THE
REASON WHY:

A CAREFUL

COLLECTION OF MANY HUNDREDS OF REASONS FOR THINGS
WHICH, THOUGH GENERALLY BELIEVED, ARE
IMPERFECTLY UNDERSTOOD.

A BOOK OF CONDENSED SCIENTIFIC KNOWLEDGE FOR THE MILLION.

By THE AUTHOR OF "INQUIRE WITHIN."

This collection of useful information on "Common Things" is put in the interesting form of "Why and Because," and comprehends a familiar explanation of many subjects which occupy a large space in the philosophy of Nature, relating to air, animals, atmosphere, caloric, chemistry, ventilation, materia medica, meteorology, acoustics, electricity, light, zoölogy, etc.

NEW YORK:
DICK & FITZGERALD, PUBLISHERS,
No. 18 ANN STREET.

PREFACE.

We are all children of one Father, whose Works it should be our delight to study. As the intelligent child, standing by his parent's knee, asks explanations alike of the most simple phenomena, and of the most profound problems; so should man, turning to his Creator, continually ask for knowledge. Not because the profession of letters has, in these days, become a fashion, and that the man of general proficiency can best work out his success in worldly pursuits; but because knowledge is a treasure which gladdens the heart, dignifies the mind, and ennobles the soul.

The occupation of the mind, by the pursuit of knowledge, is of itself a good, since it diverts from evil, and by elevating and refining the mind, and strengthening the judgment, it fortifies us for the hour of temptation, and surrounds us with barriers which the powers of sin cannot successfully assail.

It is not contended that the mere acquisition of knowledge will either ensure a good moral nature, or convey religious truth. But both religion and morals will find in the diffusion of knowledge a ground work upon which their loftier temples may discover an acceptable foundation.

The man who comprehends the order of Nature, and the immutability of Divine law, must of necessity bring himself in some degree into accordance with that order, and under submission to the law: hence the tendency of knowledge will always be found to harmonise the fragment with the mass, and to subvert the evil to the good.

The troubles of the world have arisen from the want of knowledge, not from the possession of it. And in proportion as man becomes an intelligent and reflective being, he will be a better creature in all the relations of life. If these benefits, vast and incalculable as they are, be the real tendency and result of knowledge, why is ignorance allowed to remain, and why is the world still distracted by error?

It is because the moral and intellectual qualities of man are, like all creations and gifts of God, the subjects of development, whose law is progression.

We can aid human improvement, but we cannot unduly hasten it. Whenever man has sprung too rapidly to a conclusion, he has alighted upon error, and has had to retrace his steps.

The greatest philosophers have been those who have clung to the demonstrative sciences, and have held that a simple truth well ascertained, is greater than the grandest theory founded upon questionable premises. Newton made more scientific revelations to mankind than any other philosopher; and his discoveries have borne the searching test of time, because he snatched at nothing, leaped over no chasm to establish a favourite dogma; but, by the slowest steps, and by regarding the merest trifles, as well as the highest phenomena, he learnt to read Nature correctly. He discovered that her atoms were letters, her blades of grass were words, her phenomena were sentences, and her complete volume a grand poem, teaching on every page the wisdom and the power of an Almighty Creator.

When he observed an apple fall to the ground, he asked the "Reason Why;" and in answer to that enquiry, there came one of the grandest discoveries that has ever been recorded upon the book of science. With that discovery a flood of light burst upon the human mind, illustrating in a far higher degree than had ever previously been conceived, the vastness of Almighty Power.

Why should not each of us enquire the "Reason Why" regarding everything that we observe? Why should we mentally grope about, when we may see our way? When addressed in a foreign tongue, we hear a number of articulated sounds, to which we can attach no meaning; they convey nothing to the mind, make no impression upon the in-dwelling soul. When those sounds are interpreted to us, in a language that we can understand, they impart impressions of joy, hope, surprise, or sorrow, because the words convey to us a meaning. In like manner, if we fail to understand Nature, its beauties, its teachings are lost. Everything speaks to us, but we do not understand the voices. They come murmuring from the brook, trilling from the bird, or pealing from the thunder; but though they reach the ear of the body, they do not impress the listening spirit.

