Chapter 12
ANALYSIS
SECTION 58. _Analysis._
How can people tell what things are made of?
If it were not for chemical analysis, most of the big factories would have to shut down, much of our agricultural experimentation would stop, the Pure Food Law would be impossible to enforce, mining would be paralyzed, and the science of chemistry would almost vanish.
Analysis is finding out what things are made of. In order to make steel from ore, the ore has to be analyzed; and factories could not run very well without steel. In order to test soil, to test cow's milk, or to find the food value of different kinds of feed, analysis is essential. As to the Pure Food Law, how could the government find out that a firm was using artificial coloring matter or preservatives if there were no way of analyzing the food? In mining, the ore must be assayed; that is, it must be analyzed to show what part of it is gold, for instance, and what part consists of other minerals. Also, the analysis must show what these substances are, so that they can be treated properly. And the science of chemistry is largely the science of analyzing--finding out what things are made of and how they will act on each other.
The subject of chemical analysis is extremely important. But in this course it is impossible and unnecessary for you to learn to analyze everything; the main thing is for you to know what analysis is and to have a general notion of how a chemist analyzes things.
When you tested a number of substances with litmus paper to find out which of them were acids, you were really doing some work in chemical analysis. Chemists actually use litmus paper in this way to find out whether a substance is an acid or a base.
THE BORAX BEAD TEST. This is another chemical test, by which certain substances can be recognized:
EXPERIMENT 113. Make a loop of wire about a quarter of an inch across, using light-weight platinum wire (about No. 30). Seal the straight end of the wire into the end of a piece of glass tubing by melting the end of the tube around the wire.
Hold the loop of wire in the flame of a Bunsen burner for a few seconds, then dip the looped end in borax powder. Be careful not to get borax on the upper part of the wire or on the handle. Some of the borax will stick to the hot loop. Hold this in the flame until it melts into a glassy bead in the loop. You may have to dip it into the borax once or twice more to get a good-sized bead.
When the bead is all glassy, and while it is melted, touch it lightly to _one small grain_ of one of the chemicals on the "jewel-making plate." This jewel-making plate is a plate with six small heaps of chemicals on it. They are: manganese dioxid, copper sulfate, cobalt chlorid, nickel salts, chrome alum, and silver nitrate. Put the bead back into the flame and let it melt until the color of the chemical has run all through it. Then while it is still melted, shake the bead out of the loop on to a clean plate. If it is dark colored and cloudy, try again, getting a still smaller grain of the chemical. You should get a bead that is transparent, but clearly colored, like an emerald, topaz, or sapphire.
Repeat with each of the six chemicals, so that you have a set of six different-colored beads.
This is a regular chemical test for certain elements when they are combined with oxygen. The cobalt will always change the borax bead to the blue you got; the chromium will make the bead emerald green or, in certain kinds of flame, ruby red; etc. If you wanted to know whether or not certain substances contained cobalt combined with oxygen, you could really find out by taking a grain on a borax bead and seeing if it turned blue.
THE HYDROCHLORIC ACID TEST FOR SILVER. The experiment in which you tested the action of light in effecting chemical change, and in which you made a white powder or precipitate in a silver nitrate solution by adding hydrochloric acid (page 327), is a regular chemical test to find out whether or not a thing has silver in it. If any silver is dissolved in nitric acid, you will get a precipitate (powder) when hydrochloric acid is added. Make the test in the following experiment:
EXPERIMENT 114. _Use distilled water all through this experiment if possible._ First wash two test tubes and an evaporating dish thoroughly, rinsing them several times. Into one test tube pour some nitric acid diluted 1 to 4. Heat this to boiling, then add a few drops of hydrochloric acid diluted 1 to 10. Does anything happen? Pour out this acid and rinse the dish thoroughly. Now put a piece of silver or anything partly made of silver into the bottom of the evaporating dish. Do not use anything for the appearance of which you care. Cover the silver with some of the dilute nitric acid, put the dish over the Bunsen burner on a wire gauze, and bring the acid to a gentle boil. As soon as it boils, take the dish off, pour some clean, cold water into it to stop the action, and pour the liquid off into the clean test tube. Add a few drops of the dilute hydrochloric acid to the liquid in the test tube. What happens? What does this show must have been in the liquid?
You can detect very small amounts of silver in a liquid by this test. It is a regular test in chemical analysis.
THE IODINE TEST FOR STARCH. A very simple test for starch, but one that is thoroughly reliable, is the following:
EXPERIMENT 115. Mix a little starch with water. Add a drop of iodine. What color does the starch turn? Repeat with sugar. You can tell what foods have starch in them by testing them with iodine. If they turn black, blue, or purple instead of brown, you may be sure there is starch in them. And if they do not turn black, blue, or purple, you can be equally sure that they have no starch in them. Some baking powders contain starch to keep them dry. Test the baking powder in the laboratory for starch. Often a little cornstarch is mixed with powdered sugar to keep it from lumping. Test the powdered sugar in the laboratory to see if it contains starch.
Test the following or any other ten foods to see if any of them are partly made of starch: salt, potatoes, milk, meat, sausage, butter, eggs, rice, oatmeal, cornmeal, onions.
THE LIMEWATER TEST FOR CARBON DIOXID. In crowded and badly ventilated rooms carbon dioxid in unusual amounts is in the air. It can be detected by the limewater test.
EXPERIMENT 116. Pour an inch or two of limewater into a glass. Does it turn milky? Pump ordinary air through it with a bicycle pump. Now blow air from your lungs through a glass tube into some fresh limewater until it turns milky. By this test you can always tell if carbon dioxid (CO_2) is present.
Carbon dioxid turns limewater milky as it combines with the lime in the limewater to make tiny particles (a precipitate) of limestone. If you pour seltzer water or soda pop into limewater, you get the same milkiness, for the bubbles of carbon dioxid in the charged water act as the carbon dioxid in your breath did. If you pumped enough air through the limewater you would produce some milkiness in it, for there is always some carbon dioxid in the air.
The purpose of these experiments is only to give you a general notion of how a chemist analyzes things,--by putting an unknown substance through a series of tests he can tell just what that substance contains; and by accurately weighing and measuring everything he puts in and everything he gets out, he can determine how much of each thing is present in the compound or mixture. To learn to do this accurately takes years of training. But the men who go through this training and analyze substances for us are among the most useful members of the human race.
