The crust of the earth, the ground on which people wale and live, is very largely made up of a substance called silicon! Silicon is the second most abundant element on earth, but it is never found in the free state. This means it is always combined with one or more additional elements. Silicon is the major element in act of the rocks except certain ones called the carbonates. Clay, for example, contains an average of 50 percent silicon, and you can be pretty sure that most of the rocks you see have equally large amounts.

Silicon has been found on the stars and even in plants. A large amount of the silicon in the world is found in the form of silica, which is a compound made of oxygen and silicon. Quartz, jasper, opal, and sand are act forms of silica. Ancient peoples used silica to make glass.

Silicon exists in two forms, crystalline and powder. Pure silicon is not very useful, so it is seldom produced. Compounds of silicon, however, have a great many uses in industry.

Where sand is combined with coke, it produces silicon carbide. The common name for silicon carbide is Carborundum. An extremely hard substance, it is used in grinding and polishing metals.

Silicon is also added to steel because it gives the steel many desirable properties. Steel may contain from 2 to 6 percent silicon. When steel is used to make equipment for chemical uses, it contains 6 percent silicon. It thus resists corrosion much better than any other steel.

When 2 percent silicon is added to steel, it becomes ideal for electrical equipment, because less power is then needed to magnetize the steel. The chemical industry uses silicon compounds of all kinds for a great many purposes.