The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers

Chapter I: The Anglo-Saxon Period, 449-1066 (17)

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CHEMISTRY OF THINGS FAMILIAR

WHAT IS STARCH? -- HOW MANUFACTURED? -- COMPOSITION OF WHEAT FLOUR
-- ACIDS -- ALKALIES -- SULPHURIC, NITRIC, AND MURIATIC ACIDS --
SULPHURETTED HYDROGEN -- TANNING OF HIDES TO FORM LEATHER -- VINEGAR
-- ALCOHOL -- YEAST -- FRUIT, HOW PRESERVED -- DECAY IN WOOD -- WHAT
IS ETHER? -- DISINFECTING AGENTS -- HOW SMOKING PRESERVES MEAT --
WHAT IS ALBUMEN? -- WHAT IS A POISON? -- ARSENIC -- CERTAINTY OF ITS
DETECTION -- LEAD PIPES, HOW POISON WATER -- VERDIGRIS -- CALOMEL --
PRESERVATION OF WOOD -- COMMON NAMES OF CHEMICALS

_What is starch?_

The name starch is given to a _mealy substance_ which is deposited in _most vegetables_ at the time of ripening, from the juices with which the cells of the plants are filled.

_What common vegetable especially abounds in starch?_

The _potato_, which consists entirely of cells filled with starch and water.

A cell is a little membranous bladder filled with a solid or fluid substance.

_Why does a laundress find it necessary to boil starch before using
it for stiffening linen, etc.?_

The starch, consisting of little granules, is _insoluble in cold water_; but when acted upon by hot water, the granules burst and allow their contents, which are soluble, to become mingled with the water.

Starch is manufactured as follows:--

Potatoes, for example, from which most of the starch of commerce is manufactured, after being pared, are grated to a pulp. This pulp is put upon a sieve and stirred about, while at the same time a little stream of water is made to flow upon it. A milky liquid runs through the sieve, but the fibrous portion of the potato, the vegetable tissue, remains behind. This liquid, after a short interval, deposits a white powder, which is the starch. By the simple process of tearing up the vegetable tissue, and removing the inclosed starch by washing, this substance may be procured from a great variety of plants.

_Why do potatoes, beans, rice, and most of the common vegetables,
swell up when boiled with water?_

Because the _starch absorbs water_ at the boiling temperature, which causes the _cells to swell_, thereby giving to the vegetable a rounded appearance.

_What is the composition of wheat flour?_

_Starch_ is one of the principal constituents of wheat flour, as well as of all other kinds of meal. The other principal constituent is a gray, tough, viscous substance, called _gluten_.

_To what does paste, made of wheat or rye flour, owe its
adhesiveness?_

In some measure to the _starch_, but principally to the _gluten_ contained in it.

_Can starch be converted into gum and sugar?_

It _can_; _fruits and plants effect this change naturally_: we can also produce the change artificially by chemical processes.

_Why are potatoes frozen and thawed sweet?_

Because by the _freezing action_ the starch of the potato is in part converted into sugar.

_Why are apples, pears, grapes, etc., in their unripe state sour,
and in their ripe condition sweet?_

In the unripe fruits mentioned _starch is present_; in the ripe fruits it is _absent_; in the process of ripening the starch is _converted into sugar_, and the fruit becomes sweet.

_What are acids?_

Acids are substances which excite the _taste of sourness_ when applied to the tongue; they change the _blue juices_ of vegetables to _red_, and combine with alkalies to form neutral compounds.

_What is an alkali?_

An _alkali_ is a body that possesses properties the _converse of those of an acid_. It has a _highly bitter, acrid taste_, changes the _blue juices_ of vegetables to _green_, or the juices of vegetables which have been changed red by an acid, back again to blue. Potash and soda are the representatives of the alkalies.

_When sulphur is burned in the air what is the product formed?_

_Sulphurous acid._

_What causes the suffocating odor of a lighted brimstone match?_

The _sulphurous acid_ generated by the combustion of the sulphur.

_What is sulphuric acid or oil of vitriol?_

It is a compound of _sulphur and oxygen_, containing one-third more oxygen than sulphurous acid.

_What is sulphuretted hydrogen?_

A _gas_ formed by the union of _sulphur and hydrogen_. It possesses an offensive odor, and is very poisonous.

_How is sulphuretted hydrogen formed in nature?_

Principally from the _decomposition of animal substances_, as blood, flesh, hair, etc.

_Why does the yolk of an egg tarnish a silver spoon?_

Because it contains a _little sulphur_, which, at the temperature of an egg just boiled, will decompose the water or moisture upon the spoon, and produce _sulphuretted hydrogen gas_, which will tarnish silver.

Both the white and the yolk contain sulphur, but the latter the most abundantly.

_What is it that makes an open or foul sewer so destructive of
health to any district in which it may be situated?_

The evolution of _sulphuretted hydrogen_. When inhaled, it acts directly upon the blood, thickening it, and turning it black.

_Why do surfaces painted with lead paints, in the vicinity of
sewers, soon turn black, or become discolored?_

Through the action of _sulphuretted hydrogen_.

_What is nitric acid?_

Nitric acid, or aqua-fortis, is a compound of five parts of oxygen and one of nitrogen.

It is _liquid_; when pure, _colorless_, and highly _corrosive_; it attacks almost all dead, unorganized substances, and destroys living tissues.

_What is muriatic, or, more properly, hydrochloric acid?_

A compound of _hydrogen and chlorine_ usually prepared from salt. It is an acid much used in the arts.

_What is “lunar caustic”?_

A compound of _nitric acid_ and _oxide of silver_.

