SCIENCE AND INDUSTRY. 
Fixation of Nitrogen. 
_ During the war, Germany and the Allies were all experimenting 
with the methods for the fixation of nitrogen, primarily for war purposes, 
but at the same time useful for agricultural purposes, and to render 
each country independent of Chilian nitrates. 
The original Haber process was installed on a large scale by Ger- 
many, under the control of the Badisch Anilin and Sodafabrik, at 
Oppau, near Ludwigshayen; but a modified process, by which the pres- 
sures used were reduced from 600 to 200 or 300 atmospheres, was 
established in Germany, and at the time of the armistice was producing 
over 600 tons of synthetic ammonia a day, or sufficient to make half 
a million tons of ammonium nitrate per annum. At the same time, 
England was producing only a few pounds per day in experimental 
plants; but scientists had not been idle in France, England, or America. 
It took Germany over five years to develop the Haber process, and its 
secrets were most jealously guarded. In England, a process was worked 
out, and was to be put into operation at Billingham. In addition, 
valuable discoveries, now covered by twenty .patents, were made during 
the investigations, which have brought England abreast of German 
results, and in some respects in advance. In America, as in Germany, 
the original Haber pressure-under which the gases (hydrogen from water 
gas chiefly, and nifrogen from the air) were brought into combination 
was reduced; and the Degendre, or Generel Chemical Company’s modi- 
fied process, uses a pressure of only 150 atmospheres. The relatively 
high temperatures (600 degs. C.) at which the Haber process was worked 
has remained unaltered in all countries. 
In France, a new process was patented by M. Georges Claude, by 
which the pressure was increased to 1,000 atmospheres (14,000 Ibs. to 
the square inch) without reducing the temperature at which the com- 
bination is effected. ; 
The plant required by the Claude process is both simple and cheaper 
than the German process, by an amount which is estimated all round 
as at least 25 per cent. There is great difficulty in forcing nitrogen to 
enter into combination with other gases unless brought into intimate 
contact, and this reluctance is accentuated where the gas is dealt with 
in mass, and at comparatively low temperatures. 
By thus increasing the pressure to 1,000 atmospheres, the yield of 
ammonia is increased fourfold up to 50 per cent., while the speed of 
reaction is commensurately increased. The power required for com- 
pression is admitted to be greater than at 200 atmospheres, but, along 
with certain advantages, the total power expended per ton of synthetic 
ammonia produced is no larger than what is required for compression 
at 200 atmospheres. In the German (Haber) process, the pressure 
has to be constantly maintained through a lengthy chain of operations, 
and the condensation of the ammonia has to be secured by water 
injected at the high pressure; whereas in the Claude process the com- 
pression is effected very readily by special compressors, which work as 
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