110 METALLOSALINES. [IV. 



pump. In this way the treatment is to be continued for 10 

 hours, so that the whole mass may be acted upon. As the 

 coal becomes cyanuretted, and is drawn off at the bottom, new 

 supplies must be added at the top. The heated coal is con- 

 ducted along an iron gutter into a reservoir containing pow- 

 dered native carbonate of iron diffused in water. The coal 

 becomes leeched, and the liquor on evaporation will yield 

 crystals of prussiate. 



Coke gives less product than charcoal ; and the presence 

 of even minute portions of water decomposes the cyanide and 

 generates ammonia, thus decreasing the yield of salt. 



Explosion with Med Prussiate of Potash. — During the pre- 

 paration of red prussiate (ferridcyanide of iron) in a chemical 

 work at Berlin, a violent explosion took place, without appa- 

 rent cause, which dashed to pieces the wooden vessels in which 

 the operation was performed, and shook the walls of the 

 building. Fortunately no person was injured. The chlorine 

 was generated in cast-iron vessels, from manganese, salt, and 

 sulphuric acid. Muriatic acid was also evolved, which set 

 prussic acid free from the prussiate solution. Now, an am- 

 moniacal salt is produced by the action of chlorine on prussic 

 acid ; and by the further action of chlorine on ammonia, it is 

 probable that the highly explosive chloride of nitrogen was 

 produced. (Berlin. Gewerbe-Industrie und Handelsbl. xx. 

 141.) 



Cyanide of Potassium. — C. Clemm (Annal. der Chem. u. 

 Pharm. Ixi. 250) gives the following details of Liebig's method, 

 which should be observed to obtain a white and not dark-gray 

 compound. Yellow prussiate of potash (ferrocyanide of po- 

 tassium) is thoroughly dried by calcination. 8 pts. of this 

 salt are intimately mixed with 3 pts. of fully dry carbonate of 

 potassa in a covered iron crucible, and heated until the fused 

 mass at a dull red-heat appears clear, and, when taken out 

 in an iron spatula and cooled, appears white. The crucible is 

 removed from the fire, gently struck to separate the iron, and 

 its fluid contents (after evolution of gas has ceased) poured 

 through a cullendered iron ladle (previously heated) into a 



