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FOR CHILDREN OF ALL AGES.
minutes of anxious
suspense, during OUTLINES OF POPULAR
which, many an impatient eye was ever SCIENCE
and anon directed towards the dial of the clock, the hand of which at last points to three, faintly strikes one, (as all unobtru
sive clocks in lecture theatres are wont to (A SKETCH OF PROFESSOR FARADAY'S LECTURES TO do), and the lecturer walks in. Well, CHILDREN.)
the first thing Professor Faraday does is UNDER this title we mean to present to
to assure his little friends that he is neither our young readers from time to time, going to do or to say anything which they (as frequently, indeed, as an opportunity may not all perfectly understand, -nooccurs,) a working abstract of many lec- thing which they cannot do at home as tures, which, being delivered in the metro. well as here. He bids them to join him polis to a favoured few, have hitherto been in a sort of Christmas game,-he admonlost to the multitude.
We intend to ishes mamma and papa, that long before make this abstract plain as plain can be- he has finished, they will probably say to never using learned words when common themselves—“Dear me, the man is child. words will serve; never taking anything ish.”—Childish ? to be sure, said Professor for granted that has not been told. Never Faraday. I mean to be childish–I try to describing any experiment which a child be childish–I am bound to be childish ; cannot perform.
and why ?-Because I talk to children. Now there is a good deal in the proper Professor Faraday now commenced his beginning of a subject, as everybody lecture by selecting for discussion the knows. The witty Lucian of old said " the theme or proposition -“ WHY DO CERbeginning, indeed, is half of all.” The | TAIN BODIES BURN ?” modern Spanish Proverb says :-“A thing Aye, now -Why do certain bodies burn ? well begun is in a manner finished ;" How very simple does the answer to this proverb, indeed, which in our opinion, question seem. What answer would most overshoots the mark. We do not want to children be likely to give ?-Because of think, and we should not like our young their touching fire, one would say. Stop friends to think, that our outlines just then, let us see. Doesn't a lucifer-match begun—from which we hope to have so burn when you rub it, and without touchmuch pleasure, —which we hope will give | ing fire ? Doesn't the percussion-cap of our young readers so much pleasure, --was a gun explode when you strike it, and already in a manner finished. But to the without touching fire ? It is quite clear point: What can be so fortunate a begin- then, that although certain burnable ning for us as a sketch of Professor Fara- substances will burn when they touch fire, day's Lectures on Chemistry, addressed others will burn without any such contact. especially to children, and now in the I can't tell why substances do burn, course of delivery at the Royal Institu- another child may say, but I can tell when tion ? What can be so lucky a time for the beginning, as the new year ? Let our juvenile readers picture to themselves the Royal Institution lecture theatrewhen the first juvenile lecture of this course began. Let them picture to themselves a large amphitheatre of rising seats -tier after tier upwards extending,—the whole looking down upon the lecturer's table. Let them picture to themselves all the front seats, usually occupied by the greatest philosophers, now exclusively reserved for little boys and girls, each of whom sat half hidden behind note-books, they will not burn. They won't burn almost bigger than the tiny individuals when water is thrown upon them, that's who held them. Let them fancy some very sure.
Indeed? Then just regard Professor I try the experiment-I will scoop out Faraday's first experiment. He takes a the end of a little pointed wire, fixes on to its point a soft, stick so; but much shiny something, very much like silver to deeper, (Fig. 2 ;) and look at, and he brings this something in and in the scoopedcontact with the falling water of a foun- out depression, I tain ; when, strange to behold, a burst of will squeeze the bit flame results, the shining body, which is Fig.2. of potassium ; I will potassium, and the water both take fire. then take the stick and (Fig. 1.)
