The Boy's Playbook of Science Part 1

The Boy's Playbook of Science.

by John Henry Pepper.

INTRODUCTION.

Although "The South Kensington Museum" now takes the lead, and surpa.s.ses all former scientific inst.i.tutions by its vastly superior collection of models and works of art, there will be doubtless many thousand young people who may remember (it is hoped) with some pleasure the numerous popular lectures, ill.u.s.trated with an abundance of interesting and brilliant experiments, which have been delivered within the walls of the Royal Polytechnic Inst.i.tution during the last twenty years.

On many occasions the author has received from his young friends letters, containing all sorts of inquiries respecting the mode of performing experiments, and it has frequently occurred that even some years after a lecture had been discontinued, the youth, now become the young man, and anxious to impart knowledge to some "home circle" or country scientific inst.i.tution, would write a special letter referring to a particular experiment, and wish to know how it was performed.

The following ill.u.s.trated pages must be regarded as a series of philosophical experiments detailed in such a manner that any young person may perform them with the greatest facility. The author has endeavoured to arrange the manipulations in a methodical, simple, and popular form, and will indeed be rewarded if these experiments should arouse dormant talent in any of the rising generation, and lead them on gradually from the easy reading of the present "Boy's Book," to the study of the complete and perfect philosophical works of Leopold Gmelin, Faraday, Brande, Graham, Turner, and Fownes.

Every boy should ride "a hobby-horse" of some kind; and whilst play, and plenty of it, must be his daily right in holiday time, he ought not to forget that the cultivation of some branch of the useful Arts and Sciences will afford him a delightful and profitable recreation when [Page 2]satiated with mere _play_, or imprisoned by bad weather, or gloomy with the unamused tediousness of a long winter's evening.

The author recollects with pleasure the half-holidays he used to devote to Chemistry, with some other King's College lads, and in spite of terrible pecuniary losses in retorts, bottles, and jars, the most delightful amus.e.m.e.nt was enjoyed by all who attended and a.s.sisted at these juvenile philosophical meetings.

It has been well remarked by a clever author, that bees are _geometricians_. The cells are so constructed as, with the least quant.i.ty of material, to have the largest sized s.p.a.ces and the least possible interstices. The mole is a _meteorologist_. The bird called the nine-killer is an _arithmetician_, also the crow, the wild turkey, and some other birds. The torpedo, the ray, and the electric eel are _electricians_. The nautilus is a _navigator_. He raises and lowers his sails, casts and weighs anchor, and performs nautical feats. Whole tribes of birds are _musicians_. The beaver is an _architect_, _builder_, and _wood-cutter_. He cuts down trees and erects houses and dams. The marmot is a _civil engineer_. He does not only build houses, but constructs aqueducts, and drains to keep them dry. The ant maintains a regular _standing army_. Wasps are _paper manufacturers_. Caterpillars are _silk-spinners_. The squirrel is a _ferryman_. With a chip or a piece of bark for a boat, and his tail for a sail, he crosses a stream.

Dogs, wolves, jackals, and many others, are _hunters_. The black bear and heron are _fishermen_. The ants are _day-labourers_. The monkey is a _rope dancer_. Shall it, then, be said that any boy possessing the G.o.dlike attributes of Mind and Thought with Freewill can only eat, drink, sleep, and play, and is therefore lower in the scale of usefulness than these poor birds, beasts, fishes, and insects? No! no!

Let "Young England" enjoy his manly sports and pastimes, but let him not forget the mental race he has to run with the educated of his own and of other nations; let him nourish the desire for the acquisition of "scientific knowledge," not as a mere school lesson, but as a treasure, a useful ally which may some day help him in a greater or lesser degree to fight "The Battle of Life."

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THE BOY'S PLAYBOOK OF SCIENCE.

CHAPTER I.

THE PROPERTIES OF MATTER--IMPENETRABILITY.

In the present state of our knowledge it seems to be universally agreed, that we cannot properly commence even popular discussions on astronomy, mechanics, and chemistry, or on the imponderables, heat, light, electricity, and magnetism, without a definition of the general term "matter;" which is an expression applied by philosophers to every species of substance capable of occupying s.p.a.ce, and, therefore, to everything which can be seen and felt.

The sun, the moon, the earth, and other planets, rocks, earths, metals, gla.s.s, wool, oils, water, alcohol, air, steam, and hosts of things, both great and small, all solids, liquids and gases, are included under the comprehensive term _matter_. Such a numerous and varied collection of bodies must necessarily have certain qualities, peculiarities, or properties; and hence we come in the first place to consider "The general powers or properties of matter." Thus, if we place a block of wood or stone in any position, we cannot take another substance and put it in the s.p.a.ce filled by the wood or stone, until the latter be removed. Now this is one of the first and most simple of the properties of matter, and is called _impenetrability_, being the property possessed by all solid, liquid, and gaseous bodies, of filling a s.p.a.ce to the exclusion of others until they be removed, and it admits of many amusing ill.u.s.trations, both as regards the proof and modification of the property.

