Technically, glass is an amorphous solid, existing in a state of imbalance. Devitrification occurs when the glass molecules begin to order themselves into a crystalline structure, causing the glass to become more brittle and develop a cloudy-white appearance. For more information on devitrification, click here.
Pyrex is actually a trade name for Corning borosilicate glass, but is commonly used synonymously to refer to any borosilicate glass. Borosilicate is a silicate glass with boron in it. It has a very low coefficient of expansion compared to other glass. Quartz glass is a highly pure silicate glass with a coefficient of expansion even lower than borosilicate glass and an even higher melting point.
Borosilicate glass has a melting point around 820oC (1,508oF) and is annealed around 550oC (1,022oF). Quartz glass begins to melt around 1,665oC (3,029oF) and is usually annealed around 1,140oC (2,084oF).
Small scientific glass tubes include pipettes, test tubes, and capillary tubes.
Pipettes
- Used to move small amounts of liquids, such as when adding a drop of chemical to a microscope slide
- Can be used to deliver liquids drop-wise or to measure and deliver precise volumes
Test tubes
- Small glass cylinders used to hold, mix, or heat small amounts of chemicals
- Can have round, flat, or conical bottoms
- Culture tubes are a type of test tube used in microbiology labs to grow organisms
Capillary tubes
- Used to determine packed cell volume
- Can be used with or without an anticoagulant to prevent blood from clotting