First book in chemistry

Front matter

M

Hi

K

Preface

The idea of this book was suggested by a lady, who is a stranger to me, in a letter, a portion of which I will quote here. " I can not tell you how much pleasure I have had in teaching the Child's Book of Nature to my little daughter. In giving my own opinion of that work I am also expressing the opinion of several other mothers of my acquaintance, who agree with me in pronouncing it the very best book of the kind which we have ever found. It is so plain and simple in its arrangement that any child of common capacity can learn it with ease and remember it well. The subjects upon which it treats are of a kind to interest all children, and the pleasant way in which you bring them forward is sure to awaken their powers of observation and comparison, and, better still, to lead them c through Nature up to Nature's God.' It seems to me that an elementary book on Chemistry, upon the same plan, would be interesting to children, especially if they could have some simple and safe experiments which they might try for themselves,"

Soon after receiving this letter I put the matter to a test in the following manner. I selected a few of those school-rooms in the public schools of New Haven in which the scholars were from eleven to thirteen years of age. I visited these rooms from time to time, talking to the pupils for half an hour on chemistry, without trying any yi PREFACE.

experiments, but illustrating the subject largely from common everyday phenomena. At each visit I questioned them upon what I had told them at the previous visit, and allowed them to ask me questions. In this way I found out what they could understand, and what they wanted to know about chemistry. I was surprised to see how much of this science was within the reach of their capacity, and, at the same time, could be made very interesting to them. During all this time I jotted down my results, and at length put them into the shape in which they now appear, so that the book was almost literally made in the school-room. I may add that nearly the whole has been subjected to the examination of one of the teachers whose rooms I visited, a lady to whom I am indebted for many valuable suggestions.

This book can be readily comprehended by pupils of average capacity of twelve or even eleven years of age, especially if they have gone through with my Child's Book of Nature, which it is intended to follow. At the same time it is fitted for older scholars, to whom the subject of chemistry is entirely new.

I need hardly say that there must be carefulness in experimenting, and that some of the experiments described in this book should be tried only by teachers, or by pupils under their supervision.

This book is to be followed by three other books for the next higher grade of pupils. They are to be under one title, Science for the School and the Family. Part I., Natural Philosophy. Part II., Chemistry. Part III., Mineralogy and Geology.

WOETHINGTON HOOKER.

Contents

CHAPTER PAGE

I. THE CHEMIST 9

IT. OXYGEN 15

Chapter I. The Chemist

What the chemists do. Their discoveries.

IN" this book you are to learn about Chemistry. But what is Chemistry ? you will ask. This I will explain to you in part in this chapter ; but you can not understand fully what it is till you become well acquainted with what this science can show you.

You see represented in the frontispiece a large room with a great many different kinds of vessels, and instruments, and apparatus. There are several persons, chemists, engaged in trying experiments. Their object is to find out of what things different substances are composed, and what effects will be produced when they are mixed together.

The chemists have discovered a vast many things which will surprise you. Each of the substances that you see all about you you are in the habit of thinking of as being one thing. The chalk with which you mark on the blackboard you think of as chalk, and that is all. But the chemist has discovered that chalk is made of three things put together. One of them is a gas as thin as air. In fact, it is a gas that forms a part of the air which you

THE CHEMIST.

Composition of -water.

Experiment.

breathe. Another is carbon, or charcoal. Yes, the dark charcoal makes a part of the white chalk ; but it is not dark now, because it is united with other things. The other thing in chalk is a metal. A gas, charcoal, and a metal, then, all three very unlike each other, make chalk.

