Silicon from the electric furnace appears in the form of hard, glittering metallic crystals.

An alloy of iron and silicon, ferro-silicon, made by heating a mixture of iron ore, sand and c.o.ke in the electrical furnace, is used as a deoxidizing agent in the manufacture of steel.

Since silicon has been robbed with difficulty of its oxygen it takes it on again with great avidity. This has been made use of in the making of hydrogen. A mixture of silicon (or of the ferro-silicon alloy containing 90 per cent. of silicon) with soda and slaked lime is inert, compact and can be transported to any point where hydrogen is needed, say at a battle front. Then the "hydrogenite," as the mixture is named, is ignited by a hot iron ball and goes off like thermit with the production of great heat and the evolution of a vast volume of hydrogen gas. Or the ferro-silicon may be simply burned in an atmosphere of steam in a closed tank after ignition with a pinch of gunpowder. The iron and the silicon revert to their oxides while the hydrogen of the water is set free. The French "silikol" method consists in treating silicon with a 40 per cent.

solution of soda.

Another source of hydrogen originating with the electric furnace is "hydrolith," which consists of calcium hydride. Metallic calcium is prepared from lime in the electric furnace. Then pieces of the calcium are spread out in an oven heated by electricity and a current of dry hydrogen pa.s.sed through. The gas is absorbed by the metal, forming the hydride (CaH_{2}). This is packed up in cans and when hydrogen is desired it is simply dropped into water, when it gives off the gas just as calcium carbide gives off acetylene.

This last reaction was also used in Germany for filling Zeppelins. For calcium carbide is convenient and portable and acetylene, when it is once started, as by an electric shock, decomposes spontaneously by its own internal heat into hydrogen and carbon. The latter is left as a fine, pure lampblack, suitable for printer's ink.

Napoleon, who was always on the lookout for new inventions that could be utilized for military purposes, seized immediately upon the balloon as an observation station. Within a few years after the first ascent had been made in Paris Napoleon took balloons and apparatus for generating hydrogen with him on his "archeological expedition" to Egypt in which he hoped to conquer Asia. But the British fleet in the Mediterranean put a stop to this experiment by intercepting the ship, and military aviation waited until the Great War for its full development. This caused a sudden demand for immense quant.i.ties of hydrogen and all manner of means was taken to get it. Water is easily decomposed into hydrogen and oxygen by pa.s.sing an electric current through it. In various electrolytical processes hydrogen has been a wasted by-product since the balloon demand was slight and it was more bother than it was worth to collect and purify the hydrogen. Another way of getting hydrogen in quant.i.ty is by pa.s.sing steam over red-hot c.o.ke. This produces the blue water-gas, which contains about 50 per cent. hydrogen, 40 per cent. carbon monoxide and the rest nitrogen and carbon dioxide. The last is removed by running the mixed gases through lime. Then the nitrogen and carbon monoxide are frozen out in an air-liquefying apparatus and the hydrogen escapes to the storage tank. The liquefied carbon monoxide, allowed to regain its gaseous form, is used in an internal combustion engine to run the plant.

There are then many ways of producing hydrogen, but it is so light and bulky that it is difficult to get it where it is wanted. The American Government in the war made use of steel cylinders each holding 161 cubic feet of the gas under a pressure of 2000 pounds per square inch. Even the hydrogen used by the troops in France was shipped from America in this form. For field use the ferro-silicon and soda process was adopted.

A portable generator of this type was capable of producing 10,000 cubic feet of the gas per hour.

The discovery by a Kansas chemist of natural sources of helium may make it possible to free ballooning of its great danger, for helium is non-inflammable and almost as light as hydrogen.

Other uses of hydrogen besides ballooning have already been referred to in other chapters. It is combined with nitrogen to form synthetic ammonia. It is combined with oxygen in the oxy-hydrogen blowpipe to produce heat. It is combined with vegetable and animal oils to convert them into solid fats. There is also the possibility of using it as a fuel in the internal combustion engine in place of gasoline, but for this purpose we must find some way of getting hydrogen portable or producible in a compact form.

