  Produced by Al Haines. [image] "How far off you can see at these front windows!" said Sue.—Page PROFESSOR JOHNNY BY JAK AUTHOR OF "BIRCHWOOD," "FITCH CLUB," "RIVERSIDE MUSEUM" [image] logo NEW YORK COPYRIGHT, 1887, RAND AVERY COMPANY, CONTENTS. CHAPTER
PROFESSOR JOHNNY. CHAPTER I. AN ACCIDENTAL EXPERIMENT. Johnny had been named The Professor by some of his young friends, because he wore spectacles, was fond of studying natural philosophy and chemistry, and of performing experiments. He had become so used to the name that he did not mind it much, even when some of the rude boys in the street called him Professor or Prof. His merry little sister Sue, also, was quite as apt to call him Prof. as Johnny. One evening in June, Johnny and Sue were at home alone. Their father and mother were making calls; and Kate, the girl, had gone out marketing. It was not very uncommon for them to be in the house alone; for although Sue was rather wild and thoughtless, Johnny was very quiet and thoughtful, and Sue had been taught to mind him when her parents were away. Johnny had been reading, and Sue amusing herself by undressing her doll and putting it to bed; but after the doll was in bed, and supposedly sound asleep, she could not think of any thing else to do by herself, and so began to tease Johnny to put up his book and play with her. Johnny was so much interested in his book that he paid but little attention to her at first, merely replying that he would play by and by. But finally Sue took hold of his book playfully, saying,— "I mean to take away your book, for you have read long enough: mamma would say so herself if she were here." Johnny laughed. "That's a very handy excuse for you: whenever you want me to play, you have a sudden anxiety about my eyes." "But you know it's just what papa and mamma say, that you read too much, and they ask you to stop reading a good deal oftener than I do. I'm sure, if they had been here, you would have had to put up that book half an hour ago." "I shouldn't wonder if you were right about that. Well, what shall we do? Shall we play checkers?" "Oh, no! don't let's play any thing still: let's romp a little." "Romp!" exclaimed Johnny, making up a comical face. "You know I hate romping. Let us play a game of chess." "No: you always beat me at those games, and so it isn't any fun; but I can beat you at romping, and so I like it. Besides, papa and mamma say it is better for you to exercise more, and they like to have you romp with me." "I should think you were setting up for a doctress, if I didn't know you better. You are the greatest girl to get up excuses for whatever you want to do. But I suppose there'll be no peace until I romp." Johnny put down his book with a sigh and a smile. Sue said, "Come, let's play tag. Catch me if you can!" and ran off into the dining-room. As the gas was only lighted in the front hall and in the sitting-room, it was pretty dark in the dining-room; but this suited Sue all the better: she ran around the table, with Johnny after her; and, as she hit now and then against the table, the dishes rattled ominously. She was laughing uproariously all the time, and evidently thought of nothing but the sport of dodging Johnny, at all risks. "This won't do," said Johnny, coming to a stand-still, as Sue, in trying to escape him as he turned suddenly in the direction in which she was running, knocked over a pitcher near the end of the table: "we shall be sure to break something before long, at this rate." "Let's go into the kitchen, then," replied Sue: "there isn't any fire in the stove, and we can't hurt any thing there. It'll be real nice and dark too: I'll bet I can hide where you can't find me." "All right," said Johnny; and Sue danced into the kitchen, and hid behind the door. Johnny cornered her at once, however; for it happened to be lighter there than in the dining-room. "Why, this is real queer!" exclaimed Sue, in a half vexed tone, as Johnny pulled her from her hiding-place: "it isn't dark here a single mite!" "So it isn't," replied Johnny. "I wonder what makes it so light! The light comes in at the window. There must be a lamp in the shed, or out on the platform." Johnny opened the door and went out. Sue followed him. The "platform" extended some little distance from the back-door, and was covered by a roof: it might have been called a piazza or a porch but for its width. At the side of the "platform" was what Johnny called the "shed:" it had been intended only for storage of wood and coal, but was so large that a small summer kitchen had been partitioned off next to the kitchen, with a door into the kitchen, and another opening upon the platform. This kitchen was used in warm weather for baking, washing, and ironing, in order to keep the heat out of the house. Kate had been ironing that afternoon, and the fire in the stove had not gone out. As soon as they were outside the door, Sue set up a cry of alarm. "Fire! Fire!" she cried. "The house is on fire! O Johnny, let's run off! we shall get burned up!" Johnny stood quite still, and said nothing. "O Johnny! come! come! what makes you stand