Then there is water. Water, simple water, that surely, you will say, must be one thing. People used to think so — old philosophers as well as common people and children. But the chemists found out that it was not so. Water is composed of that same gas that is in the chalk, united with another gas with which they sometimes fill balloons. These two gases are uniting together to form water continually all around you. This is going on in every fire and every light that you see burning. In the flame that you see, whether it be flame of wood, or candle, or gas or burning fluid, these two gases are busy uniting together to

Fig. 1.

form water. You do not see the water, for as fast as it is formed it flies off into the air. It makes a part of the water in the air which is so finely divided up that you can not see it, as I have explained in Chapter XIX. of the Third Part of the Child's Book of Nature. But you can catch this water that is formed in the flame as it flies off, and make it to be seen. There are many ways in which you can do this. Here is one represented in Fig. 1. There are ice and salt in the bowl, the object of which is merely to make the bowl very cold. The bowl is held so far above the candle that the soot will not

Catching water from flame. What it is to decompose.

gather upon it. Now the finely divided and heated water, as it flies up, strikes against the cold bowl, and is condensed upon it. A large drop of water therefore hangs, as you see, from the bottom of the bowl, fairly caught and brought to view. Considerable water can be caught in this way.

You can do the same thing with a silver spoon or a piece of tin, if it be cold. Held over a candle or lamp, dew will gather upon it. You do not catch as much water in this way as with the bowl of ice and salt, because the surface is not so cold, and is smaller. You can not only catch the water that flies off from flame, but Fig. 2. you can shut it up, as you see in Fig. 2. The

candle here is placed under a glass jar, and the water first makes the glass dim, but soon gathers so much as to trickle down its sides. The air outside keeps the glass cool enough to make the experiment succeed. You can try this experiment with any glass jar, but you must remember to put some little bits of wood under the edge, as you see in the figure. If you do not, the candle will soon go out, for reasons that I will explain to you in another chapter, and there will be but little water formed.

The water is composed of two gases. Now when the chemist takes some water and separates one of the gases in it from the other, we say that he decomposes the water. He does just the opposite of what is done in flame, for there the two gases, as I have told you, unite together to form water. So, when he separates the ingredients of chalk from each other, he decomposes the chalk.

Why you can understand Chemistry and be interested in it.

I shall tell you, in other parts of this book, much more particularly about these and a great many other wonderful things.

I suppose that you have thought that you are too young to know any thing about Chemistry, and that none but older and wiser persons can understand about it. But this is not so. There are a vast. many things in Chemistry that you can understand as well as the wisest man on earth. I shall try to select those things only which you can understand and which you will be interested to know, and leave all the rest for you to learn hereafter, when you get farther on in years and knowledge.

Chemistry will be interesting to you because it tells about so many things that you see every day. I suppose that you have been in the habit of thinking that the chemist is engaged in finding out only about things that have hard names, and that you have nothing to do with. But it is far otherwise. Very many things that he can tell you about are the commonest of all things. I have already spoken of chalk and water. The little that I have told you about their composition interests you, and you will be much more interested when I come to tell you more particularly about them. Then there is the air that you breathe — you will like to know about that. The chemist can tell you what part of the air keeps you alive, and how it does it. You will be surprised to learn that some of the air is continually becoming a part of your body, your flesh and bones, and that some of your body is all the time turning into air and flying off all around you. But so it is, as I shall by-and-by show you.

Chemistry will tell you how fires and lights burn. You will find that there is a great deal of chemistry in so common a thing

Common things explained by Chemistry.

as a candle. There is enough to talk about for hours. The most distinguished chemist in England lately delivered six lectures to a young audience in London on the " Chemical History of a Candle," and 'they have been published, making a book of over 200 pages.

Chemistry will tell you what it is that makes bread rise, and how it is that the grain from which it is made is fitted in growing to nourish your body.

It will tell you how wine is made from grapes and other fruits, and explain what that is in the making of cider and beer which is called working. It will explain, too, the making of vinegar.

It will tell you how soaps are made, and explain the way in which Ay operate in cleansing clothes and other things from dirt.

It will tell you about the making of different paints and dyes.

About these and very many other common things Chemistry can tell you a great deal that will interest you, and will be of use to you as you grow up to be men and women. And you can know much about these and other subjects, young as you are, that the wisest chemists did not know fifty years ago, for chemists have discovered many facts that were not known then.

You hear a great deal about the experiments that the chemists try. In this book I shall tell you of many experiments that you can try for yourselves. You can try them with bottles and tubes that you can buy with a very little money, and many of them you can try even with what you can pick up about house at your own homes by exercising a little contrivance.

