600 Scientific Intelligence. 



SCIENTIFIC INTELLIG1NCE. 



I. Chemistry and Physics. 



1. The Production and Uses of Hydrogen. — A. 1 , Seeker has 

 given an account of the technical employment of this g as. Formerly 

 it was used occasionally for the filling of balloons and in the oxy- 

 hydrogen flame of the so-called " calcium light." It has become 

 essential for the filling of dirigible balloons, but these have now 

 perhaps become of secondary importance in comparison with 

 heavier than air machines. The oxyhydrogen flame is now com- 

 monly used in working refractory metals. Liquid oils and soft 

 greases are now "hydrogenated " to produce acceptable lard and 

 butter substitutes and also fats suitable for the manufacture of 

 hard soaps. Finally the use which promises to consume enormous 

 quantities is the synthetical production of ammonia from hydro- 

 gen and atmospheric nitrogen. All these uses make the produc- 

 tion of cheap hydrogen a problem of considerable importance. 

 In view of the impending exhaustion of the Chili saltpeter beds, 

 the problem of the fixation of atmospheric nitrogen has received 

 increased attention. The production of cyanamide from calcium 

 carbide and nitrogen, and the flaming arc process for making 

 nitric acid directly from the air have been successfully established, 

 but these methods require cheap water power for the electrical 

 energy. In countries lacking cheap power the synthetic ammonia 

 process appears to be promising and it is in successful operation 

 in Germany. It consists in passing a mixture of pure nitrogen 

 and hydrogen under a pressure of 150 to 250 atmospheres through 

 a tube filled with a catalyzer and heated to 650 to 700° C. The 

 hot gases then pass through a heat regenerator and thence 

 through an ammonia absorber, after which they are replenished 

 with fresh gas mixture and forced by a pump back over the outer 

 walls of the contact tube and then through the contact mass to 

 repeat the circulatory course already described. Only a part of 

 the mixture is converted into ammonia by a single passage 

 through the converter, but the circulation is continuous. The 

 contact mass consists of pure iron containing many other sub- 

 stances called promoters. The studies of Wegener and others 

 lead to the opinion that at a height of about 75 miles the 

 atmosphere consists of pure hydrogen and nitrogen that would 

 be ideal for the synthetic ammonia process, but even if this is so 

 no means of piping these gases down to our sphere of action ar3 

 known. 



Large amounts of hydrogen are obtained as a by-product in the 

 electrolysis of salt solutions in the manufacture of chlorine and 

 caustic soda. The reaction, which is as follows : oXT a.Cl + 2H 2 

 = 2NaOH + C1 Q + H 2 , produces 245 million cubic i«_ o 



gen per year at Griesheim, Germany. In another metho^ . 