there? It's going to explode! It'll reach over here, and set the house on fire! Let's run out into the street, and call some one to come! What makes you stand there, and not call out? You'll let the house burn up! But I shan't go and let you be burned up: you've got to come too!" She took hold of his jacket, and pulled with all her might; for she thought Johnny was too frightened to stir. "Keep still, Sue: I'm thinking," he replied, looking calmly and fixedly at the alarming light in the shed-window. "I can't get at it through this door very well: I guess I'll go around through the kitchen-door." "You ain't going near it?" cried Sue, in astonishment and alarm. "Of course I am: I can't put it out without going near it." "You sha'n't do it! There! It's getting worse than ever! O Johnny, come in!—It's going to explode this minute!" Johnny came in, but it was not on account of Sue's direction: he had just thought what to do. The danger proceeded from a kerosene-lamp which stood in the summer kitchen, on a table, near the window facing the platform. It was streaming up very high, and blazing in a very remarkable and peculiar manner, as if on the point of instant explosion: the flashing and flickering were what had lighted up the kitchen so strangely. On entering the kitchen, Johnny seized a piece of carpet which was in front of the sink, and ran with it toward the inner door of the shed. "You sha'n't go in there, Johnny!" cried Sue. "You're going to kill yourself, and me, too, 'cause I sha'n't run away and leave you;" and she began to cry bitterly. But Johnny hurried on into the shed, and Sue dared not follow him: she was only just brave enough not to run out of the house, and leave him there to die or be horribly burned alone. Just then Kate returned. As she stepped upon the platform, and saw the alarming spectacle, she screamed wildly, "Fire! help! help!" Just at that moment, too, a boy in the neighborhood, who had heard Sue's cries, came rushing into the yard. Hearing Kate's outcry, and seeing the blaze in the shed, he rushed into the street, shouting "Fire!" at the top of his voice, and telling everybody he met that the back part of Mr. Le Bras' house was all in a blaze. The first man who heard the news gave the signal at the alarm-box at the corner. But before Kate or Sue could scream again, Johnny had darted through the inner door, and thrown the rug over the lamp. "O Johnny! Johnny! run! run! it'll explode now, sure!" cried Kate wildly, thinking the carpet would send the blaze down into the lamp instantly. But all was in darkness. "Johnny! Oh! where is he?" screamed Sue, almost fancying he must have died with the blaze somehow. "Sure, and there ain't any fire now at all!" said Kate, in wonderment. "Where are you, Johnny?" "Here I am," said a calm voice at her elbow. "Didn't that go out quickly? I knew it would as soon as the rug was over it, but I was a little afraid it might explode before I could get it covered: I didn't really believe it would, though; for father says he is always very careful to get the best of kerosene." "What a brave boy!" said Kate admiringly. "But you oughtn't to have risked your life so, Johnny. And what could have ailed that lamp? I'll light a candle, and go and see what the matter was; for I don't dare touch another kerosene-lamp. I left that one all right when I went off, about an hour and a half ago." After lighting the gas in the kitchen, Kate lighted a candle, and entered the shed, preceded by Johnny. Sue still feared it was unsafe, and stood on the platform, telling them they had better not go in. Kate took up the end of the rug, and peered cautiously underneath, prepared to run and pull Johnny after her if there was a spark of fire left; but, as all was dark, she assisted Johnny to remove the rug. The lamp appeared to be all right. Johnny put his hand upon the glass portion. "Why, see how hot it is, Katie!" he said: "it must have got heated standing in this little warm room so near the stove, and that made the kerosene swell, I guess, and go up in the wick, and run over at the top; and so the kerosene was on fire on the outside,—that was all." "That was all!" exclaimed Sue, who had now ventured to follow them. "Well, I should think that was enough. I never was so scared in all my life.—But there's a fire somewhere, for there's the bell ringing." "Sure enough," said Johnny; "and it's our box too!" At that moment, a number of men and boys came running into the yard. "Where's the fire?" said the foremost man, as he stepped hurriedly upon the platform. "There isn't any fire here," replied Johnny: "a kerosene-lamp was blazing, that's all; but we've put it out." Then the men went off laughing, and the boys hooting. Kate let the fire down in the grate, saying she was going to have every spark of fire out in that stove before she went to bed; and the children went back into the sitting-room. "Well, Sue," said Johnny, "I hope you've had all the romping you want for this evening." Just then a key turned hurriedly in the door, and Mr. Le Bras entered, followed by Mrs. Le Bras. Mr. Le Bras glanced at Sue and Johnny without