Glass

Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle and optically transparent.

The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica (SiO2) plus sodium oxide Na2O from soda ash, lime CaO, and several minor additives. Often, the term glass is used in a restricted sense to refer to this specific use.

In science, however, the term glass is usually defined in a much wider sense, including every solid that possesses a non-crystalline (i.e., amorphous) structure and that exhibits a glass transition when heated towards the liquid state. In this wider sense, glasses can be made of quite different classes of materials: metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications (bottles, eyewear) polymer glasses (acrylic glass, polycarbonate, polyethylene terephthalate) are a lighter alternative to traditional silica glasses.

Read more about Glass:  Silicate Glass, Structure, Glass Versus Supercooled Liquid, Glass Art

Famous quotes containing the word glass:

    When God at first made man,
    Having a glass of blessings standing by,
    “Let us,” said He, “pour on him all we can:
    Let the world’s riches, which dispersed lie,
    Contract into a span.”
    George Herbert (1593–1633)

    We are little airy creatures,
    All of different voice and features:
    One of us in glass is set,
    One of us you’ll find in jet,
    T’other you may see in tin,
    And the fourth a box within;
    If the fifth you should pursue,
    It can never fly from you.
    Jonathan Swift (1667–1745)

    ... this I conceive to be no time to prate of moral influences. Our men’s nerves require their accustomed narcotics and a glass of whiskey is a powerful friend in a sunstroke, and these poor fellows fall senseless on their heavy drills.
    Clara Barton (1821–1912)