Soda-felspar

Nearly all silicates contain some sodium, and there are several silicates which contain relatively large quantities—e.g. soda felspar or albite the soda-lime felspars —e.g. labradorite sodalite nepheline analcime lapis lazuli etc. 

The preparation of sodium carbonate from impure natural soda, and from the ashes of soda plants, has been already described. Methods have also been suggested for transforming various sodium salts—sulphate, chloride, fluoride, cryolite, nitrate, and felspar—into the carbonate. Many of these are discussed in detail by R. von Wagner s Regesten der Soda/abrik (Leipzig, 1866) and by G. Lunge s A Theoretical and Practical Treatise on the Manufacture of Sulphuric Acid and Alkali (London, 1896). Much of what is said of the sodium salts applies also to the potassium salts, and conversely. 

Preparation of Silicate of Potash,—In making silicate of potash, twelve parts of dry carbonate of potash, two parts of sand, and one part of coke or charcoal are mixed gether, and the whole melted and treated as above. In place of sand, groimd felspar may be used, in which case three parts of t is mineral are substituted for two parts of sand, and only one-half the quantity of alkali is used. Sulphate of soda or sulphate of potash may be used instead... 

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