Part 14 (1/2)

Now telldoes it take to burn?

Half a ood And how long does it take to produce that rust-stain, even though it is probably not a hundredth part the size of the paper?

Two or three days, is your reply, for so I told you e difference indeed; but frons of rejoicing or illu These are always in proportion to the quantity of oxygen which is being married at once--and this was--oh, such a slow affair! When the quantity is very small indeed, the festal illuminations are very sether In the same way that you would not be conscious of little bits of thread laid delicately one after another on your back, whereas you would plainly feel a large sheet, were it to fall on your shoulders Yet what is the large sheet but a great quantity of little bits of thread? Only in that case they would all coe illuer and we shall finish

What is there, then, in the paper which pleases the oxygen so e quantities?

What is there? Two substances of high degree, who have actually risen to the dignity of a royal alliance, by the important part they play in the world; one of these, charcoal or _carbon_, we know quite well already; the other I have only mentioned to you in connection ater, HYDROGEN Thanks to gas coen,_ at least by na, I will just tell you that it is by far the lightest body that is known It is forty and a half tih in the ht, as we have seen

The true province of hydrogen is water, where it keeps house with oxygen, in proportion of one to eight pounds, as you may reen_ and _carbon_ are in a manner inseparable friends, whoetable substances In wood, coal, oil, tallow, and spirits of wine; in everything in short that we call _coiven to this en and carbon keep themselves shut up very discreetly and very quietly; like two children playing at hide-and-seek You have sometimes played at hide-and-seek yourself, no doubt? Now, if sohted candle, ould you have done? You would have had to turn out, whether you liked it or not, and be caught Well! this is what happens to our two friends, when you bring the paper to the fire The heat forces theen, which is always at hand, seizes upon the they are s up into the air, which lasts till everything has disappeared

Hydrogen and carbon! These, then, are the two great combustibles, the two parents of fire; and as nature has lavished them upon us in e may call inexhaustible quantities; when you hear people la, that coal is di hoarm themselves, do not disturb yourself in the least

There is en in a bucket of water than is wanted to cook a large dinner There is as much and more carbon in our stone quarries than in our coal pits, and when all the woods in the world are cut dohich I trust will never be!) do you knoe shall do? Why, we shall take to burning the mountains The Jura mountains in Switzerland, for instance, (to take the reatdepends upon knowing how toplace; but that will de done when it is wanted: more difficult en, whether carbon co stone; whether the hydrogen colass of water, is a matter of perfect indifference to hiin, and ly in one case as in the other

So we have returned to the subject of _respiration_, on which I always sees us to it again? And this is the explanation

When the oxygen picked up in the lungs by the blood has traveled with it to the organs, he finds there tell-known friends--hydrogen and carbon

You smile, and exclaim at once, ”Then he marries them, does he?”

Yes, my dear child; and it is only for that purpose he enters our bodies at all And this is why I could not make you understand the nature of respiration until I had explained that of fire to you As I have told you before, it is the sa Invite air into your body by the bellows of your chest, or drive it into the fire by the kitchen bellows--it is always king Oxygen who

LETTER XXII

ANIMAL HEAT

Now, then, we have got hold of the secret of respiration; the _oxygen_ within us unites itself to the _hydrogen_ and _carbon_

And for what purpose, do you suppose?

Unquestionably it ether without doing so

But what do people make fires for? I ask next Well! surely to warm themselves, do they not?

And this is the history of your body being waren in the air foren and carbon of the wood Nature warirls inside, on precisely the saine, then, a little stove, furnished with little ar itself out of the wood-basket as it is wanted, and with little legs to run and refill it when it is e there, and the stove must be alarm

Just such a little stove is your body; yourthe little door, by which there constantly enter--not wood, that would hardly be pleasant--but--hydrogen and carbon under the forood things people have learnt to en and carbon in everything we eat, as I have already told you; but sugar, fat, flour, and _wine_ are the substances which contain thereatest quantities, and consequently they are our best _combustibles_

You are surprised, perhaps, at _wine_ being a combustible; wine, which you think would put out rather than make a fire

And it would But that is only because in it, what is good for burning isable to set it on fire But if part of this water is withdrawn, you have _brandy,_ which lights easily enough; and if part of the re water is withdrawn from the brandy, you have _spirits of wine_, which takes fire more easily still If you have ever seen a _spirit-of-wine_ lae from that what a fire spirits of wine ood deal of water with it; for it is right to tell you that your little stove is very superior to the one in the dining-room, and that it hunts out for consumption the smallest portions of coood deal puzzled to find thereater wonders to tell you yet