saying a word; and Mrs. Le Bras sank into a chair, looking very pale and helpless. Mr. Le Bras went to the dining-room and got some water, without saying a word to the children, who stood by in great alarm. "What is the matter with mamma?" asked Sue, in a hushed voice. Mr. Le Bras offered his wife the water, but she shook her head. "I shall feel better presently," she said, in a faint voice. "Can the house be on fire, and they not know it, Frank?" "No, indeed," replied Mr. Le Bras; "and I told you the engine would not have gone back into the engine-house unless it were a false alarm, or the fire was put out." Then he said, turning to Johnny, "The fire has been put out, hasn't it, my son?" "Yes," said Johnny: "it wasn't any thing but a kerosene-lamp blazing up in the summer kitchen." "And 'twas Johnny who put it out," said Sue. "Sue and Katie screamed, and made the alarm," said Johnny.—"So they got the engine started, did they?" "Yes," replied Mr. Le Bras: "it was just going back into the engine-house when we came by there. As we turned the corner, we heard a man saying our house was on fire; and I thought your mother would die before I got her home, although I called her attention to the fact that the engine was going back." "I feel better now," said Mrs. Le Bras. "So there hasn't been a fire at all! I never had such a fright before in all my life!" But Mrs. Le Bras was still so nervous that her husband would not allow the children to talk about the accident any more, after they and Katie had fully explained the occurrence. The conversation regarding it was ended for the evening by Johnny's saying to his father, "That was a pretty good experiment to illustrate how soon a fire will stop if the supply of oxygen is cut off: only it was an accidental experiment." "It could not properly be called an experiment," replied his father: "an experiment is something done purposely; but it answered the same purpose." "I don't understand why the fire went out when Johnny threw the rug over it," said Sue. "That's what I can't understand," added Kate. "I'll explain it to you to-morrow," said Johnny. "Alec Miner is coming over to-morrow after school to see me perform some experiments: and while I am performing some of them, I will explain how a fire is caused by the uniting of oxygen with carbon and hydrogen; for it is nothing but a chemical union, like ever so many that can be made; only it is so common that folks don't think any thing about it." "So common that folks don't think about it?" said Sue. "Johnny has stated it very well," said Mr. Le Bras, smiling. "If you saw a fire for the first time, Sue, you would be very anxious to know what produced the heat and the bright light; but because you have seen the phenomenon so often, ever since you can remember, you never think to ask the cause of it." CHAPTER II. THE "ILLUSTRATED LECTURE." Something happened the next day to disturb Johnny's naturally good spirits. When he got home from school at noon, Sue met him at the door with,— "Something has happened to make you feel awful bad, Johnny. It came this morning in a letter; and mamma said I might prepare your mind for it, but I mustn't tell you right out in the first place." Mr. Le Bras, who was in the sitting-room when Sue made this announcement, began to laugh heartily. "Well, well, Sue!" he said: "if your mother heard how well you tell bad news, I am afraid she would not trust you to do it again. Why, you have given Johnny a regular bomb-shell to begin with!" "I guess it isn't any thing so bad as you pretend, Sue, since father is laughing at it," replied Johnny cheerfully, although his face had fallen considerably before his father began to laugh. "I'll bet you," said Sue, looking quite disturbed at her father's interference in her news-telling, "that he's only laughing so as not to let you think it's so bad as it is: but now he's begun, he can tell it to you his own self; though mother said I might." Sue went off into the dining-room, where Kate was, with tears in her eyes, and something very like a pout about her mouth. "I think papa was too bad!" she said. "What is it, father?" asked Johnny, after Sue had disappeared. "I think I'll let Sue tell, when she gets over her pet," replied Mr. Le Bras. "The heavens are not going to fall, Johnny. I think you are enough of a philosopher to rise above the calamity, although I really suppose you will feel pretty badly in the first place." "This is funny enough," said Johnny, not knowing whether to laugh or feel anxious: although, of course, he saw it must be only an individual annoyance pertaining to himself, and not a household misfortune, since his father was inclined to laugh so heartily over it. Just then Mrs. Le Bras entered the room. "Mother," asked Johnny, "what dreadful thing has happened to me?" "Hasn't Sue told you?" replied his mother. "No," said Johnny, and he related what had occurred. Mrs. Le Bras smiled. "Very well. Sue has prepared your mind for it, then, and your father has shown that it is something that can be lived through: I think that will do until Sue gets ready to tell you the rest; for, although