Every flower, every ray of light, every drop of dew, each flake of snow, the curling smoke, the lowering cloud, the bright sun, the pale moon, the twinkling stars, speak to us in eloquent language of the great Hand that made them. But millions lose the grand lesson which Nature teaches, because they can attach no meaning to what they see or hear.

"The Reason Why" is offered as an interpreter of many of Nature's utterances. Great care has been taken that these interpretations may be consistent with the latest knowledge, obtained from the highest sources. If the author finds that his work if accepted for the good of those who seek not only to know, but to understand, he will make it his constant care to read the Book of Nature, and to add to the pages of this volume whatever interpretations the progress of enquiry and discovery may demand and supply.

INDEX, AND INDEX LESSONS.

☞ The numbers refer to the Questions. The Index Lessons do not correspond with the Chapters, but are designed to bring together in their alphabetical connection, all the Questions and Answers upon each particular subject included in the work.

"God looked down from heaven upon the children of men, to see if there were any that did understand that did see God."—Psalm liii.

THE REASON WHY.

CHAPTER I.

1. Why should we seek knowledge?

Because it assists us to comprehend the goodness and power of God.

And it gives us power over the circumstances and associations by which we are surrounded: the proper exercise of this power will greatly promote our happiness.

2. Why does the possession of knowledge enable us to exercise power over surrounding circumstances?

Knowledge enables us to understand that, in order to live healthily, we require to breathe fresh and pure air. It also tells us that animal and vegetable substances, undergoing decay, poison the air, though we may not be able to see, or to smell, or otherwise discover the existence of such poison. Knowing this, we become careful to remove from our presence all such matters as would tend to corrupt the atmosphere. This is only one of the countless instances in which knowledge gives us power over surrounding circumstances.

3. Name some other instances in which knowledge gives us power.

Knowledge of Geography and of Navigation enables the mariner to guide his ship across the trackless deep, and to reach the sought-for port, though he had never before been on its shores.

Knowledge of Chemistry enables us to separate or to combine the various substances found in nature. Thus we obtain useful and precious metals from what at first appeared to be useless stones; transparent glass from pebbles, through which no light could pass; soap from oily substances; and gas from solid bodies.

"Give instruction to a wise man, and he will be yet wiser; teach a just man, and he will increase in learning."—Proverbs ix.

Knowledge of Medicine enables the physician to overcome the ravages of disease, and to save suffering patients from sinking prematurely to the grave.

Knowledge of Anatomy and of Surgery enables the surgeon to bind up dangerous fractures and wounds, and to remove, even from the internal parts of bodies, ulcers and diseased formations that would otherwise be fatal to life.

Knowledge of Mechanics enables man to increase his power by the construction of machines. The steam-ship crossing the ocean in opposition to wind and tide, the railway locomotive travelling at 60 miles an hour, and the steam-hammer beating blocks of iron into useful shapes, are evidences of the power which man acquires through a knowledge of mechanics.

Knowledge of Electricity enables man to stand in comparative safety amid the awful war of the elements. Lightning, the offspring of electricity, has a tendency to strike upon lofty objects by which it may be attracted. By its mighty powers churches or houses may be instantly levelled with the dust. But man, knowing that electricity is strongly attracted by particular substances, raises over lofty buildings rods of steel communicating with bars that descend into the ground. The lightning, rushing with indescribable force toward the steeple, is attracted by the bar of steel, and conducted harmlessly to the earth. Man may thus be said to take even lightning by the hand, and to divert its destroying force by the aid of Knowledge. And in countless other instances "Knowledge is Power."

CHAPTER II.

4. Why do we breathe air?

Because the air contains oxygen, which is necessary to life.

5. Why is oxygen necessary to life?

Because it combines with the carbon of the blood, and forms carbonic acid gas.

"Be not as the horse, or as the mule, which have no understanding: whose mouth must be held with the bit and bridle."—Psalm xxxii.

6. Why is this combination necessary?

Because we are so created that the substances of our bodies are constantly undergoing change, and this resolving of solid matter into a gaseous form, is the plan appointed by our Creator to remove the matter called carbon from our systems.

7. Why do our bodies feel warm?

Because, in the union of oxygen and carbon, heat is developed.