_Why, when lunar caustic is applied to the flesh, does it burn and
destroy it?_

Through the agency of the _nitric acid_ contained in it.

_Do plants produce acids?_

Acids are formed in the _vegetable kingdom_ in _great abundance_; they especially exist in unripe fruits, imparting to them a sour taste.

Acids formed from mineral substances are called “mineral acids”; acids formed by or from vegetable substances are called “organic acids.”

_Why does tanning hides convert them into leather?_

Hides are steeped in water, with ground bark of the oak, hemlock, or other trees; these barks contain large quantities of _tannic acid_, which combine with the skin of animals, and form a combination which is insoluble in water and not subject to putrefaction--viz., leather.

_What is ordinary vinegar?_

An acid, called _acetic acid_, and water.

_If wine or beer be imperfectly corked, why does it rapidly turn
sour?_

Because air gets into the liquor, and the oxygen of the air combining with the alcohol of the liquor produces acetic acid, or _vinegar_.

_What is alcohol?_

Alcohol is the _spirit_ existing in wine, beer, cider, etc., _obtained in the process of fermentation_.

_What is a ferment?_

A ferment is a substance containing _nitrogen_ in a state of _decomposition_, which is able to excite fermentation in solutions of sugar; old cheese, putrefying flesh, blood, etc., all of them are ferments.

_What is yeast?_

We apply the term yeast to a particular species of ferment; the _foam of beer_ (or of some similar liquor), produced by _fermentation_.

_Can you explain why it is that a body in a state of fermentation or
putrefaction should cause unlimited quantities of similar matter to
pass into the same state?_

We only _know the fact_: the reason we are _ignorant of_. The most minute portion of milk, paste, juice of grapes, flesh, or blood, in a state of fermentation or putrefaction, causes fresh milk, paste, grape juice, flesh, or blood, to pass into the same condition, when in contact with them.

_In storing or packing fruit for future use why is it necessary to
carefully remove every decayed specimen?_

Because the decayed portions of one specimen will quickly _communicate decay to the fresh fruit in contact_ with it, and soon the whole mass of fruit will become putrescent.

_If in a vessel, or any other structure, one timber becomes decayed
what course ought to be adopted?_

It should be removed _immediately_, or the decomposition once commenced will in time affect the whole structure.

It sometimes happens that physicians, in dissection, are seriously poisoned by the slightest cut of a knife which has been used upon the dead body. The knife introduces to the healthy blood, through the wound, a _minute portion of matter in the state of decomposition or putrefaction_. This acts as a _ferment_, and causes the healthy matter in contact with it to pass into the same decomposed state. The action once commenced rapidly extends, until the whole body becomes affected, and death ensues. It is almost impossible to heal wounds of this character.

_Why is it especially dangerous to eat fruit or meats partially
decayed?_

Because the _decayed portions_ of the substance eaten are liable to induce the _same condition_ in the healthy organs of the stomach with which they may come in contact.

_Why do fruit preserves frequently turn sour?_

Because, owing to the action of some fermenting substance present either in the fruits themselves or in the air, the sugar used in preserving is _converted into alcohol_, and the alcohol into vinegar.

_Why does the housewife scald her preserved fruits to prevent their
turning sour?_

Because fermenting substances and fermenting action are _destroyed_ by a boiling temperature.

_Why do we keep preserves, beer, cider, or other substances liable
to turn sour, in a cool place?_

Because a depression of temperature _arrests fermentation_, though it does not prevent its renewal when the temperature in increased.

_What is ether?_

Ether is a product obtained by _distilling strong alcohol_ and _sulphuric acid_. The product is called sulphuric ether, but it does not contain sulphuric acid, nor has it any sulphur in its composition.

_What are the properties of ether?_

It is an _exceedingly volatile, inflammable_ body, producing insensibility when inhaled, and readily dissolving all fatty and oily bodies.

_Why will ether remove spots of oil, paint, or grease from
garments?_

Because it is a _solvent_ for all greasy, oily matters.

_What are the best agents for depriving putrid and decaying animal
and vegetable substances of their offensive odors?_

_Chloride of lime_ is the most effectual agent; and _chloride of zinc_ and _sulphate of iron_ (green vitriol) are also exceedingly efficient. On a large scale, as in the sanatory cleansing of towns, pulverized charcoal, burnt clay, and quicklime are to be recommended.

_What effect does the use of perfumes or the burning of pastiles
have upon offensive odors?_

They merely _disguise_ the odor, but do _not remove or destroy it_.

_By adopting what precautions may a person safely enter sick rooms,
or visit, without risk, the most dangerous receptacles of filth?_

By moistening a linen cloth with vinegar, and sprinkling over it finely-powdered chloride of lime.

Air breathed through this, applied to the mouth and nostrils, will enter the lungs charged with a minute quantity of chlorine, which will effectually destroy any noxious vapors or miasms that escape from diseased bodies, or from decaying animal and vegetable substances.

_What three conditions are requisite to produce putrefaction in
animal and vegetable substances?_

It is necessary that they should be exposed to the combined influence of _air_, _heat_, and _moisture_.

_Why is a substance preserved from decay by drying, or by the
exclusion of air from it?_

Because by so doing we _remove_ the _moisture_ and _air_ essential to the process of decay.

_Why does the smoking of fish or flesh contribute to their
preservation?_

Because the volatile matters of the smoke, such as creosote, pyroligneous acid, and the like, effect a species of _chemical combination_ with the fiber of the meat, and with the substances contained in the natural juices of the flesh, which combinations are _less liable_ to decay than the substances themselves.