INFERENCE EXERCISE
Explain the following:
551. A little soda used in canning an acid fruit will save sugar.
552. The fats you eat are mostly digested in the small intestine, where there is a large excess of alkali.
553. The dissolved food in the liquid part of the blood gets out of the blood vessels and in among the cells of the body, and it is finally taken into the cells through their walls.
554. Ammonia takes the color out of delicate fabrics.
555. Dishes in which cheese has been cooked can be cleaned quickly by boiling vinegar in them.
556. Prepared pancake flour contains baking powder. It keeps indefinitely when dry, but if the box gets wet, it spoils.
557. When water or milk is added to prepared pancake flour to make a batter, bubbles appear all through it.
558. When a roof leaks a _little_, a _large_ spot appears on the ceiling.
559. Gasoline burns quietly enough in a stove, but if a spark gets into a can containing gasoline vapor, there is a violent explosion.
560. Turpentine will remove fresh paint.
GENERAL REVIEW INFERENCE EXERCISE
Explain the following:
561. We can remove fresh stains by pouring boiling water through them.
562. A ship can be more heavily laden in salt water than in fresh water.
563. Water flies off a wet dog when he shakes himself.
564. In cooking molasses candy, baking soda is often added to make it lighter.
565. An egg will not stand on end.
566. Women who carry bundles on their heads stand up very straight.
567. To get all crayon marks off a blackboard, the janitor uses _vinegar_ in water.
568. Sunlight makes your skin darker.
569. Water puts out a fire.
570. You get a much worse shock from a live wire when your hands are wet than when they are dry.
571. Stone or brick buildings are cool in summer but warm in winter.
572. If you take the handle off a faucet, it is almost impossible to turn the valve with your fingers.
573. Sparks fly from a grindstone when you are sharpening a knife.
574. Violin strings are spoiled by getting wet.
575. The oxygen of the air gets into the blood from the lungs, although there are no holes from the blood vessels into the lungs.
576. You push a button or turn a key switch and an electric lamp lights.
577. A rubber comb, rubbed on a piece of wool cloth, will attract bits of paper to it.
578. People whose eyes no longer adjust themselves have to have "reading glasses" and "distance glasses" to see clearly.
579. When you look through a triangular glass prism, things appear to be where they are not.
580. Lye and hot water poured down a clogged kitchen drainpipe clear out the grease.
581. You can draw on rough paper with charcoal.
582. When little children get new shoes, the soles should be scratched and made rough.
583. You can get your face very clean by rubbing cold cream into it, then wiping the cold cream off on a towel or cloth.
584. Soft paper blurs writing when you use ink.
585. Water will flow over the side of a pan through a siphon, if the outer end of the siphon is lower than the surface of the water in the pan.
586. There is a loud noise when a gun is fired.
587. Colored cloths should be matched in daylight, not in artificial light.
588. Lamp chimneys are made of _thin_ glass.
589. When you sweep oiled floors, no dust flies around the room.
590. The ocean is salty, while lakes are usually fresh.
591. A glass gauge on the side of a water tank shows how high the Water in the tank is.
592. You burn your hand when you touch a hot stove.
593. Pounding a piece of steel held horizontally over the earth and pointing north and south will make it become a magnet.
594. When only one side of a sponge is in water, the sponge gradually gets soft all over.
595. If we breathe on a cold mirror, a fine mist collects on it.
596. Butter is kept in cool places.
597. Water will boil more quickly in a covered pan than in an open one.
598. Mucilage, glue, and paste all become hard and dry after being spread out on a surface for a while.
599. You cannot see things clearly through a dusty window.
600. In making fire grates it is necessary to have the bars free to move a little.
APPENDIX
A. THE ELECTRICAL APPARATUS
For giving children a practical understanding of such laws of electricity as affect everybody, the following simple apparatus is invaluable. It is the electrical apparatus referred to several times in the text. The only part of it that is at all difficult to get is the nichrome resistance wire. There is a monopoly on this and each licensee has to agree not to sell it. It can be bought direct from the manufacturer by the school board if a statement accompanies the order to the effect that it is not to be used in any commercial devices, nor to be sold, but is for laboratory experimentation only. The manufacturers are Hoskins Manufacturing Company, Detroit, Michigan.
The following diagram will make the connections and parts of the electrical apparatus clear:
The flush switch (G) should be open at the bottom for inspection,--remove the back. The snap switch (E) should have cover removed so that pupils can see exactly how it works.
The fuse gap (D) consists either of two parts of an old knife switch, the knife removed, or of two brass binding posts. Across it a piece of 4-ampere fuse wire is always kept as a protection to the more expensive plug and cartridge fuses. Between the resistance wire (_I_, _J_, _K_) and the wall should be either slate or sheet asbestos, double thickness. Under the fuse gap the table should be protected by galvanized iron so that the melted bits of fuse wire can set nothing on fire when the fuse wire burns out.
B. CONSTRUCTION OF THE CIGAR-BOX TELEGRAPH
The "cigar-box telegraph" shown on page 381 is made as follows: An iron machine bolt (A) is wound with about three layers of No. 24 insulated copper magnet wire, the two ends of the wire (_B_, _B_) projecting. The threaded end of the bolt (C) is not wound. A nut (D) is screwed on the bolt as far down as the wire wrapping. The threaded end is then pushed up through the hole in the top of the cigar box as that stands on its edge. Another nut (E) is then screwed on to the bolt, holding it in position. The bolt can now be raised or lowered and tightened firmly in position by adjusting the two nuts (_D_ and _E_), one above and one below the wood.
