ATMOSPHERIC NITROGEN BY MEANS OF ELECTRICITY 31 1 



heavy carbon electrodes. They also utilized the horn lightning 

 arrester consisting of two vertical horns, the lower ends of which 

 are near together, while upwards the two horns diverge from 

 each other more and more. The arc is formed between the two 

 lower ends of these electrodes and travels upwards, thereby en- 

 larging its surface and causing it finally to be automatically bro- 

 ken. None of these methods, however, resulted in securing oxi- 

 dized nitrogen on a commercial scale. The development of the 

 cyanamid furnace is fully described in this paper and the funda- 

 mental reaction by which calcium cyanamid is produced is given 

 as CaO + 2C + 2N = CaCN 2 + CO. When the price of cal- 

 cium carbid fell to a point at which it could be commercially used 

 it was found that the production of calcium cyanamid was more 

 economically secured by starting with the carbid itself. The 

 fundamental reaction in this case is CaC 2 -|-N 2 =CaCN 2 -(-C. 

 The principle of the construction of the cyanamid furnace is 

 based upon the utilization of a series of coal-fired retorts, closed 

 air-tight, and partially filled with powdered calcium carbid. After 

 the contents of the retort have reached a white heat nitrogen gas 

 is introduced therein. In these conditions the carbid rapidly ab- 

 sorbs the nitrogen. The reaction is exothermic and the heat 

 evolved promotes still more the activity of the combination. Af- 

 ter the carbid is absorbed by the nitrogen the incandescent cyan- 

 amid is removed from the retorts, cooled under exclusion of the 

 air and powdered and packed for shipping. 



The commercial calcium cyanamid is a black powder, quite 

 stable in the air and consists of 57 per cent, of calcium cyanamid 

 14 per cent, free carbon, to which the black color is due, 21 per 

 cent, caustic lime, 2^2 per cent, of silicic acid, four per cent, of 

 iron oxid, and small quantities of sulfur, phosphorus and carbonic 

 acid. The average content of nitrogen is about 20 per cent. 

 When placed in water calcium cyanamid dissolves, decomposing 

 quickly, especially in hot water, and yielding caustic lime, and, 

 by polymerization, a complicated compound called dicyanamid. 

 Subjected to overheated steam calcium cyanamid gives off its 

 nitrogen quantitatively in the form of ammonia. In aqueous 

 solution, under the influence of certain acids, a series of synthetic 

 organic compounds are produced, among which is found urea. 



