384 NO yes: nitrogen problem in relation to war 



This is the substance which is used so extensively in the manu- 

 facture of acetylene for oxy-acetylene welding. The carbon 

 monoxide escapes as a gas. This first step in the cyanamide 

 process is carried out in huge electric furnaces. The charge of 

 lime and coke in small lumps is fed down through the furnace in 

 the center of which stands a large carbon electrode. The walls 

 of the furnace form the other electrode. The mixture is heated 

 to a very high temperature, and the melted carbide is tapped off 

 at the bottom from time to time and allowed to solidify. 



The carbide is then crushed and subjected to the nitrifying 

 process. Namely, it is packed into large basket-shaped con- 

 tainers 3 to 6 feet high and 2 to 3 feet in diameter, which are 

 enclosed in an iron vessel supplied with nitrogen. The basket 

 has holes through the sides, and down the center runs a resistance 

 wire. The reaction is started electrically by heat produced by 

 passing a current through the wire. The reaction which takes 

 place is as follows: 



CaCa + N2 = CaCNo + C. 



This gives us a product properly called "calcium cyanamide" 

 which contains some unchanged carbide (about 3 per cent), 

 and some lime and carbon. 



The cyanamide process was the only one of the fixation proc- 

 esses which was being operated on any considerable scale in this 

 country when we entered the war, and which is being so operated 

 now. There is a plant operated by the American Cyanamid 

 Company at Niagara Falls, Canada, which has been producing 

 something like 20,000 tons of cyanamide a year. The product 

 has been used to a limited extent in agriculture, but unfortu- 

 nately the large amount of lime which it contains prevents it 

 from being so used in unlimited quantities. 



For the production of ammonia the cyanamide has to be treated 

 with steam, whereby the following reaction takes place: 



CaCNa + 3H2O = CaCO.3 + 2NH3. 



This process is carried out in huge autoclaves about 20 or 30 feet 

 high and 4 to 6 feet in diameter. The powdered cyanamide is 

 fed into an alkaline solution and then steam is blown in; the 



