NATURAL RESOURCES—LITTLE. 291 
sary to provide over 280,000 rounds of ammunition per machine gun 
in the field during its first year of service. 
It will be remembered that the question of shoulder rifles occa- 
sioned much discussion and concern, but the United States neverthe- 
less built in 19 months over two and one-half million of these weapons 
and about 750,000 pistols and revolvers and turned out in the same 
time nearly 4,000,000,000 rounds of small arms ammunition, including 
that for machine guns. In view of these great figures it is interest- 
ing to consider them with respect to the materials concerned in the 
make-up of some of the units of this ammunition. 
The ordinary service cartridge consists of a brass cartridge case, 
a primer with a primer charge of sulphur, chlorate of potash, and 
antimony sulphide, a propelling charge of smokeless powder, which 
refers at once to cotton and the fixation of atmospheric nitrogen, 
and finally, a bullet with a cupro-nickel jacket and a lead slug or 
core. The production, therefore, of this single small object involves 
our reserves of copper, zinc, nickel, lead, and antimony among the 
metals; the Louisiana or Texas sulphur deposits; potash, as to which 
We were experiencing a famine; water power to convert by electro- 
lysis potassium chloride to the chlorate; and finally, cotton linters, 
sulphuric and nitric acids, various organic solvents, and even the 
fixation of atmospheric nitrogen. Since there was a shortage in 
cupro-nickel, which is a hard alloy of the two metals, it might have 
become necessary to have jacketed the bullet with copper-coated 
steel. 
The armor-piercing bullet had a cupro-nickel jacket lined with a 
thin lead coat, and the core was of specially heat-treated alloy steel. 
Tracer bullets, of which 5,000,000 were produced, had a cupro- 
nickel shell with a lead core in the nose and a rear chamber charge 
of barium peroxide and magnesium, the latter being an electric 
furnace product. The shell of the incendiary bullet was the same, 
but it carried phosphorus in the nose, had a lead plug, and a special, 
low-melting solder. 
The trench mortar from the 3-inch Newton-Stokes to the 240- 
millimeter was an interesting and highly effective development of 
the war. The 3-inch mortars and the shells used therein were both 
made of steel tubing, and for the latter alone about. 2,700,000 feet 
of such tubing were made. Shells for the 6-inch mortars were of cast 
iron and made by stove manufacturers. 
The revival of the use of armor, which, of course, requires for its 
fabrication alloy steel of the highest quality, was no less significant 
_ and interesting. Good alloy steel 0.036 inch thick proved effective 
against pistol bullets, and French hospital records show that 70 to 
80 per cent of the wounded soldiers received were injured by mis- 