she is inclined to be sulky, I think I will not break my promise of letting her tell you, unless she gets to be very naughty indeed." Kate then announced that dinner was ready; and they all went into the dining-room, and sat down at the table. Sue was there in her place by Johnny's side; but she said nothing more about the bad news, and looked quite dignified as well as very sober. "Come, Sue," said Johnny coaxingly, "tell me what has happened." "No: papa can tell you, since he couldn't let me do it my own self." "I don't see what bad news could possibly come to me in a letter." "But there has, and that's all I'm going to say about it: papa can tell you," replied Sue resolutely. "Don't tease Sue to tell you," said his mother. "If it were good news, you would naturally be anxious to hear it; but since Sue assures you that it is bad news, the longer you are ignorant of it the better." "Only it rather keeps me in suspense," said Johnny, smiling.—"Come, Sue, tell me, please." "No, I sha'n't," said Sue, shaking her head resolutely. Mr. Le Bras gave Johnny a look which meant, "Don't ask her to tell;" and nothing more was said about the bad news that noon. Johnny went off to school in quite good spirits: and when he got home, and found Alec there, and his sister Belle with him, he was wholly forgetful of the calamitous news in store for him; so that he had quite a little respite between the first hint of the coming misfortune and the bitter realization of it which arrived shortly afterwards. After talking upon ordinary topics with his visitors for a little while, Johnny said, "Since you wanted to see some little experiments, if you will go up in my laboratory I will perform a few. As I haven't any but the very simplest apparatus, and besides don't know much about chemistry and philosophy, I can't show you much; but I'll do the best I can." "You know a good deal more than I do," replied Alec. "I expect to study chemistry and philosophy at the high school next year; but I don't know any thing about them now, and, of course, Belle don't; she just came over with me out of curiosity, when I told her you had promised to show me how to do a few experiments if I would come over to-day." "Is there any particular subject you would like to have illustrated?" asked Johnny politely. "No," replied Alec: "one thing will do just as well as another." "Then, perhaps you would like to see how two chemicals will combine to make a third entirely different from either of the two." "Yes," replied Belle, "I should like that very much." "So should I," said Alec. "I think I'll call Sue to go into the laboratory with us, as I promised to show her some experiments when you were here;—if you will please excuse me a moment." Presently Johnny came back with Sue. As soon as Sue got into the room, she said, "Johnny's going to tell us all about fire, and how the rug came to put the lamp out." Of course, then Johnny had to explain what Sue meant; and that led to a full account of the accident of the evening before, and how Sue and Kate got out the fire-engine, which interested and amused the visitors very much. The laboratory was a small room at the end of the upper hall. As there were plenty of rooms up-stairs, there had never been a bed in it; and after Johnny began to have so many chemicals, and to experiment so much, Mrs. Le Bras had taken up the carpet, and allowed him to use the room for a laboratory. Mr. Le Bras had hired a carpenter to put some shelves in the front part of the closet; and here were arranged the various bottles, jars, saucers, tumblers, pipes, tubes, and other appliances which Johnny had collected. There was a table in the centre of the room, with a chair beside it. "I will get some chairs," said Johnny, disappearing as soon as the guests were ushered in; while Sue politely offered the chair to Belle. "Johnny don't have company in the laboratory very often," she explained. Johnny came back immediately, bringing two chairs; but Alec said he did not care to sit down at present. As for Johnny, he was very busy taking things from the closet-shelf, and arranging them on the table, talking all the time. "I suppose you know what chemical union is?" said Johnny to Alec. "No, I don't think I do," replied Alec hesitatingly. "That is, although I know what union means, and what chemical means, I am not sure what they mean together." "You know how sugar and salt dissolve in water, the particles of sugar and salt lying between the particles of water, just as a whole lot of different kinds of little seeds might be all mixed together without uniting at all?" "I never thought about that before," replied Alec. "I didn't suppose fluid could be compared to seeds; and I had an idea that the salt and sugar became fluid somehow when they were dissolved, and so mixed in with the water." "The particles of the water are very small; and the sugar and salt, when they come into contact with water, separate into very tiny particles, which fill in the places between the particles of water until there is no room left, and then all the sugar or salt you put in afterwards settles to