_What is albumen?_

Albumen is an _animal substance_ as well as _vegetable_. It exists most abundantly, and in its purest natural state, in the _white of an egg_, from whence it derives its name (_album ovi_), which is the Latin for the white of an egg.

The serum or fluid portion of the blood (which, after exposure to the air, is separated from the more solid part), the vitreous and crystalline humors of the eye, the brain, the spinal marrow, and nerves, all contain albumen.

_What is the yolk of an egg?_

This also consists of _albumen_, but contains in addition a _yellow oil_, which imparts to it its color.

_Why is meat tough which has been boiled too long?_

Because the _albumen_ becomes hard, like the white of a hard-boiled egg.

The best way of boiling meat to make it tender is this: Put your joint in very brisk boiling water; after a few minutes add a little cold water. The boiling water will _fix_ the albumen, which will prevent the water from soaking into the meat, keep all its juices in, and prevent the muscular fiber from contracting. The addition of cold water will secure the cooking of the _inside_ of the meat, as well as of the surface.

_Why is meat always tough if it be put into the boiler before the
water boils?_

Because the water is not hot enough to _coagulate_ the albumen between the muscular fibers of the meat, which therefore runs into the water, and rises to the surface as scum.

_Why is the flesh of old animals tough?_

Because it contains _very little_ albumen, and much muscular fiber.

_What is a poison?_

A poison is any agent capable of producing a dangerous effect upon anything endowed with life.

_In cases of poisoning by substances taken into the stomach, what
course should be pursued, in the absence of medical attendance?_

The first step is to evacuate the stomach by means of powerful emetics, and when vomiting has taken place, warm water and the white of eggs may almost always be given with advantage.

_Can poisons administered for criminal purposes be almost certainly
detected?_

They can; chemical science within the last few years has made such advances that the most minute quantities of all the best known poisons can be detected with certainty long after death.

There is no poison _so liable_ and _certain_ to be found as _arsenic_, and in almost every case of poisoning with mineral poisons, science is enabled to detect the substance, even when life has been extinct for years, and the body nearly decomposed.

_What is arsenic?_

Metallic arsenic is an _exceedingly brittle metal_, of a _steel-gray color_. It vaporizes, when heated, with a strong odor of garlic, a property not possessed by any other metal.

The substance used as poison, and sometimes known as ratsbane, is arsenious acid, a compound of arsenic and oxygen. Arsenious acid has the form and appearance of a fine white powder.

_What is the best remedy in cases of poisoning with arsenic?_

The _hydrated peroxide of iron_ (iron rust) is considered the best remedy.

The following is the best method for preparing this substance: Take common copperas (sulphate of iron) four ounces; dissolve in warm water in a glass, or porcelain dish, and add a small quantity of sulphuric acid, and afterwards ammonia solution, so long as a dense red precipitate is formed. This precipitate carefully strained off, and thoroughly washed in a filter with water, is hydrated peroxide of iron. So long as kept moist, it may be preserved for a great length of time.

_Is lead a poison?_

Lead and nearly all its compounds are _dangerous_ and _secret poisons_; when received into the system, it frequently remains dormant for years, and then suddenly manifests itself in various forms of disease.

_What is the disease called “painter’s colic”?_

A disease to which painters and others _working in lead are liable_, in consequence of receiving into their system, imperceptibly, portions of lead.

_Is it dangerous to sleep in, or breathe the air of, a room newly
painted with paints containing lead?_

It is _highly dangerous_, since the air is filled with a vapor of the lead compound used as paint.

_Why are some waters, when conveyed through lead pipe, poisonous?_

Waters which are _very pure_ and contain _much oxygen_ dissolved in them; waters which contain _nitric acid_ compounds, such as those flowing from the vicinity of barn-yards, manure heaps, and those which contain _common salt_ or _organic matter_, as water flowing from swamps and fields; waters containing soluble _carbonates_--all dissolve lead from the pipes through which they may be made to pass. Constant use of such waters, in the process of time, will introduce sufficient lead into the system to produce disease, which is often attributed to other causes.

_What is verdigris?_

Verdigris is a compound of copper, oxygen, and acetic acid. This, and all the compounds of copper, are _very poisonous_. The most efficacious antidotes for poisoning with copper are white of eggs and milk.

_What is calomel?_

It is a compound of _two parts of mercury_ united to one of _chlorine_, forming the sub-chloride of mercury. The preparation, commonly known in medicine as “blue pill,” is a preparation of calomel.

_What is corrosive sublimate?_

A compound of _mercury and chlorine_ united in equal proportions, forming the perchloride of mercury.

_Are both these compounds, calomel and corrosive sublimate,
poisons?_

They _are_; corrosive sublimate, especially, is a most _deadly poison_. In case of poisoning by it, the most effectual antidote is white of eggs.

_What is the process of preserving wood from decay, commonly termed
“kyanizing”?_

It consists in _saturating_ the fibers of the wood with a _solution of corrosive sublimate_.

Poisonous substances, and corrosive sublimate especially, have the property of protecting animal and vegetable substances from decay. The skins of stuffed birds and animals, and the plants of a herbarium, may be protected from insects and decay, by washing them with a solution of corrosive sublimate. It should not, however, be forgotten that these substances by such treatment become themselves poisonous.

_Give a list of the chief antidotes for poisons._

(See Book of the Human Body.)

