Glowing splint test
The glowing splint test is a test for oxygen. It involves a thin piece of wood (splint) being lit, with the flame blown out, leaving an ember at the tip. Upon exposure to high concentrations of oxygen, the glowing ember flares and gives a flame.
When the concentration of oxygen increases, the combustion of wood occurs at a higher rate, and the flame becomes more intense, giving the flare.
Oxygen and Hydrogen are hard to distinguish from each other in a voltameter, that is when water is chemically separated into these two elements because of their colorless and clear colour, and odorless smell.
Some people may want pure oxygen for their science tests but not the hydrogen, so they would test for which is oxygen or hydrogen.