In its modern manufacture the catalyzer or instigator of the combination is not sunlight but porous carbon. This is packed in iron boxes eight feet long, through which the mixture of the two gases was forced. Carbon monoxide may be made by burning c.o.ke with a supply of air insufficient for complete combustion, but in order to get the pure gas necessary for the phosgene common air was not used, but instead pure oxygen extracted from it by a liquid air plant.

Phosgene is a gas that may be condensed easily to a liquid by cooling it down to 46 degrees Fahrenheit. A mixture of three-quarters chlorine with one-quarter phosgene has been found most effective. By itself phosgene has an inoffensive odor somewhat like green corn and so may fail to arouse apprehension until a toxic concentration is reached. But even small doses have such an effect upon the heart action for days afterward that a slight exertion may prove fatal.

The compound manufactured in largest amount in America was chlorpicrin.

This, like the others, is not so unfamiliar as it seems. As may be seen from its formula, CCl_{3}NO_{2}, it is formed by joining the nitric acid radical (NO_{2}), found in all explosives, with the main part of chloroform (HCCl_{3}). This is not quite so poisonous as phosgene, but it has the advantage that it causes nausea and vomiting. The soldier so affected is forced to take off his gas mask and then may fall victim to more toxic gases sent over simultaneously.

Chlorpicrin is a liquid and is commonly loaded in a sh.e.l.l or bomb with 20 per cent. of tin chloride, which produces dense white fumes that go through gas masks. It is made from picric acid (trinitrophenol), one of the best known of the high explosives, by treatment with chlorine. The chlorine is obtained, as it is in the household, from common bleaching powder, or "chloride of lime." This is mixed with water to form a cream in a steel still 18 feet high and 8 feet in diameter. A solution of calcium picrate, that is, the lime salt of picric acid, is pumped in and as the reaction begins the mixture heats up and the chlorpicrin distils over with the steam. When the distillate is condensed the chlorpicrin, being the heavier liquid, settles out under the layer of water and may be drawn off to fill the sh.e.l.l.

Much of what a student learns in the chemical laboratory he is apt to forget in later life if he does not follow it up. But there are two gases that he always remembers, chlorine and hydrogen sulfide. He is lucky if he has escaped being choked by the former or sickened by the latter. He can imagine what the effect would be if two offensive fumes could be combined without losing their offensive features. Now a combination something like this is the so-called mustard gas, which is not a gas and is not made from mustard. But it is easily gasified, and oil of mustard is about as near as Nature dare come to making such sinful stuff. It was first made by Guthrie, an Englishman, in 1860, and rediscovered by a German chemist, Victor Meyer, in 1886, but he found it so dangerous to work with that he abandoned the investigation. n.o.body else cared to take it up, for n.o.body could see any use for it. So it remained in innocuous desuetude, a mere name in "Beilstein's Dictionary," together with the thousands of other organic compounds that have been invented and never utilized. But on July 12, 1917, the British holding the line at Ypres were besprinkled with this villainous substance. Its success was so great that the Germans henceforth made it their main reliance and soon the Allies followed suit. In one offensive of ten days the Germans are said to have used a million sh.e.l.ls containing 2500 tons of mustard gas.

The making of so dangerous a compound on a large scale was one of the most difficult tasks set before the chemists of this and other countries, yet it was successfully solved. The raw materials are chlorine, alcohol and sulfur. The alcohol is pa.s.sed with steam through a vertical iron tube filled with kaolin and heated. This converts the alcohol into a gas known as ethylene (C_{2}H_{4}). Pa.s.sing a stream of chlorine gas into a tank of melted sulfur produces sulfur monochloride and this treated with the ethylene makes the "mustard." The final reaction was carried on at the Edgewood a.r.s.enal in seven airtight tanks or "reactors," each having a capacity of 30,000 pounds. The ethylene gas being led into the tank and distributed through the liquid sulfur chloride by porous blocks or fine nozzles, the two chemicals combined to form what is officially named "di-chlor-di-ethyl-sulfide"

(ClC_{2}H_{4}SC_{2}H_{4}Cl). This, however, is too big a mouthful, so even the chemists were glad to fall in with the commonalty and call it "mustard gas."