the bottom by itself. But there is no union at all between the salt or sugar and the water; that is, they do not unite to form any different substance." While Johnny was saying this, he was pouring some grayish powder into a cup. Then he put an old spoon in the powder, and took a vial of yellow liquid from the shelf. "This is whiting," said Johnny. "If I put some water on it, and stir them together, I shall have nothing but whiting and water. Perhaps I'd better prove that first." Here he took out a spoonful of the whiting, and put it into a little saucer, and poured some water upon it, and stirred it. "There you have a mixture similar to sugar and water, or salt and water; the ingredients are very closely mixed, but they are not united to form any different substance; if it should stand a while, the water would evaporate, and leave the same amount of real whiting.—But now I will pour some vinegar on the whiting in the cup, and you will see a difference." Johnny poured some vinegar from the vial into the cup, and stirred the mixture with the spoon. "You see all those bubbles? Those are bubbles of a kind of gas; as fast as they break, the gas that has been formed by the chemical union of the vinegar and whiting will pass into the air, and what is left in the cup will not be vinegar and whiting; there will be no real vinegar and no real whiting left; parts of each have united to make the gas; so each has lost something peculiar to itself, and cannot be the very same article that it was before." "Some of the bubbles are real big, and you can't break them easily with the spoon," said Sue, who was stirring the mixture curiously. "I wish my soap-bubbles would be as tough." "Now," continued Johnny, "mixing the whiting and the vinegar caused a real chemical union: two substances united to make a third substance entirely different from the two original ingredients." "I think I understand what a chemical union is now," said Alec. "And so do I," said Belle. "This would be a beautiful experiment to illustrate a chemical union, if it were not so very common," continued Johnny. As he spoke, he took a match from a match-safe he had placed on the table, struck it against the edge of the table, and held it out, smiling playfully. "Fire is one of the most beautiful chemical unions known; and the burning of a match is an excellent illustration of the different temperatures which different substances require, in order that they may unite with the oxygen in the air, or be on fire as we call it." As the match was pretty well burned by this time, Johnny applied the flame to a spirit-lamp upon the table, which was the principal purpose for which he had lighted the match. "A very moderate amount of heat will cause phosphorus, which is the substance on the end of the match, to form a chemical union with the oxygen in the air: brimstone requires a little higher temperature than phosphorus, but not so high as wood requires. The heat produced by a little friction is enough to light the phosphorus, the heat produced by the burning phosphorus is enough to cause the brimstone to take fire, and that produced by the burning brimstone is enough to cause the wood to burn; that is, to form a chemical union with oxygen. And, although the burning phosphorus or brimstone would not have produced sufficient heat for lighting the lamp, the burning wood furnished the necessary temperature; so that the alcohol in the wick began the union at once, when the blaze of the wood came in contact with it." "I see now how it is that we kindle a coal-fire," replied Alec. "First we put some paper in the grate, and then some pine-kindlings, and then some charcoal, and then the hard coal: then we set the paper on fire with a match, and presently the coal is burning." "And we separate the kindlings so that the oxygen can get to them more easily," said Johnny. "How queer we never understood exactly why a fire was kindled in that way, until now," said Belle. "And I should never have thought of fire being a chemical union." "You can carry on the same principle a good deal farther," said Johnny. "From having a fire of coals, you might have a house on fire, and this would produce heat sufficient to set the neighboring houses on fire; and the uniting of such a quantity of carbon and hydrogen with oxygen, to make carbonic-acid gas, would create such a vacuum by the rising of the heated air and gas, that so much oxygen would rush in about the fire, in the form of a high wind, as to make the fire hotter and hotter, until, if it surrounded an iron building, it would burn it up just as easily as wood houses are burned in an ordinary fire; as was the case at the great Chicago fire, where so many fire-proof blocks were totally destroyed." "But the iron buildings did not actually burn: they only melted down in the great heat," said Alec. "Oh, no! they burned," said Johnny: "there is no trouble about burning iron up, if you get the right degree of heat." "I should think there was a good deal of trouble about it, if great buildings they didn't mean to have burned, if there was a fire, did go and burn up right before