To many boys and girls who have acquired at school some knowledge of Science, the mere mention of the words “Scientific Experiments” recalls memories of experiments far from amusing, for the science of the laboratory is more often than not accompanied by some of the innumerable little worries of school life.

When, however, experiments are conducted at leisure in the home, the work assumes a totally different aspect, and much pleasure may be derived from it.

Not only may such experiments become a source of great amusement, but they are of considerable educational value, since it is from the study of the most elementary scientific laws that some of the greatest discoveries of modern science have been made.

The aim of this chapter is, then, to place before you a series of interesting and instructive experiments which may be performed for the amusement of yourselves and friends on occasions when outdoor recreation is impossible.

In selecting these experiments, endeavors have been made wherever possible to mention only home-made apparatus, or such requisites as are easily procurable at very slight cost.

Of what, then, do these amusing experiments consist?

Piercing a Coin with a Needle

The first is one which, at a casual glance, seems impossible to perform.

To pierce a copper coin with a needle, especially if the needle is thin, seems, indeed, a tremendous task. It is, however, very simple.

The apparatus necessary consists of a cork, a needle, and a hammer.

Stick the needle through the cork in such a manner that the point only just protrudes, and, with a pair of pincers, cut off the head of the needle remaining above the cork.

Then, having placed the coin and cork as shown in the diagram, hit the cork vigorously with the hammer (Fig. 1). The needle being unable to bend in any direction owing to the cork keeping it rigid, will pierce the coin quite easily, since we know that the steel of which the needle is composed is harder than the copper of the coin.

A Match Trick

Another very interesting experiment is that performed with an ordinary match, a bottle, and a coin.

Bend in two an ordinary large match, thus partly breaking it, in such a manner that the two parts hold together by a few fibers of wood.

Place it, thus broken, on the neck of a bottle, and then on the match place a dime or any other small coin.

Having done this ask a friend if he can make the coin fall into the bottle without touching the coin, the bottle, or the match. You will find that he will search in vain for a solution to this seemingly impossible task, which however may be overcome in a very simple manner, as may now be seen.

Dip your finger in a glass of water, and placing it above the angle formed by the match, allow one or two drops of the liquid to fall on this angle (Fig. 2).

Immediately the fibers of wood, swollen by the moisture, try to straighten themselves, and you will see the angle of the match increase little by little until the match no longer supports the coin, which then drops into the bottle (Fig. 3).

The Tricolor Glass

Most of us, if not all, know that if wine is carefully poured on water, it floats on the surface, but not every one knows how to place the wine at the bottom of the glass with the water above it, and this without mixing the two liquids. For this experiment make use of the different densities of hot and cold water.

Take an ordinary glass (moistened first with hot water to prevent its cracking) and pour some boiling water into it.

Then by means of a funnel placed almost to the bottom of the glass, pour in some wine which has previously been cooled by ice. By working carefully you will see the wine form in a red layer at the bottom of the glass (Fig. 4).

Now gently remove the funnel, and pour on the surface a bluish liquid lighter than water (for instance, alcohol colored with ink) (Fig. 5).

You will now have a layer of blue on top, thus completing the tricolor glass, which will by the aid of a light project the three colors of the flag on the wall. The tricolor glass may also be used for illumination purposes.

To make it represent fireworks is even more entertaining.

If you allow the water in the glass to cool by placing it in a vessel containing cold water, the wine will rise from the bottom of the glass in the form of thin threads, strongly resembling rockets (Fig. 6).

The different liquids mix, and the descending columns of blue, mixed with the ascending columns of red, produce a curious spectacle like that of fireworks in a glass of water.

Changing Water into Wine

This is not a reproduction of the miracle performed at the wedding feast of Cana, but it is, nevertheless, a most interesting experiment.