8. What is this union of oxygen and carbon called?

It is called combustion, which, in chemistry, means the decomposition of substances, and the formation of new combinations, accompanied by heat; and sometimes by light, as well as heat.

9. What is formed by the union of oxygen and carbon?

Carbonic acid gas.

10. What becomes of this carbonic acid gas?

It is sent out of our bodies by the compressure of the lungs, and mingles with the air that surrounds us.

11. Is this carbonic acid gas heavier or lighter than the air?

Pure carbonic acid gas is the heaviest of all the gases. That which is sent out of the lungs is not pure, because the whole of the air taken into the lungs at the previous inspiration has not been deprived of its oxygen, and the nitrogen is returned. Therefore the breath sent out of the lungs may be said to consist of air, with a large proportion of carbonic acid gas.

12. What is the composition of air in its natural state?

It consists of oxygen, nitrogen, and carbonic acid gas, in the proportions of oxygen 20 volumes, nitrogen 79 volumes, and carbonic acid gas 1 volume. It also contains a slight trace of watery vapour.

13. What is the state of the air after it has once been breathed?

It has parted with about one-sixth of its oxygen, and taken up an equivalent of carbonic acid. And were the same air to be breathed six times successively, it would have parted with all its oxygen, and could no longer sustain life.

"A prudent man forseeth the evil, and hideth himself; but the simple pass on, and are punished."—Proverbs xxvii.

14. Is the impure air sent out of the lungs lighter or heavier than common air?

At first, being rarefied by warmth, it is lighter. But, if undisturbed, it would become heavier as it cooled, and would descend.

15. Why is it proper to have beds raised about two feet from the ground?

Because at night, the bed-room being closed, the breath of the sleeper impregnates the air of the room with carbonic acid gas, which, descending, lies in its greatest density near to the floor.

16. What are the chief sources of carbonic acid gas?

The vegetable kingdom (as will be hereafter explained), the combustion of substances composed chiefly of carbon, the breathing of animals, and the decomposition of carbonic compounds.

17. Is breathing a kind of combustion?

It is. In the breathing of animals, the burning of coals, or of wood, or candles, &c., similar changes occur. The oxygen of the air combines with the carbon of the substance said to be burnt, and forms carbonic acid gas, which unfits the air for the purposes of either breathing or of burning, until it has been renewed by admixture with the air.

18. What is carbon?

It is one of the elementary bodies, and is very abundant throughout nature. It abounds mostly in vegetable substances, but is also contained in animal bodies, and in minerals. The form in which it is most familiar to us is that of charcoal, which is carbon almost pure.

19. What is meant by an elementary body?

An elementary body is one of those substances in which chemistry is unable to discover more than one constituent. For instance, the chemist finds that water is composed of oxygen and hydrogen. Water is therefore a compound body. But carbon consists of carbon only, and therefore it is called a simple, or elementary body.

"Where no wood is, there the fire goeth out: so where there is no tale-bearer, the strife ceaseth."—Proverbs xxvi.

20. Why is it dangerous to burn charcoal in rooms?

Because, being composed of carbon that is nearly pure, its combustion gives off a large amount of carbonic acid gas.

21. What is the effect of carbonic acid gas upon the human system?

It induces drowsiness and stupor, which, if not relieved by ventilation, would speedily cause death.

22. What is the reason that people feel drowsy in crowded rooms?

Because the large amount of carbonic acid gas given off with the breaths of the people, makes the air poisonous and oppressive.

23. What other causes of drowsiness are there?

The candles, gas, or fires that may be burning in the rooms where people are assembled. Three candles produce as much carbonic acid gas as one human being; and it is probable that one gas-light produces as much carbonic acid gas as two persons.

24. Have people ever been poisoned by their own breaths?

In the reign of George the Second, the Rajah of Bengal took some English prisoners in Calcutta, and put 146 of them into a place which was called the "Black Hole." This place was only 18 feet square by 16 feet high, and ventilation was provided for only by two small grated windows. One hundred and twenty-three of the prisoners died in the night, and most of the survivors were afterwards carried off by putrid fevers. Many other instances have occurred, but this one is the most remarkable.

CHAPTER III.

25. What is oxygen?

Oxygen is one of the most widely diffused of the elementary substances. It is a gaseous body.