their eyes," said Sue. "Do you mean that the iron really burned as wood does?" said Belle. "Why, certainly," replied Johnny: "iron will burn up more completely than wood; for when wood is burned, the earthy part remains in the form of ashes: but pure iron, which has no earthy matter in it, will burn up completely; it will all combine with the oxygen in the air to form gas. When iron is in a mass, it takes a very intense heat to produce this chemical union with oxygen; but when it is separated into very small particles, it will burn in an ordinary fire." "If iron will burn up, I wonder we never see it burning so," said Alec. "I've been in blacksmiths' shops and foundries, and I never saw any iron burning up, although I've seen it at a white-heat." "The fires in blacksmiths' shops and foundries are not hot enough to burn iron in the mass," replied Johnny; "or, if they are, they can't get enough oxygen near enough to combine with it. At the great Chicago fire, the intense heat caused such a high wind,—that is, such a flow of oxygen toward the fire,—that the fire became so intensely hot there was no difficulty in the iron blazing and burning more completely than the wood." Here Johnny looked rather disconcerted at Alec's apparent incredulity. "But, Alec," said he, "if little particles of iron, such as you would file off of a bar of iron, will burn up, of course the whole bar could be burned if it was all filed up; and if the filings could be burned in an ordinary lamp like this, why couldn't the whole bar be burned in a fire that was hot enough?" "Yes," said Belle, who was troubled at Alec's being so impolite as to seem to doubt Johnny's word: "it's just like the difference between a log of wood and the sawdust produced by sawing the log in two; you couldn't burn the log without building a hot fire under it, while you could set the sawdust on fire with a match." "That is a very good illustration," said Johnny. "Now, I lit this lamp to show you how nicely iron will burn." Johnny took a large-mouthed bottle from the shelf, which was about half full of rather bright particles. "These are steel-filings I got at a machine-shop; but, if you prefer, I will get a nail and file, and let you make some iron-filings yourself, which will answer just as well. I keep the steel-filings because they are so handy. I just ask the men for them, and they give me a whole lot that last ever so long." Johnny then opened his knife, and, taking out some of the filings on the end of the blade, dropped them, or rather shook them, slowly into the flame. "Oh, how pretty!" exclaimed Belle: "they burn something like gunpowder." "So they actually burn up, and don't just get red-hot and fall down and cool?" said Alec. "Oh, yes!" replied Johnny: "they burn up just like so much sawdust, only more so; for there would be some ashes left of sawdust, even though they might be invisible." "So the filings have combined with the oxygen in the air, and gone off in gas?" said Belle. "Yes," replied Johnny. "I wish you would file some iron," said Sue, "because that experiment makes such pretty fireworks." "Very well, I will, if you will go down and bring me a piece of iron from papa's tool-box." Sue ran off, and Johnny continued,— "I think I'll show you now how I make gas on a small scale." "What kind of gas?" inquired Alec. "Oh! such gas as we burn in stores and houses. I've got my pipe already prepared: if I hadn't, I couldn't show you that experiment very well to-day. I got the pipe ready to show to a boy who was coming to see me last week; but he was sick and didn't come, so I didn't use the pipe." Johnny took a common clay pipe from his closet, and showed Alec and Belle that the top of the ball of the pipe was closed with plaster of Paris. "I pounded a little piece of bituminous coal, such as they use at the gas-works," said Johnny, "and nearly filled the bowl of the pipe with it; then I wet a little plaster of Paris, and closed the end of the bowl to make it air-tight,—that is, to keep out the oxygen. There are carbon and hydrogen in the coal, and they will both combine with oxygen very quickly at the right degree of heat: the hydrogen will form a flame, and the carbon will look bright as you see it in a piece of burning wood or coal. But you see the pipe is fixed so that the oxygen can't get at the coal at that end." "Is the flame of a fire or a lamp caused by the burning of hydrogen?" inquired Belle. "Yes: the flame is the hydrogen combining with oxygen, and the glowing coal or wick is the carbon uniting with oxygen. The gas from the gas-works is the hydrogen of the coal separated from the carbon. When we heat it with a match to set it to uniting with oxygen, we have nothing but a flame. You know the coal is heated in air-tight retorts; it is heated hot enough to burn, but it can't burn because there is no oxygen for it to unite with; but the heat causes the hydrogen to separate from the carbon, and then it finds its way out through the opening in the retort into the pipes, and when it reaches the air at the end of a pipe, you can heat it a little with a match, and it will begin