A screw eye (F), large enough to form a rest for the head of another machine bolt (G), is screwed into the back of the box about three fourths of an inch below the head of the suspended bolt (A). Two or three inches away, at a slightly higher level, another screw eye (H) is screwed into the back of the cigar box. This screw eye must have an opening large enough to permit an iron machine bolt (G) to pass through it easily. A nut (I) is screwed down on the threaded end of a machine bolt until about an inch of the bolt projects beyond the nut. This projecting part of the bolt is then passed through the screw eye (H) and another nut (J) screwed on to it to hold it in place. This nut must not be so tight as to prevent the free play of the bolt as its head rises and falls under the influence of the vertical bolt. The head of the horizontal bolt rests upon the screw eye which is immediately below the head of the suspended bolt. You therefore have the wrapped bolt hanging vertically from the top of the box, with its head just over the head of the horizontal bolt. There should be about one quarter inch of space between the heads of the two bolts. An electric current passing through the wires of the vertical bolt will therefore lift the head of the horizontal bolt, which will drop back on to the screw eye when the circuit is broken.
INDEX
An asterisk (*) indicates use of one or more illustrations in connection with reference to which appended.
Acetylene, carbon and hydrogen in, 315.
Acids, 351 ff.; action of, on metals, 351-353*; action of, on cloth, 354*; action of, on nerves of taste, 354-355; distinguished from bases by litmus test, 358-359; neutralization of, by bases, 360-364.
Action and reaction, law of, 77-81*.
Adhesion, 39, 41-44; cohesion, capillary attraction, and, 47.
Air, cooling of, on expanding, 95-96; liquid, 97; heat carried by, by convection, 118-119; absorption of light by, 169; sound produced by vibrations of, 174-181*; pitch due to rapidity of vibrations of, 186; water vapor in, 275-280*; a mixture and not a compound, 309; part taken by, in making automobile go, 344; limewater test for carbon dioxid in, 375.
Air pressure, 10 ff., 14*; height water is forced up by, in vacuum, 19; high and low, 20, 282; winds caused by, 20-21.
Air pump, 14*, 15.
Alcohol, boiling of, 112; distilling, 113*-114.
Alkali, 356; in soap, 357-358.
Alloys, definition of, 310.
Alternating current, defined, 211-212.
Alum crystals, experiment with, 265-266*.
Aluminum, an element, 299.
Alum in water, testing with litmus paper, 359.
Amber, electricity produced by rubbing with silk, 196.
Ammonia, example of a common base, 356; action of, in cleaning cloth, 358; litmus test of, 359; neutralization of acid by, 363.
Ampere, defined, 246.
Analysis, chemical, 370-376.
Aneroid barometer, 285*.
Arc, the electric, 233-240*.
Atoms, description of, 196; electrons and, 197; everything in the world made of, 310-311; in molecules, 311.
Aurora Borealis, cause of, 193.
Automobile, reason for cranking, 210; how made to go, 344-345.
Automobile races, overcoming of centrifugal force in, 75*.
Automobile tires, reason for wearing of, 80; blow-outs of, 348.
Baking powder, chemical change by solution shown by, 349-350; elements of which made, 367-368.
Baking soda, a common base, 356; testing with litmus paper, 359; neutralization of sour milk by, in cooking, 362; carbon dioxid in, 366-367.
Ball bearings, used to diminish friction, 54-55.
Balloon, expansion of, 17-18, 109*; reason for rising of, 26; filling of, with hydrogen, 301-304*.
Barometer, use of, 280-285*.
Bases, substances called, 355-358; litmus test for distinguishing from acids, 358-359; neutralization of, by acids, 360-364.
Batteries, electric, 203-205*; different kinds of, 205*-207*; general principle of all, 206.
Bell, electric battery for ringing, 204-205*; working of electric, 255*.
Bending of light (refraction), 136-141*.
Black, the absence of light, 164.
Bleaching, process of, 326-327.
Blow-out of tire, a real explosion, 348.
Blue-flame heaters, 319.
Blueness of sky, reason for, 169.
Blueprints, making of, 330-331.
Boiling and condensing, 107-115*.
Borax bead test, 371*-372*.
Brass, an alloy, 310.
Bread making, chemical action in, 365.
Breath, cause of visibility of, on cold days, 288, 289*.
Bronze, an alloy, 310.
Burning, explanation of, 308, 312-313.
Calcium chlorid, 114.
Camera, lens of, 143, 148; human eye as a small, 151*-153; explanation of, 327-332.
Capillary attraction, 36*-40; difference between adhesion, cohesion, and, 47.
Carbon, in electric battery, 203-206; resistance of, to electric current, 231; an element, 293, 299; one of chief elements in fuel, 315-316.
Carbon dioxid, in seltzer siphon, 17; produced by joining of carbon with oxygen, 315; combining of water and, by plants, 332-333; releasing of, in baking powder, 349-350; bubbling of, in effervescence, 365-366; in soda water, springs, and baking soda, 366-367; limewater test for, 375-376.
Carbonic acid gas, commercial name for pure carbon dioxid, 365-366.
Cat's hairs, static electricity in, 201.
Caustic soda, a common base, 356.
Center of weight, 30-33*.
Centrifugal force, 5, 72-74; law of, 74-75.
Charcoal, production of, 316.
Charging water with carbon dioxid, 366.
Chemical analysis, 370-376.
Chemical change, and energy, 293 ff.; burning (oxidation), 312-322; caused by heat, 323-325; caused by light, 326-335; caused by electricity, 335-339; energy released by, 340-341; helped by solution, 349-351.
Chemical equations, 297-299.
Chlorine, an element, 299.
Chlorophyll in plants, work of, 332.
Cigar-box telegraph, construction of, 249*, 380-381*.
Circuits, electric, 219-220*; breaking and making, 220-221; connecting in parallel, 221-223*; grounded, 225-229*; short, 240-245*.
Cloth, action of acids on, 354*; action of an alkali on, 356, 357*.
Clouds, how formed, 277-278.
Coal, carbon and hydrogen in, 315.
Cohesion, 39, 44*-49.
Cold, caused by expansion, 94; is the absence of heat, 95, 120.
Color, 161-172*.
Comb, electricity produced by rubbing, 197-198.
Compass, use of, 190-195*.
Complete electric circuits, 219-224*.
Compounds, how elements hide in, 300; definition of, 308-309; mixtures distinguished from, 309-310.
Concave mirrors, 154*, 155*, 157; magnification by, 157; in reflecting telescopes, 157.
Conduction, of heat, 116-118; of electricity, 213-218.
Conductors of electricity, good and poor, 213.
Conduits for electric wires, 237.
