 CHAPTER VIII. WHAT IS MEANT BY BURNING. Burning is meant by burning, which has a great deal to do with the ocean of air around us. Or if there were no air, there could be no combustion. On a cold winter's day, there's a fire in the sitting room. The flames play around the coal, and gradually the lumps of coal grow smaller till they disappear. If more coal is not heaped on in time, the fire grows out. What becomes of the coal? It is burnt of course, any child could answer that question. But what does being burnt mean? Suppose we have an iron ball in the grate, lying among the burning coals to fill up some of the space. This ball gets red hot, like the coals. Though it does not, like them, pass out flames. Heat is very catching and passes readily from one object to another. The iron ball seems to burn like the coals, yet unlike the coals which shows no tendency to disappear. It does not even get receptively smaller. When the fire dies out, and the red hot ball grows cool, it is seen to be unchanged. If the one burns and vanishes, why does the other burn and not vanish? This question is easily answered. The iron ball does not burn. Some substances burn easily, and some not easily. Some will burn at any time in common air, and some only under particular circumstances. Iron is a substance which will stand fire. It can be made red hot or white hot, melted, and even turned into a gas. But it will not burn in common air. So becoming red hot or white hot is not necessarily the same as burning. But though iron will not burn in air, it can be made to burn, really to burn, lessen in size, and disappear like wood. If a piece of iron wire is placed in a vessel filled with pure oxygen gas, it can be set alight, and will burn away as easily as a wooden match. In the end of the last chapter I spoke of fast and slow combining and mentioned iron rust as an example of slow combining. Now iron rust simply comes from the union of iron with oxygen, generally at a slow rate in a damp place, and it is called oxide of iron. But this same oxide of iron, or iron rust, can also be produced quickly by burning a piece of iron in oxygen gas, as above described. Then again the iron unites with oxygen, and iron oxide, or rust is formed. Only as the union takes place fast, much more heat is given forth in a few seconds. The more rapidly heat is set out in burning, the more intense it is. Whether the rust is formed fast or slowly, the actual process is the same. It is oxidation. We call the one a case of burning, and not the other. Yet the only real difference between the two is in respect of temperature and speed. The common rusting of iron in a damp place really is a species of very slow and languid combustion. What becomes of the coal and the grate when it burns and diminishes in size. The coal is divided and goes three ways, part rises up the chimney as smoke or soot, part falls below as ashes, part unites invisibly with oxygen from the air, causing heat and flame in the act of union. You have seen that iron can unite quickly with oxygen by burning, as we usually understand the term, only what it has to do with pure oxygen unweakened by nitrogen. The coal or wood, when sufficiently heated, can take the oxygen out of the air, leaving the nitrogen behind, so we say they burn easily. If the fire has been allowed to get too low, and fresh coal put on will not catch, what then? Why, then we use the bellows, and pour a supply of fresh air and gentle streams above the reddest spot remaining, in the hope that a new and abundant supply of oxygen gas will awaken the half dead embers and revive the flame. The oxygen gas in the air lying close to the coals has been pretty well used up, but a fresh supply will give what is needed. Coal alone without oxygen gas cannot give us flame and heat, for oxygen is the great quickener and supporter of fire. If we could vanish all the oxygen gas from the room keeping only nitrogen gas, any amount of paper, wood, and coal might be put into the grate, and the bellows might be used to any extent, yet to no avail. The fire would at once die out. Nitrogen is powerless to keep it alive. So now we see the object of bellows to wake a dying fire, just that a fresh supply of the needful oxygen may be given. Wisdom is profitable to direct, say as the wisest of kings. One cannot but remember these words when watching an uneducated maid puffing away as a lump of black coal without the slightest result. A very little wisdom would teach her to direct the stream of fresh air towards a red spot where alone it can take effect. If bellows could be made as to feed the fire with pure oxygen gas, then at any time the last spark of a dying ember might be roused with ease into fresh life. Such bellows would also have a curious effect on the red hot iron ball. After a steady play of oxygen gas, the ball would begin to waste away like burning coal. When anything burns, it not only gets red hot, but also there is a rapid loss of material. It grows smaller and smaller, and almost or quite disappears. Either part or the whole of its substance unites with the oxygen of the air and passes out of sight into the atmosphere. This is what we mean by a body burning or being in combustion. To make a body red hot is enough often for combustion without flames. Where inflammable gas exists, that is a gas, which will unite quickly with oxygen, there will be flame. Early flame arises, not from a solid or a liquid, but from a gas in combination, when flames play around a burning lump of coal they are caused by the escaping hydrogen. Some substances will grow only red hot and waste, but will not show flame. Anybody intensely heated and glowing, not yet lessening in size, losing weight or uniting with oxygen does not burn. The heated object is then said to be ignited or incandescent, but not in combustion. If a piece of magnesium wire is held in the flame of a gas burner, it will take fire, burn brightly and waste away growing shorter. If a piece of coiled platinum wire is held in the flame, it will become hot and glow brightly, but there will be no perceptible loss of material. So the magnesium wire is said to be in combustion. The platinum wire is said to be in a state of incandescence. We see an instance of the latter in many of the new electric lamps. A thread of carbon is shut up in a glass bulb from which all air has been expelled and it is then made red or white hot by a stream of electricity. But it does not burn. It only glows. It cannot burn, for there is no oxygen within reach. And the burning of a substance means its union with oxygen. Another instance is known to us in the glowing gases, which play fiercely over the sun. In common speech, we talk of the burning surface of the sun, yet the term is wrong. The gases which send out so intense a glare are, it is believed, only glowing, not burning. They give forth heat and light, but they do not unite with oxygen and waste away. To speak of flames on the sun is equally incorrect. The term is gas in combustion, and the gases of the sun are believed to be only incandescent, not in combustion. For true burning, the presence of oxygen is generally needful, and the presence of some other combustible substance to combine with the oxygen is equally needful. We can no more make a fire of oxygen without coal than of coal without oxygen. For both are required. Having both, we must bring them together, and must place them under the touch of sufficient heat. When this is done, and the union of the two is started, enough heat will be given out for carrying on the work and for warming the room. In the lighting of an ordinary fire, heat is first applied by a lighted match to the paper or shavings. Some of the paper or shaving substance at once unites with a little oxygen in the air. And that act, the breaking loose of particles from the solid substance to join with particles of oxygen causes a setting free of fresh heat. This heat spreads to the wood. Another union then takes place, particles of wood breaking loose to form a combination with more oxygen. Further heat is again given out which spreads to the coal, which in its turn catches fire, entering on a course of union with the ever ready oxygen. Thus heat both causes and springs from combustion. Now one of the new substances formed by these various combinations. The particular substance which is formed must depend in each case upon the particular substance which is burnt. As a matter of fact, in the common everyday burnings around us, two special substances are by far the most common as the second party in this union. They are carbon and hydrogen. When a lump of coal is burnt, part goes up the chimney as soot, part falls below as white ash, part vanishes. So with the burning of a wax candle, part passes away as soot while the greater part slowly disappears. Yet though the coal and the wax pass out of sight, their substance is not destroyed. So far as we can tell, no matter once created is ever put out of existence. We cannot say that it never will be, for the future of the universe of matter is utterly unknown to us. But man has no power to destroy a particle of it. True, he can by using the forces of nature break up many materials, change their form, cause them to vanish. Yet the vanished particles may reappear. The old form may be restored. There is no real destruction of the tiniest atom. In the case of burning coal or wax, each particle exists still, afterwards, somewhere, and in some shape. Heart of the coal drops below as white ash. This is the mineral substance which cannot burn. Heart escapes as soot or unburned carbon. The great mass of the carbon, which is the chief portion of the coal, unites itself with oxygen and forms a new combination. This new combination called carbonic acid gas, flows away invisible, joining the hot smoke in its passage up the chimney. Meanwhile, the hydrogen gas held in the coal also joins itself to oxygen, causing bright flames as it does so. The result of that union is water in the form of vapor. The same takes place in the burning of a candle. Some of the carbon escapes as unburned soot, while the greater part unites itself to oxygen. And