Thus, a block of wood fills a certain s.p.a.ce: how is it (if impenetrable) that we can drive a nail into it? A few experiments will enable us to answer this question.

Into a gla.s.s (as depicted at fig. 1) filled with spirits of wine, a quant.i.ty of cotton wool many times the bulk of the alcohol may (if the experiment is carefully performed) be pushed without causing a drop to overflow the sides of the vessel.

Here we seem to have a direct contradiction of the simple and [Page 4]

indisputable truth, that "two things cannot occupy the same s.p.a.ce at once." But let us proceed with our experiments:--

We have now a flask full of water, and taking some very finely-powdered sugar, it is easy to introduce a notable quant.i.ty of that substance without increasing the bulk of the water; the only precaution necessary, is not to allow the sugar to fall into the flask in a ma.s.s, but to drop it in grain by grain, and very slowly, allowing time for the air-bubbles (which will cling to the particles of sugar) to pa.s.s off, and for the sugar to dissolve. Matter, in the experiments adduced, appears to be penetrable, and the property of impenetrability seems only to be a creation of fancy: reason, however, enables us to say that the latter is not the case.

[Ill.u.s.tration: Fig. 1.]

[Ill.u.s.tration: Fig. 2.]

A nail may certainly be hammered into wood, but the particles are _thrust aside_ to allow it to enter. Cotton wool may be placed in spirits of wine because it is simply greatly extended and bulky matter, which, if compressed, might only occupy the s.p.a.ce of the kernel of a nut, and if this were dropped into a half-pint measure full of alcohol, the increase of bulk would not cause the spirit to [Page 5] overflow.

The cotton-wool experiment is therefore no contradiction of _impenetrability_. The experiment with the sugar is the most troublesome opponent to our term, and obliges us to amend and qualify the original definition, and say, that the ultimate or smallest particles or atoms of bodies only are impenetrable; and we may believe they are not in close contact with each other, because certain bulks of sugar and water occupy more s.p.a.ce separately than when mixed.

[Ill.u.s.tration: Fig. 3.]

If we compare the flask of water to a flask full of marbles, and the sugar to some rape-seed, it will be evident that we may almost pour another flask full of the latter amongst the marbles, because they are not in close contact with each other, but have s.p.a.ces between them; and after pouring in the rape-seed, we might still find room for some fine sand.

The particles of one body may thus enter into the s.p.a.ces left between those of another without increasing its volume; and hence, as has been before stated, "The atoms only of bodies are truly impenetrable."

This spreading, as it were, of matter through matter a.s.sumes a very important function when we come to examine the const.i.tution of the air we breathe, which is chiefly a mechanical mixture of gases: seventy-nine parts by volume or measure of nitrogen gas, twenty-one parts of oxygen gas, and four parts of carbonic acid vapour in every ten thousand parts of air having the following relations as to weight:--

Specific gravity.

Nitrogen 972 Oxygen 1105 Carbonic acid 1524

[Ill.u.s.tration: Fig. 4.]

[Ill.u.s.tration: Fig. 5.

A. The porous cell. B. The jar of hydrogen. C. The bra.s.s cap and gla.s.s tube D, the end of which dips into the tumbler containing the solution of indigo E. F F. The wire and stand supporting the porous cell and tube in tumbler.]

It might be expected that these gases would arrange themselves in our atmosphere in the above order, and if that were the case, we should have the carbonic-acid _gas_ (a most poisonous one) at the bottom, and touching the earth, then the oxygen, and, last of all, the nitrogen; [Page 6] a state of things in which _organized_ life could not exist.

The gases do not, however, separate: indeed, they seem to act as it were like _vacuums_ to one another, and "the diffusion of gases" has become a recognised fact, governed by fixed laws. This fact is curiously ill.u.s.trated, as shown in our cut, by filling a bottle with carbonic acid, and another with hydrogen; and having previously fitted corks to the bottles, perforated so as to admit a tube, place the bottle containing the carbonic acid on the table, then take the other full of hydrogen, keeping the mouth downwards, and fit in the cork and tube: place this finally into the cork of the carbonic-acid bottle, which may be a little larger than the other, in order to make the arrangement stand firmer; and after leaving them for an hour or so, the carbonic acid, which is twenty-two times heavier than the hydrogen, will ascend to the latter, whilst the hydrogen will descend to the carbonic acid.

