CALCIUM NITRATE 331 



.sandy soil it ranks much lower. Indeed, it appears to be 

 but poorly suited to use on sandy soils. 



196. Calcium nitrate. The other process for com- 

 bining atmospheric nitrogen is of even more recent 

 invention than that for the manufacture of calcium 

 cyanamid and, like it, is not conducted on a commercial 

 scale in this country; but, with the vast opportunities 

 for developing electric power which are offered in certain 

 localities, factories for the manufacture of calcium nitrate 

 will soon be established. 



The process employs an electric arc to produce nitric 

 oxide by the combustion of atmospheric nitrogen, ac- 

 cording to the simple equation: 



N 2 + 2 = 2NO. 



A very high power is required for this synthesis, 

 involving a temperature of 2,500 to 3,000 C, and the 

 expense of the operation is determined almost entirely 

 by the cost of the electricity. 



The nitric oxide gas is passed through milk of lime, 

 giving calcium nitrate. 



The calcium nitrate produced by this process has a 

 yellowish white color, and is easily soluble in water, 

 but deliquesces very rapidly in the air. This last prop- 

 erty can be overcome by adding an excess of lime in the 

 manufacture, thus producing a basic calcium nitrate, 

 which contains only 8.9 per cent nitrogen. Another 

 way of avoiding the difficulties involved by the deliques- 

 cent property of the nitrate is practiced by the factory 

 at Nottoden, Norway. This consists in first melting 

 the product, then grinding it fine, and packing it in 



