rogen at 194 deg. C. The oxygen left is useful for other purposes. The
hydrogen needed is extracted by a similar process of fractional
distillation from "water-gas," the blue-flame burning gas used for
heating. Then the nitrogen and hydrogen, mixed in the proportion of one
to three, as shown in the reaction given above, are compressed to two
hundred atmospheres, heated to 1300 deg. F. and passed over the finely
divided uranium. The stream of gas that comes out contains about four
per cent. of ammonia, which is condensed to a liquid by cooling and the
uncombined hydrogen and nitrogen passed again through the apparatus.

The ammonia can be employed in refrigeration and other ways but if it is
desired to get the nitrogen into the form of nitric acid it has to be
oxidized by the so-called Ostwald process. This is the reaction:

NH_{3} + 4O --> HNO_{3} + H_{2}O
ammonia oxygen nitric acid water

The catalyst used to effect this combination is the metal platinum in
the form of fine wire gauze, since the action takes place only on the
surface. The ammonia gas is mixed with air which supplies the oxygen and
the heated mixture run through the platinum gauze at the rate of several
yards a second. Although the gases come in contact with the platinum
only a five-hundredth part of a second yet eighty-five per cent. is
converted into nitric acid.

The Haber process for the making of ammonia by direct synthesis from its
constituent elements and the supplemental Ostwald process for the
conversion of the ammonia into nitric acid were the salvation of
Germany. As soon as the Germans saw that their dash toward Paris had
been stopped at the Marne they knew that they were in for a long war and
at once made plans for a supply of fixed nitrogen. The chief German dye
factories, the Badische Anilin and Soda-Fabrik, promptly put
$100,000,000 into enlarging its plant and raised its production of
ammonium sulfate from 30,000 to 300,000 tons. One German electrical firm
with aid from the city of Berlin contracted to provide 66,000,000 pounds
of fixed nitrogen a year at a cost of three cents a pound for the next
twenty-five years. The 750,000 tons of Chilean nitrate imported annually
by Germany contained about 116,000 tons of the essential element
nitrogen. The fourteen large plants erected during the war can fix in
the form of nitrates 500,000 tons of nitrogen a year, which is more than
twice the amount needed for internal consumpti