those two losing their separate individuality, pass away into the air as carbonic acid gas. The hydrogen combines with surrounding oxygen, and these also float off as invisible vapor of water. If a clear coal tumbler is held over a candle flame, it will grow dim with fine moisture. This moisture is some of the newly made water condensed into a tiny fog by the chill of the glass. The bright light given out by a candle flame springs mainly from the glowing of fine carbon points, which float within the flame. Where any of the carbon is within touch of the air, it unites with oxygen and goes off as carbonic acid. Inside the body of the flame, the air has no access. And there the carbon specks can only glow. For lack of oxygen, they cannot burn, so they pass away as smoke. If the hole of the carbon contained in the wax could be at once burnt up as the flame creeps down the wick, there would be no smoke and very little light, but there would be much more heat. Hundreds of tons of coal are daily consumed in every great English city, especially in winter. It is a wonderful fact if we consider what is meant by burning. A mighty mass of solid black coal is in 24 hours utterly disposed of by the soft translucent air, not swept aside in one mighty hurricane blast, but gently lifted particle by particle, carried off and hidden away by the busy oxygen. End of Chapter 8, Recording by John Brandon Chapter 9 of The Ocean of Air, Meteorology for Beginners This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by John Brandon. The Ocean of Air, Meteorology for Beginners by Alice Giburn Chapter 9 Three Forms of Carbon Before going into the carbonic acid gas of the atmosphere, we must think a little about carbon from the union of which with oxygen springs carbonic acid. Carbon is another simple substance, another of those mysterious shut doors beyond which, at present, we cannot pass. It cannot by any means yet discovered be split up or divided into other substances. We have had so far to do with simple substances, which in their ordinary free state on Earth, are gasses such as nitrogen and oxygen. Carbon in its natural earthly state is a solid, and not only so, but it is one of the most stubborn solids known. For a long while it resisted all attempts to throw it into a liquid. When united with other substances, carbon appears in multifarious forms, the names of which are legion. It is a most abundant material, and it enters enormously into the make of all vegetable and animal bodies, of all organized bodies, or creatures with life. Without carbon, our Earth would be an uninhabited desert. Without carbon, we should have no grass, no plants, no corn, no trees. Without carbon, we should have no birds or beasts. Without carbon, there could be no men, as now constituted. For men are built up of carbon, of course, with the addition of other ingredients. In charred wood, charred meat, charred human flesh, the underlying black carbon is plainly to be seen. If the wood, meat, or flesh is entirely burnt up, then no carbon remains. The whole has united with oxygen and has vanished as carbonic acid gas. White loaf sugar is a compound substance being formed of carbon and water, or sugar is a vegetable product. If sulfuric acid or oil of vitriol is poured upon thick sugar syrup, the mass blackens and swells upward into a large quantity of loose charcoal. Carbon is abundant, too, in many rocks, such as marble and limestone, also in chalk, coral, and shells, which are largely of animal make. But while all this is true, while numberless forms of vegetable and animal substance are composed, in a great measure of carbon, yet in its most pure form, free from combination with other substances, carbon appears mainly in three distinct characters. The first form of pure carbon is charcoal. Perfectly pure charcoal is not common, any more than perfectly pure ought else in this world. Everything gets mixed up more or less with other things, but if wood is slowly burnt in a vessel, nearly closed, tolerably pure charcoal will remain. A far more important form of carbon, very nearly allied to wood charcoal, though less pure, is coal. What the world would be without coal, we can only imagine by looking back in fancy to those times when coal had not been discovered. Old modern life, modern comforts, modern appliances, modern discoveries, modern experiments, and inventions seem to depend upon the existence of coal. Without coal, unless something else should take its place, England would sink back into a kind of semi-barbarism. Coal is a form of carbon. It is made from wood which consists largely of carbon since trees, like man, are very much built up of carbon. Coal fields are the buried remains of mighty ancient forests, and the structure of wood can often be traced in a piece of coal. But this structure has generally vanished for a change has passed over the woody substance, transforming it into the fossil substance called coal. The change has been brought about by an underground operation, which is in fact much the same as that by which a log of wood is transformed into charcoal. Only in the one case the action has been very slow, in the other it is quick. The transformation of those buried forests into not very pure charcoal has really been through a course of exceedingly slow combustion or oxidation spread out over ages. Coal is the charred remains of a former vegetation. Combustion, as we have seen, does not always mean becoming red hot, though it always means some amount of union with oxygen. Is it not wonderful that all this preparation of fuel was going on through long ages, man never dreaming of any such merciful provision for the future of his race? So charcoal, coke, or coal is one form of carbon in its natural state. The second form of pure or nearly pure carbon is graphite or plumbago. We all know graphite as black lead, wrongly so called, the soft black substance used in tensiles. Curiously, unlike hard porous charcoal or shining coal, graphite is found in granite rocks and elsewhere underground. It has other uses besides that of lead for pencils, not needful to be considered here. Charcoal and graphite are not so very startlingly opposite in appearance and character, but it is when we come to the third form of carbon that we find an astonishing difference. The third form of pure carbon is diamond. Certainly no one would have a dream at first sight of putting the brilliant rare diamond under the same head as common black charcoal and graphite. Yet the three are the same, absolutely identical in nature. Each is carbon, carbon in its natural free state, uncombined or very nearly so, with any other substance. Unlike in color, unlike in shape, unlike in hardness, unlike we should say in every single particular. They are one in nature formed of the same simple substance. So we see that charcoal is carbon, plumbago is carbon, diamond is carbon. If each of the three were formed of carbon united with other materials, we should think nothing of it. The extraordinary thing is that each of the three is carbon only carbon threw out. How and under what conditions carbon takes that particular form, becoming a translucent flashing gem, we do not know. The formation of the diamond is still a mystery. We can only assert that as the black lead of a pencil is carbon, as lamp black is carbon, as coke is carbon, as charcoal is carbon, so diamond is carbon. Charcoal, plumbago and diamond, however, unlike in appearance, are one in nature. They are all three merely different developments of the one simple substance, carbon. Thus vast quantities of carbon are present on earth, floating through the atmosphere in union with oxygen as carbonic acid gas, lying on the ground in rocks and coal, residing in the bodies of plants and animals. Moreover, as we shall see, a perpetual, iterative change is kept up between the carbon of the atmosphere and the carbon of living bodies dwelling in the ocean of air. Carbon is incessantly passing from the air into living structures and out of these structures into the air again. Nay, the very carbon, which ages ago passed into living forests of trees, is in these latter days poured back into the atmosphere whenever coal is burnt. So there is a circulation of carbon in the world, as well as a circulation of oxygen, not less active, not less constant, not less widely extended. The whirlpool of life and change knows no cessation. By means of the spectroscope, we know that this same substance, carbon, which is so abundant on earth, exists also in the stars and comets of distant space. End of Chapter 9, Recording by John Brandon Chapter 10 of the Ocean of Air, Meteorology for Beginners This is a LibriVox recording. All LibriVox recordings were in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by John Brandon The Ocean of Air, Meteorology for Beginners by Agnes G. Byrne Chapter 10, The Perils of Carbonic Acid Carbonic acid gas is being perpetually made, perpetually poured into the atmosphere and perpetually broken up once more into the carbon and oxygen of which it is formed. The quantity of it present in the air to any one time or place varies exceedingly. At some times, and in some places, a much larger supply is being made and is sent floating through the air ocean than elsewhere and on other days. There are certain special modes through which this gas comes into existence. Carbonic acid gas is found wherever any substance burns which is partly made of carbon. Heart or the whole of that carbon unites itself in the act of burning with some of the oxygen roundabout, so forming carbonic acid gas. One of the chief perils of a house on fire arises from the above fact. The carbon of the great mass of burning materials combines rapidly with oxygen and large quantities of carbonic acid gas are poured forth. Many a human being unable to escape is mercifully stifled by the deadly fumes long before any flames can reach him. If the wind blows so much the worse, for the moving air brings constant fresh supplies of oxygen and as they sweep over the house the making of carbonic acid gas goes on more rapidly. In common speech the wind fans the flames and the house burns