a crystalline compound, NaF, soluble in water and very slightly soluble in ethanol; cubic... It occurs naturally as villiaumite and may be prepared by the reaction of sodium hydroxide or of a sodium carbonate with hydrogen fluoride. The reaction of sodium fluoride with concentrated sulphuric acid may be used a a source of hydrogen fluoride. The compound is used in ceramic enamels and as a preservative agent for fermentation. It is highly toxic ...