to unite with the oxygen." "And the coal that is left in the retort is called coke. I have seen it very often," said Alec: "the reason it looks different from coal, and burns differently, then, is because it has lost its hydrogen?" "Yes," replied Johnny: "almost all ordinary combustibles are composed of carbon and hydrogen,—wood, coal, oil, etc.; and there are a great many other things that oxygen has a great affinity for, and will combine with at the right temperature: the things that it won't combine with are such as have all the oxygen in them that they will contain, like dirt and stones and ashes." "And how about the pipe?" asked Alec. "Why, after Sue gets back with the piece of iron, we will go down and set the ball of the pipe in Katie's fire. When it gets hot, we shall see a smoke coming out of the pipe, which will be composed chiefly of hydrogen gas: we will touch a match to it, and there will be a flame at the end of the pipe until all the hydrogen which was in the coal in the ball of the pipe has united with oxygen. That is one way to make gas on a very small scale." "And then, if we break the plaster of Paris, and take out what is left of the coal, we shall have some coke," said Alec. "Yes," replied Johnny. Sue now appeared, bringing a small cold chisel. Johnny took a file from the closet, and, placing the chisel over the flame of the lamp, began to file it briskly: beautiful little points of light at once commenced to play about the file and chisel at the point of contact. "Why don't the filings fall down into the flame?" inquired Alec. "I suppose the current in the flame blows them up, they are so small," replied Johnny, "or perhaps the motion of the file does." Alec, Belle, and Sue then took turns at making the "fireworks," as Sue called them. "I think I understand now about fire being a chemical union between oxygen and other substances," said Alec; "but I don't understand about the heat. What makes heat? or why does a chemical union of that kind produce heat?" "Why, friction makes heat," replied Johnny; "particles of matter coming against each other violently. You know the Indians used to get the oxygen to combining with the carbon and hydrogen in two pieces of dry wood, by rubbing them together briskly; and before matches were invented, they kindled a fire by striking flint and steel over tinder; and a steel peg in your shoe-heel sometimes strikes fire on the pavement by the heat produced by friction; and I think I have seen it stated, that, when oxygen is uniting with other substances, it is the very quick motion of the little particles of matter among themselves that produces the heat." "I shouldn't think such little invisible particles as those of oxygen and hydrogen could make friction enough by their motion as to produce heat," said Alec. "Why, Alec," replied Belle, "don't you remember what terrible force the air has in hurricanes, and even in a common gale?" "But that is in an immense volume," replied Alec. "Oxygen is in a comparatively mild and harmless state when it is by itself," said Johnny; "but when it gets to combining with any thing it has a great affinity for, it is in a sort of rage. I think myself that there must be some pretty rapid motion going on in a fire, even if we can't see it." Johnny had handed the chisel to Sue, telling her to put it right back where she found it. "Well, I will," replied Sue; "but I guess things won't be put back in their right places much after Felix gets here." Sue had no sooner said this, than she clapped her hand over her mouth. "Oh!" she exclaimed, "if I haven't gone and told!" Johnny's face had grown very long in an instant. "Is that your bad news?" he said. "When is Felix coming?" "I don't know," replied Sue: "you'll have to ask mamma, for she was to decide." Sue then went back with the chisel, and Alec said,— "So your cousin Felix is coming again, is he?" "I suppose so," replied Johnny briefly, as if it was not a very pleasant topic. "What a funny boy he is!" said Belle. "I never saw him but once, and only for a few minutes; but he seemed to be ready for any kind of mischief." "Yes," replied Johnny: "he's as fond of noise and mischief as oxygen is of carbon and hydrogen; but I guess he won't stay very long." This latter reflection seemed to console Johnny, for he began to look tolerably cheerful again. "Shall we go and make hydrogen gas now?" said he. But at that moment, Sue came running back, exclaiming,— "Some folks in a carriage are having an accident right out by our front-door!" "What kind of an accident?" inquired Johnny. "Is it a runaway?" inquired Belle. "No, it isn't a runaway, for they can't get the wagon to move: at any rate, I heard a man say the wheel wouldn't turn around." "Let's go and see," said Alec. So they all went out at the front-door to see what was the matter. They found a carryall and a span of horses standing near the sidewalk. A lady and a little girl were in the carryall. Two gentlemen were examining one of the wheels, and several boys stood near looking on. "I don't know what ails it," said one of the men; "but the wheel won't turn around, that's