Chapter 9

CHAPTER IX

THE QUESTION OF THE POWDERS

There remained for consideration merely the question of powders.
The public awaited with interest its final decision. The size
of the projectile, the length of the cannon being settled, what
would be the quantity of powder necessary to produce impulsion?

It is generally asserted that gunpowder was invented in the
fourteenth century by the monk Schwartz, who paid for his grand
discovery with his life. It is, however, pretty well proved
that this story ought to be ranked among the legends of the
middle ages. Gunpowder was not invented by any one; it was the
lineal successor of the Greek fire, which, like itself, was
composed of sulfur and saltpeter. Few persons are acquainted
with the mechanical power of gunpowder. Now this is precisely
what is necessary to be understood in order to comprehend the
importance of the question submitted to the committee.

A litre of gunpowder weighs about two pounds; during combustion
it produces 400 litres of gas. This gas, on being liberated and
acted upon by temperature raised to 2,400 degrees, occupies a
space of 4,000 litres: consequently the volume of powder is to
the volume of gas produced by its combustion as 1 to 4,000.
One may judge, therefore, of the tremendous pressure on this
gas when compressed within a space 4,000 times too confined.
All this was, of course, well known to the members of the committee
when they met on the following evening.

The first speaker on this occasion was Major Elphinstone, who
had been the director of the gunpowder factories during the war.

"Gentlemen," said this distinguished chemist, "I begin with
some figures which will serve as the basis of our calculation.
The old 24-pounder shot required for its discharge sixteen pounds
of powder."

"You are certain of this amount?" broke in Barbicane.

"Quite certain," replied the major. "The Armstrong cannon
employs only seventy-five pounds of powder for a projectile
of eight hundred pounds, and the Rodman Columbiad uses only one
hundred and sixty pounds of powder to send its half ton shot a
distance of six miles. These facts cannot be called in question,
for I myself raised the point during the depositions taken before
the committee of artillery."

"Quite true," said the general.

"Well," replied the major, "these figures go to prove that the
quantity of powder is not increased with the weight of the shot;
that is to say, if a 24-pounder shot requires sixteen pounds of
powder;-- in other words, if in ordinary guns we employ a
quantity of powder equal to two-thirds of the weight of the
projectile, this proportion is not constant. Calculate, and you
will see that in place of three