POSNJAK AND MERWIN: BUCHER CYANIDE PROCESS 29 



Nitrate Division of the Ordnance Department of the Army, it 

 was found by means of microscopical examinations that the 

 nitrogen-bearing constituent of some of the crude technical 

 products manufactured by this process consisted principally 

 of some other substance than ordinary sodium cyanide. 



Ordinary sodium cyanide was found to be an essentially iso- 

 tropic substance, crystallizing in cubes, and having a refractive 

 index of 1452 =>= 0.003. After this cyanide had been fused, 

 slight double refraction amounting to about 0.005 was observed. 



The material found in the technical products above mentioned 

 appeared in weakly doubly refracting colorless grains about 

 0.03 mm. in diameter. The refractive indices are a = 1-527, 

 /3= 1.532, 7 = 1.537. The optic axial angle observed was 

 so near 90° that the optical character could not be determined. 



Evidently only chemical tests were made by Bucher. It was 

 therefore necessary to repeat his experiments to establish whether 

 sodium cyanide or this other substance was formed by his reac- 

 tion. The Bucher process, as known, consists in heating a mix- 

 ture of sodium carbonate, charcoal, and iron powder (catalyst) 

 in a stream of nitrogen at a temperature above 900°. The re- 

 action is written as follows: 



NasCOs + 4C + N2 :^ 2NaCN -f 3CO 



In our experiments, mixtures containing varying amounts of 

 sodium carbonate, carbon, and iron were prepared. Each was 

 placed in an iron boat within an electric furnace which contained 

 a reaction chamber consisting of a copper tube closely fitting 

 within one of siUca glass. A stream of nitrogen was passed 

 through the tube while a certain temperature between 900° 

 and 1000° was maintained for several hours. The reaction 

 product was rapidly cooled by lifting the tube out of the fur- 

 nace without interrupting the flow of nitrogen and was then 

 examined microscopically. In all experiments sodium cyanide, 

 together with some of the ingredients of the original mixture, 

 proved to be present, which confirms the reaction given by 

 Bucher. 



As it did not seem feasible to investigate the conditions of 

 formation of the substance in question at the factory, attempts 