faster. When a haystack or a bonfire is a light and we go to the side where the wind bears down upon us we are speedily aware of the overabundance of carbonic acid gas, whether or no we can tell its name. The fact is apparent by the choking, stifling rush which drives us from the spot. The same danger exists in the burning of a charcoal breezier in a room which has no fireplace. Terrible risk to life is involved here, for as the charcoal wastes it gradually unites with oxygen to make carbonic acid and this gas has no escape except into the air of the room. Many a solitary being has gone to sleep in such a case enjoying the warmth and has been stifled in his sleep never waking again. A sad instance happened not many years ago in Paris. A young English girl had gone there in quest of work, a quest which long proved fruitless. Success at last came and she went joyously to tell her friend an English clergyman who had kindly helped in the search. Returning to her lonely room she lit a little charcoal fire feeling in delight that she might now indulge herself in never dreaming of danger. Full of hope the poor girl went to bed leaving no outlet for the deadly gas and when morning came a hasty messenger summoned the clergyman. He arrived only to find a dead body lying in the small room. All had been over hours before. The danger is greater at night than in the day because one is taken on awareness and on consciousness because two of the recumbent position of a sleeper. Carbonic acid is a heavy gas, much heavier than oxygen or nitrogen except when stirred up by air currents. It always sinks downward and it will remain so distinct from the other gases that the lower part of a room may be full of it while the upper part has comparatively pure air. Through this heaviness it can with care be poured from one vessel to another. Carbonic acid gas is made in the fermentation of wine. The sugar contained in the grape juice is broken up by the fermenting process and fresh substances are formed from it, one of those substances being carbonic acid. A rapid fermentation first takes place. The liquid needing to be occasionally stirred up for this purpose in olden days and in some countries it was customary for a man to enter in bodily. The warmth of his frame was supposed to be advantageous by promoting quicker fermentation. It was however a perilous business for the man himself. On account of the large quantities of carbonic acid gas escaping and several lives with us lost at different times. When the more rapid fermentation is over the wine is moved to other barrels and the slow after fermentation begins lasting for months. Here again the same danger attends those who have to visit the wine vats. As a rule the escaping gas lies low and a man may walk safely upright where a dog would fall senseless and die. But if he stoops to care for the dog he too may be overpowered. Sometimes the gas collects and rises to such a height as to imperil men also. Too hasty an entrance into the place may mean no less than death and fatal results have come about not seldom. The following memoranda are of a visit paid by my father to a brewery many years ago. I was taken over one of the largest breweries in London in company with friends. The thing that struck me most was the large fermenting vat of the size and form of a small room in which the fermentation of wort was proceeding at a rapid pace. The ligger was some feet in depth and on the surface of it floated a dense body of clear bright carbonic acid gas which overflowed at the gangway where I was standing like a waterfall some 12 or 15 inches deep. On looking upwards through the bright colorless gas fall it was very curious to see the dingy dirty London air resting upon its surface and gently waving along when set in motion by blowing or fanning. I stooped down and ventured to take a small breath of the gas fall but I did not attempt to take a second it was like a sword passing down my throat. Subsequently I inquired the cause of the pain given by inhaling the carbonic acid gas given off by fermentation whereas that given off by burning charcoal is only stifling in its effect. I was told that there is no pain in inhaling dry carbonic acid gas but when mixed with damp it has the effect I experienced. Carbonic acid gas formed by the burning of coal would if we had no chimneys be poured into our rooms to the detriment of health if not to the destroying of life. Where a chimney fails to draw well that is when the upward draft is not sufficient to carry away all the gas with the smoke we are soon conscious of stinging and choking sensations extremely unpleasant in kind. Long ago English fireplaces boasted no chimneys the fire was made in the middle of the room and the smoke and newly formed gases had to meander about till they found their way out through a hole in the roof but since glazed windows were in those days unknown the absence of chimneys mattered less for there would always be a plentiful supply of pure air pouring in below as cold air is the heaviest while hot air is light the fresh cold incoming air would speedily drive upward and outward the dangerous gas. Most of us have felt more or less the ill effects of burning gas in a closed room gas like coal contains much carbon and when it burns supplies of carbonic acid gas are being steadily poured into the air unless there is a way of escape through open door window or ventilator the air of the room changes fast from good to bad. Some people are very sensitive to this suffering even in the earlier stages from headache faintness and other trying sensations while some can endure an extraordinary amount of bad air without being aware of it sooner or later however the hardiest and most insensitive frame must suffer the condition of things produced being one in a succession of stages on the high road towards suffocation. Carbonic acid gas is found wherever living creatures are no need to say living creatures which are largely made of carbon for all living creatures are largely made of carbon from them is poured out a regular intermittent stream of carbonic acid gas with every breath this is why room containing human beings if no fresh air is allowed to enter becomes close and unhealthy burning gas would make matters worse by hurrying on the evil but without any burning gas or lamp or candle we have still the same result it is no rare spectacle to see a church or room in cold weather full of men and women having every door and window fast shut from dread of the slightest draft elderly people and nervous people are often afflicted with an almost morbid horror of moving air while they are placidly indifferent to poisonous air the fact is curious but common now the air of any closed place steadily breathed by men or animals becomes gradually transformed to a slow poison nay in time to a quick poison though affairs are seldom allowed to go quite so far people are usually content to give themselves and their children over pale or over flushed faces sickly sensations and bad headaches without advancing to actual suffocation we hear a great deal of ill health among the poor of stunted frames pallid cheeks and constant suffering of course much of this in certain cases may be due to scanty food or to overwork but it is a grave question how much of it is not owing to the habitual breathing of air which has been allowed to gain too much an amount of carbonic acid gas simply from the lack of an open window there is a wonderful carelessness among the poor as to fresh air true the fresh air at their command is not always of the purest yet it is better than none nor is it in town alleys alone but also in country cottages that windows are built up with plants never to be opened and that frequent airing of a room is a thing unthought of it would be hardly fair however to speak of this indifference as a characteristic of the poor only there are houses in a higher station of society houses inhabited by the cultivator denry find where the window of a much used sitting room is closed before breakfast and is never opened again before night naturally by evening the air of that room has grown into a most undesirable compound the mixture of little oxygen with much carbonic acid is rendered not more pleasant by various floating vapors and particles of matter given off in the course of many hours from the lungs and skin of human beings present a sharp current of air between window and fireplace or window and door would speedily expel them all bringing a sufficient supply of fresh oxygen but no that would be too much trouble or nobody thinks of it or somebody might complain of cold so the unhealthy mixture has to be patiently breathed by the unfortunate individuals assembled there however as already said many people are not sensitive in the space of 24 hours a man not especially exerting himself takes into his system about 18 cubic feet of oxygen gas he also gives off from lungs and skin about the same amount of carbonic acid gas suppose a man were in a room seven feet high seven feet wide and seven feet broad shut up completely with no opening to admit fresh air the whole mass of air in that little room would in 24 hours have passed through his lungs of all the oxygen originally held by the air one quarter would have disappeared its place being filled why about the same amount of carbonic acid gas suppose no air were then admitted but the same state of things were continued for another 24 hours by that time half the oxygen present would have been exchanged for carbonic acid gas following out the same idea we may say that in three days three quarters of the oxygen would have given place to carbonic acid gas while in four days the oxygen would be all gone and only carbonic acid mixed with nitrogen would remain of course this experiment could never be really tried because long before the close the man must after great suffering have died of suffocation by burning charcoal continuously in a shut room from which all fresh air is shut off the result described could be actually brought about but through a man's breathing only the earlier stages are possible not far from the middle of the last century