on. So Germany is now not
only independent of the outside world but will have a surplus of
nitrogen products which could be sold even in America at about half what
the farmer has been paying for South American saltpeter.

Besides the Haber or direct process there are other methods of making
ammonia which are, at least outside of Germany, of more importance. Most
prominent of these is the cyanamid process. This requires electrical
power since it starts with a product of the electrical furnace, calcium
carbide, familiar to us all as a source of acetylene gas.

If a stream of nitrogen is passed over hot calcium carbide it is taken
up by the carbide according to the following equation:

CaC_{2} + N_{2} --> CaCN_{2} + C
calcium carbide nitrogen calcium cyanamid carbon

Calcium cyanamid was discovered in 1895 by Caro and Franke when they
were trying to work out a new process for making cyanide to use in
extracting gold. It looks like stone and, under the name of
lime-nitrogen, or Kalkstickstoff, or nitrolim, is sold as a fertilizer.
If it is desired to get ammonia, it is treated with superheated steam.
The reaction produces heat and pressure, so it is necessary to carry it
on in stout autoclaves or enclosed kettles. The cyanamid is completely
and quickly converted into pure ammonia and calcium carbonate, which is
the same as the limestone from which carbide was made. The reaction is:

CaCN_{2} + 3H_{2}O --> CaCO_{3} + 2NH_{3}
calcium cyanamid water calcium carbonate ammonia

Another electrical furnace method, the Serpek process, uses aluminum
instead of calcium for the fixation of nitrogen. Bauxite, or impure
aluminum oxide, the ordinary mineral used in the manufacture of metallic
aluminum, is mixed with coal and heated in a revolving electrical
furnace through which nitrogen is passing. The equation is:

Al_{2}O_{3} + 3C + N_{2} --> 2AlN + 3CO
aluminum carbon nitrogen aluminum carbon
oxide nitride monoxide

Then the aluminum nitride is treated with steam under pressure, which
produces ammonia and gives back the original aluminum oxide, but in a
purer form than the mineral from which was made

2AlN + 3H_{2}O --> 2NH_{3} + Al_{2}O_{3}
Aluminum water ammonia aluminum oxide
nitride

The Serpek process is employed to some extent in France in connection
with the aluminum industry. These are the principal processes for