But you will not need to do even this to be interested in Chem-

Chemical experiments which you try every day.

istry, because there are things happening before you continually that illustrate the subject. There are experiments, as we may say, going on all around you and even within you ; and you have only to look and to think, to get Chemistry out of the commonest things. Every time that you rub a match, or set fire to gas, or a candle, or wood, or strike fire with your heel, you try a chemical experiment. Every time that you draw a breath, you make chemical work for your lungs. Every time that you eat, you set a going in your stomach some of the chemical operations that the chemist in his laboratory sets a going in some of his queerlyshaped glass vessels. And your body is kept warm, as I shall show you in one of the chapters of this book, by a sort of chemical fire in you — a fire without a flame.

Questions, — What do chemists do ? Of how many things is chalk composed ? What are they ? Which of them are solid substances ? Why is not the charcoal dark in the chalk ? What did all people use to think about water ? What have the chemists found out about it ? Tell about the formation of water in flame. Why do you not see the water that is formed? How can you catch the water as it flies off? Tell about catching it with a spoon. Tell about catching it from a candle under a jar. What is decomposition? Why can you expect to understand much about chemistry in studying this book ? Why will chemistry be interesting to you ? What are some of the things that chemistry will show you about air? What is said about the chemistry of a candle? What can the chemist tell you about bread? What other things will Chemistry explain to you ? What is said about experiments ?

Why words are hard. What you have to do with oxygen.

Chapter II. Oxygen

Oxygen. That is a hard word, you will say. Why hard? Simply because it is new, and you do not understand what it means. "V^hen I have told you what oxygen is, and related to you the interesting facts about it, the word will be as easy to you as any other word of the same length of which you know the meaning. The names of many of your acquaintances would be hard words to you if they were not the names of those that you know. Now I expect to make you as well acquainted with oxygen as you are with any of your friends, and then it will be quite as easy a name to you as Joseph, or Caroline, or Elizabeth. There are many words which you use every day that are much longer than oxygen, such as amusement, dissatisfaction, experiment, etc. ; but they are easy to you, because you know what they mean, and you are familiar with them. And so, when you have gone through this book, oxygen and other terms now new to you, and therefore hard, will be easy to you, because you have become familiar with their meaning and use.

Though you are not yet acquainted with oxygen, you have a great deal to do with it. Indeed, you could not have done without it at any moment since you were born. Every time that you draw a breath you take some of it into your lungs, for there is some of it in the air. If what there is of it in the air should be

Oxygen part of your food. Qualities of gases.

taken out of it, you would die as quickly as you would if you were under water.

This oxygen is part of the food, the nourishment of your body. It does not, it is true, go into your stomach, but still it is just as necessary food for your body as the food that you swallow. It is food that goes into the lungs, and the lungs must have it or you will die.

The food that you put into your stomach you can do without for some time. You can live without it even for days ; but the lung-food you must have every minute.

The food that goes into you by your lungs helps to make up the solid part of your bodies — your bones, muscles, skin, etc. But it is not solid when it goes in. It is a gas. There are a great many different kinds of gases or airs. The air that you breathe is a mixture of these gases. The gas that we burn is a very different gas from that we have in the air. If you live in a village, perhaps you never saw gas burning from a gas-burner. But you see gas burning every day when you see a flame of any kind, whether it comes from wood, or coal, or a candle, or a lamp. The oil or tallow is changed into gas before it burns. What we call flame is burning gas. When wood or coal is burned, all except the ashes that are left goes off into the air, and burns as it goes.

Most gases have no color, and you can look through them as you look through glass. You are always looking through gases, for the air, as I have told you, is a mixture of three gases. You can not see the air, and so you can not see any gas that has no color. For example, if a gas-burner be left open without beinglighted, you can not see the gas coming out, although you can

Oxygen the most abundant substance in the world.

smell it. The colorless gases are said then to be perfectly transparent, like clear glass, because objects are seen or appear through them, trails being the Latin for through.

I shall tell you about many different gases in this book, but now I must speak particularly of oxygen.

