SAFE SCIENTIFIC EXPERIMENTS
AMUSING TRICKS WITH SIMPLE APPARATUS
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.
[Illustration: FIG. 1.--Coin piercing extraordinary.]
[Illustration: FIG. 2.--A match trick.]
A MATCH TRICK
Another very interesting experiment is that performed with an ordinary
match, a bottle, and a coin.
[Illustration: FIG. 3.--Coin leaving match and dropping into the
bottle.]
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).
[Illustration: FIG. 4.--The wine at the bottom of the glass.]
[Illustration: FIG. 5.--The tricolor glass.]
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.
[Illustration: FIG. 6.--Water rockets.]
[Illustration: FIG. 7.--Changing water into wine.]
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.
[Illustration: FIG. 8.--The eruption of Vesuvius.]
[Illustration: FIG. 9.--Vesuvius in eruption.]
In this way you will provide your friends with an almost exact
reproduction of Vesuvius in action (Fig. 9).
[Illustration: FIG. 10.--A peculiar candlestick.]
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.
[Illustration: FIG. 11.--The swimming paper fish.]
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.
[Illustration: FIG. 12.--The swimming fish.]
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
[Illustration: FIG. 13.--The floating pin.]
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.
[Illustration: FIG. 14.--Joined by air.]
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).
[Illustration: FIG. 15.--Glass raising extraordinary.]
[Illustration: FIG. 16.--Glass raising extraordinary.]
A NOVEL GLASS EMPTIER
If you are given a glass filled with water, and a bottle equally full,
and then asked to empty the glass by means of the bottle, and that
without emptying the bottle itself, you will imagine you have been set a
very difficult task indeed.
[Illustration: FIG. 17.--The glass-emptying bottle.]
You will soon see, however, that the solution to this seemingly
difficult experiment is quite simple.
First take a cork, and in it pierce two holes. Through these gently push
two straws, one being as long as the glass, the other considerably
longer (Fig. 17).
By means of a pellet of bread or wax close the opening of the shorter
straw, and push the cork into the bottle until the water gushes out of
the longer straw.
In order to empty the glass it is now only necessary to turn the bottle
upside down, in such manner that the little straw touches the bottom of
the glass.
Then, taking a pair of scissors, cut this straw very near the end which
is sealed.
Immediately the water in the glass will flow out by the long straw until
the glass is quite empty, despite the fact that the bottle has remained
full all the time (Fig. 18).
Now for a few words of explanation, in order to make clear the reason
for this unexpected action.
The two straws form the two arms of a siphon, and as they are full of
water it is not necessary to remove any air from them.
[Illustration: FIG. 18.--A novel glass-emptier.]
As the liquid flows out of the long straw, it tends to produce in the
bottle a vacuum. As a vacuum is contrary to nature, it is immediately
destroyed by the entrance of an equal quantity of water from the little
straw, for the atmospheric pressure exerted on the water in the glass
keeps this little straw continually full. In this way all the water is
drawn from the glass by the bottle filled with water.
A STRIKING SIPHON EXPERIMENT
A very pretty experiment with the siphon may be performed by making use
of the following simple apparatus: An ordinary glass; a little water
colored, say with aniline; a piece of rubber tubing about an inch long,
one end of which is cut obliquely, as shown in the diagram; together
with a piece of glass tubing from four to five feet long.
[Illustration: FIG. 19.--A siphon experiment.]
This tubing may be obtained from almost any druggist.
Prepare for your experiment by taking the length of tubing and, with a
gas flame, drawing one end out to a point.
Having done this, bend the tube twice, as shown in Fig. 19, particular
care being taken to avoid any sharp angles. The bending of this tubing
is easily done by holding it in a gas or spirit-lamp flame until the
flame is colored yellow. The glass is then soft enough to be gently bent
to the required angle.
Over the end which is not pointed slip the piece of india-rubber tubing,
and then place this end in the colored water.
By applying suction to the pointed end of the tube with your mouth, the
siphon may be set in motion.
If now you so arrange the tube that the oval opening is partly out of
water, the flowing liquid will draw in bubbles of air which, passing
alternately down the tube with the drops of colored water, produce a
very pretty result.
The shape and size of the air bubbles may be altered at any time by
raising or lowering the tube, and this will add to the effect of the
experiment.
The experiment may be again varied by removing the tube from the liquid,
and before lowering it again, allowing 10 or 12 inches of air to enter.
This long bubble will be seen to pass slowly down the tube until it
arrives at the small opening, when it will be expelled at a great rate.
The liquid following this bubble acquires the same velocity, and,
arriving at the point, is ejected with such force that it will rise to a
height of 6 or 7 feet.
AN ELECTRIC FOUNTAIN
Most of you would like to make an electric fountain, especially when you
learn how simple and easily arranged is this striking experiment. Your
apparatus consists solely of a glass, a long india-rubber tube, with two
small glass tubes and a piece of sealing-wax (a stick of sulphur or
piece of vulcanite will do just as well).
Make a small nozzle by drawing out a length of bent glass tubing, and,
by means of a long piece of india-rubber piping, fix it to another piece
of bent glass tubing. Place the first piece of tubing bent at two right
angles over the side of a glass filled with water, taking care that the
reservoir thus formed is from 3 to 4 feet above the nozzle (Fig. 20).
When the fountain is playing the issuing jet of water will be inclined
to one side.
Now to electrify the fountain. Take the piece of sealing-wax, vulcanite,
or sulphur, and, after seeing that both your hand and the material you
hold are perfectly dry, rub the sealing-wax on the sleeve of your coat.
[Illustration: FIG. 20.--An electric fountain.]
If now you hold the sealing-wax opposite the stream of water, at a
distance of a few feet, a remarkable change will come over the cascades.
Instead of the water falling in scattering drops, these latter will at
once unite, and descend in a solid stream, whilst directly the
sealing-wax is removed the jet of water returns to its original form. If
the water be allowed to fall on a piece of stiff paper, a difference in
sound will be noticed according as the water falls in a stream or in
drops.
THE BOTTLE CANNON
Doubtless you would like to have at home the experience of firing a
cannon, of hearing a report loud enough to frighten nervous persons, to
see the shell fly as quick as lightning, and then to witness the recoil
of your home-made piece of artillery.
Your apparatus will be quite simple, for you must first take a strong
bottle, such as a vinegar, or better still, a champagne bottle, and fill
it a third full with water.
Next take a little carbonate of soda, and also some tartaric acid, both
of which may be obtained at any druggist’s, taking care to wrap them in
packets which will not be confused one with the other.
Dissolve the carbonate of soda in the water contained in the bottle, at
the same time placing the tartaric acid in a playing card rolled in the
form of a cylinder, one end of which should be filled with a plug of
blotting-paper.
[Illustration: FIG. 21.--The bottle cannon.]
Having accomplished this much to your satisfaction, suspend the
cartridge just made from the cork of the bottle by sticking in it a pin
to which is attached a thread, particular care being taken that the
bottle is standing upright on the table, and that the open end of the
tube is the upper one.
After having regulated the length of the thread so that the bottom of
the tube does not touch the liquid in the bottle, tightly fit the cork
in.
You now have your cannon charged, and all that remains to be done is to
fire it.
This is done by laying the bottle horizontally on two pencils placed
parallel to one another, thus forming a gun-carriage. Immediately the
bottle is so placed, the water penetrates the tube, and dissolves the
tartaric acid. The carbonic acid gas which is immediately produced blows
out the cork with a violent explosion, whilst at the same time, owing to
the reaction, the bottle rolls back on the two pencils, in exact
imitation of the recoil of a piece of artillery (Fig. 21).