Part 3

One of the most remarkable facts in chemistry--a science abounding in wonders--is the circumstance that the mere contact of hydrogen, the lightest body known, with the metal platinum, the heaviest when in a state of minute division called spongy platinum, produces an intense heat sufficient to inflame the hydrogen; of course this experiment must be made in the presence of atmospheric air or oxygen. If a small piece of the metal in the state above named be introduced into a mixture of oxygen and hydrogen, it will cause them to explode. A very small quantity of gas should be employed and placed in a jar lightly covered with a card, or the explosion would be dangerous.

Crystallization.

Nearly all the metals are characterized by the crystals, which are formed as they pass from a state of intense heat to that of comparative coldness. It is by this process they have been formed when in the mine or vein in the rocks. The earth was once a fiery mass of molten matter, as seen even now when a volcano is in a state of eruption. And it was only by the cooling of the outside shell of the earth, or crust, as it is called, that it became habitable.

When the crust was cooling down the metals crystallized among the cooling rocks and gradually formed the crude arts. You may represent by a very pretty experiment the manner in which this cooling off of the earth took place. Obtain a little flour of sulphur and put it in a red earthenware unglazed jar. Thrust it well into the fire and watch the rust. As soon as the heat has penetrated the vessel the yellow powdery sulphur becomes first of all brown, and then assumes the consistency of thick birdlime. Take out a little of this on the end of a stick and plunge it into cold water. It can then be pulled backwards and forwards like cobblers’ wax. This well represents the state of the half-cooled crust of the earth.

Meanwhile the sulphur on the fire begins to boil, and looks very much like bubbling treacle. Remove it from the fire and allow it to cool. When quite cool the surface will be a flat, yellow mass, like ordinary roll sulphur, which, when ground, give the ordinary flour of sulphur.

With a sharp knife separate the mass from the vessel and look at the under-surface. There it will be found to have assumed a very different form, owing to the exclusion of the air, and consequent slower cooling. Large six-sided crystals, transparent, and of a most exquisitely delicate yellow, will be seen, piled on one another as appear the masses of ore in rocks.

Nature always works in such cases on such a gigantic scale that it seems at first difficult to believe that such huge piles as the Giant’s Causeway in Ireland, or Fingals in Scotland, or the lodes of tin ore in Cornwall, worked by the Phœnicians three thousand years ago, and still being worked, were all formed by the same process.

The time that the earth must have taken to cool fairly staggers the imagination, yet it is only from guessing, by means of such a study as this, that geologists are able to form any idea of how long ago it was that the earth’s crust became cool enough to allow animal and plant life to exist upon it.

The most beautiful crystalline form is perhaps the diamond, and yet this precious gem is but the same thing, chemically, as charcoal. Charcoal is pure carbon in the uncrystallized state, which the magic of crystallization has transformed into the symbol of all that is brilliant and beautiful.

Beauties of Crystallization.

Dissolve alum in hot water until no more can be dissolved in it; place in it a smooth glass rod and a stick of the same size. Next day the stick will be found covered with crystals, but the glass rod will be free from them. In this case the crystals cling to the rough surface of the stick, but have no hold upon the smooth surface of the glass rod.

But if the rod be roughened with a file at certain intervals, and then placed in the alum and water, the crystals will adhere to the rough surfaces, and leave the smooth bright and clear.

Tie some threads of lamp-cotton irregularly around a copper wire or glass rod. Place it in a hot solution of blue vitriol, strong as above, and the threads will be covered with beautiful blue crystals, while the glass rod will be bare.

Bore a hole through a piece of coke, and suspend it by a string from a stick placed across a hot solution of alum. It will float. But as it becomes loaded with crystals it will sink in the solution according to the length of the string. Gas-coke has mostly a smooth, shining, and almost metallic surface, which the crystals will avoid, while they will cling only to the most irregular and porous parts.

