Soluble Crystalline Sodium and Potassium Silicates

Sodium metasilicate nonahydrate Na2SiOj-9HiO (m.p. 47 C) is the only form made chemically pure for use as a standard. For industrial uses, both anhydrous Na SiOj and NajSiOs-SHaO are produced along with other more highly alkaline grades. 

The following anhydrous crystalline forms, obtained from the melt, have a SiO MjO ratio of 1 or higher  

There are numerous hydrates of meta- and disilicates, as listed by Vail (1), but NajSiOj-SHjO (m.p. 72.2 C) is the principal commercial product. 

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