hydrofluoric acid

[FLUOR HYDRIC-ACID.] hydro-flû ó-sil-1-cāte, 8. [Pref. hydro- (2); Eng. fluo ( rine ), and silicate.] Chem.: A salt of hydrofluosilicic acid, also called silicofluorides. The salt of pota ium is very insoluble, K SiF6, a gelatinous precipitate, also the barium salt, BaSiF6, a white crystalline precipitate; therefore hydrofluosilicic acid is used as a test for these metals. IMG:content-1378.png:[blocks in formation] Chem.: H SiF6. Silicofluoric acid, obtained by the action of water on fluoride of silicon (q. v.), 3SiF4+2H2O=SiO2+2(H2SiF6). The end of the tube conveying the gas must dip under mercury, or else it will be stopped up by the deposited silica. It is an acid-fuming liquid. It forms salts, called hydro fluosilicates or silicofluorides.