CYANAMIDE AND NITRATE OF LIME. 273 



TABLE LXXYIIL— ANALYSES OF CYANAMIDE (LIME NITROGEN AND 



NITROGEN- LIME). (GRANDEAU.) 



Lime nitrogen. Nitrogen lime. 



Nitrogen 20-21 20 



Calcium 40-42 45 



Carbon 17-18 19-5 



Chlorine ..... — 6-5 



The only difference between the two products is that the nitrogen 

 lime contains calcium chloride injurious to vegetation. 



Manufacture of Cijanamide.—'' Lime nitrogen " is manufactured 

 in Italy by the Societj\ generale per la Cianamide, the head office 

 of which is in Rome in association with the Berliner Zyanid 

 Gesellschaft. This company has acquired all the patents and pro- 

 cesses relating to the manufacture of cyanamide of calcium and its 

 derivatives. It afterwards assigned these patents for Italy and Austria- 

 Hungary to the Societa italiana per la fabricazione di Prodotti azotati, 

 which has installed at Piano d'Orte a factory capable of producing 

 10,000 tons a year. It has just acquired at Almissa numerous 

 waterfalls of a force of 50,000 H.P., which will enable it to manu- 

 facture 1,000,000 tons per annum. Manufacturing licences have 

 been granted in France to the Societe francaise des produits azotes 

 at N.-D. of Briancon; to the Societe Suisse near Martigny, and 

 to the North- Western Cyanamide Co. near Odde in Norway, the 

 head office of which is in London. A factory using a fall of water 

 of 40,000 H.P. is in construction in America, and two others respec- 

 tively of 2000 and 10,000 H.P. are in construction in Germany. The 

 manufacture of cyanamide according to the first of these processes 

 has just been modified by Polzenius, who adds 10 per cent of calcium 

 chloride to the calcium carbide used so as to fix the nitrogen on 

 the mixture at a much lower temperature [700° to 800° C. (1292° to 

 1472° F.)] than in the original Frank and Caro process of 2000° C. 

 (3632° F.). The product so obtained is called ''nitrogen hme " in 

 opposition to the product " lime nitrogen " by the old process. But 

 this distinction is one of pure form, for the two products have per- 

 ceptibly the same composition. The nitrogen in these products 

 costs 1-4 francs the kg. (say 6d. per lb.). The factory working this 

 process is situated at Westerregeln in Germany. It is capable of 

 producing 4000 tons of lime nitrogen per annum. 



Manufacture of Nitrate of Lime. — As just mentioned, this pro- 

 cess consists in oxidizing atmospheric nitrogen by electric means. 

 In 1903, Prof. Birkeland of Christiania observed that the electrical 

 discharges from the alternate current, at an average tension, dispersed 

 in the magnetic field, which brought about the combustion of the 

 nitrogen in the air. This process had the advantage over similar 

 ones of requiring a much lower electric tension, say 5000 volts in 

 place of 15,000, and to furnish much higher yields of nitric acid. 



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