_What are the common names of familiar chemical substances?_

COMMON NAMES OF CHEMICALS

_Common Names_ _Chemical Names and Formulæ_

Alum Sulphate of Aluminum and Potassium
Aqua Fortis Nitric Acid, HNO₃
Aqua Regia Nitro-Hydrochloric Acid
Calomel Mercurous Chloride, Hg₂Cl₂
Carbolic Acid Phenol, C₆H₅OH
Caustic Potash Potassium Hydrate, KOH
Caustic Soda Sodium Hydrate, NaOH
Chalk Calcium Carbonate, CaCO₃
Copperas Sulphate of Iron
Corrosive Sublimate Mercuric Chloride, HgCl₂
Cream of Tartar Potassium Bitartrate
Epsom Salts Magnesium Sulphate
Ether Diethyl Oxide, (C₂H₅)₂O
Fire Damp Light Carburetted Hydrogen
Galena Lead Sulphide, PbS
Glauber’s Salt Sodium Sulphate
Glucose of Grape Sugar Dextrose, C₆H₁₂O₆
Goulard Water Basic Acetate of Lead
Iron Pyrites Iron Di-Sulphide, FeS₂
Jewelers’ Putty Oxide of Tin
Laughing Gas Nitrous Oxide, N₂O
Lime Calcium Oxide, CaO
Lunar Caustic Silver Nitrate, AgNO₃
Mosaic Gold Bi-Sulphide of Tin
Muriatic Acid Hydrochloric Acid, HCl
Olefiant Gas Ethylene, C₂H₄
Plaster of Paris Calcium Sulphate
Quartz Silicon Dioxide, SiO₂
Realgar Arsenic Di-Sulphide, As₂S₂
Red Lead Oxide of Lead, Pb₃O₄
Rochelle Salt Sodium Potassium Tartrate
Salammoniac Ammonium Chloride
Salt, Common Sodium Chloride, NaCl
Salt of Tartar Potassium Carbonate
Saltpeter Potassium Nitrate, KNO₃
Salts of Lemon Oxalic Acid
Slaked Lime Calcium Hydrate
Soda Sodium Carbonate
Spelter Zinc
Spirits of Hartshorn Amm. Hydroxide, NH₄OH
Spirits of Salt Hydrochloric Acid, HCl
Sugar of Lead Lead Acetate
Tartar Emetic Potass. Antimony Tartrate
Verdigris Basic Copper Acetate
Vermilion Sulphide of Mercury
Vinegar Dilute Acetic Acid
Vitriol, Blue Copper Sulphate
Vitriol, Green Ferrous Sulphate
Vitriol, Oil of Sulphuric Acid, H₂SO₄
Vitriol, White Zinc Sulphate
Volatile Alkali Ammonia

_What is meant by radio-activity and radio-active substances?_

_Radio-activity_ is the phenomenon associated with substances which spontaneously emit rays of unique penetrating power through the escape of electrons and their striking against other substances. Chief of the radio-active substances are radium, polonium, actinium, thorium, etc.

_What is the history of these substances?_

Henri Becquerel in 1896 first observed this in the case of potassium uranyl sulphate, the rays from which he found affected a photographic plate through black paper, thin plates of metal, etc.; the property was further traced in other uranium salts and in uranium itself. These rays are known as _Becquerel rays_, and have the further power to render air a conductor of electricity, and thus to discharge any electrified substance placed near them.

A charged electroscope forms a test of radioactivity, and the rate at which the leaves fall measures the degree. Different uranium salts have different degrees of radio-activity; some varieties of pitchblende, as also chalcolite, show the property in excess of uranium contained.

Madame Curie, by using the activity test for every precipitate obtained from pitchblende, succeeded in discovering the elements _polonium_ and _radium_ in 1898. The next year Debierne discovered _actinium_, another radio-active element in the same substance. Meanwhile Schmidt and Madame Curie independently found that the same properties were associated with _thorium_, its compounds and the minerals containing it. In 1903 Ramsay and Soddy discovered that radium continuously produces helium, the lightest of the inactive gases discovered by Ramsay in 1896.

Twenty-eight elements are now classed in three divisions with the three parents, uranium, thorium, and actinium. Potassium and rubidium have been shown to be radio-active, but otherwise the alkaline metals do not enter the classes.

_Describe radium and its special properties._

WHAT IT IS LIKE.--To the eye a tiny sample of radium--or, to speak more correctly, of one of the radium salts, for radium in a pure state (_i.e._ the metal) has not been obtained as yet--presents no very striking appearance. All one sees is a few tiny crystals, or perhaps a few specks of whitish-looking powder, glowing in the dark with a faint phosphorescent light similar to that sometimes emitted by a piece of decaying fish.

THE RADIATIONS are of three kinds, comparable with those of the vacuum tube: _Alpha_-rays are heavy particles, positively charged, similar to the canal rays; _Beta_-electrons, negative like cathode rays; _Gamma_-rays resemble Röntgen rays. They penetrate matter to different degrees, behave differently under the action of a magnetic field, but under ordinary circumstances travel in straight lines.

But rays from different elements vary in penetration, and also with the absorbing substance, varying roughly with the density.

The _Alpha_-rays have a velocity of from 1.56 × 10₉ centimeters per second (radium) to 2.25 × 10₉ centimeters per second (thorium); they are particles of helium carrying a double charge of electricity. _Beta_-rays have a greater range of velocity and approach that of light. Both _Alpha_- and _Beta_-rays are absorbed by a thickness of one centimeter of lead, but _Gamma_-rays pass through an inch of lead; they carry no charge of electricity, yet ionize the air and discharge the electrometer.

All the rays on impinging on solid particles give rise to _secondary rays_, sometimes called _Delta_-rays, electrons moving with comparatively low velocity. The _Alpha_-rays possess ninety-five per cent of the energy evolved and produce brilliant fluorescence in zinc sulphide, diamond, etc., the other rays producing this best in willemite and the platino-cyanides; all become absorbed and transmuted into heat.