"Stand in awe and sin not: commune with your own heart upon your bed and be still"—Psalm iv.

26. Why do persons who are walking, or riding upon horseback feel warmer than when they are sitting still?

Because as they breathe more rapidly, the combustion of the carbon in the blood is increased by the oxygen inhaled, and greater heat is developed.

27. Why does the fire burn more brightly when blown by a bellows?

Because it receives, with every current of air, a fresh supply of oxygen, which unites with the carbon and hydrogen of the coals, causing more rapid combustion and increased heat.

28. Why does not the oxygen of the air sometimes take fire?

Because oxygen, by itself, is incombustible. The wick of a candle, which retains the slightest spark, being immersed in oxygen, will instantly burst into a brilliant flame; and even a piece of iron wire made red-hot, and dipped in oxygen, will burn rapidly and brilliantly. Oxygen, though non-combustible of itself, is the most powerful supporter of combustion.

29. Why do we know that oxygen will not burn of itself?

Because when we immerse a burning substance into a jar of oxygen, it immediately burns with intense brilliancy; but directly it is withdrawn from the oxygen, the intensity of the flame diminishes, and the oxygen which remains is unaffected.

30. Why do we know that oxygen is necessary to our existence?

Because animals placed in any kind of gas, or in any combination of gases, where oxygen does not exist, die in a very short time.

31. Where is oxygen found?

It is found in the air, mixed with nitrogen; in water combined with hydrogen; in the tissues of vegetables and animals; in our blood; and in various compounds called, from the presence of oxygen, oxides.

32. Why is the oxygen of the air mixed so largely with nitrogen?

Because oxygen in any greater proportion than that in which it is found in the atmosphere, would be too exciting to the animal system. Animals placed in pure oxygen die in great agony from fever and excitement, amounting to madness.

"As vinegar is to the teeth, and as smoke to the eyes, so is the sluggard to him that sent him."—Proverbs x.

33. What is nitrogen?

Nitrogen is an elementary body in the form of gas.

34. Where is nitrogen found?

It is chiefly found in the air, of which it constitutes 79 out of 100 volumes. It may be mixed with oxygen in various proportions; but in the atmosphere it is uniformly diffused. It is found in most animal matter, except fat and bone. It is not a constituent of the vegetable acids, but it is found in most of the vegetable alkalies.

35. What are acids?

Acids are a numerous class of chemical bodies. They are generally sour. Usually (though there are exceptions) they have a great affinity for water, and are easily soluble therein; they unite readily with most alkalies, and with the various oxides. All acids are compounds of two or more substances. Acids are found in all the kingdoms of nature.

36. What are alkalies?

Alkalies are a numerous class of substances that have a great affinity for, and readily combine with, acids, forming salts. They exercise peculiar influence upon vegetable colours, turning blues green, and yellows reddish brown. But they will restore the colours of vegetable blues which have been reddened by acids; and, on the other hand, the acids restore vegetable colours that have been altered by the alkalies. Alkalies are found in all the kingdoms of nature.

37. Could animals live in nitrogen?

No; they would immediately die. But a mixture of oxygen and nitrogen, in equal volumes, constitutes nitrous oxide, which gives a pleasurable excitement to those who inhale it, causing them to be merry, almost to insanity; it has, therefore, been called laughing gas.

38. Why does nitrous oxide produce this effect?

Because it introduces into the body more oxygen than can be consumed. It, therefore, deranges the nervous system, and being a powerful stimulant, gives an unnatural activity to the nervous centres and the brain.

"Lord, make me know mine end, and the measure of my days, that I may know how frail I am."—Psalm xxxix.

39. In what proportions are the atmospheric gases found in the blood?

The mean quantity of the gases contained in the human blood has been found to be equal to 1-10th of its whole volume. In venous blood, the average quantity of carbonic acid is about 1-18th, that of oxygen about 1-85th, and that of nitrogen about 1-100th of the volume of the blood. In arterial blood their quantities have been found to be carbonic acid about 1-14th, oxygen about 1-38th, and nitrogen about 1-72nd.

40. Then is nitrogen taken into the blood from the air?

Such a supposition is highly improbable. It is probably derived from nitrogenised food, just as carbonic acid is derived from carbonised food.