Conservation of energy, 57 ff.
Convection, carrying of heat by, 118-119.
Convex lens, 148-149*; in microscope, 155-157*; in telescope, 157.
Cooling from expansion, 94-96.
Coolness at night and in winter, 127-128.
Copper, a good conductor of electricity, 215; an element, 299; nickel plating of, 336-339*; etching of, with acid, 352*-353.
Copper nitrate, salt called, 353.
Cream, separating from milk, by centrifugal force, 75-76.
Crystals, formation of, 265-268.
Cylinder of engine, 344*.
Dead Sea, reason for salt in, 104-105*.
Decay, a kind of oxidation, 313.
Dew, 275; how formed, 287.
Dictaphone, working of, 175, 178, 179*.
Diffusion, 268-274; of light, 158-161.
Direct-current electricity, 211-212.
Distilling of liquids, 112-115*.
Doorbell, electric battery for ringing, 204-205.
"Down," meaning of word, 4.
Drainpipe, cleaning of, with lye, 358.
Dry-cell battery, 206*.
Dust, reason for clinging to walls, 43-44.
Dynamite, 343*; making of, 347.
Dynamo, how electric current is made to flow by, 207*-210*.
Earth, magnetism of, 190-195.
Easy circuit, a short circuit an, 244-245.
Echoes, explanation of, 183-185.
Effervescence, process of, 365; generally due to freeing of carbon dioxid, 367*-368; helped by stirring or shaking, 368.
Elasticity, 82-86; of form distinguished from elasticity of volume, 86-87.
Electrical apparatus, 216-217*, 222-223*; description of, 379-380.
Electric arc, the, 233*-240.
Electric battery, the, 203-206*.
Electricity, magnetism and, 190 ff.; static, 196-202; negative and positive charges of, 198*-200; action of, in thunderstorms, 200-201; flowing, 203 ff.; flowing of, in dynamo, 207-210; alternating and direct-current, 211-212; conduction of, 213*-218; chemical change caused by, 335-339.
Electric lamps, vacuums in, 12*, 317; incandescent, 125; gas-filled, 317.
Electric motors, 256*-257*.
Electrolysis apparatus, 294-295*.
Electromagnets, 247-257*.
Electrons, 193; description of, 197; number of, in negative and in positive charges, 198-200.
Elements, defined, 293; chemists' abbreviations of, 297-299; list of common, 299-300; hiding of, in compounds, 300-301.
Emulsion, defined, 261; difference between solution and, 263.
Energy released by chemical change, 340-341.
Engine, working of cylinder and piston of, 344*.
Ether, carrying of heat and light by, 124-125; light as waves of, 163-164.
Ether waves, 124-125, 163-164.
Evaporating dish, 101*.
Evaporation, 100-106*; part taken by, in formation of clouds, rain, and dew, 277.
Expansion, caused by heat, 88-93; cooling from, 94-96*.
Expansion ball and ring experiment, 91*-92.
Explosions, use of, 342* ff.; automobiles made to go by succession of, 344-345; cause of, 345; shooting of guns caused by, 345-346.
Explosives, manufacture of, 347.
Extension lights, 238.
Eye, lens of, 142; section of, 151*; working of, 151*-153.
Fading, process of, 326-327.
Filament of incandescent lamp, 125.
Fire engines, need of, to force water high, 9.
Fire extinguishers, action of, 317.
Fires, caused by electric arcs, 236; putting out of, by water, 317. _See_ Burning.
Flames, formation of, 318.
Floating, sinking and, 23-28.
Focus of light, 142*-149*.
Fogs, cause of, 288.
Food, light necessary to production of, 332-333.
Force, overcoming of extra motion by, in lever, 63-64*; reason for, of steam, 110.
Forecasters, weather, 282-285.
Form, elasticity of, 86-87.
Freckles, cause of, 327.
Freezing and melting, 96-99.
Friction, 49-55*; electricity produced by, 197-198*.
Frost, 97, 275; explanation of, 287.
Fuel, chief elements in, 315-316.
Fulcrum of lever, 59-60*.
Fuse gap, the, 241*, 379*.
Fuses, short circuits and, 240-245.
Gas, cooling of, on expanding, 94-95; carbon and hydrogen in, 315; used for filling electric lamps, 317-318; will not burn until hot enough, 323-324; an explosion the sudden release of a confined, 348.
Gases, diffusion of, 269-271; as elements, 293-294.
Gas heaters, action of, 319, 321*, 322*.
Gasoline, evaporation of, 103; boiling of, 112; distilled from petroleum, 114; elements of, 315; action of, in making automobiles go, 344-345.
Geysers, cause of, 110.
Glass, a poor conductor of heat, 118; used as insulator of electricity, 215.
Glowworms, reason for glowing of, 341-342.
Gold, an element, 293, 299; plating of, 339.
Gravitation, defined, 3.
Gravity, 1; pull of, opposed to pull of adhesion, 42-43.
Grease, friction diminished by, 53-54; combined with lye to form soap, 357.
Great Salt Lake, reason for salt in, 104-105.
Greeks, early knowledge of electricity possessed by, 196.
Green color of water, reason for, 169-171*.
Grounded circuits, 225-229*.
Gun, shooting of, caused by explosion, 345-346.
Gunpowder, action of, in shooting of a gun, 345-346; how made, 347.
Hail, explanation of, 286.
Heat, a result of friction, 53; is the motion of molecules, 90; not caused by expansion, 94-95; cold is absence of, 95, 120; required to evaporate liquids, 102-103; conduction of, 116-118; carried by air, by convection, 118-119; radiation of, 122-128; of incandescent lamp, 125-126; brought to focus by convex lens, 149; chemical change caused by, 323-325.
Heaters, hot-water, 120*; electric, 230, 232; gas, 319, 321*, 322*.
Heat waves, cause of, 141.
Hydrochloric acid, getting hydrogen from, 301-304; testing for silver with, 373.
Hydrofluoric acid, 351.
Hydrogen, an element, 294, 299; in water, 295-296; experiments with, 301-304*; one of chief elements in fuel, 315-316; part taken by, in burning, 312-319.
Ice, slight friction of, 52*; action of molecules in, on freezing and melting, 96-97; reason for floating of, 98-99.
