A white screen is set-up with a sodium light behind one half of the screen and white light behind the other half. A bunsen burner is placed in front of the sodium lit part of the screen. Using the sodium solution and a dipper from the Burning Salts demo, burn some sodium solution in the flame. A distinct shadow is formed around the flame due to the sodium vapor absorbing the sodium light. Burn some salt with the flame in front of the white light and no shadow is seen.