BURNING AIR IN A BIRKELAND-EYDE FURNACE AT THE DU PONT PLANT

An electric arc consuming about 4000 horse-power of energy is passing
between the U-shaped electrodes which are made of copper tube cooled by
an internal current of water. On the sides of the chamber are seen the
openings through which the air passes impinging directly on both sides
of the surface of the disk of flame. This flame is approximately seven
feet in diameter and appears to be continuous although an alternating
current of fifty cycles a second is used. The electric arc is spread
into this disk flame by the repellent power of an electro-magnet the
pointed pole of which is seen at bottom of the picture. Under this
intense heat a part of the nitrogen and oxygen of the air combine to
form oxides of nitrogen which when dissolved in water form the nitric
acid used in explosives.]

[Illustration: Courtesy of E.I. du Pont de Nemours Co.

A BATTERY OF BIRKELAND-EYDE FURNACES FOR THE FIXATION OF NITROGEN AT THE
DU PONT PLANT]

We might have expected that the fixation of nitrogen by passing an
electrical spark through hot air would have been an American invention,
since it was Franklin who snatched the lightning from the heavens as
well as the scepter from the tyrant and since our output of hot air is
unequaled by any other nation. But little attention was paid to the
nitrogen problem until 1916 when it became evident that we should soon
be drawn into a war "with a first class power." On June 3, 1916,
Congress placed $20,000,000 at the disposal of the president for
investigation of "the best, cheapest and most available means for the
production of nitrate and other products for munitions of war and useful