The effectiveness of "mustard" depends upon its persistence. It is a stable liquid, evaporating slowly and not easily decomposed. It lingers about trenches and dugouts and impregnates soil and cloth for days. Gas masks do not afford complete protection, for even if they are impenetrable they must be taken off some time and the gas lies in wait for that time. In some cases the masks were worn continuously for twelve hours after the attack, but when they were removed the soldiers were overpowered by the poison. A place may seem to be free from it but when the sun heats up the ground the liquid volatilizes and the vapor soaks through the clothing. As the men become warmed up by work their skin is blistered, especially under the armpits. The mustard acts like steam, producing burns that range from a mere reddening to serious ulcerations, always painful and incapacitating, but if treated promptly in the hospital rarely causing death or permanent scars. The gas attacks the eyes, throat, nose and lungs and may lead to bronchitis or pneumonia. It was found necessary at the front to put all the clothing of the soldiers into the sterilizing ovens every night to remove all traces of mustard. General Johnson and his staff in the 77th Division were poisoned in their dugouts because they tried to alleviate the discomfort of their camp cots by bedding taken from a neighboring village that had been sh.e.l.led the day before.

Of the 925 cases requiring medical attention at the Edgewood a.r.s.enal 674 were due to mustard. During the month of August 3-1/2 per cent. of the mustard plant force were sent to the hospital each day on the average.

But the record of the Edgewood a.r.s.enal is a striking demonstration of what can be done in the prevention of industrial accidents by the exercise of scientific prudence. In spite of the fact that from three to eleven thousand men were employed at the plant for the year 1918 and turned out some twenty thousand tons of the most poisonous gases known to man, there were only three fatalities and not a single case of blindness.

Besides the four toxic gases previously described, chlorine, phosgene, chlorpicrin and mustard, various other compounds have been and many others might be made. A list of those employed in the present war enumerates thirty, among them compounds of bromine, a.r.s.enic and cyanogen that may prove more formidable than any so far used. American chemists kept very mum during the war but occasionally one could not refrain from saying: "If the Kaiser knew what I know he would surrender unconditionally by telegraph." No doubt the science of chemical warfare is in its infancy and every foresighted power has concealed weapons of its own in reserve. One deadly compound, whose ident.i.ty has not yet been disclosed, is known as "Lewisite," from Professor Lewis of Northwestern, who was manufacturing it at the rate of ten tons a day in the "Mouse Trap" stockade near Cleveland.

Throughout the history of warfare the art of defense has kept pace with the art of offense and the courage of man has never failed, no matter to what new danger he was exposed. As each new gas employed by the enemy was detected it became the business of our chemists to discover some method of absorbing or neutralizing it. Porous charcoal, best made from such dense wood as coconut sh.e.l.ls, was packed in the respirator box together with layers of such chemicals as will catch the gases to be expected. Charcoal absorbs large quant.i.ties of any gas. Soda lime and pota.s.sium permanganate and nickel salts were among the neutralizers used.

The mask is fitted tightly about the face or over the head with rubber.

The nostrils are kept closed with a clip so breathing must be done through the mouth and no air can be inhaled except that pa.s.sing through the absorbent cylinder. Men within five miles of the front were required to wear the masks slung on their chests so they could be put on within six seconds. A well-made mask with a fresh box afforded almost complete immunity for a time and the soldiers learned within a few days to handle their masks adroitly. So the problem of defense against this new offensive was solved satisfactorily, while no such adequate protection against the older weapons of bayonet and shrapnel has yet been devised.

Then the problem of the offense was to catch the opponent with his mask off or to make him take it off. Here the lachrymators and the sternutators, the tear gases and the sneeze gases, came into play. Phenylcarbylamine chloride would make the bravest soldier weep on the battlefield with the abandonment of a Greek hero.

Di-phenyl-chloro-arsine would set him sneezing. The Germans alternated these with diabolical ingenuity so as to catch us unawares. Some sh.e.l.ls gave off voluminous smoke or a vile stench without doing much harm, but by the time our men got used to these and grew careless about their masks a few sh.e.l.ls of some extremely poisonous gas were mixed with them.

