Some gases are hard to distinguish by sight or smell alone. For example, hydrogen, oxygen and nitrogen are all colourless and odourless. Several laboratory experiments are capable of producing relatively pure gas as an end product, and it may be useful to demonstrate the chemical identity of that gas. Burning splints or glowing splints can be used to identify whether a gas is flammable, whether it is oxidising, or whether it is chemically inert.

These tests are not safe for completely unidentified gases, as the energy of their explosion could be beyond the safe confinement of a fragile glass tube. This means that they are really only useful as a demonstration of a gas that is already strongly suspected, and so is known to be safe. In a high school chemistry class, a typical use would be to show the presence of hydrogen (after electrolysis of water, or by reacting a metal with an acid.