41. What is venous blood?

Venous blood is that which is returning through the veins of the body from the organs to which it has been circulated.

42. What is arterial blood?

Arterial blood is that which is flowing from the heart through the arteries to nourish the parts where those arteries are distributed.

43. What is the difference between venous and arterial blood?

Venous blood contains more carbonic acid, and less oxygen and nitrogen than arterial blood.

44. Will nitrogen burn?

It will not burn, nor will it support combustion.

45. What is the difference between "burning" and "supporting combustion?"

Oxygen gas will not burn of itself, but it aids the decomposition by fire of bodies that are combustible. It is therefore called a supporter of combustion. But hydrogen gas, though it burns of itself will extinguish a flame immersed in it. It is therefore said to be a body which will burn, but will not support combustion.

"As coals are to burning coals, and wood to fire; so is a contentious man to kindle strife."—Proverbs xxvi.

46. What becomes of the nitrogen that is inhaled with the air?

It is thrown off with the breath, mixed with carbonic acid gas, and flies away to be renewed by a fresh supply of oxygen.

47. Where does nitrogen find a fresh supply of oxygen?

In the atmosphere. Nitrogen is said to possess a remarkable tendency to mix with oxygen, without having a positive chemical affinity for it. That is to say, neither the oxygen nor the nitrogen undergoes any change by the union, except that of admixture. The oxygen and the nitrogen still possess their own peculiar properties. Oxygen and nitrogen are found in nearly the same proportions in all climates, and at all altitudes.

48. In combustion does any other result take place besides the union of oxygen and carbon forming carbonic acid gas?

Yes. Usually hydrogen is present, which in burning unites with oxygen, and forms water.

CHAPTER IV.

49. What is hydrogen?

Hydrogen is an elementary gas, and is the lightest of all known bodies.

50. Will hydrogen support animal life?

It will not. It proves speedily fatal to animals.

51. Will hydrogen support combustion?

Although it will burn, yielding a feeble bluish light, it will, if pure, extinguish a flame that may be immersed in it. Hydrogen will therefore burn, but will not support combustion.

52. Why will hydrogen explode, if it will not support combustion?

When hydrogen explodes it is always in combination with oxygen, or with the common air, which contains oxygen. Two measures of hydrogen and one of oxygen form a most explosive compound.

"As smoke is driven away, so drive them away: as wax melteth before the fire, so let the wicked perish at the presence of God."—Psalm xlvi.

53. Why does hydrogen explode, when mixed with oxygen, upon being brought in contact with fire?

Because of its strong affinity for oxygen, with which, upon the application of heat, it unites to form water.

54. Where does hydrogen chiefly exist?

In the form of water, where it exists in combination with oxygen. Eleven parts of hydrogen, and eighty-nine of oxygen, form water.

55. Is hydrogen found elsewhere?

It is never found but in a state of combination; united with oxygen, it exists in water; with nitrogen, in ammonia; with chlorine, in hydro-chloric acid; with fluorine, in hydro-fluoric acid; and in numerous other combinations.

56. Is the gas used to illuminate our streets, hydrogen gas?

It is; but it is combined with carbon, derived from the coals from which it is made. It is therefore called carburetted hydrogen, which means hydrogen with carbon.

57. How is hydrogen gas obtained from coals?

It is driven out of the coals by heat, in closed vessels, which prevent its union with oxygen.

58. What becomes of the water which is formed by the burning of hydrogen in oxygen?

It passes into the air in the form of watery vapour. Frequently it condenses, and may be seen upon the walls and windows of rooms where many lights or fires are burning. Sometimes, also, portions of it become condensed in the globes of the glasses that are suspended over the jets of gas. A large volume of these gases forms only a very small volume of water.

59. What becomes of the carbonic acid gas which is produced by combustion?

It is diffused in the air, which should be removed by adequate ventilation.

"I will both lay me down in peace and sleep: for thou, Lord, only, makest me dwell in safety."—Psalm iv.

60. What proportion of carbonic acid gas is dangerous to life?

Any proportion over the natural one of 1 per cent. may be regarded as injurious. But toxicologists state that five per cent. of carbonic acid gas in the atmosphere is dangerous to life.