Aluminum, like silicon, sodium and calcium, has been rescued by violence from its attachment to oxygen and like these metals it reverts with readiness to its former affinity. Dr. Goldschmidt made use of this reaction in his thermit process. Powdered aluminum is mixed with iron oxide (rust). If the mixture is heated at any point a furious struggle takes place throughout the whole ma.s.s between the iron and the aluminum as to which metal shall get the oxygen, and the aluminum always comes out ahead. The temperature runs up to some 6000 degrees Fahrenheit within thirty seconds and the freed iron, completely liquefied, runs down into the bottom of the crucible, where it may be drawn off by opening a trap door. The newly formed aluminum oxide (alumina) floats as slag on top. The applications of the thermit process are innumerable.

If, for instance, it is desired to mend a broken rail or crank shaft without moving it from its place, the two ends are brought together or fixed at the proper distance apart. A crucible filled with the thermit mixture is set up above the joint and the thermit ignited with a priming of aluminum and barium peroxide to start it off. The barium peroxide having a superabundance of oxygen gives it up readily and the aluminum thus encouraged attacks the iron oxide and robs it of its oxygen. As soon as the iron is melted it is run off through the bottom of the crucible and fills the s.p.a.ce between the rail ends, being kept from spreading by a mold of refractory material such as magnesite. The two ends of the rail are therefore joined by a section of the same size, shape, substance and strength as themselves. The same process can be used for mending a fracture or supplying a missing fragment of a steel casting of any size, such as a ship's propeller or a cogwheel.

[Ill.u.s.tration: TYPES OF GAS MASK USED BY AMERICA, THE ALLIES, AND GERMANY DURING THE WAR

In the top row are the American masks, chronologically, from left to right: U.S. Navy mask (obsolete), U.S. Navy mask (final type), U.S. Army box respirator (used throughout the war), U.S.R.F.K. respirator, U.S.A.T. respirator (an all-rubber mask), U.S.K.T. respirator (a sewed fabric mask), and U.S. "Model 1919," ready for production when the armistice was signed. In the middle row, left to right, are: British veil (the original emergency mask used in April, 1915), British P.H.

helmet (the next emergency mask), British box respirator (standard British army type), French M2 mask (original type), French Tissot artillery mask, and French A.R.S. mask (latest type). In the front row: the latest German mask, the Russian mask, Italian mask, British motor corps mask, U.S. rear area emergency respirator, and U.S. Connell mask]

[Ill.u.s.tration: PUMPING MELTED WHITE PHOSPHORUS INTO HAND GRENADES FILLED WITH WATER--EDGEWOOD a.r.s.eNAL]

[Ill.u.s.tration: FILLING Sh.e.l.l WITH "MUSTARD GAS"

Empty sh.e.l.ls are being placed on small trucks to be run into the filling chamber. The large truck in the foreground contains loaded sh.e.l.l]

For smaller work thermit has two rivals, the oxy-acetylene torch and electric welding. The former has been described and the latter is rather out of the range of this volume, although I may mention that in the latter part of 1918 there was launched from a British shipyard the first rivotless steel vessel. In this the steel plates forming the sh.e.l.l, bulkheads and floors are welded instead of being fastened together by rivets. There are three methods of doing this depending upon the thickness of the plates and the sort of strain they are subject to. The plates may be overlapped and tacked together at intervals by pressing the two electrodes on opposite sides of the same point until the spot is sufficiently heated to fuse together the plates here. Or roller electrodes may be drawn slowly along the line of the desired weld, fusing the plates together continuously as they go. Or, thirdly, the plates may be b.u.t.t-welded by being pushed together edge to edge without overlapping and the electric current being pa.s.sed from one plate to the other heats up the joint where the conductivity is interrupted.

It will be observed that the thermit process is essentially like the ordinary blast furnace process of smelting iron and other metals except that aluminum is used instead of carbon to take the oxygen away from the metal in the ore. This has an advantage in case carbon-free metals are desired and the process is used for producing manganese, tungsten, t.i.tanium, molybdenum, vanadium and their allows with iron and copper.

During the war thermit found a new and terrible employment, as it was used by the airmen for setting buildings on fire and exploding ammunition dumps. The German incendiary bombs consisted of a perforated steel nose-piece, a tail to keep it falling straight and a cylindrical body which contained a tube of thermit packed around with mineral wax containing pota.s.sium perchlorate. The fuse was ignited as the missile was released and the thermit, as it heated up, melted the wax and allowed it to flow out together with the liquid iron through the holes in the nose-piece. The American incendiary bombs were of a still more malignant type. They weighed about forty pounds apiece and were charged with oil emulsion, thermit and metallic sodium. Sodium decomposes water so that if any attempt were made to put out with a hose a fire started by one of these bombs the stream of water would be instantaneously changed into a jet of blazing hydrogen.