If powdered turmeric be added to the hot solution of alum the crystals will be of a bright yellow. Litmus will cause them to be of a bright red. Logwood will yield purple; and common writing ink, black. And the more muddy the solution the finer will be the crystals.

To keep colored alum crystals from breaking or losing their color, place them under a glass shade with a saucer of water.

This will preserve the atmosphere moist, and prevent the crystals getting too dry.

If crystals be formed on wire they will be liable to break off, from the expansion and contraction of the wire by changes of temperature.

To Crystallize Camphor.

Dissolve camphor in spirit of wine, moderately heated, until the spirit will not dissolve any more; pour some of the solution into a cold glass, and the camphor will instantly crystallize in beautiful tree-like forms, such as we see in the show-glasses of camphor in druggists’ windows.

ANOTHER EXPERIMENT.

Heat some blue vitriol (sulphate of copper) in an iron ladle till all the water contained in the crystals is driven off, and the color changes to a gray. Take the lumps out without breaking them, and lay the dried blue vitriol on a plate. If this be moistened with water steam is produced; and if a slice of phosphorus is then laid on the sulphate of copper it ignites, demonstrating again that the condensation of a liquid produces heat. The addition of the water restores the blue color, thus proving that water was necessary to the composition of blue vitriol.

A Solid Changed to a Liquid.

Mix five parts by weight of powdered sal ammoniac, five parts of nitre in powder, and sixteen parts of water. A temperature of twenty-two degrees below the freezing point of water is produced; and if a phial of water, or any convenient metallic cylinder containing water, be surrounded with a sufficient quantity of the freezing mixture, ice is formed. The ice clings to the interior of the tube, but may easily be removed by dipping it in tepid water.

This experiment is the reverse of the last and proves that the sudden reduction of a solid to the liquid condition always affords cold.

An amusing combination of two experiments may be made by putting some fresh-burned lime into one tea pot and this freezing mixture into another. When water is poured on the one containing lime, it gives out steam from the spout, while the addition of water to the other produces so much cold that it can hardly be kept in the hand. Thus heat and cold are afforded through the same medium, water.

Magic of Heat.

Melt a small quantity of the sulphate of potash and copper in a spoon over a spirit lamp. It will be fused at a heat just below redness, and produce a liquid of a dark-green color. Remove the spoon from the flame, when the liquid will become a solid of a brilliant emerald green color, and so remain until its heat sinks nearly to that of boiling water, when suddenly a commotion will take place throughout the mass, beginning from the surface, and each atom, as if animated, will start up and separate itself from the rest, till in a few moments the whole will become a heap of powder.

Sublimation by Heat.

Provide two small pieces of glass; sprinkle a minute portion of sulphur upon one piece, lay thin slips of wood around it, and place upon it the other piece of glass. Move them slowly over the flame of a lamp or candle, and the sulphur will become sublimed, and form gray, nebulous patches, which are very curious microscopic objects. Each cluster consists of thousands of transparent globules, imitating in miniature the nebulæ which we see figured in treatises on astronomy. By observing the largest particles we shall find them to be flattened on one side. Being very transparent, each of them acts the part of a little lens, and forms in its focus the image of a distant light, which can be perceived even in the smaller globules, until it vanishes from minuteness. If they are examined again after a certain number of hours, the smaller globules will generally be found to have retained their transparency, while the larger ones will have become opaque, in consequence of the sulphur having undergone some internal spontaneous change. But the most remarkable circumstance attending this experiment is that the globules are found adhering to the upper glass only; the reason of which is that the upper glass is somewhat cooler than the lower one, by which means we see that the vapor of sulphur is very powerfully repelled by heated glass. The flattened form of the particles is owing to the force with which they endeavor to recede from the lower glass, and their consequent pressure against the surface of the upper one. This experiment is considered by its originator, Mr. H. F. Talbot, to be a satisfactory argument in favor of the repulsive power of heat.

Heat Passing Through Glass.

