A. Apparatus: A ring stand, a Florence flask, a square of wire net, a chemical thermometer, a Bunsen burner. Method: Place the Florence flask, half full of water, on the square of wire net upon the large ring of the ring stand over the Bunsen burner. Put the chemical thermometer in the Florence flask, clamping it in such a way that the bulb is covered by the water and yet does not touch the bottom of the flask. Make record in the notebook as follows:
(1) The temperature when the first small bubbles appear on the side of the flask.
(2) Temperature when the first large bubbles appear on the bottom.
(3) Temperature when many bubbles rise rapidly to the top.
(4) Point at which temperature ceases to rise.
(5) Temperature when vapor first appears at the mouth of the flask.
(6) What differences are apparent in the amount and motion of the vapor before and after boiling?
(7) Lift the thermometer above the water and note the temperature just above the surface, when the water is rapidly boiling. The small bubbles are bubbles of air. The large are bubbles of steam. A complete study of the boiling process should be made in the Physics class. The boiling point is the point at which water becomes steam, and also the point at which steam condenses again to water. The temperature of boiling water and steam are the same. Under pressure steam may be heated to a higher temperature.
B. Boil water in a small saucepan closely covered.
(1) Note the sounds of the water just before boiling, and the change in sound as the boiling begins.
(2) Note the difference between the vapor escaping, before boiling, and after. This experiment is best performed in a teakettle.
C. Test the temperature of the inner part of the double boiler, when the water boils rapidly below. To be exact, a hole should be bored in the cover of the boiler, a cork with a hole inserted, the thermometer run through the cork. An approximate result is obtained by putting in the thermometer, setting on the cover tilted, and covering the opening with a cloth.
D. Stir salt into rapidly boiling water in the lower part of the double boiler until no more salt will dissolve (a saturated solution). Test the temperature. E. Put the inner part of the double boiler containing water into this boiling solution of saturated salt, being sure that the inner part is sufficiently deep in the salt solution. Note the temperature of the water in the inner boiler when it becomes heated.