Besides its use in combining and separating different elements the electric furnace is able to change a single element into its various forms. Carbon, for instance, is found in three very distinct forms: in hard, transparent and colorless crystals as the diamond, in black, opaque, metallic scales as graphite, and in shapeless ma.s.ses and powder as charcoal, c.o.ke, lampblack, and the like. In the intense heat of the electric arc these forms are convertible one into the other according to the conditions. Since the third form is the cheapest the object is to change it into one of the other two. Graphite, plumbago or "blacklead,"

as it is still sometimes called, is not found in many places and more rarely found pure. The supply was not equal to the demand until Acheson worked out the process of making it by packing powdered anthracite between the electrodes of his furnace. In this way graphite can be cheaply produced in any desired quant.i.ty and quality.

Since graphite is infusible and incombustible except at exceedingly high temperatures, it is extensively used for crucibles and electrodes. These electrodes are made in all sizes for the various forms of electric lamps and furnaces from rods one-sixteenth of an inch in diameter to bars a foot thick and six feet long. It is graphite mixed with fine clay to give it the desired degree of hardness that forms the filling of our "lead" pencils. Finely ground and flocculent graphite treated with tannin may be held in suspension in liquids and even pa.s.s through filter-paper. The mixture with water is sold under the name of "aquadag," with oil as "oildag" and with grease as "gredag," for lubrication. The smooth, slippery scales of graphite in suspension slide over each other easily and keep the bearings from rubbing against each other.

The other and more difficult metamorphosis of carbon, the transformation of charcoal into diamond, was successfully accomplished by Moissan in 1894. Henri Moissan was a toxicologist, that is to say, a Professor of Poisoning, in the Paris School of Pharmacy, who took to experimenting with the electric furnace in his leisure hours and did more to demonstrate its possibilities than any other man. With it he isolated fluorine, most active of the elements, and he prepared for the first time in their purity many of the rare metals that have since found industrial employment. He also made the carbides of the various metals, including the now common calcium carbide. Among the problems that he undertook and solved was the manufacture of artificial diamonds. He first made pure charcoal by burning sugar. This was packed with iron in the hollow of a block of lime into which extended from opposite sides the carbon rods connected to the dynamo. When the iron had melted and dissolved all the carbon it could, Moissan dumped it into water or better into melted lead or into a hole in a copper block, for this cooled it most rapidly. After a crust was formed it was left to solidify slowly. The sudden cooling of the iron on the outside subjected the carbon, which was held in solution, to intense pressure and when the bit of iron was dissolved in acid some of the carbon was found to be crystallized as diamond, although most of it was graphite. To be sure, the diamonds were hardly big enough to be seen with the naked eye, but since Moissan's aim was to make diamonds, not big diamonds, he ceased his efforts at this point.

To produce large diamonds the carbon would have to be liquefied in considerable quant.i.ty and kept in that state while it slowly crystallized. But that could only be accomplished at a temperature and pressure and duration unattainable as yet. Under ordinary atmospheric pressure carbon pa.s.ses over from the solid to the gaseous phase without pa.s.sing through the liquid, just as snow on a cold, clear day will evaporate without melting.

Probably some one in the future will take up the problem where Moissan dropped it and find out how to make diamonds of any size. But it is not a question that greatly interests either the scientist or the industrialist because there is not much to be learned from it and not much to be made out of it. If the inventor of a process for making cheap diamonds could keep his electric furnace secretly in his cellar and market his diamonds cautiously he might get rich out of it, but he would not dare to turn out very large stones or too many of them, for if a suspicion got around that he was making them the price would fall to almost nothing even if he did sell another one. For the high price of the diamond is purely fict.i.tious. It is in the first place kept up by limiting the output of the natural stone by the combination of dealers and, further, the diamond is valued not for its usefulness or beauty but by its real or supposed rarity. Chesterton says: "All is gold that glitters, for the glitter is the gold." This is not so true of gold, for if gold were as cheap as nickel it would be very valuable, since we should gold-plate our machinery, our ships, our bridges and our roofs.