a terrible deed was worked in Calcutta by the guards of the so-called Nabob Saruja Daula upon his English prisoners no more awfully forcible illustration can be found of the desperate need for fresh air to keep human beings alive the story may well be given in the vivid words of McCauley then was committed that great crime memorable for its singular atrocity memorable for the tremendous retribution by which it was followed the English captives were left to the mercy of the guards and the guards determined to secure them for the night in the prison of the garrison a chamber known by the fearful name of the black hole even for a single european malefactor that dungeon would in such a climate have been too close and narrow the space was only 20 feet square the air holes were small and obstructed it was the summer solstice the season when the fierce heat of Bengal could scarcely be rendered tolerable to natives of England by lofty halls and by constant waving of fans the number of the prisoners was 146 when they were ordered to enter the cell they imagined that the soldiers were joking and being in high spirits on account of the promise of the Nabob to spare their lives they laughed and gested at the absurdity of the notion they soon discovered their mistake they expostulated they entreated but in vain the guards threatened to cut down all who hesitated the captives would drive it into the cell at the point of the sword and the door was instantly shot and locked upon them nothing in history or fiction approaches the horrors which were recounted by the few survivors of that night they cried for mercy they strove to burst the door hallwell who even in that extremity retained some presence of mind offered large bribes to the jailers but the answer was that nothing could be done without the Nabob's orders that the Nabob was asleep and that he would be angry if anybody woke him then the prisoners went mad with despair they trampled each other down fought for the places at the windows fought for the pittance of water with which the cruel mercy of the murderers mocked their agonies raved prayed blasphemed implored the jailers the fire among them the jailers in the meantime held lights to the bars and shouted with laughter at the frantic struggles of their victims at length the tumult died away in low gaspings and moanings the day broke the Nabob had slept off his debauch and permitted the door to be opened but it was some time before the soldiers could make a lane for the survivors by piling up on each side the heaps of corpses on which the burning climate had already begun to do its loathsome work when at length a passage was made 23 ghastly figures such as their own mothers would not have known staggered one by one out of the charnel house a pit was instantly dug the dead bodies 123 in number were flung into it promiscuously and covered up dead for lack of air to keep them in life the small amount of air within breathed by 146 pairs of lungs grew rapidly worse and worse as oxygen gave place to carbonic acid and the small window openings were blocked up by the struggling mass of human beings fighting in the agony of gradual suffocation for one breath of air the marvel was not that 123 died but that so many as 23 outlive the horrors of that awful night carbonic acid gas is found abundantly in many coal mines everybody has heard of the terrible fire damp and choke damp of mines but many would be at a loss to define the difference between the two fire damp wrongly known among miners as sulfur is a gas made of carbon and hydrogen that contains no sulfur whatever and the word damp is a corruption of dump the germans of vapor in many coal mines especially in many english ones large quantities of this gas often collect amid the coal seams and when released by a stroke of the pickaxe it flows out in streams by itself it is not a dangerous gas it'll burn if lighted but quietly with a blue flame once let it become mixed however with a certain amount of common air and it becomes at once tremendously explosive if it comes in contact with any flame an explosion instantly follows rendering rocks and dealing death to miners within reach usually there are many men in a mine where such an explosion takes place beyond touch of the actual flames but though not burned to death another danger not less terrible awaits them and this is from the choke damp or after damp the gas called fire damp is made as we have seen of carbon and hydrogen when that gas takes fire and burns in a great outburst of flame large quantities of carbonic acid gas spring into being through the union of carbon with oxygen and the dangerous carbonic acid gas or choke damp flows through the passages searching out the miners in their retreats if overtaken by it they are soon overwhelmed a few breaths of the deadly gas and they fall in unconsciousness unless speedily rescued never again to wake in the great heartly Collier disaster more than 200 men died of the choke damp who might otherwise have escaped the coal gas which we burn in our houses though not quite the same and make as the fire damp of mines is very likely it in one respect coal gas properly managed is harmless enough but when mixed with a particular amount of atmospheric air it becomes explosive if a little air gets into a gas pipe or if the gas escapes and mixes with air there is likelihood of an explosion gas as used in private houses under the control of people who do not in the least understand it is a perpetual danger to mankind the one real safeguard lies in its unpleasant smell for when gas escapes it always makes its presence known still even this is not enough uneducated persons will take a candle or light a match to examine the source of the odor about the maddest feet they can well perform the wonder is that more lives are not lost thus and indeed gas explosions on a small scale are by no means uncommon carbonic acid gas is found wherever volcanoes exist and fiery underground forces are at work in such regions great outpourings of it are want to take place alike from open craters from springs of water and from casual cracks and splits in the earth herein lies one peril of volcanic districts a man carelessly approaching a crater or leaning over an open fissure may be choked by the rising fumes while in no peril from flames or hot lava miss bird describing the fiery lake of Kilauea writes at times the level of the lava in the pit within a pit is so low and the suffocating gases are evolved in such enormous quantities that travelers are unable to see anything and again at a later date the whole region vibrated with the shock of the fiery surges to stand there was to snatch a perfect joy out of a pain and terror which was unendurable for two or three minutes we kept going to the edge seeing the spectacle as with a flash through half closed eyes and going back again but a few trials in which throats nostrils and eyes were irritated to torture by the acid gases convinced us that it was unsafe to attempt to remain by the lake as the pain and gasping for breath which followed each inhalation threatened serious consequences the same abundance of escaping carbonic acid gas is found near vissuvius etna and other volcanoes and also in the neighborhood of extinct craters in lands where eruptions are no longer known carbonic acid gas is found wherever decaying herbage exists or dead bodies of animals lie the carbon of which both plants and animals are largely made it gives back to the atmosphere when they decay it unites with the oxygen of the air and again carbonic acid is formed by a slower process indeed than that of burning but with consequences no less deadly herein lies one danger of living among or near great masses of dying or dead vegetation the fall of the leaf in a wooded country is counted unwholesome every fallen leaf in its decay sends forth a little stream of carbonic acid gas and the many small streams joined to cause a serious total the evil would be greater yet but for the busy worms who work so hard drawing the dead leaves underground there they decay still but not injuriously helping to form new mold to feed plant life instead of helping to poison the atmosphere for animals and men still despite all that worms can do a good deal of unwholesomeness does exist in such places even in england more markedly it is seen in the swampy lands roundabout tropical rivers covered with luxuriant vegetation also the presence of dead bodies in or near human dwellings is a danger to life besides sending out germs of disease their decay produces a large amount of this gas carbonic acid gas is the precise opposite of oxygen gas the latter is life supporting the former is life destroying whether it is in any sense an act of poison has been questioned if the amount of it in common air is increased and the amount of oxygen is increased in the same proportion the carbonic acid seems not to be hurtful so it appears that a man who dies from breathing carbonic acid like one who dies from breathing nitrogen dies not from a poison but from a want he dies not because he has taken in too much carbonic acid but because he has not taken in enough oxygen under great cold and pressure carbonic acid can be liquefied and has even been solidified to a light snow like substance generally however as it floats in the ocean of air we know the said substance only as a gas in taste it is slightly acidic end of chapter 10 recording by john brandon chapter 11 of the ocean of air meteorology for beginners this is a libra vox recording all libra vox recordings are in the public domain for more information or to volunteer please visit libravox.org recording by john brandon the ocean of air meteorology by agnes giburn chapter 11 what is meant by breathing something is meant by breathing which has a very close connection with the atmosphere in which we live or if there were no air how could any creatures breathe but before going into what is meant by breathing we must have a few words about the right balance between exertion and food if a man takes an hour sharp walk at the end of the hour he's not in all respects the same as when he started he has lost