sure. I think we'll have to go and ask a blacksmith to come and see to it." Johnny and Alec went out on the sidewalk, while Belle and Sue stood on the doorstep. "I guess it's a hot wheel," said Johnny to Alec. "What did you say?" asked one of the gentlemen, turning around quickly. "I said perhaps it is a hot wheel," replied Johnny. "Oh, no!" said the gentleman, looking rather perplexed: "the wheel is not hot at all." "No," said Johnny, "it isn't hot now; but perhaps it has been hot, and that caused the wheel to get welded to the axle so that it wouldn't turn; and after it wouldn't turn, there was no friction, and so the wheel cooled." "I shouldn't wonder if he is right," said the other gentleman: "that often happens to car-wheels on a fast train, and we have been driving pretty fast, you know." "Well, young man," said the other gentleman, "since you know so much about wheels, can you tell me why this wheel should act so, while the others are all right?" "I presume it wasn't greased so well as the others," replied Johnny. Just then a man who was passing by stopped to see what was the matter: he was a mechanic coming home from the rifle-factory, which closed at five o'clock. He asked a few questions, looked at the wheel, and said, "Oh! that's a hot wheel: you'll have to prop the carriage up, and pound it off from the axle. You've been doing a little blacksmithing as you came along. I presume the wheel and the axle are pretty neatly welded together, but yet not so much so but that a little artificial blacksmithing will set it all right again." Then there was considerable stirring about: the carriage was propped up under the directions of the mechanic, and, after a good deal of hammering, the wheel was pronounced all right. Johnny brought out an oil-can; and, after the wheel was well oiled, the gentleman thanked everybody around, and offered to pay all who had helped, including Johnny. But every one refused to take any pay, except two or three boys who had hindered more than they had helped. "That was a pretty good illustration of the effect of friction," said Alec. "Yes," replied Johnny. "Now let us go in and make the gas." "I sha'n't be able to stop any longer now, thank you," said Alec, "as my father told me to be home by half-past five. But I'll get a pipe and fix it myself, if I can find a piece of the right kind of coal, and that will save your pipe until another time." "Sawdust, or almost any thing that will burn well, will answer to fill it with," said Johnny. "I am ever so much obliged for your illustrated lecture," said Alec. "I've learned a good deal, and I wish you would come over to our house some day before long. I can't perform many experiments yet, but we'll have a good time somehow. I mean to begin to perform experiments, and study up about these things. I am two years older than you are, but I don't know half as much as you do." "You know ever so much more than I do about history," said Johnny, "and Dick knows more about carpentry, and Fred about printing." "And that's the way it is with grown-up folks," said Belle: "one takes to one thing, and another to another; and so, between them all, the different kinds of work in the world get done." "As for me," said Sue, "I like to have a good time most any way." After their visitors were gone, Johnny went in to ask his mother about Felix. "Why, my dear," replied Mrs. Le Bras, "your aunt Mary is in very poor health, and is going to Europe on a three months' trip with your uncle Louis. Your uncle thinks she will be much better if she does not have the care of Felix; and yet she is unwilling to leave him behind, unless we will let him come here. Of course, we could not refuse; although it will be a great care for me, and a worry to you; but we are well, and aunt Mary is ill." Johnny tried not to cry, but the tears rolled down his cheeks in spite of all his efforts to restrain them. "There won't be any peace and quiet and comfort in the house after Felix comes," he said; "and to stay a whole three months'—But then, if aunt Mary is sick"— "Perhaps he has improved since we saw him," replied Mrs. Le Bras: "if not, your father says he shall be made to mind and behave himself. Since his father and mother will not be here, he will be obliged to obey your father and me, and we shall be decided with him." "When will he come?" "In about two weeks." "I shall try to enjoy myself as well as I can before he comes, because I know it won't be very pleasant after he gets here." Mrs. Le Bras said nothing, because she was afraid Johnny was about right. As Johnny went up to the laboratory to put up his pipe and the other articles, he looked very sober and thoughtful: he was already planning how he could escape from Felix's racket and nonsense. When Johnny came down again, Sue said,— "You didn't explain, after all, how the rug put out the lamp last night." "Put out the light, you mean. Why, don't you see? The rug prevented the air from reaching the fire, and, as there was no more oxygen to combine with the hydrogen and carbon, there could be no fire." |
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