But if diamonds were cheap they would be good for nothing except grindstones and drills. An imitation diamond made of heavy gla.s.s (paste) cannot be distinguished from the genuine gem except by an expert. It sparkles about as brilliantly, for its refractive index is nearly as high. The reason why it is not priced so highly is because the natural stone has presumably been obtained through the toil and sweat of hundreds of negroes searching in the blue ground of the Transvaal for many months. It is valued exclusively by its cost. To wear a diamond necklace is the same as hanging a certified check for $100,000 by a string around the neck.

Real values are enhanced by reduction in the cost of the price of production. Fict.i.tious values are destroyed by it. Aluminum at twenty-five cents a pound is immensely more valuable to the world than when it is a curiosity in the chemist's cabinet and priced at $160 a pound.

So the scope of the electric furnace reaches from the costly but comparatively valueless diamond to the cheap but indispensable steel. As F.J. Tone says, if the automobile manufacturers were deprived of Niagara products, the abrasives, aluminum, acetylene for welding and high-speed tool steel, a factory now turning out five hundred cars a day would be reduced to one hundred. I have here been chiefly concerned with electricity as effecting chemical changes in combining or separating elements, but I must not omit to mention its rapidly extending use as a source of heat, as in the production and casting of steel. In 1908 there were only fifty-five tons of steel produced by the electric furnace in the United States, but by 1918 this had risen to 511,364 tons. And besides ordinary steel the electric furnace has given us alloys of iron with the once "rare metals" that have created a new science of metallurgy.

CHAPTER XIV

METALS, OLD AND NEW

The primitive metallurgist could only make use of such metals as he found free in nature, that is, such as had not been attacked and corroded by the ubiquitous oxygen. These were primarily gold or copper, though possibly some original genius may have happened upon a bit of meteoric iron and pounded it out into a sword. But when man found that the red ocher he had hitherto used only as a cosmetic could be made to yield iron by melting it with charcoal he opened a new era in civilization, though doubtless the ocher artists of that day denounced him as a utilitarian and deplored the decadence of the times.

Iron is one of the most timid of metals. It has a great disinclination to be alone. It is also one of the most altruistic of the elements. It likes almost every other element better than itself. It has an especial affection for oxygen, and, since this is in both air and water, and these are everywhere, iron is not long without a mate. The result of this union goes by various names in the mineralogical and chemical worlds, but in common language, which is quite good enough for our purpose, it is called iron rust.

[Ill.u.s.tration: By courtesy _Mineral Foote-Notes_.

From Agricola's "De Re Metallica 1550." Primitive furnace for smelting iron ore.]

Not many of us have ever seen iron, the pure metal, soft, ductile and white like silver. As soon as it is exposed to the air it veils itself with a thin film of rust and becomes black and then red. For that reason there is practically no iron in the world except what man has made. It is rarer than gold, than diamonds; we find in the earth no nuggets or crystals of it the size of the fist as we find of these. But occasionally there fall down upon us out of the clear sky great chunks of it weighing tons. These meteorites are the mavericks of the universe.

We do not know where they come from or what sun or planet they belonged to. They are our only visitors from s.p.a.ce, and if all the other spheres are like these fragments we know we are alone in the universe. For they contain rustless iron, and where iron does not rust man cannot live, nor can any other animal or any plant.

Iron rusts for the same reason that a stone rolls down hill, because it gets rid of its energy that way. All things in the universe are constantly trying to get rid of energy except man, who is always trying to get more of it. Or, on second thought, we see that man is the greatest spendthrift of all, for he wants to expend so much more energy than he has that he borrows from the winds, the streams and the coal in the rocks. He robs minerals and plants of the energy which they have stored up to spend for their own purposes, just as he robs the bee of its honey and the silk worm of its coc.o.o.n.

Man's chief business is in reversing the processes of nature. That is the way he gets his living. And one of his greatest triumphs was when he discovered how to undo iron rust and get the metal out of it. In the four thousand years since he first did this he has accomplished more than in the millions of years before. Without knowing the value of iron rust man could attain only to the culture of the Aztecs and Incas, the ancient Egyptians and a.s.syrians.

