FIXED XITROGEN RESEARCH LABORATORY. 637 



thesis of ammonia, using waste hydrogen. This equipment has been 

 in continuous operation for several montlis and important informa- 

 tion on the various steps of the process was obtained. This work, 

 when completed, will provide the information necessary for the 

 installation and operation of small ammonia plants throughout the 

 country. 



In connection with the engineering features of the process, the 

 construction of a synthetic ammonia plant on a semicommercial 

 scale Avas begun, so that the numerous mechanical problems involved 

 can be better studied. The plant will also afford a means of testing 

 catal3'sts under conditions more closely approximating those in 

 commercial operation. 



Another problem of great importance and considerable complexity 

 IS that of obtaining a material suitable for the construction of the 

 catalvst chambers in which the reaction between nitrogen and 

 liydrogen to form ammonia takes place. Ordinary carbon steel can 

 not be employed, since it rapidly deteriorates, becoming porous and 

 in many cases so brittle that it can be broken with the hngers. To 

 obtain reliable information on this problem, the laboratory has had 

 under test 25 bombs made from different materials. Although the 

 test is still in progress, very important information as to suitable 

 materials for construction of catalyst chambers has already been 

 obtained. 



The design and development of apparatus to operate at very 

 much higher pressure than is now regarded as commercially feasi- 

 ble was also undertaken, since ammonia formation is greatly favored 

 by increasing pressure. Although this problem is quite beyond the 

 range o*f present engineering experience, satisfactory progress was 

 made and important developments along this line are to be expected. 



The removal of ammonia from the gas mixture after its passage 

 through the catalyst is a problem of considerable importance in 

 this process. The difficulty lies in removing practically all of the 

 ammonia from the mixture, of which it forms about 5 to 15 per cent, 

 v.'ithout introducing impurities in the gases which are harmful to 

 the catalyst. The Bureau of Soils, in cooperation with this labora- 

 tory, has studied various methods of effecting the removal, and has 

 developed a promising method based on scrubbing the gas under 

 high pressure with a relatively concentrated solution of ammonia, 

 recovering the ammonia thus removed by releasing the pressure on 

 the solution, and liquefying the liberated gas by compression. 



Tlie laboratory has published during the past year eight articles 

 in Chemical and Metallurgical Engineering and in the Journal of 

 the American Chemical Society on various phases of the work on 

 the direct synthetic ammonia problem. 



CYANAMIDE PROCESS. 



In the cyanamide process of nitrogen fixation, calcium carbide is 

 lirst produced by fusing a mixture of coke and lime in an electric 

 furnace. The carbide is then powdered, heated to a high tempera- 

 tare, and subjected to the action of nitrogen, usually obtained by 

 fractional distillation of liquid air, with which it combines to form 

 a solid compound, calcium cyanamide. The nitrogen thus fixed can 

 be transformed into a great variety of nitrogen compounds. The 



