388 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Utilization of Atmospheric Nitrogen for Agricultu- 

 ral and Industrial Purposes. — In an address before the recent 

 International Congress for Applied Chemistry at Berlin, Dr. 

 Frank stated that we are now in a position, by the help of 

 electric power, to combine the hitherto passive nitrogen of the 

 air and to make it useful for the fertilization of land and for the 

 production of nitrogenous chemical products. The particular 

 process described depends on the fixation of nitrogen by calcium 

 carbide, a product of the electric furnace which is now exten- 

 sively manufactured. The product of this reaction is not cal- 

 cium cyanide, as might be expected, but calcium cyanamide : 



CaC, + N,= CaCN, + C. 

 From this product cyanamide itself is readily prepared, and 

 both substances yield ammonia when heated with water under 

 high pressure : 



CaCN, + 3H,0 = CaCO, -f 2NH3 

 CN,H,-t-3H,Ozz=(NHJ,C03. 



Experiments with plants have been made which indicate that 

 the crude calcium cyanamide will serve very well when used 

 directly as a fertilizer. The substance contains from 14 to 22 

 per cent of nitrogen, according to the process used for its manu- 

 facture, so that it approaches Chili saltpeter and ammonium-sul- 

 phate in its richness in this fertilizing element. As an indication 

 of the availability of these substances for plant-food, it may be 

 mentioned that cyanamide, by simply taking up water, is con- 

 verted into urea : 



CN,H,-fH,0 = CH,N,0. 



The importance of a cheap method of fixing atmospheric 

 nitrogen can hardly be over-estimated, in view of the fact that 

 about three-quarters of the Chili saltpeter and ammonium sul- 

 phate are used for agricultural purposes. It may be expected 

 also that the supply of Chili-saltpeter would otherwise soon be 

 exhausted, since the export of this salt from the western coast of 

 South America increased from 68,500 tons in 1860 to 1,453,000 

 tons in 1900. The world's future food-supply largely depends 

 upon the supply of nitrogenous fertilizers. — Zeitschr. angeio. Cheni., 

 xvi, 5:^6. H. L. w. 



2. The Use of Calcium Cyanamide for Producing Alkaline Cy- 

 anides. — The production of calcium cyanamide has been described 

 in the preceding notice. At the recent International Congress 

 for Applied Chemistry at Berlin, Dr. G. Erlwein has explained 

 the use of this new material in the manufacture of cyanides. He 

 states that calcium carbide, with proper treatment, can be made 

 to take up from 85 to 95 per cent of the theoretical amount of 



