Test tubes intended for general chemical work are usually made of glass, for its relative resistance to heat.

Their spherical bottom and vertical sides reduce mass loss when pouring, make them easier to wash out, and allow convenient monitoring of the contents.

By tilting the tube, the bottom can be heated to hundreds of degrees in the flame, while the neck remains relatively cool, possibly allowing vapours to condense on its walls.

A test tube filled with water and upturned into a water-filled beaker is often used to capture gases, e.g. in electrolysis demonstrations.

Culture tubes for biology are usually made of clear plastic (such as polystyrene or polypropylene) by injection molding[2] and are often discarded after use.

("light blue") (weak calcium chelator/anticoagulant) Plasma separator gel ("navy") Fluoride Oxalate Grey, Green, Yellow, Purple 1.

A boiling tube is a small cylindrical vessel used to strongly heat substances in the flame of a Bunsen burner.

They are designed to be wide enough to allow substances to boil violently as opposed to a test tube, which is too narrow; a boiling liquid can explode out of the end of test tubes when they are heated, as there is no room for bubbles of gas to escape independently of the surrounding liquid.