Take two small glass jars and close them with corks. In each of these pierce two holes and introduce a glass tube curved in the form of a lengthened V. The two extremities of this tube must not reach further than just a little below the inner surface of the corks. In one jar pour water until it is three-quarters full, and pass through the second hole of the cork a straight glass tube, open at both ends and reaching nearly the bottom. This jar must be hermetically corked. (If necessary, seal the top.) In the other jar put some chalk, and in the second hole of the cork, left free, pass the extremity of a paper funnel in which you place a pellet of wax or putty.

Your apparatus thus being ready, through the funnel pour some vinegar, or better still, some sulphuric acid. The latter ingredient coming in contact with the chalk, forms carbonic acid, which, not being able to escape through the funnel closed by the pellet, passes through the curved tube into the other jar and is dissolved in the water.

After some time a strong pressure will be exercised on the liquid, and the water rising rapidly up through the vertical tube, will spout out as from a fountain.

This experiment may be varied and reduced to a simpler one. Take one jar, fill it up two-thirds with water, and fit it with a cork with two holes, through which pass two tubes; the one going to the bottom, the other resting just over the surface of the liquid. The latter should be fitted with a receiver.

Seal the cork so as to render it air-tight. In the top receiver pour water, which will go down into the jar and raise the level of the water already contained in it.

The air, being compressed, will act upon the liquid mass in the lower jar, and the water will escape through the free tube in a jet with more or less force according to the pressure exercised.