The prosperity of modern states is dependent on the amount of iron rust which they possess and utilize. England, United States, Germany, all nations are competing to see which can dig the most iron rust out of the ground and make out of it railroads, bridges, buildings, machinery, battleships and such other tools and toys and then let them relapse into rust again. Civilization can be measured by the amount of iron rusted per capita, or better, by the amount rescued from rust.

But we are devoting so much s.p.a.ce to the consideration of the material aspects of iron that we are like to neglect its esthetic and ethical uses. The beauty of nature is very largely dependent upon the fact that iron rust and, in fact, all the common compounds of iron are colored.

Few elements can a.s.sume so many tints. Look at the paint pot canons of the Yellowstone. Cheap gla.s.s bottles turn out brown, green, blue, yellow or black, according to the amount and kind of iron they contain. We build a house of cream-colored brick, varied with speckled brick and adorned with terra cotta ornaments of red, yellow and green, all due to iron. Iron rusts, therefore it must be painted; but what is there better to paint it with than iron rust itself? It is cheap and durable, for it cannot rust any more than a dead man can die. And what is also of importance, it is a good, strong, clean looking, endurable color.

Whenever we take a trip on the railroad and see the miles of cars, the acres of roofing and wall, the towns full of brick buildings, we rejoice that iron rust is red, not white or some leas satisfying color.

We do not know why it is so. Zinc and aluminum are metals very much like iron in chemical properties, but all their salts are colorless. Why is it that the most useful of the metals forms the most beautiful compounds? Some say, Providence; some say, chance; some say nothing. But if it had not been so we would have lost most of the beauty of rocks and trees and human beings. For the leaves and the flowers would all be white, and all the men and women would look like walking corpses.

Without color in the flower what would the bees and painters do? If all the gra.s.s and trees were white, it would be like winter all the year round. If we had white blood in our veins like some of the insects it would be hard lines for our poets. And what would become of our morality if we could not blush?

"As for me, I thrill to see The bloom a velvet cheek discloses!

Made of dust! I well believe it, So are lilies, so are roses."

An etiolated earth would be hardly worth living in.

The chlorophyll of the leaves and the hemoglobin of the blood are similar in const.i.tution. Chlorophyll contains magnesium in place of iron but iron is necessary to its formation. We all know how pale a plant gets if its soil is short of iron. It is the iron in the leaves that enables the plants to store up the energy of the sunshine for their own use and ours. It is the iron in our blood that enables us to get the iron out of iron rust and make it into machines to supplement our feeble hands. Iron is for us internally the carrier of energy, just as in the form of a trolley wire or of a third rail it conveys power to the electric car. Withdraw the iron from the blood as indicated by the pallor of the cheeks, and we become weak, faint and finally die. If the amount of iron in the blood gets too small the disease germs that are always attacking us are no longer destroyed, but multiply without check and conquer us. When the iron ceases to work efficiently we are killed by the poison we ourselves generate.

Counting the number of iron-bearing corpuscles in the blood is now a common method of determining disease. It might also be useful in moral diagnosis. A microscopical and chemical laboratory attached to the courtroom would give information of more value than some of the evidence now obtained. For the anemic and the florid vices need very different treatment. An excess or a deficiency of iron in the body is liable to result in criminality. A chemical system of morals might be developed on this basis. Among the ferruginous sins would be placed murder, violence and licentiousness. Among the non-ferruginous, cowardice, sloth and lying. The former would be mostly sins of commission, the latter, sins of omission. The virtues could, of course, be similarly cla.s.sified; the ferruginous virtues would include courage, self-reliance and hopefulness; the non-ferruginous, peaceableness, meekness and chast.i.ty.

According to this ethical criterion the moral man would be defined as one whose conduct is better than we should expect from the per cent. of iron in his blood.

The reason why iron is able to serve this unique purpose of conveying life-giving air to all parts of the body is because it rusts so readily.

Oxidation and de-oxidation proceed so quietly that the tenderest cells are fed without injury. The blood changes from red to blue and _vice versa_ with greater ease and rapidity than in the corresponding alternations of social status in a democracy. It is because iron is so rustable that it is so useful. The factories with big sc.r.a.p-heaps of rusting machinery are making the most money. The pyramids are the most enduring structures raised by the hand of man, but they have not sheltered so many people in their forty centuries as our skysc.r.a.pers that are already rusting.