<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> <P> The glowing splint test is a test for an oxidising gas, such as oxygen . In this test, a splint is lit, allowed to burn for a few seconds, then blown out by mouth or by shaking . Whilst the ember at the tip is still glowing hot, the splint is introduced to the gas sample that has been trapped in a vessel . </P>

How to test for the presence of oxygen gas