Oxygen has an affinity for iron, readily combining with the latter—which is the reason why iron is liable to rust. This rust is a chemical compound of iron and oxygen; in other words, oxide of iron. But oxygen has a much greater affinity for aluminum. And so, when the two metals are powdered and mixed together and heat is applied the oxygen flies out of the iron rust and combines with the aluminum.
The process is started in the bomb by the burning magnesium. And then the oxygen passes out of the iron and into the aluminum so rapidly that an enormously high temperature is developed. It runs up to 3500 or 4000 degrees Fahrenheit—which means, of course, a tremendous combustion. The mixture of aluminum and iron burns like so much tinder—though such a way of putting it is absurdly feeble.
The present war has been conspicuously marked by reversions to ancient methods of fighting. In this line the incendiary bomb offers an excellent illustration. It is in effect merely an adaptation of an idea utilized by the Saracens—we should call them Turks nowadays—in their warfare with the Crusaders of the Middle Ages.
DREAD INSTRUMENT OF WAR.
The instrument of war most dreaded by the Crusaders, as they found it in the hands of the Turks, was the incendiary bomb—a projectile that flew through the air "like a fiery dragon" as they described it, and set fire to whatever it touched. Sometimes it was provided with iron barbs, by which it clung to buildings.
This was one of the ways in which the Saracens employed the celebrated "Greek fire"—an inflammable compound that is understood to have been a mixture of petroleum, saltpeter and pitch. The chief horror of it, from the Crusaders' point of view, was that it was unquenchable. Mere water had no effect upon it. Hence they were sure that it must be of diabolical origin.
But the up-to-date incendiary bomb is a great improvement on its original of the Middle Ages. The modern contrivance is thoroughly scientific, and it does its destructive business with certainty and dispatch.
No less effective are the gas bombs which were introduced by the German soldiers at Rheims, and which when exploding near the trenches occupied by the French and English threw off vapors and poisonous gases which killed or overwhelmed thousands of brave men. These devices used in violation of all rules of civilized warfare sent hundreds to the hospitals. Seventy-five victims were taken at one time from the trenches to the hospital at Zuydcoote, north of Dunkirk, where it was found that some of those who had inhaled the fumes turned a violet tinge.
Altogether it was estimated that from 3000 to 5000 men were affected by the gas fumes in this first onslaught and at least 10 per cent of those who were overcome succumbed to the deadly fumes. Many of those who inhaled the poisons expectorated blood and for days afterward were racked by terrible coughing. In many cases fever developed in a few days ending with pneumonia. When the men were not sufficiently poisoned to cause death they were so affected that their usefulness as soldiers was ended for all time. The poison made them confirmed invalids.