Creative Chemistry | Page 8

just as likely to
kill a knight as a peasant, and a brave man as a coward. You cannot
fence with a cannon ball nor overawe it with a plumed hat. The only
thing you can do is to hide and shoot back. Now you cannot hide if you
send up a column of smoke by day and a pillar of fire by night--the
most conspicuous of signals--every time you shoot. So the next step
was the invention of a smokeless powder. In this the oxygen necessary
for the combustion is already in such close combination with its fuel,
the carbon and hydrogen, that no black particles of carbon can get away
unburnt. In the old-fashioned gunpowder the oxygen necessary for the
combustion of the carbon and sulfur was in a separate package, in the
molecule of potassium nitrate, and however finely the mixture was
ground, some of the atoms, in the excitement of the explosion, failed to
find their proper partners at the moment of dispersal. The new
gunpowder besides being smokeless is ashless. There is no black sticky
mass of potassium salts left to foul the gun barrel.
The gunpowder period of warfare was actively initiated at the battle of
Cressy, in which, as a contemporary historian says, "The English guns
made noise like thunder and caused much loss in men and horses."
Smokeless powder as invented by Paul Vieille was adopted by the
French Government in 1887. This, then, might be called the beginning
of the guncotton or nitrocellulose period--or, perhaps in deference to
the caveman's club, the second cellulose period of human warfare.
Better, doubtless, to call it the "high explosive period," for various
other nitro-compounds besides guncotton are being used.
The important thing to note is that all the explosives from gunpowder
down contain nitrogen as the essential element. It is customary to call

nitrogen "an inert element" because it was hard to get it into
combination with other elements. It might, on the other hand, be looked
upon as an active element because it acts so energetically in getting out
of its compounds. We can dodge the question by saying that nitrogen is
a most unreliable and unsociable element. Like Kipling's cat it walks by
its wild lone.
It is not so bad as Argon the Lazy and the other celibate gases of that
family, where each individual atom goes off by itself and absolutely
refuses to unite even temporarily with any other atom. The nitrogen
atoms will pair off with each other and stick together, but they are
reluctant to associate with other elements and when they do the
combination is likely to break up any moment. You all know people
like that, good enough when by themselves but sure to break up any
club, church or society they get into. Now, the value of nitrogen in
warfare is due to the fact that all the atoms desert in a body on the field
of battle. Millions of them may be lying packed in a gun cartridge, as
quiet as you please, but let a little disturbance start in the
neighborhood--say a grain of mercury fulminate flares up--and all the
nitrogen atoms get to trembling so violently that they cannot be
restrained. The shock spreads rapidly through the whole mass. The
hydrogen and carbon atoms catch up the oxygen and in an instant they
are off on a stampede, crowding in every direction to find an exit, and
getting more heated up all the time. The only movable side is the
cannon ball in front, so they all pound against that and give it such a
shove that it goes ten miles before it stops. The external bombardment
by the cannon ball is, therefore, preceded by an internal bombardment
on the cannon ball by the molecules of the hot gases, whose speed is
about as great as the speed of the projectile that they propel.
[Illustration: © Underwood & Underwood
THE HAND GRENADES WHICH THESE WOMEN ARE BORING
will contain potential chemical energy capable of causing a vast
amount of destruction when released. During the war the American
Government placed orders for 68,000,000 such grenades as are here
shown.]

[Illustration: © International Film Service, Inc.
WOMEN IN A MUNITION PLANT ENGAGED IN THE
MANUFACTURE OF TRI-NITRO-TOLUOL, THE MOST
IMPORTANT OF MODERN HIGH EXPLOSIVES]
The active agent in all these explosives is the nitrogen atom in
combination with two oxygen atoms, which the chemist calls the "nitro
group" and which he represents by NO_{2}. This group was, as I have
said, originally used in the form of saltpeter or potassium nitrate, but
since the chemist did not want the potassium part of it--for it fouled his
guns--he took the nitro group out of the nitrate by means of sulfuric
acid and by the same means hooked