When sand is fused with sodium or. potassium carbonate, a reaction occurs forming a silicate of these metals, SiO2+Na2Co3=Na2SiO2 (sodium silicate) + Co2. The silicates of sodium and potassium are commonly known as water-glass, and are soluble in water, whereas silicates of other metals are generally insoluble. When a mixture of fluor-spar and any silicious substance, as sand, is heated in a retort with H2So4, the resulting gas being distilled over through mercury into water, which holds it in solution, and which is then filtered to remove the free silicon which precipitates, the result is hydro-fluosilicic acid.

Medical Properties And Therapeutic Uses

Sodium silico-fluo-ride, in the form of a white powder, is antiseptic, disinfectant and styptic. Experiments with this salt by Mr. Wm. Thomson, F. B. F. C, F. C. S., show that the compounds of fluorine were powerful disinfectants, and of these the sodium silico-fluo-ride was the most serviceable. It has been employed as a substitute for peroxide of hydrogen on account of the changeable nature of the latter agent. Even in a saturated solution, sodium silico-fluoride is not an escharotic coagulant, but it is a slight irritant in such a form, which is not a positive disadvantage in the treatment of some affections, such as alveolar pyorrhoea for example.

Dental Uses

Sodium silico-fluoride has been used with good results in cases of putrescent pulps, chronic alveolar abscesses, pyorrhoea alveolaris. Also as a deodorizer in pulp canals by destroying the putrescent hydrogen. As a disinfectant, it is powerful enough, even in weak solution to antagonize, in a marked degree, the germs of putrefaction; as a coagulant, it is non-escha-rotic; as a deodorant, it is strong enough to destroy the most penetrating of putrefactive odors; as a stimulant, it is powerful enough in full solution to bring about the formation of new tissue, and not act as an irritant to surrounding tissue; it is comparatively unchangeable. Such properties may render it one of the most useful salts in the dental pharmacopoeia.