bolical products, ranging all
the way from high explosives to poison gases, it would have few of the
characteristics of ultra-frightfulness that render it unique in the
history of international struggles.

But of all the instruments of destruction used in this war, there is
none more horrifying than the so-called "incendiary bomb," which sets
instant fire to whatever it touches and which spreads flame in a manner
so terrific that three or four such gravity-projectiles dropped from an
aeroplane burned up the whole of a peaceful Dutch village in a few
minutes.

Now, what is the fearsome stuff with which such bombs are loaded? A new
chemical compound? Not at all. What they contain is simply the mixture
of two of the most harmless things in the world--oxide of iron (which
is simply iron rust) and powdered aluminum.

When these two innocent substances are mixed together the result is a
compound truly infernal in its potentialities for mischief. It is not an
explosive but if set on fire it burns with an intensity that is
positively appalling. Nothing will put it out; no quantity of water has
any effect upon the raging flames it engenders.

This is the material used for loading incendiary bombs. It is ignited in
such projectiles by a mercury-fulminate cap that sets off a fuse
containing powdered magnesium--the stuff photographers employ for
flashlights.

THIN SHELLS OF STEEL.

These bombs are thin shells of steel or iron--mere containers for the
mixture before described. They are so contrived that the fuse is
instantly ignited when they strike.

Whereupon the shell is melted by the heat generated within it and a
flood of fiercely burning metal is scattered in all directions. All of
this seems rather extraordinary, and it is worth explaining.

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 combustio