weight he has paid away in active effort some of his substance both solid and liquid the former has gone off in clouds of carbonic acid gas the latter in clouds of steam or vapor this loss of substance means a pressing need before long of something to take the place of that which is gone so long as the furnace fires of an engine burn there is the constant need of fresh coal to feed the flames otherwise the fire will die out and the engine must come to a standstill so long as the fire of life burns in a man there is a constant need of fresh fuel fuel to support it otherwise life will fail and the man must die while life lasts perpetual waste goes on but the rapidity of waste depends upon the amount of effort and exertion used an engine traveling at the rate of 60 miles an hour uses up coal much faster than an engine traveling at the rate of 30 miles an hour the man had sat still in his chair or had loitered lazily about there would still have been loss of substance but not nearly so much as in his hours brisk walk if instead of merely taking a brisk walk he had climbed fast up a steep mountainside the loss of substance would have been yet greater active exertion quickens the breathing the heart's action the circulation of the whole frame it means the more rapid using up of material and the greater need of fresh material in place of that which is used the same result would be brought about if the man stood still and lifted a succession of heavy weights there would again be exertion quickened waste increased need of renewal as compared with when he stands still and does nothing the supply of fresh material can come only in three ways one as food two as drink three as air every human being every kind of animal requires these three and requires them imperatively he must have air always he must have food and drink at regular intervals just so the engine must have food and must have air to keep it going if the carbon of the coal or the oxygen of the air is cut short then the engine fires die out many people take too much food and many others take too much drink for their requirements while some take too little food and others too little drink with each human being there is a certain exact amount of both needed just enough in fact to balance the amount of exertion and bodily waste less exertion means less waste and consequently less need of renewed supplies more exertion means more waste and consequently more need of renewed supplies the food and the drink taken are too much if they are not balanced by a sufficient amount of exertion and of resulting waste they are too little if not enough to supply the amount of waste caused by exertion so the more a man does the faster he loses substance and the more food he requires to make up for the waste of his frame this rule is of course modified by particular conditions in particular cases what seems a slight exertion to one person may be a severe exertion to another and certain states of illness may induce as much waste as any amount of active exertion the very same results are seen strange to say in the matter of thought and brain work as in bodily effort the harder a man thinks the more intensely his brain is exerted the greater is the animal waste therefore the greater is the need of sustenance now the renewal of lost substance the sustaining of the fire of life takes place as already said in three ways more strictly by two modes one feeding two breathing the food includes both kinds solid and liquid of these two much or too little may very easily be taken but there is no fear of a man breathing too much or too little air since his body settles that matter for him independently of his own will all that his will can do in the matter is to choose a place where he is surrounded by good air containing enough oxygen and not too much carbonic acid everybody breathes as a matter of course not at all as a matter of choice men breathe beasts breathe birds breathe insects breathe whales and porpoises breathe even fishes breathe and breathe air containing oxygen though they get it out of the ocean of water in which they live and do not need like whales and porpoises to come to the surface that a man cannot live without breathing his patent to everybody he may cease eating or drinking for a while even for days though not without much suffering he cannot cease breathing for more than a few minutes at the most or he will die as he moves to and fro on the floor of the air ocean he draws every few seconds into his lungs a certain amount of air and as regularly sends at least a portion of it out again this we know for ourselves from actual experience we may not be able to explain how or why we breathe but that we do breathe and must breathe we know well there are many things in this world which we feel to be true with the knowledge which amounts to absolute certainty while yet we are not in the least able to explain why they are so or from what causes they spring even the lower animals are aware of the need of air an experiment was once tried of putting a cat into an air pump enclosure and pumping out the air or pussy felt it going and she had the sense to try to cover with her little paw the hole through which the air was withdrawn seeking thus to hinder the escape of any more it is to be hoped that those who tried the experiment were content with so much and did not put her to further needless suffering of course the cat could not have told why she needed the air and by what particular process the air entering her lungs kept her in life and health she only knew her own need and knew what met that need without any theories and without any definitions she was aware and many human beings no wiser scientifically than was pussy are aware too that not to have air for breathing means death some higher needs of our nature are after the same mode felt and met without clear understanding on our part either of exactly what need we feel why we feel it and how that need is supplied a grown man of full ordinary height and size sitting still breathes on an average about 18 times each minute if he walks fast still more if he runs mounts a steep hill or lifts a heavy weight his breathing is quickened each time that he breathes he draws into his chest about 20 cubic inches of air perhaps somewhere about three quarters of a pint and sends out again almost as much in so doing he does not empty his lungs for the lungs of a man contain usually between one and two quarts of air the whole amount is undergoing change constantly but gradually and not at every breath since a good deal of air always remains behind now the air which a man breathes out is markedly different from the air which he breathes in there are four main points of difference it is much hotter it is much damper it contains much less oxygen it contains much more carbonic acid the jay may be ever so cold the water may be frozen into ice the ground may be hard the air that he breathes in may be down in temperature as low as the freezing point all this makes no difference the air which he breathes out will be up to nearly 100 degrees or almost as hot as his blood oppressive summer heat the day may be ever so sultry the ground may be caked in hard little moisture may be floating in the atmosphere the air breathed in may be dry as air can be all this again makes no difference the air breathed out will be soaked with vapor of water turning rapidly in the cold outside air to a little fog of visible water droplets does not a child know this when he breathes on his slate that he may be able to rub out faulty figures in the course of 24 hours nearly half the pint of water is commonly given off from a man's lungs but the amount varies much whatever the day may be hot or cold dry or damp the air breathed into a man's lungs is simple atmospheric air it is the usual mixture of oxygen and nitrogen with a slight addition of water gas and so my Newton amount of carbonic acid has to be hardly worth thinking about but when the air is poured out again from the lungs an extraordinary change has passed upon it the quantity of nitrogen alone is almost unchanged the quantity of oxygen has run down to only a little over three quarters as much as it was the quantity of carbonic acid has shot up to almost one quarter of the former amount of oxygen in other words the lost oxygen is nearly replaced by carbonic acid if a pint of air as breathed in were divided into 10 000 tiny equal portions the gases being separated nearly 8 000 of them would be nitrogen more than 2000 would be oxygen and only three would be carbonic acid a pint of air being not very much more than the quantity drawn in by a large man the same amount breathed out would contain about the same amount as before of nitrogen only about 1500 portions of oxygen some 470 portions of carbonic acid gas and a greatly increased amount of water vapor where has the oxygen gone and where has the carbonic acid come from the answer is very simple it is a case of combustion when a lump of coal or a candle burns do you remember what happens there is a waste of a substance there is a giving forth of heat the hydrogen in the coal or wax unites with oxygen from the air and makes vapor of water the carbon in the coal or wax unites with oxygen from the air and makes carbonic acid gas that is a case of combustion of rapid burning combustion is not always rapid it may be very gradual indeed as we have seen in the case of coal fields there buried forests of trees were slowly transformed by a kind of underground combustion into a species of charcoal in the case of a man we have slow combustion again not nearly so slow as the combustion of buried forests but not nearly so fast as the combustion of a burning candle or a piece of coal it is rapid enough for the giving off of a great deal of heat which heat is born by rushing streams of blood to all parts of the body it is not rapid enough for the burning parts to become red hot combustion is or at least includes the union under a certain degree of heat of a substance such as carbon with the oxygen of the air that is just what goes on night and day in the body of every man woman and child living not to speak