Glass is made of a mixture of different silicates. Ordinary glass, also known as soda glass, is a mixture of sodium silicate, calcium silicate, and excess silicon dioxide. It is usually made by the eutectic of sand, sodium carbonate, and calcium carbonate; it can also be made by fusion of sodium sulfate and carbon instead of sodium carbonate.
Some other glasses, such as potassium glass, is a kind of glass that is more resistant to high temperature, harder, and more chemically resistant. It can be made by partially replacing sodium salt with potassium carbonate or potassium sulfate when melting glass. It is mainly used for manufacturing experiments. Chemical containers are commonly used in the laboratory. Flint glass is a kind of high-density and high-refractive-index glass. It can be made by replacing the calcium in soda glass with lead when melting glass. It is suitable for manufacturing optical glass and engraving glass products. Extra-hard glass has a small thermal expansion coefficient, is resistant to sudden cold and heat, is resistant to high temperature and chemical corrosion. It can reduce the sodium content and maintain the high content of silicon dioxide when melting the glass, and add 12% to 15% of trioxide. It is made from diboron and is mainly used to make higher-level chemical reaction vessels.
A small amount of glass colorant is added when melting glass, and various colored glasses can be produced. Copper oxide (Ⅱ) or chromium oxide (Ⅲ) produces green; cobalt oxide (Ⅱ) produces blue; manganese dioxide produces purple; tin dioxide or calcium fluoride produces milky white; uranium compounds produce yellow-green fluorescence; colloidal selenium produces Ruby color; colloidal gold produces red, red-violet or blue; cuprous oxide produces red, green or blue; ferrous compounds produce green, black when the amount is large; iron (Ⅲ) compounds produce yellow. When making glass, because the raw material contains impurities of ferrous iron, the glass is often greenish. A small amount of manganese dioxide or selenium can be added to make it colorless glass.