in the manufacture of fertilizers and other useful products by water
power or any other power." But by the time war was declared on April 6,
1917, no definite program had been approved and by the time the
armistice was signed on November 11, 1918, no plants were in active
operation. But five plants had been started and two of them were nearly
ready to begin work when they were closed by the ending of the war.
United States Nitrate Plant No. 1 was located at Sheffield, Alabama, and
was designed for the production of ammonia by "direct action" from
nitrogen and hydrogen according to the plans of the American Chemical
Company. Its capacity was calculated at 60,000 pounds of anhydrous
ammonia a day, half of which was to be oxidized to nitric acid. Plant
No. 2 was erected at Muscle Shoals, Alabama, to use the process of the
American Cyanamid Company. This was contracted to produce 110,000 tons
of ammonium nitrate a year and later two other cyanamid plants of half
that capacity were started at Toledo and Ancor, Ohio.

At Muscle Shoals a mushroom city of 20,000 sprang up on an Alabama
cotton field in six months. The raw material, air, was as abundant there
as anywhere and the power, water, could be obtained from the Government
hydro-electric plant on the Tennessee River, but this was not available
during the war, so steam was employed instead. The heat of the coal was
used to cool the air down to the liquefying point. The principle of this
process is simple. Everybody knows that heat expands and cold contracts,
but not everybody has realized the converse of this rule, that expansion
cools and compression heats. If air is forced into smaller space, as in
a tire pump, it heats up and if allowed to expand to ordinary pressure
it cools off again. But if the air while compressed is cooled and then
allowed to expand it must get still colder and the process can go on
till it becomes cold enough to congeal. That is, by expanding a great
deal of air, a little of it can be reduced to the liquefying point. At