THE FIXATION OF ATMOSPHERIC NITROGEN. 
of a catalyst, which, while enormously accelerating the velocity of 
combination, has no effect on that of decomposition. For such a pro- 
cess to succeed commercially it must be-continued, and the catalyst used 
(uranium, &e.), like other contact catalysts, is rendered inactive 
(“poisoned”) by small traces of impurity, so that the nitrogen and 
hydrogen must be most carefully purified. 
Other processes which, though they did not supply much, if any, 
fixed nitrogen during the war, are of interest, and may assume com- 
mercial importance, are— 
1. The Serpek process, in which nitrogen passes over a heated 
mixture of carbon and bauxite. The product is Al N from which 
ammonia is formed by the action of water. 
2. The Bucher Process—This is the latest and, on its face, the 
simplest. It has aroused much interest in America, where it originated. 
Under the catalytic action of metallic iron nitrogen is absorbed by 
sodium carbonate at about 800° ©., with the formation of sodium 
eyanide. The advantages claimed by the inventor for this process are 
its cheapness, arising from the low cost of the raw materials, including 
the nitrogen, which may contain a high proportion of carbon monoxide 
(e.g., producer gas may be employed), and the comparatively low tem- 
perature. The roseate predictions of the future of the method, 
originated in 1916, have not yet been realized, work on a large scale 
paid for by the United States Government having failed, it would seem, 
to reproduce the results of semi-commercial tests. It is to be hoped 
that the difficulties will ultimately disappear, as the process has many 
advantages over its rivals. In this case, as in all, except that of the 
are process, ammonia can be obtained. 
From the point of view of the manufacturer of nitric acid, it is not 
a serious disadvantage that ammonia is an intermediate product. The 
oxidation of this gas by passing it mixed with air or oxygen over 
heated platinum was successfully carried out commercially by Ostwald 
ten years ago. Much attention has been devoted to the process during 
the war, and improved methods worked out in England and America. 
The main difficulty inherent in the method is the tendency of the oxida- 
tion to complete itself, water and nitrogen being the products. This is 
overcome by using smooth platinum, and preventing long contact of the 
gases with the catalyst. Platinum wire gauze and a rapid stream of 
gas are used. 
The present position of the nitrogen-fixation industry appears to be 
that it is firmly established in Germany, as far as the Haber and 
cyanamide processes are concerned, and that are processes will continue 
to be operated in Norway and other countries in which electricity can be 
obtained at about £1 10s. per H.P. year, or less. The Government of 
the United States of America has spent several millions sterling on 
cyanamide and modified Haber plants, but, in spite of the protests of 
chemists, appears to be inclined to scrap them. One reason for this is 
that the process for the synthesis of ammonia patented by the General 
Chemical Company had not, at the date of the signing of the armistice, 
been brought to the productive stage, serious difficulties still remaining 
to be overcome. In England the one solid achievement in this line of 
work was the production of an efficient ammonia oxidizer. Much 
© .18302.—5 497 