Fill two tumblers (A), or wine glasses, of equal diameter, with water, by completely immersing them in a basin of that liquid, standing one upright and the other upside down upon it. When they are both completely full, with not a bubble of air in either, join their rims and remove them from the basin. Now place them upright on a dish, and, if their rims fit accurately upon each other, the water will remain in them. It is now necessary to place on the top of the upper glass a third glass, (B), containing wine, or better still, spirits of wine in which is dissolved a little aniline dye.

Now announce to your friends that without touching any of the glasses, you will, before the eyes of the audience, cause the wine to pass from the glass (B) into the upper (A) glass without a drop entering the lower (A) glass.

In order to perform this amazing experiment take a strip of wool or cotton, moisten it with the liquid contained in the top glass (B), and hang it over the edge of this glass with one end completely immersed in the liquid.

This forms an excellent siphon, for it allows the liquid in the top glass (B) to flow away in drops which fall on and run down the glass underneath until they reach the junction of the rims. Here they are drawn in by capillary attraction, and, the wine being lighter than the water, they rise to the top of the upturned glass (A), displacing the water contained therein by causing it to flow out between the rims, after which it collects in the dish below.

This action will go on until the top glass (B) is empty, when the whole of its contents will find their way into the upturned glass, whilst the lower one (A) remains perfectly clear (Fig. 7).

The Eruption of Vesuvius

Many of us, no doubt, have often tried to picture to ourselves a volcano in eruption, but most will confess that unless we have seen some very good pictures of an actual eruption, we are not at all certain that our self-made picture is correct.

Now to detail an experiment which gives a vivid idea of a volcano in action.

At the bottom of a large glass bowl put a flask containing red wine, or spirits of wine, in which has been dissolved a little aniline (B, Fig. 8). This flask should be closed by a cork pierced with a very narrow hole. By the aid of plaster, or, simpler still, of earth or clay, fashion a mountain around the flask, leaving at the top a hole through which the cork can just be seen. This will form the crater.

Having made your volcano, fill the bowl with water (A, Fig. 8), and you will now witness the eruption.

We know that, owing to the difference in the density of the two liquids, the water will penetrate into the flask, thus displacing the wine, which escapes in a thin red column. As this column nears the surface, it will spread out, thus resembling a cloud of fiery smoke as seen issuing from a volcano.

Care must be taken to shake the water, in order that the streak of color may represent in as realistic a manner as possible the reddish smoke of a volcano disturbed by the wind.

In this way you will provide your friends with an almost exact reproduction of Vesuvius in action (Fig. 9).

A Peculiar Candlestick

Water supporting a lighted candle seems a very peculiar form of candlestick; and yet despite this it will be found quite as serviceable as any other.

To make the candlestick is quite easy. All you have to do is first to weight the end of a piece of candle (previously used) with a nail or piece of metal, in such a manner that, when placed in a vessel of water, the liquid will be flush with the edge of the candle without wetting the wick.

Next light the candle, and announce that, in spite of the unfavorable surroundings, your candle will burn to the end.

This may at first seem extraordinary, but a little reflection will show that your statement is correct, for this experiment is only a striking example of the Law of Archimedes, which states that “when a body is immersed in water, it loses in weight an amount equal to the weight of the water displaced.”

Now, whilst the candle is being consumed it is becoming shorter, but, on account of its diminution in weight, it rises in the water at the same rate at which it is consumed (Fig. 10).

Making a Paper Fish Swim

The title of this experiment suggests something rather wonderful, indeed, for it seems impossible to impart motion to a paper fish.

It may be done, however, and quite easily, as will be seen from the following.

From a piece of ordinary paper cut out a fish like that shown in the diagram, and of the size of an ordinary fish. In the center make a circular hole (A), communicating with the tail by a narrow canal. (A B) (Fig. 11). Having done this, fill an elongated vessel with water, and place the fish on the surface of the liquid in such a manner that the underneath face is completely moistened, while the other remains quite dry.

