"Remove the paper blotters from the clear plastic chamber. Leave the black cardboard base in the chamber. Soak the blotters in alcohol then return them to the chamber. The blotters must be adjusted so the hole in the side of the chamber is not blocked but the gap between blotters must also be as small as possible. The viewing will be better soon and last longer, if alcohol is also poured on the black cardboard to the extent that it will be absorbed and not form a "lake." Cover the chamber with its lid and warm in the hands for a minute or so. The point is to allow the alcohol to vaporize well, displacing water vapor.
Carefully remove the stopper containing the alpha and beta particle sources form its container and insert the stopper into the hole in the side of the chamber. Position the tip of the source near the center of the chamber and as close to the bottom of the chamber as possible.
Place the chamber on a Styrofoam pad and make observations. Alternatively, place a slab of dry ice in the bottom of a shallow Styrofoam or cardboard tray to cut down on room air currents.
Darken the room and shine light in the side of the chamber. The needle tip should be close to the base of the chamber."
Quoted from the Science Source: www.thesciencesource.com