plunge its armed end down Well, now, is it not quite clear, that through a glass of water, at least one body, will even burn on coming so. (Fig. 3.) into contact with water? At this point
Bravo! I have found out let us pause. Is it not evident, children, one reason at any rate, why bodies burnthat you do not know why it is that cer- they must be in contact with air-for the tain substances, combustibles, burnables potassium now does not burn until it esas I will term them, in themselves, take capes from the hollow stick and floats on fire ?-How are you to know ?—How does the water. the philosopher know ?-How do we all That is quite true, all exclaim; of course know ?-Simply by trying experiments;
it is, how could we be and remember that whatever in chemistry
so stupid. I'll prove it has once occurred, will always, under the
another way, says same circumstances, occur again ; be sure
young gentleman, as of that. Potassium will always burn when
follows. I will take a you touch it with water, as I touched it
short wax taper, light
Fig. 4. just now. Lucifer-matches well made,
it, put it on a table and will always inflame when rubbed under cover it with a tumbler, so. (Fig. 4.) similar circumstances, with equal force. Ah, there it goes ; dim and more dim Percussion - caps will always explode if, burns the flame, and see, now the flame being equally good, they be struck with goes out. Isn't it quite certain that comequal force.
bustible bodies won't burn without air ? This way of getting knowledge by trying “Be very careful of what you consider experiments, and seeing in what they end, proved,” remarked Professor Faraday ; is called the practice of inductive philo- this is the essence of philosophy.” Now sophy-what can be more natural than it may be proved that a candle won't burn such a plan of proceeding? What more without air, but it is not proved from anynatural ? do we not all follow it, almost thing we have as yet seen, that all subunknown to ourselves ; old and young, stances are thus limited; on the contrary. are we not all inductive philosophers ?- I shall now show an experiment which What boy purchases a top without liking will prove that we may get bodies to burn to try beforehand, whether it will spin without air. Into this glass ( pour first or not; or a kite, without liking to see
some water, then whether it will fly ?-or what girl buys a
crystals of a salt, called doll, warranted to speak, without trying
the chlorate of potash-a whether she will speak? However little
substance, which although we know it, then, we are all inductive
soluble in water, is not philosophers. Under what circumstances,
soluble all at once. Upon again to put the question, will a combus
this, I drop some fragtible body burn ?--what is the reason of
ments of phosphorus; then its burning? Let us all be inductive
through a small glass tube, philosophers, and think.
with funnel mouth, I “ I will try one experiment upon that
pour a little oil of vitriol. matter,”—let us fancy an interlocutor to
(Fig. 5.) See what now say; one thing I noticed was, that the potas
takes place,-there is fire sium although touching water, also, when it under water. burned touched the air.-Suppose, then, Nor is it absolutely necessary to take
this trouble to arrive at our conclusion. substance more combustible than a candle. If the firework, called a serpent, be Thus, if into a little tin dish I put a bit ignited and plunged under water, it will of phosphorus, place the dish to float upon still continue to burn. Indeed, this pro- the surface of water, ignite the phosphorus vision is necessary, not only as regards by touching it with a hot wire, and then fireworks for amusement, but as applied invert over it the glass as before, combusto the more terrible applications of war.
tion will proceed, We are none of us warriors here, we are
the phosphorus will philosophers ; yet I shall not hesitate, re
ultimately go out, marked Professor Faraday, to illustrate
and the water will my subject by reference to what is termed
rise to the extent of
Fig. 7. a shell or carcase fuse,-a contrivance
one - fifth, or, in which being thrust into the aperture of a other words, one-fifth of the atmospheric bomb-shell, or a carcase (which is a variety air will have been burned away, leaving of bomb-shell), filled with slow-burning four - fifths behind, totally incapable of materials, ignites with the blast of the supporting combustion. (Fig. 7.) mortar and burns. Now it is necessary, “ It is evident then that for substances that that not only provision be made for the burn in the air, not all the air is capable continuous burning of this carcase of supporting combustion but only a porbomb-shell fuse in air, but also that it tion of it ; and now comes a shall not be extinguished even if it come question, what becomes of that part which into contact with water. Hence when is burned away ? What becomes, for inignited and held under water it does not stance, of that part which the phosphorus go out. (The experimenter may try burned away ? Evidently it did not escape, this experiment with a serpent).
because the glass very carefully kept it in. “We have not only learned by our ex- What, then, became of it ? —Why, in periments,” remarked Professor Faraday, answer to that, you must take my word. I " that certain bodies can burn without air, cannot demonstrate all things, I say, in but we also begin to see certain gleamings the course of a rapid lecture, but must of our general truth. We shall presently ask you to believe me. That portion of see what it is in air that makes things the air which the phosphorus burns away, burn. Because, reflect on this. Even unites with the phosphorus into the solid limiting our remarks to the candle, which form, and constitutes the red-looking solid placed burning under an inverted glass which remains. soon went out, it cannot be correct to 'Here, then, we appear to have some say that the flame went out for want of clue to the mystery. We learn that one air. At the period of extinction of flame portion of the air at least can be solidified there is air left, as can be seen.
