1007.] on Problems of Applied Chemistry. 571 



"Willson in 1892, and about the same time by Moissan. True, the 

 expectations that were entertained in various quarters in connection 

 with this remarkal)le chemical product have not been fully realised 

 to the extent anticipated by the inventors ; but, on the other hand, 

 an entirely novel use has been discovered for it by Professor Adolf 

 Frank and Dr. Caro, of Berlin. They found that when nitrogen is 

 passed over red-hot calcium carbide it is absorbed with formation of 

 calcium cyanamide. This latter, when treated with water under high 

 pressure, is made to yield ammonia ; but it is not necessary to do this, 

 since the crude product, which they have called " lime-nitrogen," 

 can serve directly as nitrogenous fertiliser, and is in that respect 

 equivalent to its own weight of ammonium sulphate. This is, indeed, 

 its principal use for the present and the near future ; but, as a matter 

 of fact, the discoverers go much further. From the lime-nitrogen 

 they prepare cyanogen derivatives of various kinds, some of which 

 are valuable as constituents of explosives, and they are earnestly try- 

 ing to employ it in the manufacture of nitric acid. They have also 

 brought in several other industries — the manufacture of pure graphite, 

 •of pure hydrogen, of urea, and so forth. The pure nitrogen required 

 for all this was at first produced by passing atmospheric air over 

 Ted-hot copper ; but it is now made by hquefying air and distilling off 

 the oxygen, which is thus obtained as a valuable by-product. The 

 inventors expressly recognise the invaluable aid which they have in 

 this respect derived from the world-renowned researches of Sir James 

 Dewar, carried out in the Royal Institution. The works already in 

 operation, or in course of construction, will by the end of this year 

 utilise water-power to the extent of some 55,000 horse-power, and 

 will produce lime-nitrogen equivalent to 100,000 tons of nitrate of 

 soda, and this with an expenditure of force less than one-third of 

 that required for the process of Birkeland and Eyde, of which I shall 

 speak directly. 



I must, however, first say a word about the strenuous efforts made 

 by Professor Frank and Dr. Caro, this time in connection with 

 Dr. Ludwig Mond, to extract horn, peat both power and ammonia. 

 Enormous, but hitherto almost worthless, deposits of peat exist in 

 Ireland and North Germany ; and the ultimate success of these 

 endeavours, which we have every reason to hope for, will prove an 

 incalculable boon to these countries. At the same time, all fears of 

 a scarcity of ammonia for agricultural purposes would be thus removed 

 for generations to come. 



Important as ammonia is as a fertiliser, it ranks after the nitrates 

 in that respect ; and, unhke ammonia, the nitrogen of the nitrates 

 is of immense importance for other purposes as well, viz. the manu- 

 facture of nitric acid and of explosives. The very limited quantities 

 of nitrates required in former times, amounting to a few tens of 

 thousands of tons per annum, were furnished by Indian saltpetre, that 

 is, crude potassium nitrate. A far more abundant supply was opened 



