AxrGTJST 7, 1914] 



SCIENCE 



185 



air into nitric acid by means of the electric 

 arc. 



As early as 1902, they published their 

 results as well as the details of their appa- 

 ratus. Although they operated only one 

 full-sized unit, they demonstrated conclu- 

 sively that nitric acid could thus be pro- 

 duced from the air in unlimited quantities. 

 We shall examine later the reasons why this 

 pioneer enterprise did not prove a commer- 

 cial success ; but to these two American in- 

 ventors belongs, undoubtedly, the credit of 

 having furnished the first answer to the 

 distress call of Sir "William Crookes. 



In the meantime, many other investi- 

 gators were at work at the same problem, 

 and soon from Norway's abundant water- 

 falls came the news that Birkeland and 

 Eyde had solved successfully, and on a 

 commercial scale, the same problem by a 

 differently constructed apparatus. The 

 Germans, too, were working on the same 

 subject, and we heard thait Schoenherr, also 

 Pauling, had evolved still other methods, 

 all, however, based on the Cavendish- 

 Priestley principle of oxidation of nitrogen. 

 In Norway alone the artificial salpeter 

 factories use now, day and night, over 200,- 

 000 electrical horse-power, which will soon 

 be doubled; while a further addition is 

 contemplated which will bring the volume 

 of electric current consumed to about 500,- 

 000 horse-power. The capital invested at 

 present in these works amounts to $27,- 

 000,000. 



Frank and Caro, in Germany, succeeded 

 in creating another profitable industrial 

 process whereby nitrogen could be fixed by 

 carbide of calcium, which converts it into 

 calcium cyanamide, an excellent fertilizer 

 by itself. By the action of steam on cya- 

 namide, ammonia is produced, or it can be 

 made the starting point of the manufacture 

 of cyanides, so profusely used for the treat- 

 ment of gold and silver ores. 



Although the synthetic nitrates have 

 found a field of their own, their utilization 

 for fertilizers is smaller than that of the 

 cyanamide; and the latter industry repre- 

 sents, to-day, an investment of about $30,- 

 000,000, with three factories in Germany, 

 two in Norway, two in Sweden, one in 

 France, one in Switzerland, two in Italy, 

 one in Austria, one in Japan, one in Can- 

 ada, but not any in the United States. The 

 total output of cyanamide is valued at 

 $15,000,000 yearly and employs 200,000 

 horse-power, and preparations are made at 

 almost every existing plant for further 

 extensions. An English company is con- 

 templating the application of 1,000,000 

 horse-power to the production of cyanam- 

 ide and its derivatives, 600,000 of which 

 have been secured in Norway and 400,000 

 in Iceland. 



But still other processes are being devel- 

 oped, based on the fact that certain metals 

 or metalloids can absorb nitrogen, and can 

 thus be converted into nitrides; the latter 

 can either be used directly as fertilizers 

 or they can be made to produce ammonia 

 under suitable treatment. 



The most important of these nitride 

 processes seems to be that of Serpek, who, 

 in his experimental factory at Niedermor- 

 schweiler, succeeded in obtaining alumi- 

 num nitride in almost theoretical quan- 

 tities, with the use of an amount of elec- 

 trical energy eight times less than that 

 needed for the Birkeland-Eyde process and 

 one half less than for the cyanamide proc- 

 ess, the results being calculated for equal 

 weights of "fixed" nitrogen. 



A French company has taken up the 

 commercial application of this process 

 which can furnish, besides ammonia, pure 

 alumina for the manufacture of alTiminum 

 metal. 



An exceptionally ingenious process for 

 the direct synthesis of ammonia, by the 



