6i4 



NATURE 



[January 13, 192 1 



In a series of researches beginning in 1889 

 Hermann found that the analyses of phonograph 

 curves showed the vowels to be constructed of 

 puffs and inharmonics. He thus independently re- 

 discovered the principle of Willis. This theory- 

 has been substantiated and developed by thou- 

 sands of analyses in my work for the Carnegie 

 Institution of Washington, and published in "The 



Study of Speech Curves" (Carnegie Inst. I'ubl. 

 No. 44), from which the above results are taken. 

 It should be added that this extensive and some- 

 what expensive work was made possible by the 

 support of Yale University and the liberality of the 

 Carnegie Institution of Washington. 



{^o be continued.) 



Nitrate Supplies and the Nitrogen Industry. 



THE Imperial Mineral Resources Bureau has 

 recently issued a report on the nitrate in- 

 dustry of the British Empire and of foreign 

 countries, containing all available statistics with 

 regard to the production and prices of nitrates 

 during the war period. In conjunction with 

 this report may be considered a paper deal- 

 ing with the nitrogen industry contributed by 

 H. E. Fischer to the Journal of the Franklin In- 

 stitute (August, 1920, vol. cxc, No. 2). This 

 paper gives a comprehensive survey of the sources 

 of the world's nitrogen supply, particularly as it 

 affects America. Nitrogenous compounds are 

 absolutely necessary to agriculture, to the manu- 

 facture of munitions, to refrigeration, and to the 

 general applications of chemistry, and although 

 nitrogen in its inert gaseous state forms four- 

 fifths of the atmosphere, yet this is of no use for 

 the above objects until it has been combined or 

 " fixed " by some method. 



In the combined form, nitrogen is found in 

 Nature as mineral deposits, as organic com- 

 pounds, and in carboniferous deposits. By far the 

 most important of the mineral deposits are those 

 of Chile. Before the war the greater part of the 

 world's requirements in respect of nitrate and 

 nitric nitrogen was met by the export of nitrate 

 of soda from Chile. The Chilean nitrate industry 

 is one of long standing, and expanded steadily 

 from 100,000 tons per annum in the middle of 

 thenineteenthcentury to 2,400,000 tons in 191 3. It 

 has been stated that the Chilean nitrate deposits 

 are nearly exhausted, but according to the Chilean 

 Nitrate Committee's report "there is no fear of, 

 the Chilean nitrate deposits being exhausted for 

 200 years." The nitrate occurs as scattered de- 

 posits in a formation known as caliche, consisting 

 of a conglomerate of rock material cemented with 

 a mixture of soluble salts, in which sodium 

 chloride is the chief constituent as regards quan- 

 tity, while sodium nitrate is second. It is only 

 in scattered patches that the caliche contains 

 nitrate in quantities large enough to warrant 

 treatment. These patches ■ are sought out and 

 excavated, and the picked ore is hauled to the 

 extraction plant, where the soluble salts are 

 extracted in solution, and the nitrate is separated 

 from the other salts by crystallisation. 



A considerable amount of sodium nitrate is also 

 produced in Egypt. For one company in 191 3 

 the output was 4740 metric tons, but the total 

 output is not known definitely. In India potass- 

 ium nitrate has been produced from very early 

 NO. 2672, VOL. 106] 



times, but the trade has always been subject to 

 great fluctuations. It attained its highest values 

 during the American Civil War, for then India 

 had practically a monopoly of the supplies of salt- 

 petre needed for explosives. At that time the 

 average annual expKjrts were 30,000 tons, but the 

 development of the Chilean industry caused the 

 Indian trade to decline, until in the years just 

 before the war the exports were only 13,000 or 

 14,000 tons per annum. The war period again 

 stimulated the trade, and in 1918 the output was 

 25,145 metric tons. The potassium nitrate is 

 found in the soils of old villages, mixed with 

 nitrates of calcium and magnesium and with 

 sodium chloride. The process of extraction con- 

 sists in dissolving out the mixed salts from the 

 surface soil, roughly separating the sodium 

 chloride and the potassium nitrate, and then 

 purifying the nitrate. 



Nitrogen compounds are also obtained as by- 

 products in a large number of industries. In deal- 

 ing with animal, vegetable, and fish products, 

 organic ammoniates are obtained, and these are 

 left as such for use in agriculture, while from 

 sources such as coal distillations, bone carbon- 

 isation, oil-shale distillation, and blast-furnace 

 operations, nitrogen is recovered as ammonia and 

 ammonium salts — chiefly ammonium sulphate, 

 which is available in all capacities. The organic 

 nitrogen recovered in these various by-product 

 connections probably constitutes about 40 to 

 50 per cent, of the total supply, but this nitrogen 

 has to compete for its market against the supplies 

 of nitrates from natural sources and against those 

 of synthetic nitrates, i.e. those obtained from 

 combined atmospheric nitrogen. 



As early as 1781 Cavendish discovered that a 

 nitric reaction was shown by water obtained by 

 burning hydrogen in excess of air, and since his 

 time very many chemists have studied the 

 problem. In 1900 two Americans erected an ex- 

 perimental plant at Niagara for producing nitric 

 acid from atmospheric nitrogen by means of a 

 very high electric current, but this soon proved 

 unremunerative and was abandoned. The lumin- 

 ous arc process for fixing atmospheric nitrogen was 

 the first to be established commercially. In this 

 process a dilute gaseous mixture of nitric oxides 

 with air is obtained from the oxygen and nitrogen 

 in the air ; the nitric oxide is converted into nitric 

 dioxide, and then absorbed in water to form 

 nitric acid. It was started in Norway in 1903, 

 and, owing to the cheap horse-power there avail- 



