]\Iarch 8,_ 19 1 7] 



NATURE. 



33 



for other circumstances, could conceivably account 

 for the whole effect.. If atmospheric ha^e be proved 

 insufficient, it is alternatively suggested that the 

 differential effects may possibly be accounted, for by 

 assuming the production of a spectrum of non-rotating 

 matter in the solar atmosphere. 



. The Ninth Satellite of Jcpiter. — An -investigation 

 of the ninth satellite of Jupiter has led Messrs. 

 Nicholson and Shapley to estimate its diameter as 

 Iving between 11 and 17 miles {The Observatory , 

 vol. xl.,p. 107). From photographs of this tiny object 

 taken with the 6o-in. reflector at Mt. Wilson, the 

 photographic magnitude at mean opposition was 

 found to be i8-6, as compared with 17-5 and 180 for 

 the seventh and eiehth satellites respectively. Allow- 

 ing for a probable colour-indgx of one magnitude, the 

 angular diameter of the ninth satellite at mean opposi- 

 tion works out at 0:006* or 0009", according to the 

 value adopted for the visual albedo, and these lead 

 to the limits of diameter stated above. 



GERMANY'S EFFORT TO OBTAIN 

 NITROGENOUS COMPOUNDS. 



ALTHOUGH elementary nitrogen is not only use- 

 less, but positively antagonistic, to the life of 

 plants and animals (except to that of some bacteria 

 which take free nitrogen from the atmosphere and 

 convey it to the roots of leguminous plants), combined 

 nitrogen is absolutely necessary- for their metabolism. 

 Animals obtain nitrogen from the vegetables they con- 

 sume, plants from the nitrogenous constituents of the 

 soil. The soil obtains part of its combined nitrogen 

 from decaying vegetable matter and from the waste 

 products of animals ; the remainder has to be added. 

 The two chief forms in which it is added are sodium 

 nitrate and ammonium sulphate, whicli to a large 

 extent are interchangeable. But for the manufacture 

 of explosives sodium nitrate is absolutely necessan,' 

 and ammonium sulphate useless. Germany, fore- 

 seeing that its' supply of Chilean nitrate would 

 cut off by the blockade of the British Fleet, 

 5 faced with irremediable disaster unless it could 

 lay in a sufficient stock before declaring war, or 

 devise methods of synthesising nitric acid. The 

 manner in which this difficulty has been overcome is 

 described by Prof. Camille Matignon in the Revue 

 ^generale des Sciences (January 15 and 30). Before 

 the war Germany was the greatest consumer of com- 

 bined nitrogen. In 1913 the consumption amounted to 

 750,000 tons of Chilean nitrate, 3S,ooo tons of Nor- 

 wegian nitrate, 46,000 tons of ammonium sulphate, 

 and 30,000 tons of cyanamide. In 1913 great efforts 

 were devoted in Germany to the preparation of mate- 

 rials necessary for war, and no attempt was made 

 to conceal them. The German Ammonium Sulphate 

 Syndicate had a reser\e of 43,000 tons, and on the 

 declaration of war there was probably a stock of 

 100,000 tons of Chilean nitrate. Immediately after 

 the battle of the Marne, when a long war was 

 evidently certain, the production of artificial nitrates 

 and of ammonium sulphate was stimulated, the 

 Badische Aniline Company and Bayer and Co. being 

 subsidised t"> the extent of 30,000,000 marks for the 

 installation Of factories to convert ammonia into nitric 

 acid. In peace time 550,000 tons of ammonium 

 sulphate were produced annually in Germany, but this 

 output was reduced once war was declared. As this 

 substance is a by-product in the manufacture of gas 

 and cast-iron, people in Germany were instigfated to 

 use gas and coke instead of coal, and by such means 

 an annual output of 250,000 tons of ammonium 



NO. 2471, VOL. 99] 



sulphate was attained. The problem of converting' 

 the ammonia into nitric acid was solved by the Frank 

 and Caro and the Kayser processes. A French 

 chemist, Kuhlmann, had discovered that ammonia is 

 oxidised to nitrogen peroxide when mixed with air 

 and passed over warm, finely divided platinum. The 

 reaction was employed on a commercial scale by Ost- 

 wald, and improved both by Kayser and by Frank 

 and Caro. By the end of 1915 the Anhaltische 

 Maschinenbau Society of Berlin had established thirty 

 installations for the conversion by Frank and Caro's 

 process, and these had a capacity of more thai* 

 100,000 tons of nitric acid per month. But this was- 

 only one of the methods adopted. Given a cheap- 

 source of electrical energy, it was known to be com- 

 mercially practicable to prepare nitric acid by' the 

 direct oxidation of nitrogen in the electric flame, and 

 this process had been established in Norway by Birke- 

 land and Eyde, who used the waterfalls as a source- 

 of energy. The Germans have established a factor}' 

 employing Pauling's process (a modification of thar 

 of Birkeland and Eyde) at Muhlenstein, in Saxony, 

 in the neighbourhood of the lignite beds, which form 

 the source of energv, and this has an annual output 

 of 6000 tons of nitric acid. 



The third principal method adopted for the prepara- 

 tion of combined nitrogen was the direct synthesis of 

 ammonia. Bosch and Mittasch, two chemical 

 engineers of the Badische Company, had adapted 

 Haber's synthesis to industrial conditions, and the 

 company had established a factory with an annual out- 

 put of 30,000 tons of synthetic ammonium sulphate. 

 In April, 19 14, the company increased its capital in 

 order to raise the output to 130,000 tons, and after 

 the battle of the Marne it was subsidised by the Ger- 

 man Government to increase the production to 300,000 

 tons. • 



Before the war the production of cyanamide in Ger- 

 many was comparatively small, but it has iricreased 

 largelv under Government stimulus. The c\'anamide 

 manufacturers desired a monopoly, but this was op- 

 posed by the Badische and other companies and by the 

 g[as manufacturers, and the project seems to have 

 been abandoned. 



In the direction of the manufacture of manures, It 

 was necessar\' to economise sulphuric acid, so 

 ammonia was neucralised with nitre cake, and the 

 resulting mixture of sodium- and ammonium sulphates 

 was mixed with superphosphate. Moreover, it was 

 found that superphosphate will absorb gaseous 

 ammonia, and although the ca'cium acid phosphate 

 is thereby converted into the insoluble tricalcic phos- 

 phate, it is formed in an easily assimilable condition, 

 and the product is found by experience to act both 

 as a nitrogen and phosphorus manure. 



Prof. Matignon seems to be correct in claiming' that 

 chemistrv has saved Germany from disaster. 



E. H. 



SUBSIDENCE RESULTING FROM MINING. 



THE ver\* important question of subsidence result- 

 ing from mining operations has ' recently been 

 discussed in a bulletin issued by the Engineering 

 Experiment Station of the University- of Illinois. The 

 report is prepared by Dr. L. E. Young, mining en- 

 gineer for the IllirKMS Coal Mining Investigations, and 

 Prof. H. H. Stock, professor of mining engineering 

 in the University of Illinois, under a co-operative 

 agreement between the University, as represented by 

 its Engineering Experiment Station, the Illinois State 

 Geological Survey, and the United States Bureau of 

 Mines. Apparentlv, whilst we in this country' content 

 ourselves tv-ith talkirig about the need for closer co- 