Oxygen, besides being a part of the air, is a part of almost every thing that you see. It forms a large part of all the water in the world. As I have already told you, it is in your skin, and muscles, and bones, and every part of your bodies, and is the most important part of the blood that runs in your veins and arteries. It is in all animals and all plants. It makes a part of the ground beneath your feet, and even the solid rocks are made in part of oxygen. This gas is the most abundant substance in the world, and so it is more in use than any other substance.

It may seem strange to you that so light and thin a substance as gas is can make a part of any solid, as flesh or bone. But you see every winter a liquid become solid, for ice is solid water. Now this same water, that is sometimes liquid and sometimes solid, is sometimes also as thin as air or gas. There is always some water in the air, even when it seems to be very dry ; and as in the clear air that seems so dry there is no water to be seen, the water must be as thin as the air itself. It is no more strange that oxygen gas can become a part of a solid, than that this water, as thin as gas, can be turned into solid ice.

Oxygen gas can be separated from some of the substances with which it is united, and so can be obtained alone by itself. The chemist commonly uses for this purpose a certain powder. What this powder is I will not tell you now, but shall notice its compo-

B

OXYGEN.

How oxygen is obtained separate from other substances.

sition in another part of this book, when you can understand it better than you can at present. This powder is heated in a glass

Fig. 3.

vessel, called a retort, by a spirit lamp placed underneath, as represented in Fig. 3.

The oxygen, separated from the J powder by the heat, passes over through the neck of the retort, and bubbles up from the beak, as it is called, which you see dips under the water in the large tin vessel. There is over the beak a glass vessel, a common candy -jar, with its open end down. This jar is full of water at first, the water being kept in it by the pressure of the air on the surface of the water around it, as explained in the Child's Book of Nature, Part III., Chapter IV. As the beak of the retort is put under the mouth of the jar, the gas goes up, as you see, in bubbles through the water, because it is lighter than water, and takes its place in the upper part of the jar. In this way the jar may be filled with the oxygen gas. In collecting this gas, the first bubbles must be allowed to escape, and not be caught in the jar, for there is of course air in the retort above the powder, and this is driven out

Pneumatic trough. Simple contrivances.

by the gas as it rises. You do not want to catch the air. You let that go, and catch the gas that comes out after it.

In the large vessel, which is called the pneumatic trough, there is always a shelf on one side, a little under the surface of the water. The jars stand on this shelf. They are filled by having the beak of the retort near the edge of the shelf, and bringing the jar to be filled over the beak. Or there may be an opening in the shelf, through which the beak may discharge the gas into the jar over it. In this way you can fill quite a number of jars with the gas, and have them stand on the shelf ready for use. You see a pipe on the side of the trough. This is to keep the water from rising too high, as it is forced down from the jars by the gas going up into them.

It is vejy easy to take a jar of gas out from the trough when you want to use it for experiments. Your own ingenuity may contrive several ways. One is to slip a plate or a piece of window-glass under the mouth of the jar as you remove it.

In Fig. 4 you see a more simple apparatus for getting oxygen Fig> 4> gas. At a is a glass flask, with a cork in its

I/^X^ mouth. Into this cork is fitted the tube 5,

A \ fil which lets the gas pass into the jar c. The - "g? \ jjjg small trough, you see, has a shelf. You can m .^^dH^M ma ^ e a pneumatic trough of almost any z&y 1 W thing that will hold water, contriving a shelf

of some kind. Indeed, you can make the whole apparatus even more simple than is represented here.*

* Assistance will, of course, be rendered by the teacher to pupils that may wish to try experiments, in arranging apparatus. A little ingenuity can make very com-

OXYGEN.

Burning various substances in oxygen.

There are many beautiful experiments that can be tried with oxygen. I will notice some of them.

Put a lighted candle into a jar of oxygen, as in Fig. 5. It will Fig. 5. burn now with a dazzling brightness, and will be rapidly consumed. The reason is this. It is the oxygen in the air that makes the candle burn at all. Of course, the more oxygen gets to the candle, the brighter will it burn. Now only about one fifth of the air is oxygen, and so the candle will burn five times as fast and as brightly as in common air.

For the same reason, if a lighted piece of charcoal, which, you know, in the air is only of a dull red color for a little while, and then goes out, be placed in a jar of oxygen, it will burn very actively, and throw off sparks all around, as Fig. i.

represented in Fig. 6.