Radium every hour generates sufficient heat to raise its own weight of water from freezing to boiling point.

THE SPINTHARISCOPE.--This is a simple piece of apparatus invented by Sir William Crookes, by means of which some of the effects of the _Alpha_-ray particles can be observed in a very striking manner. It consists of a little screen covered with powdered zinc sulphide. A small fragment of radium is placed directly in front of the middle of the screen and in close proximity to it. On observing this screen in the dark through a suitable lens, scintillating little points of light are seen to be continually flashing into view and dying away. Each tiny spark is thought to be produced by the impact of a single _Alpha_-ray particle. That these particles or emanations must be matter in a state of extreme attenuation is proved by an experiment of Professor Curie’s in which a box constructed of platinum was pierced with two holes so minute as to be capable of retaining a vacuum, and yet these radium emanations passed through quite freely.

_What are the medical uses of radium?_

Ulcerous growths, birth-marks, and scars are beneficially treated, but so far the selective action of radium on tissue has not been determined, nor its bactericidal effect. Its results in the treatment of cancer have not yet reached a definite stage, though it has been widely heralded as a specific for that dreadful malady.

The application of the rays is by various methods: inhalation of the emanation; external application or injection of the emanation condensed on glycerine, vaseline, oil, water, etc.; or the taking of quinine, arsenic, bismuth, etc., on which the emanation has been condensed. Injections of very dilute solutions of radium salts, or insoluble salts suspended in water, are made. But external applications of the rays are considered most important; copper plates or linen are coated with varnish containing the salts, or glass tubes contain them, and the radiations are directly applied, the surrounding parts being protected with lead foil.

HOW TO READ A GAS METER

The dial marked “1 thousand” in the accompanying illustration is divided into hundreds; the dial marked “10 thousand” is divided into thousands; that marked “100 thousand” into ten-thousands, and that marked “1 million” into hundred-thousands. When 1,000 cubic feet of gas have been consumed, the pointer on the dial marked “1 thousand” will have made a complete rotation and the fact will be indicated by the pointer of the next dial at the left, which will point to the figure 1. When 10,000 cubic feet of gas have been consumed, the pointer on the “10 thousand” dial will point to 1, and so on. In reading a gas meter, put down the hundreds first, then the thousands, and so on, always counting the figure just under, or which has just been passed by, the pointer. In the illustration about half a hundred is indicated on the “1 thousand” dial, three thousands is indicated on the next dial, two ten-thousands on the next dial, and one one-hundred-thousand on the “1 million” dial. The reading will be 123,050. The dial marked “ten feet” is called the units dial. It is used for testing the meter to discover whether it is in working order or not. Each mark represents a cubic foot and the complete circle 10 cubic feet. If the pointer moves when no gas is burning, it indicates a leak. If it does not move when the gas is burning, or if its motion is unsteady, it indicates a derangement in the mechanism and shows that the meter requires attention.

=OUTLINE COURSE OF ELEMENTARY SCIENCE FOR THE GRADES=

SOME GREAT MECHANICAL INVENTIONS

STEAM ENGINES

_What are steam engines?_

_Steam engines_ are machines in which the elastic force of steam is used as a motive power. In the ordinary engines the alternate expansion and condensation of steam imparts to a piston an alternating rectilinear motion, which is changed into a circular motion by means of various mechanical arrangements.

The engine is unquestionably the grandest and most influential for
good of all the great inventions in the realm of physics. No other
contrivance of man can be compared with this gigantic, yet tractable
motor, in relieving both man and beast of ceaseless toil and irksome
drudgery; in preventing suffering and starvation, and promoting
intercourse, progress and civilization among the nations of the
earth.

_Give a description of the steam engine._

Every steam engine consists essentially of two distinct parts: the apparatus in which the steam is produced, and the engine proper. We shall first describe the former.

STEAM BOILER.--The boiler is the apparatus in which steam is generated. Usually a cylindrical boiler is used for fixed engines; those of locomotives and of steam vessels are very different.

The steam is produced from water at a pressure considerably above that of the atmosphere, and is delivered to the engine with as little loss of pressure and heat as possible. The higher the pressure of the steam, the greater will be the amount of heat available, in a given weight of steam, for conversion into mechanical energy. Only a fraction of the total heat energy given to the steam in the boiler is converted into the mechanical work in the engine. By far the greater portion still remains in the steam after it has passed through the engine. The proportion of heat utilized depends on the thermal efficiency of the engine, amounting from twelve to fifteen per cent in good condensing engines; in the very best engines of large size it may be as high as twenty per cent.

The terms axis, axle, arbor, and shaft, in mechanics, are generally
understood to mean the bar, or rod, which passes through the center
of a wheel. A gudgeon is the pin, or support, on which a horizontal
shaft turns; the pins upon which an upright shaft turns are called
pivots.

The engine proper consists of a hollow _cylinder_ closed at both ends; inside it is the _piston_, a sliding partition which fits the bore of the cylinder sufficiently close to prevent the steam leaking past it, but having sufficient freedom to allow it to move from end to end of the cylinder with as little friction as possible.

In modern engines the pressure of the atmosphere is not employed to drive the piston down. The steam is admitted into the cylinder above the piston at the same time that it is condensed or withdrawn from below, and thus exerts its expansive force in the returning as well as in the ascending stroke. This results in a great increase of power.