of lower creatures the carbon of which they are largely made unite perpetually with oxygen drawn into the lungs by breathing and the two united are given off as carbonic acid gas in the burning of a piece of wood the carbon of the wood is needful also the oxygen of the air also enough heat to cause their union in the slower combustion of a man's body these three are equally needed the carbon of his body the oxygen of the air and sufficient heat to make them combine something else is necessary also before burning can begin the carbon and oxygen must touch and the heat which is applied must reach them both at the point of contact we see easily how this comes about in the matter of a burning candle or lump of coal the air flows over and around so that fresh particles of oxygen are constantly running against particles of carbon in the wax or coal while heat spreads to other parts but in the case of animal combustion the matter is not so simple the mass of carbon helping to compose a man's body is chiefly inside him and the mass of oxygen in the air is chiefly outside him so how are the two to come together and how is sufficient heat to be brought to bear with regard to the heat one can say little the high steady temperature of a man's frame is still in great measure a mystery partly accounted for by the combustion always going on within that frame but connected with the greatest mystery of all the life which reigns there it is easy to see that the right measure of heat once given the combustion once started burning will go steadily on whether in a fire of coal or in the fire of a man's body so long as favorable conditions last that is to say it will continue until either the supply of fuel of food or the supply of oxygen shall run short but how the fire which set that combustion going in man was first applied is another question i know no answer to it except in words familiar to us from infancy god breathed into his nostrils the breath of life and man became a living soul now about the needful contact of carbon and oxygen in a man's body more than one great and worldwide circulation has been spoken of in earlier chapters in the frame of a man we have a yet more wonderful circulation though on a smaller scale than that of gases it is more wonderful than the circulation of any mere material substances for this is a circulation on which life hangs nice and day day and night it goes on hour by hour minute by minute it continues rivers of blood rush at full speed through the larger vessels of a man's body then it's dividing into smaller streams these career through lesser vessels subdividing again and yet again till the tiny capillaries the most minute vessels of all countless in number and reaching everywhere are filled with infinitesimal rivulets from the capillaries the streams meet converging into larger and yet larger vessels till once more they reach their starting point and begin the round anew through all the round as the stream flows onward it is incessantly leaving part of itself behind and incessantly taking up something new on its way two kinds of vessels carry the blood these are called arteries and veins the arteries bear blood away from the heart the veins bear it back to the heart the arteries contain bright scarlet blood the veins contain dark purplish blood often called black blood between the two kinds there was a marked difference in most respects except coloring they are much alike as to make in one respect they are gravely unlike the red blood of the arteries has in it plenty of oxygen and very little carbonic acid the purple blood of the veins has in it much less oxygen and much more carbonic acid when the stream starts from the heart it is red and pure but as it passes through different parts of the body it incessantly hearts with its oxygen for the needs of the body not only this it incessantly takes up and carries away useless particles of matter waste materials no longer needed there so gradually the pure red blood loses its purity and brightness getting overloaded with carbonic acid and other hurtful matters by the time it has worked its way back through the veins to nearly its starting point it is in dire need of being charged anew with oxygen but how by being brought into touch with the outside atmosphere taking there from new supplies of oxygen and giving off superfluous supplies of carbonic acid a certain amount of this has taken place already whenever tiny streams have flowed in minute vessels close under the skin of the body where the air could reach them their carbonic acid has been given off but much more is required is indeed an absolute necessity if the dark blood flow again and again through the man's body he must die the blackened stream reaches the lungs and is there spread out over a wonderful network of tiny vessels all enclosed in a skin so delicate that air can pass through it without the least difficulty and then why then those tiny vessels are met by pure air from outside atmospheric air laden with oxygen rushing in with every breath each breath drawn in brings fresh supplies of oxygen and each breath poured out gets rid of new supplies of dangerous carbonic acid so very soon the blood is sent careening on its way no longer purple but bright red no longer laden with bad materials but full of good gas once more it hastens through the man's frame leaving more oxygen on the road carrying away more evil things which if left must endanger the man's life now what is the direct object of all this oxygen why such constant supplies of it carried into the lungs by breathing born from the lungs by the blood to all parts of the system to support combustion simply that the man is slowly burning if he is to live he must burn combustion is life stagnation is death so long as the fires are kept alive in him he lives let them die out and he dies combustion means the union of oxygen with other substances for instance with carbon to make carbonic acid gas with hydrogen to make water gas both these processes go on constantly inside a man burning means burning away not simply glowing with a changeless heat man burns away as distinctly as a candle burns away the more energetically he lives the faster he burns away and the greater his need for fresh air and food if food sees as he dies soon if air sees as he dies immediately whatever else he has or has not he must have sufficient air perpetually to over master and carry off the superfluous carbon of his body otherwise the carbonic acid will speedily overpower him second in importance to this is the keeping of a just balance between exertion and food the more exertion the better so long as the amount of waste can be always and steadily repaired life means the putting forth of energy of heat of force life means incessant waste and incessant renewal life means perpetual circulation and perpetual need of fresh purification life means unceasing combustion by which i mean simply animal life the life of the body there is a life above this which does not depend on movement of gases liquids and solids within and without the human frame yet even in the higher spirit life of man it seems as if somewhat the same laws prevailed there too stagnation means decay absence of energy means death there too without circulation without perpetual renewal without incessant taking in and giving out a healthy existence is not possible and of chapter 11 recording by john brandon chapter 12 of the ocean of air meteorology for beginners this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Greg Giordano the ocean of air meteorology for beginners by Agnes G. Byrne how plants work but if from the burning of every substance which contains carbon if from the breathing of every creature which has life streams of carbonic acid are being perpetually poured into the atmosphere how is it that the whole ocean of air has not by this time become unfit for mankind a room filled with people and having no outlet would after a while be incapable of supporting life what should prevent the entire atmosphere once a healthy mixture of gases from changing in the course of ages to a noxious and deadly mixture there are enormous quantities of carbon upon earth if this great mass of carbon through burning by fire through breathing of animals through decay of dead vegetation and dead bodies became gradually united to yet greater masses of oxygen drawn from the air and remain permanently in that condition what other result could follow exactly that which takes place in a fast shut room containing an open pan of burning charcoal and no chimney exactly that would take place with the ocean of air the amount of alkygen would grow steadily less and less the amount of carbonic acid would grow steadily more and more till all living creatures on earth would die of suffocation things would inevitably be so but for the antidote provided this antidote is found in the green vegetation of earth plant existence is not less wonderful or less mysterious than animal existence though different in kind plants live grow take in food give out vapor breathe digest even work and sleep alternately as animals do only not after the same modes a plant can no more live and grow can no more keep in health and do its rightful tasks without a sufficient supply of light of air and of food than the man can plants by which I mean grasses herbs shrubs and trees as well as all small garden and field plants are fed in more ways than one through their roots they suck up liquid out of the earth not pure water the water containing many different kinds of substance in the liquid form drawn by the water from various kinds of earth through which it has filtered this liquid food passes slowly upwards through the slender channels of the stem or trunk spreading through countless tinier vessels like the capillaries in a man's body till it reaches the minute veins of the leaves there much the same takes place with the sap of the plant as we have seen to take place with the blood of a man on reaching the vessels in his lungs or close to his skin it flows in little vessels made of so thin and delicate a membrane that gas can easily pass through and thus the sap