You are now ready to set the fish in motion; but to add to the interest of the experiment, challenge any of your friends to make the fish move without touching or even blowing upon it.

This may seem to them impossible. This is how it is performed.

With great care pour one large drop of oil into the opening (A); the oil at once tries to spread over the surface of the liquid, but that is only possible if it escapes by the narrow passage (A B).

This it does, and owing to the reaction the fish is thrust in the direction opposite to the flowing of the oil—i.e. it will be thrust forward, the movement lasting long enough for the spectators to view with astonishment the unusual sight of a paper fish swimming (Fig. 12).

Floating Pins and Needles

If a drop of water is placed on glass it will at once spread, but if the same thing is done with a drop of mercury, the liquid will not spread, but remain in the form of a bead.

These two different results are due to the fact, that whilst the water wets the glass the mercury does not.

Now take a pin which has been well dried; it is a body which water will moisten, but owing to its very smooth surface, not so easily as in the case of glass.

Suppose, then, that by some means or other you can place the pin so gently on the surface of the liquid that the water does not make it wet, you will notice that the water takes on either side of the pin a convex shape, and in this way a sufficient volume of water is displaced to allow the pin to float as if it were a match.

The experiment may, of course, be as easily performed with a needle; nor must it be thought it is confined to pins and needles which are thin, for, with care, you may even succeed with big darning-needles.

It has not yet been shown, however, how to place the pin on the water in such a manner that it is not made even wet.

There are several ways of doing this, some requiring considerable practice.

The following is the simplest.

Float on the surface of the water a cigarette paper; place the pin upon it; leave the paper to sink to the bottom when it has become soaked, and the pin will float without any difficulty, for on either side of the pin the water takes the convex shape before mentioned, thus displacing sufficient water to allow the pin to float.

In order to hide from the spectators the stratagem you have employed, gently remove the paper before showing them the floating pin.

Joined by Air

The picture below is not taken from a prospectus advertising cement for joining glass and porcelain, but is simply used to show how atmospheric pressure may be utilized for joining glasses and plates.

In order to accomplish this it is necessary to form a vacuum, but as an air-pump is not at the disposal of every boy a partial vacuum must suffice.

To obtain this partial vacuum suspend a glass from the ceiling, or any other suitable place, by means of a string, and under it burn a piece of paper. This will cause the air it contains to expand. Immediately afterwards place the plate over the mouth of the glass, and it will adhere quite firmly.

In order to prevent the entrance of any external air, and thus destroy the vacuum, the edges of the glass may be smeared with tallow.

Now, how is it that the glass and plate are so easily fixed? Well, directly the hot air contained in the glass comes in contact with the cold surface of the plate, the air contracts, and as the plate prevents the entrance of any more air, a partial vacuum is formed within the glass.

As the atmospheric pressure is much greater than the pressure from within, the plate remains firmly fixed to the glass (Fig. 14).

Glass Raising Extraordinary

This experiment, similar in principle to the last, is quite as striking in its effect.

It consists of raising in air a glass filled with water, by causing it to adhere to the hand when the latter is held quite open.

With the last experiment fresh in our minds, it is not difficult to guess that this phenomenon is due to the existence of a partial vacuum under the hand, but it is not so easy to know how to obtain this vacuum.

The means of carrying out the experiments are as follows:—

Put the glass filled with water on the table, and over the top place the palm of the hand, taking care that the four fingers are bent almost at right angles, as shown in the first of the accompanying figures (Fig. 15).

If, continuing to press the palm of the hand on the edge of the glass, you raise the four fingers quickly, thus having the palm stretched out, you will force out most of the air which is between your palm and the surface of the water, and in this way you will produce under your hand a partial vacuum. This vacuum will be sufficient to allow the atmospheric pressure to overcome the weight of the glass and its contents; thus a sucker is formed which allows the glass to remain attached to the hand (Fig. 16).

Fig. 15.—Glass raising extraordinary.