Although glass is a bad conductor it yet allows heat to pass through it, and the purer the glass the more easy is this done. Heat a poker red hot, and having opened a window, apply the poker very near to the outside of the pane, and the hand to the inside. A strong heat will be felt at the instant, which will cease as soon as the poker is withdrawn, and may be again renewed and made to cease as quickly as before. It is well known that if a piece of glass be so much warmed as to convey the impression of heat to the hand, it will retain some part of that heat for a minute or more; but in this experiment the heat will vanish in a moment. It will not, therefore, be the heated pane of glass that we shall feel, but heat which has come through the glass in a free or radiant state.

Metals Unequally Influenced by Heat.

All metals do not conduct heat at the same rate as may be proved by holding in the flame of a candle at the same time a piece of silver wire and a piece of platina wire, when the silver wire will become too hot to hold, much sooner than the platina. Or cut a cone of each wire, tip it with wax, and place it upon a heated plate (as a fire-shovel), when the wax will melt at different periods.

Spontaneous Combustion.

Mix a small quantity of chlorate of potash with spirit of wine in a strong saucer; add a little sulphuric acid, and an orange vapor will arise and burst into flame with a loud crackling sound.

Inequality of Heat in Fire-Irons.

Place before a fire a set of polished fire-irons, and beside them a rough, unpolished poker, such as is used in the kitchen, instead of a bright poker. The polished irons will remain for a long time without becoming warmer than the temperature of the room, because the heat radiated from the fire is all reflected, or thrown off, by the polished surface of the irons, and none of it is absorbed. The rough poker will, however, become speedily hot, so as not to be used without inconvenience. Hence, the polish of fire-irons is not merely ornamental, but useful.

Expansion of Metal by Heat.

Provide an iron rod, and fit it exactly into a metal ring; heat the rod red hot, and it will no longer enter the ring.

Observe an iron gate on a warm day, when it will shut with difficulty; whereas it will shut loosely and easily on a cold day.

The Alchemist’s Ink.

Dissolve in water a small quantity, about as much as will lay on a ten-cent piece, of chloride of cobalt, which is of a bluish-green color, and the solution will be pink; write with it and the characters will scarcely be visible; but if gently heated they will appear in brilliant green, which will disappear as the paper cools.

Dissolve in water a few grains of prussiate of potash; write with this liquid, which is invisible when dry; wash over with a dilute solution of iron, made by dissolving a nail in a little aqua fortis; a blue and legible writing is immediately apparent.

Chameleon Liquids.

Put a small portion of the compound called mineral chameleon into several glasses. Pour upon each water at different temperatures and the contents of each glass will exhibit a different shade of color. A very hot solution will be of a beautiful green color; a cold one a deep purple.

Make a colorless solution of sulphate of copper; add to it a little ammonia equally colorless, and the mixture will be of an intense blue color; add to it a little sulphuric acid, and the blue color will disappear; pour in a little solution of caustic ammonia, and the blue color will be restored. Thus may the liquor be changed at pleasure.

Magic Dyes.

Dissolve indigo in diluted sulphuric acid, and add to it an equal quantity of solution of carbonate of potash. If a piece of white cloth be dipped in the mixture it will be changed to blue; yellow cloth, in the same mixture, may be changed to green; red to purple; and blue litmus paper to red.

Nearly fill a wine glass with the juice of beet-root, which is of a deep red color; add a little lime water and the mixture will be colorless; dip into it a piece of white cloth, dry it rapidly, and in a few hours the cloth will become red.

Wine Changed into Water.

Mix a little solution of subacetate of lead with port wine; filter the mixture through blotting-paper, and a colorless liquid will pass through; to this add a small quantity of dry salt of tartar; distill in a retort, when a spirit will arise, which may be inflamed.

The Chemistry of Water.

More than two-thirds of the earth’s surface is water, so that in mere quantity alone it is the most important substance with which we are acquainted. Without it life would be impossible, for, owing to its quality of dissolving other bodies, it may be regarded as the great purifier, as well as the vehicle which brings nourishment to plants and animals alike.