Incandescence, defined, 125.
Incandescent lamps, 125-126; number of electrons in, 197; working of, 229-232.
Inertia, 66-71; definition of, 70.
Insulators, of heat, 118; of electricity, 213; substances used as, 215.
Iodine, an element, 299; testing with, for starch, 373-374.
Iron, a good conductor of heat, 118; an element, 299.
Irons, electric, 229*, 230, 232.
Iron salt, formed by lemon juice on steel, 353.
Iron ships, reason for floating, 24*-26.
Kerosene, boiling of, 112; distilled from petroleum, 114; carbon and hydrogen in, 315.
Laughing gas, 309.
Lava in volcanoes, 110.
Lead, an element, 299.
Lead pencils, arc light from, 233*-234*.
Leaning Tower of Pisa, 29*-30.
Lemon juice, action of, on silver and on steel, 353; litmus test of, 359.
Lens, of eye, 142, 151*-153; of camera, 143, 149*, 328; convex, 148-149; concave, 149*; in telescope, 157.
Levers, 57-65*.
Light, radiation of, 122, 123*-128; reflection of, 129-135*; refraction of, 136*-141; focus of, 142-149*; brought to focus by convex lens, 149; diffusion of, 158-161*; color a kind of, 162; speed of, 182; chemical change caused by, 326-335; and manufacture of food in plants, 332-333.
Lightning, cause of, 200-201.
Limewater test for carbon dioxid, 375*-376.
Liquid air, 97, 112.
Liquids, absorption of, 36-40; diffusion in, 272.
Litmus paper, experiments with, 358-359.
Litmus test, the, 358-359.
Lye, a common base, 356; experiment with, 356; soap made from, 357; used for clearing out drainpipe, 358; neutralization of, by acids, 363.
Machinery, oiling of, to decrease friction, 53-54.
Magdeburg hemispheres, 15, 16*-17.
Magnetism, 190 ff.
Magneto, of automobile, 210, 211*; of old-fashioned telephone, 210-211.
Magnets, 190-195*.
Magnification, 150-157; by concave mirror, 157.
Magnifying glass, convex lens in, 149; operation of, 150-156*.
Manganese dioxid, an essential in explosives, 347.
Megaphone, working of, 184.
Melting, freezing and, 96-99.
Membrane, diffusion through a, 272.
Mercury, cohesion of, 47-48*; use of, in thermometer, 89*, 90-91; an element, 299.
Mercury-vapor lamps, 167-168*, 172.
Metals, good conductors of heat, 118; good conductors of electricity, 215; as elements, 310; plating of, 336-339*; action of acids on, 351-353.
Microscope, 88; working of, 155-157*.
Mirrors, concave, 154*, 155*, 157.
Mixtures, distinguished from compounds, 309-310.
Molecular attraction, 36 ff.
Molecules, pull of, on each other, 46-47; explanation of, 88-89; heat defined as the motion of, 90; action of, in evaporation, 102-103*; action of, in boiling water, 107; action of, in conduction of heat, 117; action of, in radiation of heat and light, 125; action of, in magnetizing, 194*-195; made up of atoms, 196, 310; mingling of, 259 ff.; action of, in formation of clouds, rain, and dew, 277.
Moon, cause of ring around, 131.
Morse telegraph code, 253.
Motion-picture machines, lenses of, 143, 148.
Motor, the electric, 255-257*.
Mountains, rainfall on, 286-287.
Musical instruments, pitch of, 185-187*, 188; vibrating devices of, 188.
Nail plug, the, 241*, 379*.
Needle, magnetizing of, 192*, 193*-195.
Negative charges of electricity, 198-200.
Neutralization of acids and bases, 360-364.
Niagara Falls, electricity generated by, 210.
Nickel, an element, 299.
Nickel-plating copper, process of, 336-339*.
Night, reason for coolness at, 127-128.
Nitric-acid, etching copper with, 352*-353; action of, on cloth, 354*.
Nitrogen, an element, 299; a non-burning gas, 308; used in electric lamps, 317.
Northern Lights, cause of, 193.
Ocean, why salt, 104-105.
Oil, reason for floating of, 26-27; decreasing of friction by, 53-54; softening due to, 290-292; carbon and hydrogen in crude, 315; why water will not put out burning, 317.
Oil heaters, action of, 319.
Orange, litmus test of, 359.
Osmosis, process called, 272-274.
Osmotic pressure, 272-273*.
Oxidation, 312-322.
Oxygen, an element, 293, 299; an element of water, 295-296; experiments in getting, from two solids, 305-308*; function of, in burning, 308; part taken by, in burning (oxidation), 312-313; released in manufacture of plant food, 333-335; a compound of, an essential in explosives, 347.
Pancakes, made from sour milk, 362.
Paper, carbon and hydrogen in, 315.
Paraffine, production of, 114.
Parallel circuits, 221-223*.
Peat, carbon and hydrogen in, 315.
Pencils, making arc light with, 233*-234*.
Periscope experiment, 134-135*.
Petroleum, gasoline and kerosene distilled from, 114.
Phonograph, working of, 177-178*.
Phosphorescence, cause of, 341-342.
Phosphorus, an element, 300; meaning of name, 341.
Photographs, process of making, 327-332*.
Pitch of sound, explanation of, 185-188*.
Plants, light and the manufacture of food in, 332-333; how oxygen is supplied by, 333-335.
Plating of metals, 336-339*.
Platinum, an element, 300.
Poles, positive and negative, 206-207.
Porcelain, used as insulator, 215.
Positive charges of electricity, 198-200.
Potassium, experiment with, 304.
Potassium chlorate, an essential in explosives, 347.
Precious stones, formation of, 263-264.
Prism, refraction of light by, 136-140*; separation of light into rainbow colors by, 162-163*.
Quicksilver. _See_ Mercury.
Radiation of heat and light, 122*-128.
Radium, an element, 300.
Rain, 275; cause of, 278-280.
Rainbow, making a, on wall, 162*-163; how formed, 170-171.
Reading glasses, 144*; convex lens in, 150.
Red color of sky at sunset, reason for, 170.
Reflecting telescopes, 157.
