240 ANNUAL EEPORT SMITHSONIAN INSTITUTION^ 1912. 



Cologne), 19,000 tons are made in Niagara Falls by the American 

 Cyanamide Co., and during the next tliree years the total production 

 is to be increased to 200,000 tons], nor is it necessary to describe the 

 Serpek process for the production of ammonia from aluminium 

 nitrides combined with the utilization of alumina which is simultane- 

 ously obtained. I will mention, however, that the problem of con- 

 centrating the dilute nitric acid, as obtamed in the large absorption 

 apparatus from nitrous gases, has been solved by Pauling's method, 

 in which sulphuric acid is used in a battery of towers. It is also 

 possible now to convert economically cyanamide into ammonia and 

 this again into nitric acid. 



SODA AND CHLORINE. 



• The 50-year-old Solvay process, which has conquered the whole 

 world, still remains master of the situation. This is all the more 

 remarkable since it is still imperfect as far as the yield is concerned, 

 for a quarter of the salt used in the process is lost as such, and the 

 whole amount of chlorine in the form of calcium chloride. 



Although the materials employed in the Le Blanc process are com- 

 pletely utilized, this fact will not give it any chance of surviving, and 

 it would seem to be now chiefly of historical interest. 



Not less remarkable is the 25 years' career of the alkali-chloride 

 electrolysis. The limited market for chlorine compounds and the 

 great space taken up by the electrolyzing baths were gi-eat obstacles 

 to the progress of this apparently so simple method. For the same 

 reasons the most approved processes, such as the Griesheim cement 

 cell, the quicksilver cathodes of Castner and his successors, the 

 Aussig Bell and the Avire-gauze diaphragm of Hargreaves, mth its 

 many varieties, of which the Townsend cell is the latest and best, did 

 not develop as expected. The limited demand also quickly restricted 

 the operation of the brilliant method of manufacturing chlorates by 

 electrolj^sis. 



TIN. 



Tin is not only produced from natural ores but also in more than 

 20 dctinning establishments from tin-plate and tin-can waste; 200,000 

 tons of tin-plate waste are subjected to this treatment and about 

 24,000,000 marks (-16,000,000) worth of .tin and kon are recovered. 

 The electrolytic detinning process, on account of high wages, the 

 great cost of current, and the considerable manufacturing loss, has 

 been replaced — where there is a market for chloride of tin — by the 

 patented process of Tliomas Goldschmidt, of Essen. This process 

 takes advantage of the properties of chlorme gas, in the dry state, to 

 greedily take up tin without reacting on iron if certain temperatures 

 are observed. Instead of the inferior quality of electrolytic tin mud, 



