FIXATION OF ATMOSPHERIC NITROGEN 403 



and the latter passes into ammonium carbonate : 

 (H 2 N) 2 CO+2H 2 0=(H 4 N) 2 C0 3 . 



Other uses, however, have been found for nitrolime, and it is 

 probable that still further applications may be made of its 

 combined nitrogen. Thus by melting with proper alkaline salts 

 alkaline cyanides may be made, and the manufacture has been 

 established at Spandau near Berlin. The consumption of 

 cyanides for the extraction of gold from quartz is very large, and 

 hence the cheapest possible production of these salts is very 

 desirable. The simplest form of the reaction is represented by 

 the following equation : 



CaNCN+C ^ > Ca(CN) 2 



in which the carbon already present in the nitrolime is concerned, 

 and no addition is necessary except some fusible material to act 

 as a flux. The process is, however, at present a secret. 



Cyanamide treated with super-heated steam gives off all its 

 nitrogen in the form of ammonia, and inasmuch as this process 

 leaves all the lime and one-third of the required carbon in the 

 form suitable for the manufacture of carbide, it is probable that 

 this may prove to be an economical method for the manufacture 

 of ammonia, and hence of such salts as ammonium sulphate, 

 which is so largely used in agriculture. 



Nitrates from Atmospheric Air 



So long ago as 1781 and the few following years experiments 

 placed on record by the Hon. Henry Cavendish show that he 

 had established the fundamental facts which more than one 

 hundred and twenty years later have found practical application 

 on a large scale. He found that when hydrogen and air are 

 exploded together the water which is formed is always accom- 

 panied with a small quantity of nitric or nitrous acid. He also 

 showed 1 that when common air mixed with some oxygen is 

 exposed to electric sparks the mixture is wholly absorbed by an 

 alkaline solution with production of common nitre. (See passage 

 quoted in connection with discovery of Argon, p. 136.) 



Attempts to utilise these facts for manufacturing purposes led 

 to no practical result till in 1897 Lord Rayleigh gave an account 

 of his " Observations on the Oxidation of Nitrogen Gas " in the 

 Transactions of the Chemical Society. The experiments described 



1 Philosophical Transactions of the Royal Society, vol. 75 (1785). 