The ideal gas for belligerent purposes would be odorless, colorless and invisible, toxic even when diluted by a million parts of air, not set on fire or exploded by the detonator of the sh.e.l.l, not decomposed by water, not readily absorbed, stable enough to stand storage for six months and capable of being manufactured by the thousands of tons. No one gas will serve all aims. For instance, phosgene being very volatile and quickly dissipated is thrown into trenches that are soon to be taken while mustard gas being very tenacious could not be employed in such a case for the trenches could not be occupied if they were captured.

The extensive use of poison gas in warfare by all the belligerents is a vindication of the American protest at the Hague Conference against its prohibition. At the First Conference of 1899 Captain Mahan argued very sensibly that gas sh.e.l.ls were no worse than other projectiles and might indeed prove more merciful and that it was illogical to prohibit a weapon merely because of its novelty. The British delegates voted with the Americans in opposition to the clause "the contracting parties agree to abstain from the use of projectiles the sole object of which is the diffusion of asphyxiating or deleterious gases." But both Great Britain and Germany later agreed to the provision. The use of poison gas by Germany without warning was therefore an act of treachery and a violation of her pledge, but the United States has consistently refused to bind herself to any such restriction. The facts reported by General Amos A. Fries, in command of the overseas branch of the American Chemical Warfare Service, give ample support to the American contention at The Hague:

Out of 1000 gas casualties there are from 30 to 40 fatalities, while out of 1000 high explosive casualties the number of fatalities run from 200 to 250. While exact figures are as yet not available concerning the men permanently crippled or blinded by high explosives one has only to witness the debarkation of a shipload of troops to be convinced that the number is very large. On the other hand there is, so far as known at present, not a single case of permanent disability or blindness among our troops due to gas and this in face of the fact that the Germans used relatively large quant.i.ties of this material.

In the light of these facts the prejudice against the use of gas must gradually give way; for the statement made to the effect that its use is contrary to the principles of humanity will apply with far greater force to the use of high explosives. As a matter of fact, for certain purposes toxic gas is an ideal agent. For example, it is difficult to imagine any agent more effective or more humane that may be used to render an opposing battery ineffective or to protect retreating troops.

Captain Mahan's argument at The Hague against the proposed prohibition of poison gas is so cogent and well expressed that it has been quoted in treatises on international law ever since. These reasons were, briefly:

1. That no sh.e.l.l emitting such gases is as yet in practical use or has undergone adequate experiment; consequently, a vote taken now would be taken in ignorance of the facts as to whether the results would be of a decisive character or whether injury in excess of that necessary to attain the end of warfare--the immediate disabling of the enemy--would be inflicted.

2. That the reproach of cruelty and perfidy, addressed against these supposed sh.e.l.ls, was equally uttered formerly against firearms and torpedoes, both of which are now employed without scruple. Until we know the effects of such asphyxiating sh.e.l.ls, there was no saying whether they would be more or less merciful than missiles now permitted. That it was illogical, and not demonstrably humane, to be tender about asphyxiating men with gas, when all are prepared to admit that it was allowable to blow the bottom out of an ironclad at midnight, throwing four or five hundred into the sea, to be choked by water, with scarcely the remotest chance of escape.

As Captain Mahan says, the same objection has been raised at the introduction of each new weapon of war, even though it proved to be no more cruel than the old. The modern rifle ball, swift and small and sterilized by heat, does not make so bad a wound as the ancient sword and spear, but we all remember how gunpowder was regarded by the dandies of Hotspur's time:

And it was great pity, so it was, This villainous saltpeter should be digg'd Out of the bowels of the harmless earth Which many a good tall fellow had destroy'd So cowardly; and but for these vile guns He would himself have been a soldier.

The real reason for the instinctive aversion manifested against any new arm or mode of attack is that it reveals to us the intrinsic horror of war. We naturally revolt against premeditated homicide, but we have become so accustomed to the sword and latterly to the rifle that they do not shock us as they ought when we think of what they are made for. The Const.i.tution of the United States prohibits the infliction of "cruel and unusual punishments." The two adjectives were apparently used almost synonymously, as though any "unusual" punishment were necessarily "cruel," and so indeed it strikes us. But our ingenious lawyers were able to persuade the courts that electrocution, though unknown to the Fathers and undeniably "unusual," was not unconst.i.tutional. Dumdum bullets are rightfully ruled out because they inflict frightful and often incurable wounds, and the aim of humane warfare is to disable the enemy, not permanently to injure him.