Reflection of light, 129-135*.
Refraction of light, 136-141*.
Resistance, electrical, 229-232.
Retina of eye, 151*, 153.
Reverberation of sound, 183-185.
Ring around moon, cause of, 131.
Rock candy, how made, 267.
Rubber, used as insulator, 215.
Rusting of iron, 349.
Safety valves on steam boilers, 347.
Salt, reason for, in sea, 104-105*; a compound, 308; elements of, 310-311; formed by hydrochloric acid and zinc, 351; iron, formed by lemon juice on steel, 353; acids and bases turned to water and, by combining, 361-362.
Salt water, litmus test of, 359.
Samson cells, 204.
Scattering of light (diffusion), 158-161*.
Seesaw, example of a lever, 57-58*.
Seltzer siphon, working of, 17.
Ships, reason for floating, 24*-26.
Shock, electrical, 214-215.
Short circuits and fuses, 240-245.
Silver, an element, 300; plating of, 339; hydrochloric acid test for, 373.
Silver chlorid, formation of, 327.
Sinking and floating, 23-28*.
Siphon, 18*.
Sky, reason why blue, 169; why red at sunset, 170.
Smoke, consistency of, 318-319.
Snow, 275; formation of, 285-286.
Snowflakes, 97, 286*.
Soap, how made, 357-358.
Soda water, how made, 365-366.
Sodium, experiment with, 304.
Softening due to oil or water, 290-292.
Soil, litmus test of, 359.
Solution, defined, 261; difference between emulsion and, 263; a mixture and not a compound, 309; chemical change helped by, 349.
Sound, cause of, 174; rate of speed, 181-182; action of, in echoes, 183-185*; pitch of, 185-188.
Sour milk, litmus test of, 359; neutralization of, by baking soda, 362.
Sourness, taste of, caused by acids, 353, 354-355.
Spectroscope, use of the, 172.
Spectrum, the, 172.
Spring water, carbon dioxid in, 366.
Stability, 29-34.
Starch, iodine test for, 373-374.
Stars, twinkling of, 141; how to tell of what made, 171-172.
Static electricity, 196-202*.
Steam, reason for force exerted by, 110; geysers and volcanoes caused by, 110; real, not visible, 112 n.
Steel, generally an alloy, 310.
Stereopticons, lenses of, 148.
Storage battery, 206, 207*; action of electricity in, 339.
Stoves, electric, 230, 232.
Street car, electric motor of, 255-257.
Suction pump, 19*.
Sugar, making of, by plants, 332-333; litmus test of, 359.
Sulfur, an element, 300.
Sulfuric acid, action of, on cloth, 354; litmus test of, 359.
Sun, radiation of heat and light from the, 122-128; how to tell of what made, 171-172.
Sunbeams, explanation of, 131.
Sweat glands, function of, 291.
Tanning, process of, 327.
Telegraph apparatus, 247-252*, 380-381*.
Telegraph code, 253.
Telephone, working of, 253-255.
Telescopes, 156*, 157; how made, 157; reflecting, 157.
Temperature, finding the, by reading a thermometer, 90-91.
Thermometer, the, 89*-91*.
Thermos bottle, how made, 126-127*.
Thunder, cause of, 200-201.
Tin, an element, 300.
Tin salt, poisonous, 353.
Toasters, electric, 230, 232.
Tomatoes, use of soda to neutralize acid of, 362-363.
Tungsten, in incandescent lamps, 231.
Tuning-fork experiments, 181*, 186-187*.
Twinkling of stars, cause of, 141.
"Up," meaning of word, 4.
Vacuum, defined, 11; reason for, in electric lamp, 12*, 317; use of, in manufacture of thermos bottles, 126-127*; impossibility of producing sound in, 176-177.
Valves, safety, on boilers, 347.
Vaseline, production of, 114.
Vibrations, of air, 174-181*; pitch due to rapidity of, 186.
Vinegar, litmus test of, 359; neutralization of lye by, 363.
Violin, tuning of, 187.
Volcanoes, cause of, 110; explosions and, 346*.
Volume, elasticity of, 86-87.
Washing soda, a common base, 356; litmus test of, 359.
Water, seeks its own level, 6-10; gurgling of, when poured from bottle, 13; experiment with, to show centrifugal force, 73-74; used for making thermometer, 90*-92; expansion of, when frozen, 98; evaporation of, 100-106; action of, in geysers and volcanoes, 110; absorption of light by, 169-170; as conductor of electricity, 216; use of, for generating electricity, 256-257; softening due to, 290-292; elements of, 294-297; a compound and not a mixture, 308; formed by burning fuel, 316; why fire is put out by, but not burning oil, 317; combining of carbon dioxid and, by plants, 332-333; rusting of iron by, 349; acids and bases turned to salt and, by combining, 361-362.
Wear, a result of friction, 53.
Weather, forecasting of, 282-285.
Weight, center of, 30-33*.
Wet battery, 204-205*.
White, a combination of all colors, 162.
Winds, cause of, 20-21.
Winter, reason for cold in, 127-128.
Wiring for arc lamps, 236-239.
Wood, poor conductor of heat, 118; carbon and hydrogen in, 315.
Yardstick, experiment with, to show leverage, 59*-60.
Yeast, action of, in bread making, 365.
Yellow, in flames, 318.
Yerkes Observatory, telescope of, 156*.
Zinc, in electric battery, 203-206; an element, 300; used for driving hydrogen out of acid, 301, 304.
* * * * *
_CONSERVATION SERIES_
Conservation Reader
_By_ HAROLD W. FAIRBANKS, _Ph. D._
_Lecturer, University of California; Geography Supervisor Berkeley Public Schools_
A small book bringing out in a simple and interesting manner the principles of conservation of natural resources has long been wanted, or there has been little on the subject that could be placed in the hands of pupils. It is to answer this need that Fairbanks' CONSERVATION READER has been prepared.
The book touches upon every phase of conservation, but it deals at greatest length with saving the soil, the forests, and wild life. It is one of the author's main purposes to arouse a stronger sentiment for preserving what remains of the forests as well as for extending their areas. This is because proper forestation will lessen the danger of floods and of erosion of the soil, and it will encourage the return of the wild creatures that are of so much economic importance and add so much to the joy of life.