Not only is water useful, but is among the most beautiful of Nature’s products. It has carved the valleys between mountain ranges by its slow dropping for ages, and has made the fairy glens by rushing down their sides in torrents. The stately rivers and the roaring oceans are but forms of its might.

In another state it works out those fantastic grottoes, mountains and fields of glittering white, that make the Polar seas the very head center of dreamland.

In still another form it paints the rainbow in the sky, and hangs like a veil over the landscape, passing from the most delicate blue over the plain to the deep purple clinging to distant hills.

To it the golden and red hues of sunrise and sunset are due. The light fleecy clouds that speak the beauty of spring, and the great thunder stocks that gleam, with lightning flashes are all composed of water, and water alone.

It drives our engines and machinery, and speeds our ships across the sea. Neither is it confined to this earth alone, for astronomers tell us that vast seas and even clouds can be seen on the next great planet to the earth, Mars.

Surely, then, as this wondrous substance is examined, the ancients can be excused for worshiping the ocean as a god, and the old alchemists for believing it to be an element.

Nevertheless, water is not a simple substance. It is composed of two gases, which must be combined before water is produced. These gases are oxygen and hydrogen. Every atom of water consists of one part of the former gas and two parts by volume of the latter. This you may prove in the following way:

Buy a piece of sodium, a metal that must not be touched with the fingers, and thrust it into a small one-ounce jar half full of water; cork the jar tightly.

Through a hole in the cork pass a glass tube, the outer end being drawn in a flame to a fine point. Apply a light at the end of the tube. The escaping gas will catch fire and burn with a light blue flame. This gas is hydrogen.

Next empty the jar and fill with warm water, and place by means of another cork a small glass jar on to the tube. Into the lower jar drop a piece of blazing hot platinum. Repeat this again and again with the same piece of platinum, being careful not to uncork the upper jar, so that every time the metal is dropped into the lower jar, you remove the upper jar with the tube and two corks. After doing this a dozen times or more take a match that is still glowing after having been extinguished, and plunge it into the upper jar. It will burst into flame immediately, and the gas in the upper jar is oxygen.

Two Bitters Make a Sweet.

It has been discovered that a mixture of nitrate of silver with hyposulphite of soda, both of which are remarkably bitter, will produce the sweetest known substance.

Visible and Invisible.

Write with French chalk on a looking-glass; wipe it with a handkerchief and the lines will disappear; breathe on it and they will reappear. This alteration will take place for a great number of times, and after the lapse of a considerable period.

To Form a Liquid from Two Solids.

Rub together in a mortar a small quantity of sulphate of soda and acetate of lead, and as they mix they will become liquid.

Carbonate of ammonia and sulphate of copper, previously reduced to powder separately, will also, when mixed, become liquid, and acquire a most splendid blue color.

The greater number of salts have a tendency to assume regular forms, or become _crystallized_, when passing from the fluid to the solid state; and the size and regularity of the crystals depends in a great measure on the slow or rapid escape of the fluid in which they were dissolved.

Sugar is a capital example of this property; the ordinary loaf-sugar being rapidly boiled down, as it is called; while to make rock-candy, which is nothing but sugar in a crystallized form, the solution is allowed to evaporate slowly, and as it cools it forms into those beautiful crystals termed rock-candy. The threads found in the center of some of the crystals are merely placed for the purpose of hastening the formation of the crystals.

Restoration of Color by Water.

Water being a colorous fluid ought, one would imagine when mixed with other substances of no decided color, to produce a colorless compound. Nevertheless, it is to water only that blue vitriol or sulphate of copper owes its vivid blueness, as will be plainly evinced by the following simple experiment. Heat a few crystals of the vitriol in a fire-shovel, pulverize them, and the powder will be of a dull and dirty white appearance. Pour a little water upon this when a slight hissing noise will be heard, and at the same moment the blue color will instantly reappear.