[Ill.u.s.tration: From "America's Munitions" THE CHLORPICRIN PLANT AT THE EDGEWOOD a.r.s.eNAL

From these stills, filled with a mixture of bleaching powder, lime, and picric acid, the poisonous gas, chlorpicrin, distills off. This plant produced 31 tons in one day]

[Ill.u.s.tration: Courtesy of the Metal and Thermit Corporation, N.Y.

REPAIRING THE BROKEN STERN POST OF THE U.S.S. NORTHERN PACIFIC, THE BIGGEST MARINE WELD IN THE WORLD

On the right the fractured stern post is shown. On the left it is being mended by means of thermit. Two crucibles each containing 700 pounds of the thermit mixture are seen on the sides of the vessel. From the bottom of these the melted steel flowed down to fill the fracture]

In spite of the opposition of the American and British delegates the First Hague Conference adopted the clause, "The contracting powers agree to abstain from the use of projectiles the [sole] object of which is the diffusion of asphyxiating or deleterious gases." The word "sole"

(_unique_) which appears in the original French text of The Hague convention is left out of the official English translation. This is a strange omission considering that the French and British defended their use of explosives which diffuse asphyxiating and deleterious gases on the ground that this was not the "sole" purpose of the bombs but merely an accidental effect of the nitric powder used.

The Hague Congress of 1907 placed in its rules for war: "It is expressly forbidden to employ poisons or poisonous weapons." But such attempts to rule out new and more effective means of warfare are likely to prove futile in any serious conflict and the restriction gives the advantage to the most unscrupulous side. We Americans, if ever we give our a.s.sent to such an agreement, would of course keep it, but our enemy--whoever he may be in the future--will be, as he always has been, utterly without principle and will not hesitate to employ any weapon against us.

Besides, as the Germans held, chemical warfare favors the army that is most intelligent, resourceful and disciplined and the nation that stands highest in science and industry. This advantage, let us hope, will be on our side.

CHAPTER XIII

PRODUCTS OF THE ELECTRIC FURNACE

The control of man over the materials of nature has been vastly enhanced by the recent extension of the range of temperature at his command. When Fahrenheit stuck the bulb of his thermometer into a mixture of snow and salt he thought he had reached the nadir of temperature, so he scratched a mark on the tube where the mercury stood and called it zero. But we know that absolute zero, the total absence of heat, is 459 of Fahrenheit's degrees lower than his zero point. The modern scientist can get close to that lowest limit by making use of the cooling by the expansion principle. He first liquefies air under pressure and then releasing the pressure allows it to boil off. A tube of hydrogen immersed in the liquid air as it evaporates is cooled down until it can be liquefied. Then the boiling hydrogen is used to liquefy helium, and as this boils off it lowers the temperature to within three or four degrees of absolute zero.

The early metallurgist had no hotter a fire than he could make by blowing charcoal with a bellows. This was barely enough for the smelting of iron. But by the bringing of two carbon rods together, as in the electric arc light, we can get enough heat to volatilize the carbon at the tips, and this means over 7000 degrees Fahrenheit. By putting a pressure of twenty atmospheres onto the arc light we can raise it to perhaps 14,000 degrees, which is 3000 degrees hotter than the sun. This gives the modern man a working range of about 14,500 degrees, so it is no wonder that he can perform miracles.

When a builder wants to make an old house over into a new one he takes it apart brick by brick and stone by stone, then he puts them together in such new fashion as he likes. The electric furnace enables the chemist to take his materials apart in the same way. As the temperature rises the chemical and physical forces that hold a body together gradually weaken. First the solid loosens up and becomes a liquid, then this breaks bonds and becomes a gas. Compounds break up into their elements. The elemental molecules break up into their component atoms and finally these begin to throw off corpuscles of negative electricity eighteen hundred times smaller than the smallest atom. These electrons appear to be the building stones of the universe. No indication of any smaller units has been discovered, although we need not a.s.sume that in the electron science has delivered, what has been called, its "ultim-atom." The Greeks called the elemental particles of matter "atoms" because they esteemed them "indivisible," but now in the light of the X-ray we can witness the disintegration of the atom into electrons. All the chemical and physical properties of matter, except perhaps weight, seem to depend upon the number and movement of the negative and positive electrons and by their rearrangement one element may be transformed into another.

