<P> 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 . </P> <P> 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). </P> <P> A burning splint can be used to test for a combustible gas . A sample of the gas is trapped in a vessel such as a boiling tube with a stopper . A splint is lit and held near the opening of the tube, then the stopper is removed to expose the splint to the gas . </P> <P> If the gas is flammable, the mixture ignites . This test is most commonly used to identify hydrogen, which ignites with a distinctive' squeaky pop' sound . Hydrogen is easily ignited, as it is flammable over a wide range of concentrations in air, making this test quite robust . If the gas is non-flammable, the burning splint will be extinguished . As many other common gases are not flammable (such as carbon dioxide, nitrogen, and argon, etc .), this test cannot be used to definitively conclude what the gas actually is . Further analytical chemistry techniques can clarify the identity of the gas in question . </P>

What is the test for hydrogen gas called