Under the microscope the beauty of this experiment will be increased, for the instant that a drop of water is placed in contact with the vitriol, the powder may be seen to shoot into blue prisms. If a crystal of prussiate of potash be similarly heated its yellow color will vanish, but reappear on being dropped into water.

Two Liquids Make a Solid.

Dissolve chloride of lime in water until it will dissolve no more; measure out an equal quantity of oil of vitriol; both will be transparent fluids; but if equal quantities of each be slowly mixed and stirred together, they will become a solid mass, with the evolution of smoke or fumes.

Two Solids Make a Liquid.

Rub together in a mortar equal quantities of the crystals of Glauber salts and nitrate of ammonia, and the two salts will slowly become a liquid.

A Solid Opaque Mass Makes a Transparent Liquid.

Take the solid mixture of the solutions of muriate of lime and carbonate of potash, pour upon it a very little nitric acid, and the solid opaque mass will be changed to a transparent liquid.

Two Cold Liquids Make a Hot One.

Mix four drams of sulphuric acid (oil of vitriol) with one dram of cold water, suddenly, in a cup, and the mixture will be nearly half as hot again as boiling water.

To Make Ice.

Although this trick is performed by means of chemicals, yet its product is obtained really by the use of mechanical laws. We must remember that ice is exactly the same thing as water so far as its composition is concerned, differing only in its state of density.

Ice, water, and steam differ in density through the possession of a greater or less quantity of heat. Hence, the turning of water into ice really is a case of the operation of mechanical laws.

Now for the experiment. Put into a wide-mouthed jam-jar a smaller glass vessel containing the water to be frozen. Around the latter put a mixture of sulphate of soda (Glauber’s salt) and hydrochloric acid (spirits of salts). The proportions must be eight parts of the former to five of the latter.

The action of these two chemicals on one another is to cause a cold of fifteen to seventeen degrees below zero, or forty-seven degrees below freezing point.

The same result may be obtained by mixing equal parts of nitrate of ammonia and water. In winter-time when the snow is on the ground, with a mixture of one part snow and one part common table salt an intense cold of twenty degrees below zero is obtained.

From this last fact we see how stupid are those people who sprinkle the salt on the pavements to get rid of the snow. True, the latter melts, but only after the production of intense cold, which is the cause of many diseases, not only slight ones like colds and chilblains, but too often the forerunners of consumption and other lung troubles.

Curious Change of Colors.

Let there be no other light than a taper in the room; then put on a pair of dark-green spectacles, and having closed one eye view the taper with the other. Suddenly remove the spectacles and the taper will assume a bright red appearance; but if the spectacles be instantly replaced, the eye will be unable to distinguish anything for a second or two. The order of colors will therefore be as follows: green, red, green, black.

The Protean Light.

Soak a cotton wick in a strong solution of salt and water, dry it, place it in a spirit lamp, and when lit it will give a bright yellow light for a long time. If you look through a piece of blue glass at the flame, it will lose all its yellow light and you will only perceive feeble violet rays. If before the blue glass you place a pale yellow glass, the lamp will be absolutely invisible, though a candle may be distinctly seen through the same glasses.

To Change the Colors of Flowers.

Hold over a lighted match a purple columbine or a blue larkspur, and it will change first to pink and then to black. The yellow of other flowers held as above will continue unchanged.

Thus, the purple tint will instantly disappear from a heart’s-ease, but the yellow will remain; and the yellow of a wall-flower will continue the same, though the brown streak will be discharged. If a scarlet, crimson, or maroon dahlia be tried, the color will change to yellow, a fact known to gardeners, who by this mode variegate their growing dahlias.

Changes of the Poppy.

Some flowers which are red, become blue by merely bruising them. Thus, if the petals of the common corn-poppy be rubbed upon white paper, they will stain it purple, which may be made green by washing it over with a strong solution of potash in water. Put poppy petals into very dilute muriatic acid, and the infusion will be of a florid red color; by adding a little chalk, it will become the color of port wine; and this tint, by the addition of potash may be changed to green or yellow.

Changes of the Rose.