The practical construction of the piston and cylinder, and the arrangement of connecting pipes by which steam is admitted alternately above and below the piston, is fully shown in Figure A. This gives a sectional view of the cylinder, of the piston, and of the distribution of steam. The entire engine is of iron. To the piston, T, is fixed a rod, A, which slides with gentle friction in a tubulure, U, placed at the center of the plate which closes the cylinder. As it is very important that no steam shall escape between the piston-rod and this tubulure, the latter is formed of two pieces, one attached to the plate, while the other, which fits in the first, can be pressed as tightly as is desired, so as to compress the material soaked with fat which is between the two tubulures. This arrangement is called a _stuffing-box_; it prevents the escape of steam without interfering with the motion of the piston.

VALVE-CHEST.--This is the arrangement by which steam passes alternately above and below the piston.

Figure A presents a vertical section of this valve-chest and shows its relation to the cylinder. The steam enters the valve-chest from the boiler by the brass tube _x_. From the valve-chest two conduits, _a_ and _b_, are connected with the cylinder, one above and the other below. If they were both open at once, the steam, acting equally on the two faces of the piston, would keep it at rest. But one of these is always closed by a _slide-valve_, _y_, fixed to a rod, _i_. This moves alternately up and down, by means of an eccentric, _e_, placed on the horizontal shaft. The slide-valve closes the conduit _a_, and allowing the steam to enter at _b_, below the piston, the latter rises. But when it reaches the top of the stroke the rod _i_ sinks, and with it the slide-valve, which then closes the conduit _b_, and allows the steam to enter at _a_. The piston then sinks, and so forth at each displacement of the slide-valve.

It now remains to explain what happens when the steam presses below the piston. It must not remain above, otherwise the piston could not move. But while the steam enters below by the conduit _b_, the top of the cylinder, by means of the conduit _a_, is connected with a cavity, O, from which passes the tube L. Through this tube the steam which has already acted upon the piston passes into the atmosphere, or else is condensed in a vessel filled with cold water, which is called the _condenser_. If, on the other hand, the piston sinks, the vapor below the piston passes, by the conduit _b_, to the cavity O, and to the tube L.

TRANSMISSION OF MOTION.--The alternating rectilinear motion thus generated within the cylinder is transmitted, by means of a rod attached to the piston, to a strong beam _ff_, movable upon a central axis, a system of jointed rods _ee_, called the _parallel motion_, being interposed for the purpose of neutralizing the disturbing action which the circular path of the beam would otherwise exert upon the piston. The reciprocating motion of the beam is now, through the intervention of the connecting-rod _g_ and crank _h_, converted into a circular or rotatory motion, which is rendered continuous and uniform by the fly-wheel _i_, to the axis of which the machinery to be impelled is connected.

The air-pump, _p_, for withdrawing the vapor and water from the condenser, the feed-pump, _s_, for supplying the boilers, and cold-water pump, _t_, for supplying the condenser cistern, are all worked by rods from the beam; and the governor, _u_, for maintaining uniformity of motion, is driven by a band from the crankshaft. The above description refers more immediately to that class of steam engines called _low-pressure_ engines.

TYPES OF ENGINES.--The various forms of the steam engine have received a varied form of classification. There are the general divisions into _condensing_ and _non-condensing_ engines, _compound_ and _non-compound_, and _single_, _double_, or _direct acting_. Again there is the classification connected with the position of the cylinder, as in the _horizontal_, _vertical_, and _inclined_ cylinder engines. Another classification divides steam engines into the uses to which they are applied, such as stationary engines, portable engines, marine, locomotive, electric generating, pumping, mill driving, winding, etc.

STEAM TURBINE.--The steam turbine, though the most modern form of the steam engine in practice, is the most ancient in actual history, the germ of the invention dating from Hero of Alexandria, in the second century B. C.

_a_, The steam-cylinder; _b_, the piston; _c_, the upper steam-port or passage; _d_, the lower steam-port; _ee_, the parallel motion; _ff_, the beam; _g_, the connecting-rod; _h_, the crank; _ii_, the fly-wheel; _kk_, the eccentric and its rod for working the steam-valve; _l_, the steam-valve and valve-casing; _m_, the throttle-valve; _n_, the condenser; _o_, the injection-cock; _p_, the air-pump; _q_, the hot-well; _r_, the shifting-valve for creating a vacuum in the condenser previous to starting the engine; _s_, the feed-pump for supplying the boilers; _t_, the cold-water pump for supplying condenser cistern; _u_, the governor.]

One kind of steam turbine is really worked on the same principle as a windmill, only steam is used instead of the wind. Instead, however, of the sails making one revolution in seven or eight seconds, it sometimes makes three thousand revolutions a minute, or fifty revolutions a second. In another kind the blades of the turbine are something like the pockets on a water-wheel, and the steam shoves the wheel round by its great velocity.

Turbine engines are now fitted to vessels of large dimensions, up to ocean liners and battleships, with extremely satisfactory results. Turbine engines have also been applied in various other ways, _e.g._, to the driving of fans and blowers.

The principle of internal combustion, as used in gas and oil engines, has also been applied to the turbine with marked success, and has done much to solve the all-important problem of efficiency. It is extremely improbable that the long-range activities of the submarine would be nearly so effective were it not for the application of the same principle to their engines.