So the electric furnace, where the highest attainable temperature is combined with the divisive and directive force of the current, is a magical machine for accomplishment of the metamorphoses desired by the creative chemist. A hundred years ago Davy, by dipping the poles of his battery into melted soda lye, saw forming on one of them a shining globule like quicksilver. It was the metal sodium, never before seen by man. Nowadays this process of electrolysis (electric loosening) is carried out daily by the ton at Niagara.

The reverse process, electro-synthesis (electric combining), is equally simple and even more important. By pa.s.sing a strong electric current through a mixture of lime and c.o.ke the metal calcium disengages itself from the oxygen of the lime and attaches itself to the carbon. Or, to put it briefly,

CaO + 3C --> CaC_{2} + CO lime c.o.ke calcium carbon carbide monoxide

This reaction is of peculiar importance because it bridges the gulf between the organic and inorganic worlds. It was formerly supposed that the substances found in plants and animals, mostly complex compounds of carbon, hydrogen and oxygen, could only be produced by "vital forces."

If this were true it meant that chemistry was limited to the mineral kingdom and to the extraction of such carbon compounds as happened to exist ready formed in the vegetable and animal kingdoms. But fortunately this barrier to human achievement proved purely illusory. The organic field, once man had broken into it, proved easier to work in than the inorganic.

But it must be confessed that man is dreadfully clumsy about it yet. He takes a thousand horsepower engine and an electric furnace at several thousand degrees to get carbon into combination with hydrogen while the little green leaf in the sunshine does it quietly without getting hot about it. Evidently man is working as wastefully as when he used a thousand slaves to drag a stone to the pyramid or burned down a house to roast a pig. Not until his laboratory is as cool and calm and comfortable as the forest and the field can the chemist call himself completely successful.

But in spite of his clumsiness the chemist is actually making things that he wants and cannot get elsewhere. The calcium carbide that he manufactures from inorganic material serves as the raw material for producing all sorts of organic compounds. The electric furnace was first employed on a large scale by the Cowles Electric Smelting and Aluminum Company at Cleveland in 1885. On the dump were found certain lumps of porous gray stone which, dropped into water, gave off a gas that exploded at touch of a match with a splendid bang and flare. This gas was acetylene, and we can represent the reaction thus:

CaC_{2} + 2 H_{2}O --> C_{2}H_{2} + CaO_{2}H_{2}

calcium carbide _added_ to water _ gives_ acetylene _and_ slaked lime

We are all familiar with this reaction now, for it is acetylene that gives the dazzling light of the automobiles and of the automatic signal buoys of the seacoast. When burned with pure oxygen instead of air it gives the hottest of chemical flames, hotter even than the oxy-hydrogen blowpipe. For although a given weight of hydrogen will give off more heat when it burns than carbon will, yet acetylene will give off more heat than either of its elements or both of them when they are separate.

This is because acetylene has stored up heat in its formation instead of giving it off as in most reactions, or to put it in chemical language, acetylene is an endothermic compound. It has required energy to bring the H and the C together, therefore it does not require energy to separate them, but, on the contrary, energy is released when they are separated. That is to say, acetylene is explosive not only when mixed with air as coal gas is but by itself. Under a suitable impulse acetylene will break up into its original carbon and hydrogen with great violence. It explodes with twice as much force without air as ordinary coal gas with air. It forms an explosive compound with copper, so it has to be kept out of contact with bra.s.s tubes and stopc.o.c.ks. But compressed in steel cylinders and dissolved in acetone, it is safe and commonly used for welding and melting. It is a marvelous though not an unusual sight on city streets to see a man with blue gla.s.ses on cutting down through a steel rail with an oxy-acetylene blowpipe as easily as a carpenter saws off a board. With such a flame he can carve out a pattern in a steel plate in a way that reminds me of the days when I used to make brackets with a scroll saw out of cigar boxes. The torch will travel through a steel plate an inch or two thick at a rate of six to ten inches a minute.

[Ill.u.s.tration: Courtesy of the Carborundum Company, Niagara Falls