61. What are toxicologists?

Persons who study the nature and effects of poisons and their antidotes.

62. Which kind of combustible used for lighting tends most to vitiate the air?

Assuming all the lights to be of the same intensity, the degree in which the substances burnt would vitiate the atmosphere may be gathered from the number of minutes each would take to exhaust a given quantity of air. This has been found to be: rape oil, 71 minutes; olive oil, 72; Russian tallow, 75; town tallow, 76; sperm oil, 76; stearic acid, 77; wax candles, 79; spermaceti candles, 83; common coal gas, 98; canal coal gas, 152. Thus it is shown that rape oil is most destructive of the atmosphere, and that coal gas is the least destructive.

63. Is an escape of hydrogen gas from a gas-pipe dangerous to life?

It is dangerous, first, by inhalation. There are no less than six deaths upon record of persons who were killed by sleeping in rooms near to which there was a leakage of gas.

It is dangerous, secondly, by explosion.

In 1848, an explosion of gas occurred in Albany-street, Regent's-park, London. The gas accumulated in a shop for a very short time only. It had been escaping from a crack in the meter for about one hour and twenty minutes. The area of the room was about 1,620 cubic feet. When the gas exploded, it blew out the entire front of the premises, carried two persons through a window into an adjoining yard, and forced another person on to the pavement on the opposite side of the street, where she was killed. The effect of the explosion was felt for more than a quarter of a mile on each side of the house, and most of the windows in the neighbourhood were shattered. The iron railings over the area of the house directly opposite were snapped asunder; and a part of the roof, and the back windows of another house, were carried to a distance of from 200 to 300 yards. The pavement was torn up for a considerable length, and the damage done to 103 houses was afterwards reported to amount to £20,000. Other serious explosions have taken place. The explosions of "coal damp," which frequently occur in mines, are of a similar character.

"O Lord, our Lord, how excellent is thy name in all the earth! who hast set thy glory above the heavens."—Psalm viii.

64. What proportion of hydrogen gas with atmospheric air will explode?

According to the researches of Sir Humphrey Davy, seven or eight parts of air, to one of gas, produce the greatest explosive effect; while larger proportions of gas are less dangerous. A mixture of equal parts of gas and air will burn, but it will not explode. The same is the case with a mixture of two of air, or three of air, and one of gas; but four of air and one of gas begin to be explosive, and the explosive tendency increases up to seven or eight of air and one of gas, after which the increased proportion of gas diminishes the force of the explosion.

65. What is the best method of preventing the explosion of gas?

Observe the rule, never to approach a supposed leakage with a light. Fortunately the gas, which threatens our lives, warns us of the danger by its pungent smell. The first thing to be done is to open windows and doors, and to ventilate the apartment. Then turn the gas off at the main, and wait a short time until the accumulated gas has been dispersed.

66. Does hydrogen gas rise or fall when it escapes?

Being twelve times lighter than common air it rises, and therefore it would be better for ventilation to open the window at the top than at the bottom. But all gases exhibit a strong tendency to diffuse themselves, and therefore they do not rise or fall in the degree that might be anticipated.

67. What proportion of hydrogen in the air is dangerous to life, if inhaled?

One-fiftieth part has been found to have a serious effect upon animals. The effects it produces upon the human system are those of depression, headache, sickness, and general prostration of the vital powers. It is therefore advisable to observe precautions in the use of gas.

"From the place of his habitation he looketh upon all the inhabitants of the earth."—Psalm xxxiii.

68. What proportion of gas in the air may be recognised by the smell?

By persons of acute powers of smelling it may be recognised when there is one part of gas in five hundred parts of atmospheric air; but it becomes very perceptible when it forms one part in a hundred and fifty. Warning is, therefore, given to us long before the point of danger arrives.

69. What other sources of hydrogen are there in our dwellings?

It arises from the decomposition of animal and vegetable substances, containing sulphur and hydrogen. These give off a gas called sulphuretted hydrogen, from which the fætid effluviam of drains and water-closets chiefly arise. We should, therefore, take every precaution to secure effective drainage, and to keep drain-traps in proper order.

