ON THE NITROGEN INDUSTRY. 417 



culties were encountered, and several explosions have recently occurred 

 in these plants. Tlie nitric acid works on the Bu-keland-Eyde system 

 i.'rected during the War in France are now closed, it having been found 

 necessary for the power employed to revert to its original purpose — 

 railway electrification. 



Turning now to the ammonia process, which has often been 

 described, this was originally worked out by Haber and his colleagues, 

 among whom I should specially mention Dr. Le Eossignol, an English- 

 man boi'n in Jersey, and the late Dr. H. C. Greenwood, the brilliant 

 young investigator whose death three years ago we all deplore. The 

 ]3rocess was translated into a technical success by the Badische Com- 

 pany, and is now employed on a huge scale at their original works at 

 Oppau, on the Rhine, and at the much larger works recently completed 

 at Merseburg, in Saxony. But to-day this is by no means the only 

 jirocess for the manufacture of ammonia from its elements. From the 

 table you will see that there are now many other synthetic ammonia 

 processes, distributed over the leading countries of the world. In the 

 original German process the scale is large and the gas velocities are 

 low, the reaction vessels being enormous flanged tubes of steel nearly 

 40 feet long and over 3 feet external diameter, with walls 6 inches 

 thick. In the process worked out independently during the War, at tlie 

 research laboratory of the Nitrogen Products Committee at University 

 College, much higher gas velocities were employed, giving about twelve 

 times as much ammonia per hour for each litre of space filled with 

 catalyst. 



In the plant to produce 11,000 tons of nitrogen annually in the form 

 of ammonium nitrate, erected at Sheffield, Alabama, by the American 

 Government from the designs of the General Chemical Company in 

 1917-18, activated sodamide was used as catalyst. As the activity, at 

 first fairly high, was permanently destroyed even by small quantities of 

 water vapour, it is not surprising that tins plant did not reach the stage 

 of commercial operation. Profiting by the lesson, an American com- 

 pany formed by the General Chemical Company and the Solvay Process 

 Company have erected near New York an improved plant on somewhat 

 similar lines, which has for over a year been producing liquid ammonia 

 for the refrigerator industry at the rate of ten tons per day. The pro- 

 cess invented by M. Claude, which operates at the high pressure of 

 about seven tons per square inch, has been recently described in detail. 

 The issuing gas contains about 25 per cent, of ammonia. Multiple 

 stage working replaces circulation, and the dimensions of a full-sized 

 unit plant appear almost absurdly small in comparison with the monu- 

 mental structures employed in the German process. The last time I 

 was at Montereau M. Claude showed me at work his latest catalyst 

 tube, made, I am pleased to say, by a well-known firm of steel-makers 

 at Sheffield, of a new material which stands up extremely well at high 

 temperatures. It is to the preparation of cheap hydrogen from coke- 

 oven gas that M. Claude is at present devoting his attention. In the 

 Casale process, now working at Terni, near Eome, tlie hydrogen is 

 generated electrolytically by water-power, and some of it is then burnt 

 with ail', [iroducing the required mixture of hydrogen and nitrogen. 



