Giambattista della Porta observed in 1567 that tartari salis (cream of tartar, potassium hydrogen tartrate) caused powdered crystallum (quartz) to melt at a lower temperature. Soluble silicates of alkali metals (sodium or potassium) were observed by European alchemists already in the 1500s. Those with a higher SiO 2:Na 2O ratio are described as neutral. Grades with ratio below 2.85:1 are termed alkaline. The ratio can vary between 1:2 and 3.75:1. In industry, the various grades of sodium silicate are characterized by their SiO 2:Na 2O weight ratio (which can be converted to molar ratio by multiplication with 1.032). The commercial product, available in water solution or in solid form, is often greenish or blue owing to the presence of iron-containing impurities. The product has a wide variety of uses, including the formulation of cements, passive fire protection, textile and lumber processing, manufacture of refractory ceramics, as adhesives, and in the production of silica gel. Sodium silicate is also the technical and common name for a mixture of such compounds, chiefly the metasilicate, also called waterglass, water glass, or liquid glass. These compounds are generally colorless transparent solids or white powders, and soluble in water in various amounts. Sodium silicate is a generic name for chemical compounds with the formula Naħ. Please consider expanding the lead to provide an accessible overview of all important aspects of the article. This article's lead section may be too short to adequately summarize the key points.
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