70. May the use of gas for purposes of illumination be considered highly dangerous?

Not if it is intelligently managed. The appliances for the regulation of gas are so very simple and perfect, that accidents seldom arise except from neglect. In England 6,000,000 tons of coal are usually consumed in the manufacture of gas, producing 60,000,000,000 cubic feet of gas. And yet accidents are of very uncommon occurrence.

CHAPTER V.

71. What is heat?

Heat is a principle in nature which, like light and electricity, is best understood by its effects. We popularly call that heat, which raises the temperature of bodies submitted to its influence.

72. What is caloric?

Caloric is another term for heat. It is advisable, however, to use the term caloric when speaking of the cause of heat, and of heat as the effect of the presence of caloric.

"While the earth remaineth, seed-time and harvest, and cold and heat, and summer and winter, and day and night, shall not cease."—Gen. viii.

73. What is the source of caloric?

The sun is its chief source. But caloric, in some degree, exists in every known substance.

74. What are the effects of caloric?

Heat which, in proportion to its intensity, acts variously upon all bodies, causing expansion, fusion, evaporation, decomposition, &c.

75. Why is caloric called a repulsive agent?

Because its chief effects are to expand, fuse, evaporate, or decompose the substances upon which it acts.

76. What is an attractive agent, in contradistinction to a repulsive agent?

Chemical attraction, or affinity, is an attractive agent—as when bodies seek of their own natures to unite and form some new body.

77. When is a body said to be hot?

When it holds so much caloric that it diffuses heat to surrounding objects.

78. When is a body said to be cold?

When it holds less caloric than surrounding objects, and absorbs heat from them.

79. How may caloric be excited to develop heat?

By any means which cause agitation, or produce an active change in the condition of bodies. Thus friction, percussion, sudden condensation or expansion, chemical combination, and electrical discharges, all develope heat.

80. Why do "burning glasses" appear to set fire to combustible substances?

Because they gather into one point, or focus, several rays of caloric as they are travelling from the sun, and the accumulation of caloric developes that intensity of heat which constitutes fire.

81. What is a focus?

In optics, it is the point or centre at which, or around which, divergent rays are brought into the closest possible union.

"Yet man is born to trouble, as the sparks fly upward.—I would seek unto God, and unto God would I commit my cause."—Job v.

82. What is fire?

It is a violent chemical action attending the combustion of the ingredients of fuel with the oxygen of the air.

83. What are the properties of fire?

It imparts heat, which has the effect of expanding both fluids and solids.

It cannot exist without the presence of combustible materials.

It has a tendency to diffuse itself in every direction.

It cannot exist without oxygen or atmospheric air.

84. What elements take part in the maintenance of a fire?

Hydrogen, carbon, and oxygen. Hydrogen and carbon exist in the fuel, and oxygen is supplied by the air.

85. How does the combustion of a fire begin?

A match made of phosphorous and sulphur (highly inflammable substances) is drawn over a piece of sand-paper; the friction of the match induces the presence of caloric, which developes heat, and ignites the match, the burning of which is sustained by the oxygen of the air. The flame is then applied to paper or wood, and the heat of the flame is sufficient to drive out hydrogen gas, which unites with the oxygen of the air, and burns, imparting greater heat to the carbon of the coals, which assumes the form of carbonic acid gas by union with oxygen, and in a little while all the conditions of combustion are established.

86. What are the properties of heat?

It may exist without fire or light.

It is not sensible to vision.

It makes an impression upon our feelings.

It acts powerfully upon all bodies.

It has no weight.

It attends, or is connected with, all the operations of nature.

It radiates from all bodies in straight lines, and in all directions.

It strikes most powerfully in direct lines.

Its rays may be collected into a focus, just as the rays of the sun.

It may be reflected from a polished surface.

It is more easily conducted by some substances than by others.

"For my days are consumed like smoke, and my bones are burned as an hearth."—Psalm cii.

87. What is animal heat?

Animal heat is derived from the slow combustion of carbon in the blood of animals with the oxygen of the air which the animals breathe.

88. What is latent heat?

Latent heat (or more properly latent caloric) is that which exists, in some degree, in all bodies, though it may be imperceptible to the senses.

89. Is there latent caloric in ice, snow, water, marble, &c?

Yes; there is some amount of caloric in all substances.