Signedsticker on tube: RICH. MÜLLER-URI / 2132 / BRAUNSCHWEIG
FunctionThis is a reproduction of a system used to demonstrate how cathode rays striking on different minerals produce a characteristic colored glow in them. As in other Crookes tubes, when a large voltage is applied to the electrodes, electrons fly from the cathode towards the anode. As the platform with its contents stands on their way, many will strike the minerals. Instead of just heating the minerals, which would produce a similar glow in all of them, the striking electrons knock away the minerals' own electrons from their energy levels, and these will emit a characteristic radiation when going back to them. Each mineral has a characteristic spectrum that is easily observable when the system is in operation.