The presence of the carbonic acid in the hydrogen bottle is easily proved by pouring in a wine-gla.s.sful of clear lime-water, which speedily becomes milky, owing to the production of carbonate of lime; whilst the proof of the hydrogen being present in the carbonic acid is established by absorbing the latter with a little cream of lime--_i.e._, slacked lime mixed to the consistence of cream with some water--and setting fire to the hydrogen that remains, which burns quietly with a yellowish flame if unmixed with air; but if air be admitted to the bottle, the mixture of air and hydrogen inflames rapidly, and with some noise. One of the most elegant modes of showing the diffusion of gases is by taking a large round dry porous cell, such as would be employed in a voltaic battery, and having cemented a bra.s.s cap with a gla.s.s tube attached to its open extremity, it may then be supported by a small tripod of iron [Page 7] wire, and the end of the gla.s.s tube placed in a tumbler containing a small quant.i.ty of water coloured blue with sulphate of indigo. If a tolerably large jar containing hydrogen is now placed over the porous cell, bubbles of gas make their escape at the end of the tube, because the hydrogen diffuses itself more rapidly into the porous cell than the air which it already contains pa.s.ses out. When the jar is removed, the reverse occurs, hydrogen diffuses out of the porous cell, and the blue liquid rises in the tube.

This diffusive force prevents the acc.u.mulation of the various noxious gases on the earth, and spreads them rapidly through the great bulk of the atmosphere surrounding the globe.

Although air and other gases are invisible, they possess the property of impenetrability, as may be easily proved by various experiments. Having opened a pair of common bellows, stop up the nozzle securely, and it is then impossible to shut them; or, fill a bladder with air by blowing into it, and tie a string fast round the neck; you then find that you cannot, without breaking the bladder, press the sides together.

[Ill.u.s.tration: Fig. 6. represents the water overflowing, as the gla.s.s, with the orifice closed, is pressed down, proving the impenetrability of air.]

[Ill.u.s.tration: Fig. 7. The orange has entered the gla.s.s vessel, and the air having pa.s.sed from the orifice, no water overflows.]

It is customary to say that a vessel is empty when we have poured out the water which it contained. Having provided two gla.s.s vessels full of water, place each of them in an empty white pan, to receive the overflow, then lay an orange upon the surface of the water of one of them, and being provided with a cylindrical gla.s.s, open at one end, with a hole in the centre of the closed end, place your finger firmly over the orifice, and endeavour, by inverting the gla.s.s over the orange, and pressing upon the surface of the water, to make it enter the interior of the gla.s.s cylinder; the resistance of the air will now cause the water to overflow into the white pan, whilst the orange will not enter. The [Page 8] orange may now be transferred to the other vessel of water, and on removing the finger from the orifice of the cylindrical gla.s.s, and inverting it as before over the orange, the air will rush out and the orange and water will enter, whilst there will be no overflow as in the preceding experiment. The comparison of the two is very striking, and at once teaches the fact desired.

[Ill.u.s.tration: Fig. 8. Gas-jar with stop-c.o.c.k closed, and pota.s.sium in ladle; air prevents the entrance of the water.]

[Ill.u.s.tration: Fig. 9. Gas-jar; stop-c.o.c.k open; the air pa.s.ses, the water enters, and the pota.s.sium is inflamed.]

Whilst the vessels of water are still in use, another pretty experiment may be made with the metal pota.s.sium. First throw a small piece of the metal on the surface of the water, to show that it takes fire on contact with that fluid; then, having provided a gas-jar, fitted with a cap and stop-c.o.c.k, and a little spoon screwed into the bottom of the stop-c.o.c.k inside the gas-jar, place another piece of pota.s.sium in the little spoon, and, after closing the stop-c.o.c.k, push the jar into one of the vessels of water: as before, the impenetrability of the air prevents the water flowing up to the pota.s.sium; but, on opening the stop-c.o.c.k, the air escapes, the water rushes up, and directly it touches the pota.s.sium, combustion ensues.

Having sufficiently indicated the nature and meaning of impenetrability, we may proceed to discuss experimentally three other marked and special qualities of matter--viz., _inertia_, _gravity_, and _weight_.

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INERTIA, OR Pa.s.sIVENESS.

_Inertia_ is a power which (according to Sir Isaac Newton) is implanted in all matter of resisting any change from a state of rest. It is sometimes called _vis inertiae_, and is that property possessed by all matter, of remaining at rest till set in motion, and _vice versa_; and it expresses, in brief terms, resistance to motion or rest.