-can exist in a solid; therefore, now we limit our remark, then, to the expression may begin to ask ourselves whether some that it went out for want of fresh air. material existing in our compound which
That would be cor- we got to burn under water does not conrect. But let us go tain a portion of air solidified. Whether a little further. Does some material of serpents and carcase the candle, by burn-fuses does not contain the same.
Let us ing, remove any of then proceed to examine this subject. Fig. 6.
the air; and what | You will remember that in my experiment sort of air remains ? Let us see :(Fig. 6.) of getting phosphorus to burn under water,
"If I take the same wax-candle, and I used chlorate of potash—perhaps you ignite it, put it to stand in the middle of know also that nitre, or nitrate of potash, a soup-plate, containing water, invert over is one of the ingredients of gunpowder, and it a glass and allow the whole to stand at consequently of serpents, portfires, carcase rest; the candle after a time goes out, and fuses and so forth. Let us examine these vater runs in the glass,--thus proving that two substances :- First, as regards nitre, one portion of the air has been burned | I am going to try an experiment which I
But the demonstration may be am sure every boy knows. I am going to still better effected by employing some make some touch-paper. Paper is combustible we are all aware,—that is to say, if tirmly bound together with wire ; a comlighted it flames and burns away. If the mon clay flower-pot similarly fitted up, ftame be blown out, the remaining coal answers perfectly well; but as we said soon becomes extinguished; but if I before, the fire - pan will serve for the moisten the paper with a solution of nitre nonce ; presently an air or gas will come in water, and dry it, then ignite it, see over and would fill the bottle if collected; what a remarkable effect takes place. If it is better, however, to allow the first I cause it to burst into flame it burns like portions to escape. any other paper, but if I blow out the flame As soon as the bottle becomes full of then combustion still proceeds; not a flam
slide under its mouth a ing combustion but a combustion in sparks.
fat plate of glass ; reverse If instead of nitre I make a solution of
the bottle and put it to stand chlorate of potash and moisten another
on the table, thus. (Fig. 10.) piece of paper in a similar way, I also
“So it appears,” continued make touch-paper. Is it not evidenta
the lecturer, " that we have therefore that nitre and chlorate of potash
actually succeeded in getting both of them increase the combustibility
from this solid chlorate a gas of paper ?
or air,-for gas only another name for For aught we know from the evidence air. Let us see what sort of air it is, and before us, they may both contain, in the what will it do. Remember we are hunting solid form, that part of the air which for a certain something that shall enable has the power of supporting combustion.” burnable substances to burn. Let us try
And let the reader try it, let him learn by experiment what sort of a gas he has got. Let him take a long slip of wood, and having set fire to one end, let him blow out the flame, so that only a little
ignited charcoal point shall remain. Fig. 8.
Plunge this glowing end into the gas. Now in order to do what Professor Faraday and mark how the stick bursts into flame. did (or something like it,-for we don't How beautiful is this ! how simple is inean to pledge ourselves to be literal all becoming! how clearly do appearances copyists), let our young readers proceed unveil themselves ! From a solid body as follows. Into a retort made of German we have got out an air, a gas, for the glass without lead, or English green terms are the same, and this gas is the glass, but not common English white flint same, the very same, test it as you will, glass, which too easily melts,-put about that forms that part of the atmosphere, a teaspoonful of chlorate of potash ; then and enables bodies to burn. It is the plunge the back of the retort under the very virtue of the air, so to speak, -we mouth of a bottle previously filled with won't give it a name just yet, -the very water, inverted in a wash-basin full of j essence. Chlorate of potash contains water, and tilted up in such a manner, by much of it ; nitre contains an equal means of two bits of brick, or any other quantity ; therefore how easy is it to learn heavy substance, that the back of the the reason why touch-paper burns so well. retort will easily be under the inverted We may now put our knowledge together; mouth of the bottle. Now apply burnable bodies burn, not universally heat to the retort, by means of some because fire is applied to them, for some
lighted charcoal placed burn without, and some, as will be shown upon a fire-pan, or any hereafter, don't burn even then; but they other convenient support, burn when they are heated to a certain we are not particular about extent in contact with a supporter of com. that. Professor Faraday bustion in a convenient form. That is all
used a crucible of black our experiments warrant us in saying at Fig. 9.
