1920.] 



Nitrate of Lime. 



43 



NITRATE OF LIME : 



ITS MANUFACTURE AND USE. 

 G. A. Cowie, M.A., B.Sc, A.I.C. 



The fixation of the nitrogen of the air and its conversion 

 into a suitable chemical and mechanical form for application 

 to the land constituted for a long time attractive problems 

 for the chemist and the engineer alike. The actual discovery of 

 a practical system of tapping this inexhaustible reservoir of 

 gaseous nitrogen was, therefore, of unique importance, affording 

 a valuable protection against a shortage of combine'd nitrogen 

 for fertiliser and other purposes. In order to realise adequately 

 the extent of this source of nitrogen it is interesting to recall 

 that the atmosphere consists approximately of 21 per cent, of 

 oxygen and 79 per cent, of nitrogen by volume. 



In experiments described by himself in 1785, Cavendish 

 caused the nitrogen and oxygen constituents of the air to 

 combine by the aid of electric sparks, and in the presence of 

 water or caustic potash obtained nitric acid or potassium 

 nitrate. For a long time these experiments remained merely 

 interesting class-room demonstrations, and all attempts to 

 utilise them on a practical scale proved abortive. Research 

 and investigation, however, were greatly stimulated by the 

 growing realisation of the importance of nitrogen in plant 

 nutrition and the necessity for providing fresh supplies, so 

 as to render possible a more intensive system of food production 

 to meet the requirements of a constantly expanding population. 

 In 1898 Sir William Crookes depicted in rather despondent 

 terms the grave effects of a shortage of nitrogenous fertilisers 

 on our food supplies. His remedy for a shortage of wheat 

 supplies was the artificial production and application to the 

 land of much larger amounts of nitrates. While all may not 

 agree with the conclusions of this eminent authority, his warning 

 doubtless proved an incentive to the search for a practical 

 method of producing nitrates from the nitrogen of the air. 



The first practical success was achieved by two Norwegians, 

 viz., Professor Birkeland of the University of Christiania, and 

 Dr. Samuel Eyde, an engineer of Christiania, who established 

 the now famous works at Notodden below Lake Tinnsj 6. 

 Since 1905, when the first factory was established, this industry 

 has undergone a steady development until it has now assumed 

 a position of enormous size and importance in Norway. During 

 the late War there was a very considerable extension of the 



