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JOURNAL OF THE ROYAL HORTlCQLTURAL SOCIETY. 



CONTRIBUTIONS FROM THE WISLEY LABORATORY. 

 IX. — Calcium Cyanamidb and Nitrate of Lime. 

 By F. J. Chittenden, F.L.S. 



Considerable progress has been made in bringing free nitrogen into 

 combination in forms suitable for use as manures costing no more than 

 already existing ones, since Sir William Crookes in his memorable 

 address on " The Wheat Supply of the World " at the British Asso- 

 ciation in 1898, pointed out that the world's supply of combined nitrogen 

 was rapidly approaching exhaustion. 



Sir William Crookes then looked to the direct combination of the 

 two gases, nitrogen and oxygen, as the solution of the difficulty, and he 

 showed, as Priestley had shown long before, that under the influence 

 of high temperature they would combine together. With the cheapen- 

 ing of electrical current through the utilization of power heretofore 

 running to waste in waterfalls this direct combination has been rendered 

 possible on a commercial scale, and while technical difficulties soon 

 brought the manufacture of nitric acid at Niagara to a conclusion, the 

 Berkeland-Eyde process in use at Notodden has been at work some 

 time. The nitric acid made there is caused to combine with lime, and 

 the nitrate of lime is crystallized out of the solution obtained. 



Before this method of combining nitrogen and oxygen on a com- 

 mercial scale had been successfully worked out, another nitrogenous 

 manure called nitrolim or calcium cyanamide had been put upon the 

 market. This, like nitrate of lime, depended upon cheap electrical 

 power for its manufacture at a price that would compare favourably 

 with that of ammonium sulphate, since calcium carbide is used in 

 making it. It was first made on a large scale by an Italian firm at 

 Piano d'Orta, in Central Italy, but since 1905 several factories have 

 sprung up in various parts of the world, including the great works of 

 the North-Western Cyanamide Company at Odda, at the head of Har- 

 danjer Fjord, in Norway. This company supplied the calcium cyan- 

 amide used in the trials detailed below. 



The processes of manufacture of these two fertilizers need not be 

 further alluded to. They have been described in many recent publica- 

 tions,* but the fact that both contain lime in combination with nitrogen 

 may be emphasized. 



It is probable that in some districts at least the growth of motor 

 traction will cause a marked decrease in the quantities of stable manure 

 available. Stable manure has been the main source of nitrogen for 



* E.g. Fertilisers and Manures, by A. D. Hall, F.R.S. ; Principles and 

 Practice of Agricultural Analysis, vol. ii. (Ed. 2), by H. W. WHey; Trans, of 

 the Farce'ay Society, vol. iv. pt. 2, October 1908; etc. 



