September 12, 1918] 



NATURE 



27 



advantage that it can be installed in many places 

 in the country, and that it requires little power. 

 It has probabl) a great future before it — certainly 

 immediately — but whether it is ultimately desl 

 to be supplanted by the synthetic process time 

 alone can show. 



The cyanide method is still in process of 

 development, and is carried out in various ways. 

 Several concerns are working it, among them the 

 Nitrogen Products Co. at Saltville, Virginia, 

 and the Air Reduction Co., and the Govern- 

 ment is also building a plant. The product first 

 formed is sodium cyanide, which, as in the case 

 of cyanamide, can be made to yield ammonia under 

 the action of steam. Sodium cyanide is, however, 

 metallurgical adjunct that it will 

 not pay to convert it into ammonia until the 

 market for cyanide has been satisfied. 



The synthetic process was already worked in 

 America by the General Chemical Co. before 

 the outbreak of w^ar, and it had so far per- 

 il the process — well beyond the point which 

 the Germans had reached- that it was able to 

 operate at lower temperatures and pressures. The 

 Government has taken over the process of the 

 company, and is now working it at Sheffield, 

 Alabama, with a plant capable of producing 

 20,000 tons of ammonium nitrate per annum. A 

 portion of the ammonia produced is put through 

 the oxidation process, converting it into nitric 

 li 11], which is combined with more ammonia to 

 form ammonium nitrate. 



The arc process is especially suitable for the 

 production of nitric acid. The reactions involved 

 hemically very simple, but they need a large 

 amount of energy, which, under American con- 

 ditions, would be very expensive to produce. By 

 recent agreements with the Norwegian Govern- 

 ment the United States and the Allies will receive 

 about 112,000 metric tons of calcium nitrate per 

 annum, made by the arc process, as against the 

 limit of Sooo tons sent to Germany. As matters 

 --tand it is very unlikely that the arc process will 

 obtain any very extensive application in America. 

 . Prof. Noyes concludes his lecture with some 

 remarks upon the relative economies of the dif- 

 ferent processes, but the conditions at present are 

 so abnormal that it is impossible to make any 

 very definite statements as to their ultimate com- 

 mercial prospects. In the meantime the Govern- 

 ment is using all its resources, expanding its im- 

 ports of Chile saltpetre, introducing as rapidly as 

 possible "by-product " coke-ovens, and developing 

 new fixation processes through the Nitrate 

 ion of the Ordnance Department with the 

 co-opera"tion of the Bureau of Mines. 



The oxidation process of turning ammonia 

 into nitric acid has been so far perfected that a 

 conversion of from 92 to 95 per cent, is now pos- 

 sible, and the process of absorption of the nitric 

 irs has been much simplified. It is certain 

 that, as one result of the war, there will be a very 

 marked development in the States within the next 



•car or tv I American processes of nitrogen 



fixation. 



2550, VOL. 102] 



INDIGO IX BIHAR. 



AN account of the ecent history and present 

 position of indigo in Bihar, by Mr. W. A. 

 Davis, indigo research chemist to the Government 

 of India, was reviewed 1 of July 18 last. 



In two further communications Mr. Davis has 

 disi ussed the future cultural prospects of the in- 

 dustry, 1 outlined the dil cul urmounted 

 ccess is to be attained, and detailed the con- 

 clusions indicated by a study of Bihar indigo- 

 soils. 2 



Among the various factors — careful seed-selec- 

 tion, improved cultivation, better manufacture, 

 and sounder business organisation — on which the 

 late of natural indigo depends, the most urgent is 

 the cultural. The evidence presented indicates 

 that tin- indigo-soils of Bihar have been steadily 

 losing fertility through exhaustion of their avail- 

 able phosphate. This conclusion is based on the 

 results of actual soil-analyses, the -.uccess with in- 

 digo grown outside Bihar in soils still containing 

 adequate available phosphate, and the response of 

 indigo within Bihar to the manurial use of super- 

 phosphate. 



The treatment appropriate for Indigofera siima- 

 Immi, until 1898 the indigo exclusively grown in 

 Bihar, does not suit I. arrecta, introduced in 1S99. 

 After this difficulty was overcome the results with 

 /. arrecta appeared to justify the hope that ex- 

 tended cultivation of this new plant might save 

 the natural indigo industry. The product of 

 /. sumatrana may no longer be expected to com- 

 pete successfully against artificial indigo. But 

 actual results, secured in 1906-7, indicate that 

 natural indigo from I. arrecta may be manufac- 

 tured and profitably sold at rates " cutting " the 

 lowest pre-war quotations for synthetic. 



The disappointment of this hope is popularly 

 attributed to two blights — psylla and "wilt." The 

 entomological malady can scarcely be accounted 

 serious. There is no evidence that psylla injures 

 indigo of normal vigour ; there is evidence that 

 affected plants which regain thrift may " grow- 

 through " and " shake off " psylla attack. The 

 " wilt" is not induced by any pathogenic organ- 

 ism ; it is the sequel to defective nutrition, explic- 

 able by the phosphate-exhaustion now character- 

 istic of Bihar soils. 



The remedy then for Bihar is to employ super- 

 phosphate. Even so, the only hope for the future 

 lies in the cultivation of /. arrecta; that of 7. suma- 

 trana is contra-indicated on economic grounds. Seed- 

 selection to secure strains of J. arrecta rich in indi- 

 can is also a pressing need. There is doubtless 

 another possibility. Outside Bihar, under climatic 

 conditions hitherto deemed unsuitable for indigo, 

 7. arrecta thrives well. It may in time prove more 

 economic to transfer indigo from Bihar to localities 

 with sods suffieientlv rich in available phosphate 

 than to transport phosphate to indigo in Bihar. 



What lies outside debate is that, if the natural 



I "The Present Position and Future Prospects of :iie Natural Indigo 

 Industry.' By W. V Davis, Ind.go Research Chemist to the Government 

 of India. Agricultural Journal of India, vol. xii , iii. (July, 1918). 



\ Study of the Indigo Soils of Bibar." By W. A. Davis. Agricultural 

 Research Institute. Pusa. Indigo Publication N'o. 1 (1918). 