comes into contact with the outer air but the sap is exposed to light as well as to air which is not the case in the man's lungs the leaves of a tree are often and justly called the lungs of a tree in some way a strange change is worked in the sap when it reaches the green leaves or probably this change has begun in its upward passage through the stem and branches to be perfected in the leaves a change of some sort always but by no means always the same change but when the sap is passed through the tiny leaf veins and slowly returns into the twigs the bowels in the trunk traveling downward it is no longer the same liquid that first rose from the roots into the stem traveling upward what it has become depends upon the kind of tree in one tree or plant the sap has become sweet like sugar in another it has become acid in another sticky like gum in one it is wholesome and good for food in another it is rank poison how these different results are broad about no man can explain to us we do not even know what causes the sap to rise upward through the tubes of a tall tree still less can we describe the manner of its transformation into such different liquids some plants will grow in certain soils and will not grow in others that was because the particular food that they need is not to be sucked out of all soils each particular kind of tree wherever it may grow always produces or secretes as it is called the same particular kind of sap or juice the deadly nightshade can never in any soil or climate be made to secrete harmless sugar juice the orange tree can never be induced to secrete lemon juice the gum tree can never be trained to secrete ought else but gum the mysterious power which we call life dominates the whole existence of the plant it controls the form and manner of growth forces the rejection of some materials and the choice of others uses the selected materials after definite mode how and why each plant should follow its own mode at some other mode it is impossible to say certain characteristics are stamped upon its being and it acts in accordance with those characteristics this is all we know and that is no explanation the gardener may modify these natural tendencies by training but the gardener's power is limited do what he will the deadly nightshade is deadly nightshade still and the orange tree never becomes a fig tree plants have another mode of taking in food as well as through the roots this is through the leaves the leaves are not only a perfect laboratory with the most delicate appliances for the manufacturer of various juices out of crude material in addition to this they have another work to carry out a work of worldwide importance to the human race they have to act as the antidote of which i have spoken they have to undo that which men and beasts and burning substances are always doing on earth the leaves of a plant or tree have an extraordinary power of sucking carbonic acid gas out of the atmosphere and drawing it into themselves for the use of the plant it is an absolute necessity that every plant and tree should have a goodly amount of carbon from somewhere for growing purposes plants like men are built up of carbon so may be obtained through their roots out of the earth but by far the greater part is gained by the leaves straight from the air for men as for plants carbon is a necessity of growth but a man cannot receive it straight from the air he gets his share in quite another way through those very plants which have first secured and made it ready fitting it for his use every time a man feeds upon vegetable food or upon animals which are fed upon vegetable food he takes into his frame carbon prepared by plants for his use footnote plants therefore are the hewers of wood and drawers of water for other living things and this property which they so largely possess of constructing for materials not directly available for animal nutrition substances which are so is found to be uniformly attended with the presence of a peculiar green coloring matter known as chlorophyll huxley and dire encyclopedia Britannica end of footnote you have seen already the animals do in breathing exactly what is done by burning coal or wood they carry on a work called oxidation they unite some of the carbon in themselves to some of the oxygen out of the air at a certain degree of heat and send forth streams of carbonic acid gas the plants of earth large and small by means of their delicate green leaves do precisely the opposite of this they seize upon the carbonic acid gas which ever growing in amount threatens in time to fill the air ocean and stifle every living creature by some mysterious means helped by the sunlight they separate the carbon and the oxygen of which it is made they hold the carbon fast and send it down little channels for the use of the growing plants lastly they pour back into the atmosphere the pure life-supporting oxygen broken loose from its union with the carbon and wants more fit to be breathed by man see what an extraordinary contrast between animals and plants suppose you have a shut room containing several people and containing also in a bow window where the sun shines brightly a mass of plants each person there is stealing oxygen from the air and sending out streams of carbonic acid as fast as he can each plant there is taking in carbonic acid from the air and sending out streams of oxygen as fast as it can so the man undoes the work of the plant and the plant undoes the work of the man each counteracting the other if you have exactly the right number of plants to balance the people present if the plants are all in a healthy condition and if there is plenty of sunlight then there is no fear that the air of the room will become too full of carbonic acid gas for just as fast as the people breathed out the plants will take it in supplying its place with oxygen gas but such a balance could only be secured in daytime the leaves have no power to carry on the work of which i am telling except with the help of sunlight so markedly is this the case the plants are sometimes said to be made of carbon and sunlight and when coal is burnt it is said to be giving out in heat the bottled up sunlight of past ages not long ago it was customary to say that plants breathe in a mode exactly the reverse of our mode that while man in breathing kept the oxygen and got rid of the carbonic acid plants in breathing kept the carbonic acid and got rid of the oxygen now however scientific men do not as a rule regard this operation as the breathing but rather as the digestion of a plant so if the leaves act the part of lungs and exposing to outside air the sap or blood of the plant they also act the part of the stomach and digesting the food obtained from the air plants like animals do breathe and must breathe at least when actively living and growing not only in the day but also at night plants like animals must have oxygen they like ourselves breathe in air keeping the oxygen and getting rid of the carbonic acid this goes on constantly digestion does not go on constantly it ceases at night for leaves can only digest in sunlight so by the breathing of a plant is meant something analogous to the breathing of an animal by the digestion of a plant is meant the peculiar work done by green leaves and breaking up carbonic acid under sunlight keeping one part getting rid of the other it has been long known that plants send forth oxygen by day and carbonic acid at night if they breathe like animals they doubtless give forth carbonic acid both night and day that however which escapes in the daytime is at once caught up again and digested as food only the oxygen being freed so practically no carbonic acid is added to the atmosphere by a plant in daylight at night when digestion stops it is able to escape for this reason plants in the bedroom at night are not wholesome in any case and would ever be the precise explanation of these processes there can be no doubt that the great work of green leaves upon earth is out of air purification the work must be of necessity be fitful and intermittent and such a climate as ours in the tropics the luxuriant masses of vegetation carry it on with ceaseless vigor month after month so long as the blazing sun is above the horizon there is the real safeguard for the life of mankind in the ocean of air there is the mighty antidote to carbon burning to animal breathing all over the world the relays of air are born from north and south in ceaseless streams for perpetual repurification end of chapter 12 recording by greg giardano newport richie florida chapter 13 of the ocean of air meteorology for beginners this is a liber vox recording all liber vox recordings are in the public domain for more information or to volunteer please visit liber vox.org the ocean of air meteorology for beginners by agnes giburn water in the atmosphere air is never perfectly dry we talk of damp air or dry air and of very dry air but the dryness is at most only comparative atmospheric air is not found utterly devoid of moisture the use of the word very shows this if the air were absolutely dry we should not call it very dry a perfect square is not very square but simply square if something is spoken of as very square we understand that the said thing is not usually square and that for once it nearly approaches squareness so when we talk of air that is very dry we only mean that it approaches more nearly than usual to complete dryness the ocean of air which surrounds our earth is commonly spoken of as the atmosphere more strictly it consists of two atmospheres each separate from the other there is the atmosphere of dry air formed of oxygen and nitrogen mixed together and there is also the atmosphere of water vapor the atmosphere of dry air remains always gaseous except when locally interfered with for the moment by burning and breathing operations it also remains the same in quantity and quality the atmosphere of vapor is in a state of perpetual change the amount of vapor present in any one place is always varying these two atmospheres float together intermingled in the closest companionship the particles of each lie among and between the