43 8 POPULAR SCIENCE MONTHLY. 



oxide is heated with ammonium chloride, the potassium is converted 

 into chloride and is easily separated from the melt. If this reaction 

 could be extended to orthoclase and the ammonia recovered by treat- 

 ment with lime, the enormous quantity of potash contained in this 

 mineral would be at our service. 



It is, however, to the supply of available nitrogen that the greatest 

 importance attaches. The sodium nitrate producing countries of South 

 America exported last year 1,300,000 tons, a large percentage of which 

 came to America. Egypt and the southwestern United States have 

 nitrate deposits, but of their extent and value little is as yet known. 

 Of the other form of available nitrogen, ammonia, our main supply is 

 at present from the destructive distillation of coal. Although the 

 introduction of by-product coke ovens has increased this supply, our 

 domestic production is now not over 40,000 tons a year. 



In the atmosphere, however, we have a never-failing source of 

 nitrogen which needs only to be converted into other forms to be of 

 the greatest value. It is interesting to note that even as long ago as 

 1840 this same problem was the subject of considerable experimenta- 

 tion and the basis of several technical processes. In this year there 

 was erected in France a plant for the manufacture of potassium 

 ferrocyanide which depended on the atmosphere for the supply of 

 nitrogen, and which at one time turned out almost a ton of product 

 per day. From this time until the present, the utilization of this 

 inexpensive and inexhaustible supply of raw material has been an at- 

 tractive field and has held the attention of many investigators. It had 

 long been known that while carbon and nitrogen alone could not be 

 made to unite, the union was effected when these elements were brought 

 together in the presence of a strong alkali. The technical difficulties 

 in the way of successfully applying this reaction seem to have been 

 the rapid destruction of the retorts and the loss of alkali through 

 volatilization. With the advent of cheap electricity and the consequent 

 development of the electric furnace, this idea was made the basis of 

 further work. The destruction of the retorts was largely overcome 

 by generating the heat within the apparatus rather than without. 

 When a non-volatile alkali was used to eliminate the loss from this 

 source and a higher temperature maintained, it was found that a 

 carbide was formed as .an intermediate product and that nitrogen 

 readily reacted with the carbon thus held in combination. 



Among the investigators who have thus far taken advantage of this 

 reaction may be mentioned the Ampere Chemical Company, located 

 at Niagara Falls, and the group of men represented by the Siemens 

 and Halske Company, of Berlin. The former first produces a carbide 

 of barium and then converts it into barium cyanide by passing over it 

 air from which the oxygen has either been removed or converted into 



