Porous Materials Practically everything is porous, but some articles are more so than others. In the case of things which are only slightly porous, it requires tremendous pressure to reveal their porosity and, for ordinary purposes, we might say they are non-porous. A piece of sheet tin, for instance, might come under the heading of non-porous bodies, but a postcard …

Misleading Reflections You can perform quite a number of curious experiments by the agency of reflections. In fact, many of the optical illusions seen on the stage are the result of misleading reflections. Here is one item that will be certain to mystify a good many of your friends. Construct a cardboard box that is a perfect cube. A 6 …

Writing in Fire The following piece of chemical magic is rather interesting. Take a thin sheet of paper, about the size of this page, and draw or write on it a simple design, taking care to note that the lines of the drawing are continuous; that is to say, they must follow on. For ink, use a strong solution of …

Cooling a Candle Flame Take a long length of copper wire, the thicker the better, and wind it loosely around a round ruler. When you have made a spiral coil about an inch and a half long, slip it off the ruler and leave a length of the wire to serve as a handle. Now, light a candle, and hold …

Electrified Mirror A silver-backed hand mirror on a lady’s dressing table looks very unlike an electrical instrument, yet a number of electrical experiments can be made with its help. A friend of the writer once described how he had used one in intercepting a wireless message. Perhaps he will be inducted to tell the story some day, but it is …

Floating Match Take a small enamelled bowl and fill it with water. When all the ripples have died away and there is no movement, gently place a matchstick on the surface, in the centre. An inch from the middle of the match, suspend a lump of sugar so that it is partly submerged. This can be done by running a …

How Air Comes In and Goes Out of a Room This is an experiment which can best be performed on a winter’s evening when your dining-room is nice and warm because the fire has been alight for some hours. Just open the door an inch or more and hold a lighted candle near the opening. First, we want you to …

A Home Made Rainbow Probably you have made rainbows in the garden many a time by playing the hose-pipe on the flowers while the sun was shining. It only requires a little experimenting to get the correct angle for the jet of water, and you have a quite decent rainbow in miniature. But here is a much better way, though …

Comparing The Strength of Different Illuminants It is not at all an easy matter to say that one kind of light is two, three, four, or more times as strong as another. We can make a rough guess and say that this illuminant is more powerful than that; but it is difficult to go further, if depending merely upon the …

A Question of Balance Take a piece of cardboard cut to some very irregular shape and endeavor to balance it on the end of a pencil. You will have to try a good many spots before you find the one that gives you a true balance. Of course, if you are dealing with a square or a circle, it will …