92 CHEMICAL FERTILIZERS 



presents some difficulties. Electrical heating produces many 

 complications, but the temperature can be maintained by 

 injecting into the chamber a sufficiently small amount of air 

 to produce the necessary heat by the combustion of some 

 of the hydrogen. Sometimes combustion is not complete, 

 and small amounts of oxygen begin to accumulate in the 

 gases which are circulating, resulting in a great increase in 

 the proportion of oxygen, which may suddenly cause an 

 explosion. It is estimated that the cost of synthetic ammonia 

 under normal conditions should not amount to more than 

 10 to 12 per ton. There is at present such a general 

 tendency for prices to rise all round, that this is probably a 

 much under-estimated figure. 



Ammonia can also be made from calcium cyanamide by 

 passing steam at high pressure over that material. 



Ammonium sulphate can be made from ammonia and 

 sulphur dioxide which are pumped into water at about 

 50 C. (112 F.) in the presence of a catalyst. Many 

 substances act as catalysts, but sulphur is one of the most 

 convenient. Under such circumstances reaction occurs as 

 follows : 



6NH 4 HS0 3 + 3(NH 4 ) 2 S0 3 = 6(NH 4 ) 2 SO 4 + 3$ + 3H 2 O 



The sulphur separates out and if the solution be strong 

 enough ammonium sulphate crystallizes out. Heat is given 

 out during the reaction. 



At present hardly any other ammonia salts have been 

 used for fertilizing purposes, but ammonium nitrate (see 

 p. 101) may before long come into more general use. 



It is now well known that modern improvements in the 

 fixation of nitrogen are likely to affect the sulphate of 

 ammonia industry ; indeed both technical journals and 

 daily press give articles as follows : 



" Germany has solved the problem of the fixation of 

 nitrogen as a commercial undertaking on a gigantic scale. 

 In future, from the point of agricultural fertilizers, she is 

 independent of any blockade." 



The above is the substance of a statement made by Dr. 