4 Air Signal Hose
5 Air Brake Hose
11 Front Frame
12 Cinder Chute
14 Extension Front
15 Headlight Step
16 Signal Lamp
18 Smoke Arch Door
19 Smoke Arch Front
22 Headlight Case
23 Headlight Reflector
27 Deflector Plate
28 Deflector Plate Adjuster
29 Air Pump Exhaust Pipe
38 Smoke Stack
39 Arch Hand Rail
44 Steam Chest
51 Steam Passages to Chest
52 Valve Seat
56 Steam Ports
57 Cylinder
58 Back Cylinder Head
59 Piston Packing
60 Piston Rod
61 Piston Head
62 Piston Packing Rings
64 Front Cylinder Head
65 Cylinder Head Casing
66 Cylinder Lagging
67 Cylinder Casing
68 Cylinder Cocks
69 Cylinder Cocks Rigging
70 Engine Truck
71 Engine Truck Wheel
73 Engine Truck Axle
75 Engine Truck Box
77 Engine Truck Frame
80 Engine Truck Equalizer
82 Engine Truck Spring
86 Truck Brake
87 Wheel Guard
88 Signal Pipe
92 Main Rod
97 Main Frame
99 Air Drum
100 Pump Connection
101 Train Pipe Connection
102 Valve Stem Rod
103 Train Pipe
104 Wash Out Plugs
108 Link Block
112 Tumbling Shaft Arm
113 Tumbling Shaft
114 Tumbling Shaft Lever
120 Check Valve Case
121 Check Valve
122 Flues
123 Oil Pipe
124 Horizontal Boiler Seam
125 Circumferential Seam
126 Boiler Lagging
127 Boiler Jacket
128 Jacket Bands
132 Bell
133 Steam Bell Ringer
134 Sand Box
135 Pneumatic Sander
136 Sand Pipe
137 Driving Wheel Tire
138 Driving Wheel Centers
140 Driver Brakes
141 Driver Springs
150 Driving Box
151 Driving Axle
155 Main Frame
158 Go Ahead Eccentric
159 Back Up Eccentric
165 Rocking Grates
168 Running Board
169 Air Cylinder Brake Pump
170 Steam Cylinder Brake Pump
173 Drip Cock
174 Pump Piston Packing
177 Governor
186 Fire Box
192 Stand Pipe
195 Throttle Valve
198 Dome
201 Safety Valves
202 Chime Whistles
203 Whistle Rig
204 Ventilator
205 Cab
207 Air Gauge
208 Steam Gauge
209 Steam Turret
213 Signal Whistle
214 Air Pump Throttle
215 Throttle Lever
216 Pneumatic Sander
216a Sand Lever
217 Reverse Lever
218 Engineer’s Brake Valve
219 Gauge Cocks
222 Fire Door
229 Whistle Signal Valve
233 Signal Pipe
236 Feed Pipe]

LOCOMOTIVES

_Locomotive engines_, or simply _locomotives_, are steam engines which, mounted on a carriage, propel themselves by transmitting their motion to wheels.

The parallel motion, the beam, and the fly wheel of the ordinary stationary engine form no part of a locomotive. The principal parts are the _framework_, the _fire box_, the _casing_ of the boiler, the _smoke box_, the _steam cylinders_, with their valves, the _driving wheels_, and the _feed pump_.

The framework rests on the axles of the wheels. The illustration on another page shows clearly the arrangement and parts of a typical locomotive. It will be observed that in the lower part of the _steam dome_ is the _fire box_, from whence the flame and the products of combustion pass into the smoke box, and then into the chimney after having previously traversed the numerous brass _fire tubes_ which pass through the boiler. The _boiler_, which connects the fire box with the smoke box, is made of iron, and is cylindrical.

The steam passes from the boiler into two _cylinders_, placed on either side of the smoke box. There, by means of a steam chest similar to that already described, it acts alternately on the two faces of the piston, the motion of which is transmitted to the axle of the large driving wheels. After having acted on the pistons, the steam is forced through the blast pipe into the chimney, thus increasing the draft.

The motion of the pistons is transmitted to the large driving wheels by two connecting rods, which, by means of cranks, connect the piston rods with the axles of the wheels. The alternating motion of the slide valve is effected by means of eccentrics placed on the axles of the large wheels.

WHEELS OF THE LOCOMOTIVE.--The wheels range ordinarily from forty-five to eighty-five inches in diameter for drivers, thirty to forty-two inches for truck wheels. They are made of castiron or steel body and steel rim shrunk on. Spoked wheels are usual for drivers, solid wheels for trucks. The tread is four to five inches wide, the flange (one to one and one-quarter inch high) increasing this to five and one-half to seven inches. A counterbalance weight is cast between the spokes opposite the crank-pin seat. The axles, forged steel, are six to eight inches in diameter (for drivers); the wheels are forced on their ends by a powerful press. Cranked axles (for inside cylinders) are forged to shape, rarely built up.

CONTROL.--The locomotive is controlled by the throttle-valve and the reverse lever. Both are located in the cab, which is built at the rear around the fire box, and serves also as firing platform.

AUXILIARIES.--The necessary auxiliaries of the locomotive are those required for its operation as a power generator, and those necessary to its service as a railroad vehicle or as a tractor. The _tender_ is the most important in the first group. It is a separate vehicle attached behind the locomotive, carrying a water tank of three to eight or nine thousand gallons capacity, and a coal bin of two to ten tons capacity. Eight-wheel (two-truck) tenders are usual. The coal space is at the front of the tender, and the water tank occupies the rear half and extends forward along the sides of the coal bin. The coal thus is reached directly from the rear of the engine cab.

Water is supplied to the engine by pipes leading from the tank to injectors on the engine. Feed pumps are rarely used for pumping the water into the boiler, injectors in duplicate being depended on. The safety valve, mounted on the top of the boiler, is of the spring poppet type. A steam whistle is placed alongside, for use as warning and train-movement signal; a bell operated from the cab by a cord is also mounted on the boiler.

