable property of the fluoride of silicon is to produce, with neutralsalts of potassa, soda and lithia, precipitates which are gelatinous, and so transparentas to be scarcely visible at first in the liquid; and with salts of baryta, a white andcrystalline precipitate, which appears in a few seconds. It is often employed todecompose a salt of potassa, for the purpose of isolating its acid. It also serves todistinguish salts of baryta from salts of strontia; the salts of baryta producing withthis acid a salt scarcely soluble in water, while the salts of strontia are not METALLIC ELEMENTS 363 Almost all the basic metallic oxides decompose this acid, when they are employedin excess, separating silica, and giving rise to metallic fluorides. When, on theother hand, no more of the base is applied than the quantity required to neutralizethe free hydrofluoric acid, combinations are obtained with all bases, which are ana-logous to double salts; consisting of a metallic fluoride combined with fluoride ofsilicon, the proportion of the latter containing twice as much fluorine as the formula of one of these compounds, the double fluoride of silicon and potassium,is 2SiF3 + 3KF; and those of other metals are similar. The ratio of 2 to 3, in theequivalents of the two fluorides which form these double salts, is unusual. But thedouble fluorides in question may be represented by single equivalents of fluoride ofsilicon and metallic fluoride, as was suggested by Dr. Clark, by ad
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