376 



ANNUAL REPOKT SMITHSONIAN INSTITUTION, 1913. 







The powder is then filled into electric furnaces, of which, in the 

 first installation at Odda, there are 196, each holding 300 kg. 



Figure 7 is a rough sketch of the furnace, and it will be noticed 

 that down the center there is a cardboard tube to provide a space 

 for the carbon pencil. After the carbide has been filled in the carbon 

 pencil is fixed in position and the lid fastened down and made air- 

 1 ight. 



Alternating current is now switched on and the temperature is 

 raised to 800° to 1,000° C. The cardboard tube and certain card- 

 board partitions which had been placed in the furnace when the 

 calcium carbide was run in are burnt up, and they leave spaces which 

 allow the nitrogen gas, which is admitted under pressure, to circulate 



freely. Electric current is 

 ctr&v>/>frKj/ kept on for 25 hours, and at 



the end of 35 hours all the 

 nitrogen has been absorbed, as 

 shown by the meter. 



At Odda this nitrogen is 

 made by the Linde distillation 

 process, but in one of the 

 French factories the Claude 

 process is used. 

 ^ar.i.n />e.c./ rpj^^ ^gg fumaces make 



about 30 tons of calcium cyan- 

 amide, containing 18 per cent 

 of nitrogen, per day of 24 

 hours. 



Wlien it is turned out of the 

 furnace the cyanamide looks 

 like black clinker. After be- 

 ing broken up it is fed into 

 jaw crushers and then goes to 

 roulette mills, where it is 

 ground up fine for market. 

 It is then packed in a paper-lined bag, which is in a jute bag. For 

 tropical countries there are two outer jute bags. 



Recently improvements have been introduced at the Odda Works 

 whereby, with the same amount of power and labor, the output has 

 been increased from 12,000 tons to 15,000 tons per annum. 



The furnaces are now being made to hold 4:50 kg., instead of 

 300 kg. Another improvement is that the cyanamide is treated with 

 enough atomized water to reduce free carbide to less than one-half 

 of 1 per cent. 



From the point of view of engineers in this country, the installa- 

 tion of A. G. Stickstoffdunger at Knapsack in Germany (see Table 



Moun 



/irifier 



Fro. 7.— Electric Fuenace for making Calcium 

 Ctanamide. 



