MANUFACTURE OF AMMONIA 7 



utterance, which after more than fifty years have passed seems 

 nearing its fulfillment. He says : 



" In terminating these remarks on the subject of manures, 

 I would once more call attention to the salts of ammonia. 

 Should these really be found to produce the beneficial effects 

 anticipated, we shall possess at home, within the limits of our 

 own island, resources for the improvement of agriculture, 

 compared with which guano and nitrate of soda, and all such 

 things, are quite insignificant ; resources which only require to 

 to be judiciously used to produce the most extraordinary re- 

 sults. Coal contains nitrogen. When distilled at a red heat 

 for the purpose of getting illuminating gas, the greater part of 

 this nitrogen unites with hydrogen, and gives rise to ammonia, 

 which is afterwards separated more or less completely, and 

 manufactured, although frequently in a very wasteful and 

 imperfect manner, into ammoniacal salt. Admitting that coal 

 contains one per cent of nitrogen which can thus be employed 

 (a supposition probably not far from the truth), it is easy to 

 see what a prodigious quantity of ammonia might be furnished 

 by our coal-gas works, properly conducted." 



We must now refer in a little more detail to the produc- 

 tion of ammoniacal salts from coal, which furnishes almost 

 the w r hole of the enormous quantity now manufactured, and is 

 capable of still further development. 



Coal (excluding anthracite) usually contains 1-2 to 1-6 

 per cent of nitrogen ; the average proportion may be taken as 

 about 1-33 per cent. Anthracite contains about 0.9 per cent. 

 About 90 per cent of the coal annually consumed is burnt in 

 such a way that none of the nitrogen which it contains is 

 obtained in a useful form. It is only when the coal is heated 

 in closed vessels that the manufacture of ammonia salts 

 becomes possible. The most favourable conditions for the 

 recovery of the nitrogen in the form of ammonia are those 

 found in a gas works, but even here only a small proportion 

 of the nitrogen originally present is finally obtained as am- 

 monia, the proportion so obtained never exceeds one-fifth, 

 and sometimes is no more than one-tenth of that originally 

 present in the coal. One ton of coal containing 1-33 per cent 