The air-brake equipment of the locomotive comprises the brake mechanism for the engine itself, and an air pump with its governor, a main reservoir, and the engineer’s valve, for supplying and manipulating the brakes of the entire train. The air pump is a direct-coupled compressor whose steam and air cylinders have a common piston-rod, attached in vertical position to the side of the boiler in front of the cab. The cylinder diameter is eight to ten inches. It pumps air into the main reservoir, a cylindrical tank hung under the boiler. An automatic pressure governor starts the compressor when the pressure falls and stops it when the full reservoir pressure is restored.

The locomotive brake equipment consist of brake cylinder and lever system connected to the wheel brake-shoes, but its valve control differs somewhat from that of a car, so as to permit braking the engine alone if desired. The engineer’s valve is a flat-seat rotary valve with positions for supplying brakes, recharging the train-pipe, and closing all connections. A separate valve is usually supplied to operate the engine brake alone, working this as “straight-air” or non-automatic brake. Reservoir and train-pipe gauges are mounted in the engine cab near the brake handles. Steam brakes are no longer fitted on American locomotives. The driving-wheels only of the locomotive are braked, but the tender is fully braked.

The sand-box for increasing the driving-wheel friction on wet or greasy rail is commonly set on top of the boiler with discharge pipes ending in front of the drivers just above the rail. A compressed-air ejector is now often used (pneumatic sander), in which case the sand-box may be placed on the front sill or in other convenient position with equal effectiveness.

THE CAB, with windows in front and sides, is built around the fire box, providing a seat on either side which commands a view ahead over the track. The reverse lever is placed on the right-hand, or engineer’s side, from where also the throttle lever and brake-valve handles are reached. Injector, whistle, sander, bell, drain cocks, traction-increaser, and other appliances are controlled from here. The headlight, set on top of the boiler in front of the stack, is usually an oil lamp, with parabolic reflector. Acetylene and electric headlights are extensively used in recent years, the latter supplied by a small steam-turbine and dynamo combination.

CLASSES AND TYPES OF LOCOMOTIVES.--The wheel-arrangement of a locomotive is, in conjunction with its total weight, the chief characteristic. Freight locomotives, running at slow speeds, utilize a large adhesion, and therefore have a large proportion of their weight carried on drivers; they have less need for good guiding quality and steadiness at great speeds. Passenger locomotives, working at high speeds, develop a much lower tractive force, and therefore require less weight on drivers, but need leading wheels for guiding quality and steadiness.

The number and arrangement of cylinders is another characteristic of classification. Most locomotives have two cylinders, both simple. Compounds are built with two, three or four cylinders.

RECENT DEVELOPMENTS.--The chief factor in the modern modification of locomotive types and details is increase of size. The only limiting factors are boiler capacity and weight on drivers.

Economy of operation has brought compounding into much favor even for single-frame engines, and more recently has led to the wide adoption of super-heating; these improvements also allow increased power to be obtained from a boiler of given size.

WEIGHT AND POWER.--Locomotives weighing seventy-five to one hundred and twenty-five tons (without tender) are common. In power, road locomotives range from three hundred to one thousand five hundred horse power and occasionally to two thousand horse power, the more modern ranging from seven hundred to one thousand five hundred. High-speed passenger locomotives are usually more powerful than heavier freights.

BOILER PERFORMANCE.--The distinguishing feature of the locomotive boiler is its high evaporative capacity, and the very high rates of fuel-burning. At full power one hundred pounds coal are burned per square foot of grate surface per hour, by virtue of the strong draft produced by the exhaust-steam blast. At moderate speeds twenty-five to forty pounds are burned.

ELECTRIC LOCOMOTIVES.--The operation of heavy railroad service (_i.e._ trains of freight cars and long passenger trains) by electric power requires the use of electric locomotives in place of the car-motor arrangement of street railroads. Such locomotives have been built since the middle of the nineties, and in considerable number since 1905. The earlier ones had the motors geared to the axles, or directly mounted thereon, but recent constructions have the motors mounted on the frame or platform, above the wheels, so that their weight is carried by the frame springs, and the motors drive the wheels through coupling-rods either direct or by way of an intermediate jack-shaft. This form is found to give smoother running and exert less destructive effect on the track than the prior forms. In wheel arrangement these locomotives vary greatly, but recent machines exhibit combinations of coupled drivers with leading and trailing trucks not unlike the arrangement of steam locomotives. Electric locomotives of two thousand to three thousand horse power have been built, and are in regular use hauling trunk-line trains.

AËROPLANES

Flying-machines are distinguished from balloons and dirigibles in being “heavier than air,” and consequently raised and supported by dynamic means alone, by the reaction of the air on surfaces driven through it.

Essentially, the aëroplane may be compared to a kite in which the pull of the string is replaced by the thrust of the propeller.

On December 17, 1903, the Brothers Wright, in America, made their first power-flight; while the very first public flight was made in France by Santos-Dumont on September 14, 1906.

Before it was possible to produce a power-driven aëroplane, experiments over a long course of years were made with aëroplanes not provided with propelling apparatus.

In its earliest form the aëroplane consisted of a flat surface moved through the air in a position slightly inclined from the horizontal; in its forward movement the plane experiences resistance from the air. As this resistance is directed partly on the under side, it will be partly converted into a lifting force. Of these two forces--head resistance or drift, and the lifting or sustaining force or lift--the first, being unproductive, must be reduced as far as possible; the second, lift, must, on the other hand, be raised to the highest possible degree.

This end is achieved by employing, instead of flat surfaces or planes, surfaces curved in the direction of flight.

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The Circle of Knowledge: A Classified, Simplified, Visualized Book of AnswersChapter I: The Anglo-Saxon Period, 449-1066 (17)

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