particles of the other this is a common state of things with gases because gas particles are far apart two solids or liquids cannot occupy the same spot but two bodies of gas or vapor do so without difficulty strictly speaking the loose floating particles of one slip freely among the loose floating particles of the other as the atmosphere of dry gases is very much the more abundant of the two we usually speak of it as the atmosphere par excellence and of the floating moisture as an important and changeable ingredient in the atmosphere enormous quantities of watery vapor float at all times in the ocean of air for the air is incessantly at work hiding away supplies of vapor in its secret recesses giving forth fresh supplies for the use of the world you have watched the long cloud of white fog pouring from the funnel of a steam engine not smoke for smoke is unburnt carbon and not steam for real steam is invisible but white fog or mist springing from steam you have noted how quickly it vanishes that fog is made entirely of water when it disappears the water has passed into the atmosphere there to float as invisible vapor you have observed a similar white fog pouring from the spout of a kettle more correctly from the stream of invisible steam which issues from the spout when the water boils if you look closely you will notice a little space between the end of the spout and the beginning of the small white cloud this little space apparently empty is filled with real invisible steam that cloud is all made of water and it too passes rapidly away as vapor into the air you have seen how a wet cloth hung before a fire or placed with warm sunshine will gradually lose its dampness and become dry all the water which soaked that cloth and made it wet has passed into the air to float as water vapor in the atmosphere you have known ponds and rivulets shrink and lessen perhaps quite dry up in a spell of hot weather the whole body of pond or rivulet water has been so to speak drunk up by the thirsty air no longer visible as liquid water it wanders free and unseen as vapor through the ocean of air this passing of water into the atmosphere is called evaporation water as already explained maybe at any time in any one of the three forms of matter the solid the liquid and the gaseous it is solid as ice it is liquid as water it is gaseous as steam or vapor that which causes it to pass from one state to another is increase or decrease of heat the effect of heat upon almost all substances is to make them expand or grow larger the effect of cold is to make them contract or grow smaller suppose you have an iron ball which will just drop through a ring with no spare space left if you heat the ball it will grow larger and will rest upon the ring instead of falling through the heat has expanded the substance driving farther apart the minute separate particles of which it is made so that as a whole it must take up more room when a solid substance is melted or thawed into a liquid the liquid as a rule occupies more room than the solid did it has expanded or grown larger its particles are further apart there are a few apparent exemptions to this rule owing to the manner in which solids are formed through crystallization when water freezes into ice the minute ice needles cross one another in a peculiar method of arrangement by which large unfilled gaps are left in the midst of them thus ice is really larger and occupies more space than the same quantity of water even though the tiny particles of each ice needle have actually drawn more closely together the same thing is seen with the solid and liquid forms of iron of bismuth and of antimony well for us that it is so with water if water becoming a solid shrink in size and increased in weight results would be disastrous every water surface in the winter of temperate regions would form on the first frosty day a layer of ice the ice would shrink and remain at the bottom another and another ice layer forming above and shrinking to bear company in this manner every pond every lake nay even ocean waters not far north would become dense masses of ice no moderate summer heat would suffice to thaw these masses that iron and bismuth follow the same rule is interesting but comparatively unimportant to mankind that water should do so does appear to be a most merciful provision for the world generally when a liquid substance is changed into a gas or vapor the gas or vapor takes up always a great deal more room than the liquid did how much more depends on its degree of heat in any case it expands enormously the particles floating far apart this change of size or volume goes on to such an extent that one cubic inch of water will spread out into nearly one cubic foot of steam a solid substance is of a certain definite shape and occupies a definite amount of room the amount varies slightly since even a solid swells and shrinks a little by being made hotter or colder the gold ring which just fits your finger on a cold day will probably be rather tight on a very hot day for your finger is apt to swell with the heat and to shrink with the cold to a greater degree than the gold of the ring still the variation with the solid is at its most slight the shape and generally speaking the size are constant if put into a large empty box it will not alter its shape or grow larger to fill the box a liquid substance has no definite shape of its own but flows easily into the outlines of any vessel that may contain it while it too occupies a definite amount of space a pint of water poured from a pint measure into a quart measure will not swell out to fill the bigger vessel it will only spread to cover the bottom remaining in quantity one pint still most liquids like solids gently expand with heat and shrink with cold but to no great extent as gas or vapor has no particular shape and occupies no particular space we may talk of a cubic foot of steam referring to the stream as it first springs from boiling water or to a cubic foot of air at a certain distance above earth's surface in reality the amount of steam or vapor gas or air which fills a small vessel will also fill a large one gas is so elastic as to be able to stretch itself to any extent in the matter of compressing gas into a smaller space there are early limits for a gas will by no means endure any amount of squeezing the separate particles of gas more especially of a heated gas are always striving to get farther apart to give them extra room is to fall in with their inborn tendencies to press them closer together is to go in the teeth of those natural tendencies suppose you have a pint measure full of gas of any gas you choose or if you like of common air and a court measure emptied of air you pour the contents of the pint measure into the court measure taking care to let none escape the pint of gas will at once expand to fill the court measure you then pour the contents of the court measure into a gallon measure with the same precautions the gas will instantly expand to fill the gallon measure in thus expanding the gas or air grows thinner if you pull out a piece of elastic it becomes thinner as well as longer the particles of gas move farther and farther apart a less and less number of them are to be found in each cubic inch of space but however large the containing vessel may be there is always as much gas in one part as in another part the gas is always equally distributed through the hole it always accommodates itself to the size and shape of the vessel stretching out in every direction so as to pervade the entire space it is more or less dense according to the space it has to fill the density of the air in the lower levels of the air ocean is much affected by heat one cold morning we will suppose a man encloses exactly one cubic foot of air and weighs it he weighs not the vessel containing the air but the air itself just that amount of it which will fill without stretching a measure one foot high one foot broad and one foot deep there are delicate instruments made for such delicate wing operations the weather changes and becomes much warmer some hours later the man does the same again he encloses another cubic foot of air and weighs it he finds that the second supply being warmer is lighter in weight than the first supply the reason why is not distant increased heat has driven the particles of air farther apart the number of floating particles in a cubic foot of air is not so great as a few hours earlier something more than a cubic foot of air would now be required to weigh the same as a cubic foot of air did in the early morning for the material of which it is made is stretched out more widely therefore it has grown thinner if we knew exactly how many air particles were in the cubic foot of cold air and if we could now enclose a supply of warm air containing just that number of particles it would weigh the same as the cubic foot of cold air but it would not be a cubic foot of air it would be larger warm air near the level of the sea is always lighter than cold air warm air swells occupies more room and is disposed to flow upward cold air shrinks takes up less room and is disposed to flow downward this is equally true of the two interwoven atmospheres that of dry gases and that of water vapor in the higher levels of the ocean of air a somewhat different state of things is found the density of the air is mainly the result of the earth's attraction though also affected by heat and cold if it were not for the changing power of gravitation each particle of air would rush as far as possible from all other particles of air till the entire atmosphere had melted away into distant space this binding power steadily lessens mile by mile with greater distance from earth's surface and the weight of the down pressing air above lessens also so in upper regions of the atmosphere air expands not from heat but from lessened weight and attraction the cold in those higher levels is intense nevertheless the air particles spring farther apart and the air grows thinner the atmosphere of vapor reaches to a great height but like the atmosphere of dry gases it is far less dense above than below end of chapter 13