The matter is presented in an easy narrative style that is calculated to arouse the intelligent interest of children. The text is illustrated with photographs of wild animals, trees, landscapes, and rarely beautiful birds, printed in colors. The subject is timely and the treatment is happy throughout.
CONSERVATION READER should be used as a reader or as a book for regular study in every elementary school in the country.
_Cloth_, vi + 216 _pages_. _Price $1.40_.
WORLD BOOK COMPANY
YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO
* * * * *
_INDIAN LIFE AND INDIAN LORE_
INDIAN DAYS OF THE LONG AGO
IN THE LAND OF THE HEAD-HUNTERS
TWO BOOKS FOR YOUNG PEOPLE BY
EDWARD S. CURTIS
_Author of "The North American Indian"_
In _Indian Days of The Long Ago_ the author gives an intimate view of Indian life in the olden days, reveals the great diversity of language, dress, and habits among them, and shows how every important act of their lives was influenced by spiritual beliefs and practices.
The book tells the story of Kukúsim, an Indian lad who is eagerly awaiting the time when he shall be a warrior. It is full of mythical lore and thrilling adventures, culminating in the mountain vigil, when Kukúsim hears the spirit voices which mark the passing of his childhood. _Illustrated with photographs by the author and drawings by F. N. Wilson._
* * * * *
Theodore Roosevelt once said that Mr. Curtis has caught glimpses, such as few white men ever catch, into the strange spiritual and mental life of the Indians. In _In the Land of the Head-Hunters_ these glimpses are shared with his readers.
The story centers about Motana, the son of the great War Chief. The mountain vigil, the wooing and winning of Naida, the raid of Yaklus and his warriors, the rescue of the captured Naida, and the final victory, celebrated by ceremonial dances, are all described. The action is rapid and the story is told in the direct, simple style of the true epic. _Illustrated with thirty full-page photographs by the author._
_Price $1.60 each._
WORLD BOOK COMPANY
YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO
* * * * *
INSECT ADVENTURES
_By_ J. HENRI FABRE
_Selected and Arranged for Young People by Louis Seymour Hasbrouck_
A new supplementary reader in nature study for the intermediate grades. A book containing a vast amount of information relating to insect life--the life story of the spider, the fly, the bee, the wasp, and other insects--told by one who was at once a lover of nature, a great scientist, and a most entertaining writer. Maeterlinck calls Fabre the "insects' Homer," and declares that his work is as much a classic as the famous Greek epic, and deserves to be known and studied as a classic.
This is the first time that Fabre's writings have been made available for school use, and the book will prove a delight to school children wherever they are given the chance to read it. No live boy or girl could fail to be interested in nature subjects presented by so gifted a naturalist as Fabre in the form of such absorbing adventures.
The many quaint sketches with which the book has been illustrated by Elias Goldberg complete its charm.
A useful index is included.
_Cloth. 300 pages. Price $1.48._
WORLD BOOK COMPANY
YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO
* * * * *
_NEW-WORLD SCIENCE SERIES_
_Edited by John W. Ritchie_
TREES, STARS _and_ BIRDS
A BOOK OF OUTDOOR SCIENCE
By EDWIN LINCOLN MOSELEY
_Head of the Science Department, State Normal College of Northwestern Ohio_
The usefulness of nature study in the schools has been seriously limited by the lack of a suitable textbook. It is to meet this need that _Trees, Stars, and Birds_ is issued. The author is one of the most successful teachers of outdoor science in this country. He believes in field excursions, and his text is designed to help teachers and pupils in the inquiries that they will make for themselves.
The text deals with three phases of outdoor science that have a perennial interest, and it will make the benefit of the author's long and successful experience available to younger teachers.
The first section deals with trees, and the discussion of maples is typical: the student is reminded that he has eaten maple sugar; there is an interesting account of its production; the fact is brought out that the sugar is really made in the leaves. The stars and planets that all should know are told about simply and clearly. The birds commonly met with are considered, and their habits of feeding and nesting are described. Pertinent questions are scattered throughout each section.
The book is illustrated with 167 photographs, 69 drawings, 9 star maps, and with 16 color plates of 58 birds, from paintings by Louis Agassiz Fuertes.
It is well adapted for use in junior high schools, yet the presentation is simple enough for pupils in the sixth grade.
_Cloth. viii + 404 + xvi pages. Price $1.80._
WORLD BOOK COMPANY
YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO
* * * * *
_NEW-WORLD SCIENCE SERIES_
_Edited by John W. Ritchie_
SCIENCE _for_ BEGINNERS
_By_ DELOS FALL
_Professor of Chemistry, Albion College_
To supply the need for a course that will give the preparatory training which any scientific study demands, SCIENCE FOR BEGINNERS by Professor Delos Fall was made. The aim in this text is to win the interest of pupils, to give them conceptions of nature that are fundamental, and above all to ground them in the method of science.
The subject matter has to do with the earth sciences, and principally with physics and chemistry. In the development of each topic, every advantage that the pupils' experience and interest may afford is utilized. Exercises or experiments are interspersed throughout the work, and for these only the simplest materials are required. The studies are carried to those connecting principles which permit the organization of knowledge. The book is illustrated with a number of excellent photographs and over 200 drawings of more than usual merit.
The text is adapted _for use in grades seven, eight, and nine_, or in any classes that are about to take up their first work in science. It will prove helpful to the teachers and pupils who use it directly, and its influence will continue with classes as they advance. It will thoroughly ground pupils in those ideas that are prerequisite to any right work in science.
_xi + 388 pages. Price $1.68_
WORLD BOOK COMPANY
YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO
* * * * *
NEW-WORLD SCIENCE SERIES
_Edited by_ JOHN W. RITCHIE
The publication of books that "apply the world's knowledge to the world's needs" is the ideal of this house and it is intended that the different volumes of this series shall express this ideal in a very concrete way.
