Compressed Air
An interesting and effective experiment may be performed with compressed air. The arrangements are very simple and the requirements few.
Fig. 18.—Walnut shell with necessary holes bored.
Divide a walnut shell into two, and bore a hole in the bottom of each half. In one of the cups thus obtained make another hole half-way up the side, as in [Fig. 18]. Now, with a little sealing-wax fasten three straws into these holes.
In the cork of a fair-sized jar, which should be of some opaque glass, bore two holes, through which the straws must be placed at unequal heights, as shown in [Fig. 19]. Having almost filled the jar with clear water, place the cork with the straws so tightly that no air can possibly enter either at the sides or by any other means than through the straws.
The following strange effect will now be obtained. Pouring some colored liquid into the top shell A, plain clear water will come from the spout C of the lower shell B, and will continue as long as you pour from above ([Fig. 20]).
The reason of this is that the compressed air in the jar forces the clear water through the straw at B, which, being plunged deep into the clear liquid, carries off none of the colored matter passed into the jar by means of A.
Fig. 19.—Showing positions of straws for experiment.
Fig. 20.—Pouring the colored liquid into the top shell.
This experiment may be performed with red wine and water, but the result is not quite so satisfactory on account of the ease with which wine and water mix.