lead, perforated with holes; present; by-and-by other points will be (Fig. 9.) supplied with an iron grating , made out. Now don't imagine there is
only one supporter of combustion there of a sort of fern, we repeat, and of this are several, but the most important, the lycopodium mimic lightning may be made. grandest in its effects, the most glorious It burns, therefore,--burns in air, yet under in its action, is what we will at present just those circumstances alone which please call the virtue of atmospheric air. And itself, as we shall see. now one word more. Did we not say that Put a little lycopodium flat upon a bodies before they can burn must be plate, and touch it with a lighted match ; heated to a certain extent ?—and was the the substance will not burn yet. Treat it potassium heated by coming into contact thus : put it into a little sieve tied to the with cold water ? Assuredly it was. That end of a stick, knock the end of the stick point can be demonstrated, and so on for the rest. Friction heats the lucifer-match; percussion heats the gun-cap; in every ease heating in one way or another must be applied.
One thing more must here be remembered. Burnable bodies will not all burn under precisely similar circumstances. Potassium will burn if it touches water, but it won't burn under water. Phosphorus and chlorate mixed, will burn under water
Fig. 11. perfectly well; so will a firework serpent, or a carcase fuse. The wick of a candle with a mallet or hammer, or anything of and its contained oil will burn, but not that kind, so that the lycopodium may fill the surrounding wax or grease, whereas a the air as a cloud. Hold now a lighted piece of camphor (try it) will burn all candle in the cloud, and see what takes
Thus burnable bodies have most place; the whole cloud burns with a vivid of them different burning propensities; fash. Thus do we learn that the lycopoand many which you think won't burn at dium, though perfectly willing to burn, all, will burn perfectly well when their will only burn when the air is mixed with caprices are favoured, as we shall see it in a particular way.
Children, put hereafter. All combustible or burn- | together all these facts. In a future able bodies have their caprices, or fancies, Number we will proceed to learn someso to speak; not only must they be heated thing more about that distilled gas, which, in contact with a supporter of combustion, for the present, shall still be called the but they must be heated under parti- virtue of atmospheric air. cular circumstances. As a special illustration of this fact we cannot do better Desire of APPROBATION.-I am much than conclude this sketch by describing less regardful of the approbation of man, an experiment performed by Professor and set much lighter by contemptor Faraday. The experiment is pretty, in- applause, than I did long ago. I am oft teresting and instructive; moreover, it suspicious that this is not only from the shows the exact way of making lightning increase of self-denial and humility, but as adopted in plays and pantomimes. partly from my being glutted and surfeited Lycopodium may be called a sort of seed with human applause ; and all worldly of a sort of fern. Don't be too severe things appear most vain and unsatisfactory on the Editor, young gentlemen and ladies when we have tried them most. But who know hotany; he is perfectly aware | though I feel that this hath some hand in that lycopodium is not a fern; he is also the effect, yet, as far as I can perceive, aware that neither ferns nor lycopodiums the knowledge of man's nothingness, and have any seeds but spores. He knows all God's transcendent greatness, with whom this just as well as the facts that wheat, it is that I have most to do, and the sense barley, and cats, are not seeds but fruits; of the brevity of human things, and the that strawberries, pine-apples, and figs, nearness of eternity, are the principal are no fruits ; or that cactus plants have causes of this effect; which some have 110 leaves. Lycopodium is a sort of seed imputed to self-conceitedness and morosity.