_Completed_
HUMAN PHYSIOLOGY. By _John W. Ritchie_, Professor of Biology, College of William and Mary. A text on physiology, hygiene, and sanitation for upper grammar or junior high schools. _$1.60._
LABORATORY MANUAL FOR HUMAN PHYSIOLOGY. By _Carl Hartman_, University of Texas. A manual to accompany Ritchie's Human Physiology. BOUND IN PAPER AND CLOTH. _60 cents and $1.00._
SCIENCE FOR BEGINNERS. By _Delos Fall_, Albion College, Michigan. A beginning text in general science for intermediate schools and junior high schools. _$1.68._
EXERCISE AND REVIEW BOOK IN BIOLOGY. By _J. G. Blaisdell_, Yonkers, N. Y., High School. A combined laboratory guide, notebook and review book for students' use. Written from the standpoint of efficiency and furnishing material for a year's work and to accompany any one of several high-school texts in general biology. BOUND IN STRONG PAPER. _$1.20._
TREES, STARS, AND BIRDS. By _E. L. Moseley_, Ohio State Normal College, Bowling Green. A book of outdoor science for junior high schools and the upper grammar grades. _$1.80._
PERSONAL HYGIENE AND HOME NURSING. By _Louisa C. Lippitt_, University of Wisconsin. A practical text for use with classes of young women in vocational and industrial high schools, colleges, and normal schools. _$1.68._
SCIENCE OF PLANT LIFE. By _E. N. Transeau_, Ohio State University. A scientific and very practical text for high schools. _$1.88._
ZOÖLOGY. By _T. D. A. Cockerell_, University of Colorado. A text for college use. _$3.60._
EXPERIMENTAL ORGANIC CHEMISTRY. By _A. P. West_, University of the Philippines. A text for college use. _$3.20._
COMMON SCIENCE. By _Carleton W. Washburne_, Superintendent of Schools, Winnetka, Illinois. Especially made for junior high schools. _$1.68._ Also _Manual_ for above, _20 cents_.
_Other volumes are also in preparation._
WORLD BOOK COMPANY
YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO
* * * * *
INDIAN LIFE AND INDIAN LORE
THE HERO OF THE LONGHOUSE
By MARY E. LAING
_Illustrations from 27 paintings by David C. Lithgow_
This story gives a portrayal of the noblest of Indians--Hiawatha. It follows established facts, and bares to the reader the heart of his race. It is a convincing tale.
The training of the Indian youth is shown; the career of the hero as a warrior is told; his great work for peace with the Five Tribes is described.
Besides the story, there is an account of the historical Hiawatha; also a complete Glossary giving definitions as well as pronunciations of the new Indian words. A map of the country of the Longhouse will enable the reader to follow the journeys of the Indian people.
The book is intended as a supplementary reader in schools, being adapted to the sixth grade or above. It will also be valuable in groups of the Wood-craft League, Camp-fire Girls, and Boy Scouts.
_Cloth, xxvi + 329 pages. Price $1.60._
WORLD BOOK COMPANY
YONKERS-ON-HUDSON, NEW YORK 2126 PRAIRIE AVENUE, CHICAGO
* * * * *
REGISTERED TRADE MARK
CHEMCRAFT
THE CHEMICAL OUTFIT
Makes You an Amateur Chemist!
You can perform a great many useful and practical chemical experiments, have a lot of fun, and learn the principles of chemistry, if you have a CHEMCRAFT outfit. And an outfit now will help you in chemistry later on.
Each CHEMCRAFT outfit is a complete chemical laboratory containing many harmless chemicals, all needed apparatus, and a Manual of Instruction giving accurate information on the subject. CHEMCRAFT is real chemistry. These outfits are now used by many schools and are endorsed by professors and teachers. You can choose your outfit from
FIVE SIZES=NO. 0--75C. NO. 1--$1.50. NO. 2--$2.50. NO. 3--$5.00. NO. 4--$10.00
(_West of Denver, Colo., 10% additional_)
Sold by most toy stores and in any toy departments. If not obtainable near your home, any outfit will be delivered from the factory at the price listed. More complete descriptions will be sent Free to any boy or girl, or school authority, upon request.
THE PORTER CHEMICAL COMPANY
Porter Products Put Science at Your Service
HAGERSTOWN--MARYLAND
* * * * *
The Biggest Thing of its kind in the World
CALUMET BAKING POWDER
It may be interesting to know which is the largest city in China--the largest river in Africa--but it is MORE important to know about the industrial life of your country--because when most of you go out into the world you will become active figures in the making, buying and selling of things.
The Calumet Baking Powder factories, in Chicago and East St. Louis are the largest, most modern and sanitary plants of their kind on earth. More pounds of Calumet are sold than of any other brand of baking powder.
That is because Calumet is the best purest, most dependable baking powder made; makes the finest, most wholesome, tasty pies, cakes, biscuits, doughnuts, etc.
You will find the same rule applies to everything you do in life. If you do a thing better than any one else--your services will always be in demand and you will surely be a leader in your line of work. Calumet Baking Powder is sold at a moderate price--has more than the usual leavening strength--and NEVER fails.
A slip in pound can tells how to get the beautifully illustrated Calumet Cook Book.
* * * * *
VENUS PENCILS
_The largest selling QUALITY pencil in the world_
As soft as you wish; as hard as you please; but always smoother than you had dreamed. Any Venus Pencil you select glides over the paper with a restful freedom from friction.
17 BLACK DEGREES, 3 COPYING
For bold, heavy lines 6B-5B-4B-3B For writing sketching 2B-B-HB-F-H For clean fine lines 2H-3H-4H-5H-6H For delicate, thin lines 7H-8H-9H
PLAIN ENDS, PER DOZ. $1.00 RUBBER ENDS, PER DOZ. 1.20
VENUS ERASERS
12 SIZES
Of the same superb quality as the Venus Pencil
_Send for free sample._
_At all Stationers and Stores_
American Lead Pencil Co. 220 Fifth Ave., N. Y. _and London, Eng._
* * * * *
Transcriber's Notes:
page 238: changed "diagramed" to "diagrammed" (As there diagrammed, the electricity passes out...)
page 253: the Morse telegraph code is as in the original; this is not the modern International Morse code
Page 412, changed "conrcete" to "concrete" (... shall express this ideal in a very concrete way.)
General: variable spelling of iodin/iodine in the original has been preserved
General: spelling of dioxid and chlorid in the original has been preserved