FAMILY FUN

New Zealand Tablet, Volume XXXVII, Issue 12, 25 March 1909, Page 478

FAMILY FUN

A Hammer Made of Water. — Take a small stoppered flask and fill it three parts full of water. Then, with the stopper out, set it upon the fire in a saucepan of salt water. Salt water boils at 109deg, and % you will thus obtain enough heat to cause the water in the flask to boil. As soon as the escaping vapor has driven out the air, remove it from the saucepan, cork it quickly, and by means of sealing wax prevent the risk of any air re-entering. The vapor of water contained in the flask will condense as it cools down, and thus produce a vacuum sufficient to exemplify the socalled^ water hammer. Gently turn your magic flask upside down and then up-end it -quickly, or else shake it briskly to and - fro. In either event you will observe that the water will strike the side or bottom of the flask as though it were one solid mass, making a noise as though a hammer had struck it. The reason of this is that the water is now no longer divided into isolated drops, as it would be if open to the air, but behaves exactly as .though it were a solid body. Our. apparatus also serves for another experiment. You can succeed in making the water in the flask boil by' simply blowing on it. In order to do this place the bottle in the saucepan cf boiling water once more, this time without taking out the stopper.' Remove it now and allow the ebullition 'io to cease. After a little while apply a lump of ice to the • upper part of the flask, and you will see the water begin to boil again quite furiously, although by this time it may be little more than tepid.