424 EXPERIMENT STATION RECORD. 



influence of the electric spurk, the (luestion of preparino- nitrogenous 

 compounds from the free nitrogen of the air has engaged the attention 

 of sci(MitiH(' men from time to time. It is only within comparative!}^ 

 recent years, however, that the great industrial importance of utiliz- 

 ing this vast store of nitrogen has been full}' realized, and serious 

 attempts made to develop practical processes of rendering it available 

 for connnercial purposes. 



The matter is highly important from an agricultural standpoint, for, 

 as every one knows, nitrogen is the most expensive of the fertilizing 

 constituents and is restricted in supply. The exhaustion of the nitrate 

 deposits which constitute so prominent a source of supplv has been 

 placed by reliable estimates at a matter of only a generation or so dis- 

 tant. The air contains nitrogen enough for all, and it has seemed 

 highly probable that ultimately a way would be found for utilizing it 

 for other plants than legumes. 



Siemens and Lovejoy and Bradley have made important advances in 

 this direction by the use of high power electric currents for producing 

 nitric acid from the nitrogen of the air. The development in 1894 by 

 Moissan and Willson of an efficient electrical method for preparing 

 calcium carbid has done much to insure the success of a very different 

 process of fixing the free nitrogen of the air, namely, in the form of 

 cyanamids of the alkaline earths. The recent work of Frank and Caro, 

 Ptieger, Erlwein, Rothe, and others in the development of this method 

 gives reasonable ground for hope that the problem of the manufacture 

 of nitrogenous compounds from the nitrogen of the air in a practical 

 way has to a large extent been solved. 



The investigations of these men, which have been briefly reviewed 

 in the Record., show that by fusion of the carbids of the alkaline 

 earths, especialh^ calcium carbid, in the presence of atmospheric nit- 

 rogen freed from the larger part of the associated oxygen, calcium 

 cyanamid is produced. In practice it is found best to combine the 

 preparation of the calcium carbid and of the cyanamid into a single 

 operation, b}^ starting with a mixture of calcium carbonate and coal (as 

 in the making of carbid) and fusing these in the presence of the deoxj^- 

 genized air. The crude product formed has admixed Avith it more or 

 less lime and carbon, and contains from 10 to 22 per cent of nitrogen. 

 By further treatment this product can be made to yield free ammonia, 

 cyanid, or a dicyanamid containing 66 per cent of nitrogen, and other 

 compounds. The experiments of Gerlach and Wagner, however, indi- 

 cate this to be unnecessary from an agricultural standpoint, since the 

 cj^anamid can be used directly as a fertilizer. It has no injurious 

 effects on plants, and shows an efficienc}' fully equal to, if not exceed- 

 ing, that of the ammonium salts, and but slightly inferior to that of 

 nitrate of soda. 