Fig. 6.

There is no substance that makes so brilliant a light on burning in oxygen as phosphorus, Figure 7. A very thick white smoke arises, which is most brilliantly illuminated.

If sulphur be burned in oxygen gas, the smoke has a most beautiful blue color; and the smoke is arranged in a very singular way, as seen in Fig. 8.

mon household things available. Professoi Porter has very prettily shown this in his Chemistry — a phial, a test tube, a bowl, some tobacco-pipes, and a spirit lamp being all that is necessary in some cases. Glass tubes are often very convenient. These can be bent readily into any required shape by heating over a spirit lamp. Holes can be made through corks with a round file, so that the tubes can be passed through them.

Burning of iron in oxygen.

It goes up straight in the middle of the jar, and then falls in curious rings down the sides.

There are some substances which most people think can not burn at all, that will burn very readily in oxj^gen. Iron is one of these. If you take a piece of steel wire, and twist it as you see in Fig. 9, you can make a splendid fire with it in the oxygen. But how will you manage it? You can not set it on fire in the air, and then introduce it into the oxygen, as is done with the phosphorus, charcoal, etc. It is managed in this way. The end of it is dipped in sulphur, or has a bit of something which will burn in common air fastened to it, as cotton or charcoal. You light this substance, and then introduce the wire into the jar of oxygen. The substance on the end of the wire, in burning, sets fire to the wire itself, and now the sparks fly most merrily.

Questions. -*What is said about the word oxygen? How do you have a great deal to do with oxygen ? What would happen to you if you could not get any of it into your lungs ? What is said about oxygen as food ? Give the comparison between stomach-food and lung-food. What does oxygen gas help to make in your body ? What is flame ? Of what is the gas made in a candle or lamp ? What is said about gases being transparent ? What does the word transparent come from ? Mention some of the things in which there is oxygen. What is said about its making a part of solid substances ? Tell about obtaining oxygen gas. Describe the pneumatic trough, and the way in which it is used in collecting gas in jars. Describe the apparatus represented in Fig. 5. Describe and explain the experiment with a lighted candle. Give the experiment with charcoal. How does phosphorus burn in oxygen ? Describe the experiment with sulphur. Describe the experiment with iron.

How nitrogen differs from oxygen. Why nothing can burn in nitrogen.

CHAPTEE in.

NITROGEN.

To every gallon of oxygen in the air there are about four gallons of another gas called nitrogen.

This gas is very different, in some respects, from oxygen. Nothing will burn in it. Suppose that you have two jars, in one of which is oxygen, and in the other nitrogen. If you put a lighted candle into the jar of oxygen, it will, you know, burn brighter than it does in the air. But if you take it out of the oxygen, and put it into the jar of nitrogen, it will go out. Not even phosphorus will burn in nitrogen. So, if all the oxygen should be taken out of the air, every fire and light would go out.

Besides this, no animal can live in nitrogen gas. If you put a mouse into a jar of oxygen he will be more lively than in common air, and will act as if he were crazy, jumping about in the most singular manner; but if you should put him into a jar of nitrogen, he would die at once. And if all the oxygen should be taken out of the air, all animals would die, just as all the fires and lights would be extinguished.

But this nitrogen gas does not really put out fires and lights. A light, when pla^d in a jar of nitrogen, goes out merely because there is no oxygSp It must have oxygen to keep on burning. Only put a little oxygen in with the nitrogen, and the candle will burn ; for it does burn well in a mixture of oxygen and nitrogen,

Why animals can not live in nitrogen. What would happen if the air were all oxygen.

that is, common air, in ^hich there is four times as much nitrogen as oxygen.

So, too, nitrogen does not kill any animal, although he can not live in it. It does not act as a poison when it goes into the lungs ; for there is going into the lungs of all animals, all the time, four times as much nitrogen as oxygen. The mouse dies in the jar of nitrogen simply because nitrogen can not keep him alive, as oxygen does.

Of what use, then, is the nitrogen in the air, as it does not help to make any thing burn, or keep any thing alive? I will tell you.