When oxygen or other gas is to be collected over water, use a milk pan or similarly shaped vessel.
SPIRIT-LAMP
Use an ink-bottle to contain the alcohol and several strands of string for the wick; make a hole in a piece of tin and draw the wick through; then let the tin rest on the neck of the bottle to support the wick.
BAROMETER
A siphon barometer takes less mercury than a cistern barometer. To the open end of the barometer tube attach a piece of strong rubber tubing 4 in. long and to this a piece of glass tubing 3 in. long. Fill the tube thus formed with mercury to within 3 in. from the top. Holding the short glass tube open end up, turn the long tube closed end up. (A tube of 1/8 in. bore needs only one quarter of the mercury required to fill a tube 1/4 in. bore.)
HYGROMETER
For a hygrometer, suspend two dairy thermometers side by side against the wall, cover the bulb of one with thin muslin, and let the muslin hang down and dip into water in some small vessel placed about three inches below the bulb on a little shelf.
HINTS
To avoid explosions, a spirit-lamp should be kept filled.
Toy rubber balloons answer well for sheet rubber.