It is obtained by neutralization ol hydrofluoric acid with sodium carbonate. Colorless or opalescent crystals. With difficulty soluble in 25 parts of water. It is very seldom required in the combination of artificial mineral waters, (for the production of calcium fluoride, etc.), and never kept in solution. Whenever employed, it is generally dissolved for immediate use, or added in its dry state. A solution is prepared by dissolving one part of commercial sodium fluoride in ninety-nine parts of distilled water. One hundred parts represent one part of the salt, and the proportion for the artificial combination of mineral waters is 100 to 1.