the
fixation of nitrogen now in use, but they by no means exhaust the
possibilities. For instance, Professor John C. Bucher, of Brown
University, created a sensation in 1917 by announcing a new process
which he had worked out with admirable completeness and which has some
very attractive features. It needs no electric power or high pressure
retorts or liquid air apparatus. He simply fills a twenty-foot tube with
briquets made out of soda ash, iron and coke and passes producer gas
through the heated tube. Producer gas contains nitrogen since it is made
by passing air over hot coal. The reaction is:

2Na_{2}CO_{3} + 4C + N_{2} = 2NaCN + 3CO
sodium carbon nitrogen sodium carbon
carbonate cyanide monoxide

The iron here acts as the catalyst and converts two harmless substances,
sodium carbonate, which is common washing soda, and carbon, into two of
the most deadly compounds known to man, cyanide and carbon monoxide,
which is what kills you when you blow out the gas. Sodium cyanide is a
salt of hydrocyanic acid, which for, some curious reason is called
"Prussic acid." It is so violent a poison that, as the freshman said in
a chemistry recitation, "a single drop of it placed on the tongue of a
dog will kill a man."

But sodium cyanide is not only useful in itself, for the extraction of
gold and cleaning of silver, but can be converted into ammonia, and a
variety of other compounds such as urea and oxamid, which are good
fertilizers; sodium ferrocyanide, that makes Prussian blue; and oxalic
acid used in dyeing. Professor Bucher claimed that his furnace could be
set up in a day at a cost of less than $100 and could turn out 150
pounds of sodium cyanide in twenty-four hours. This process was placed
freely at the disposal of the United States Government for the war and a
10-ton plant was built at Saltville, Va., by the Ordnance Department.
But the armistice put a stop to its operations and left the future of
the process undetermined.

[Illustration: A CHEMICAL REACTION ON A LARGE SCALE

From the chemist's standpoint modern warfare consists in the rapid
liberation of nitrogen from its compounds]

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

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 o