M. TECHNOLOGY. 517 



IMPROVEMENT IN THE MANUFACTURE OF STEARIC ACID. 



A recent improvement in the manufacture of stearic acid 

 involves the employment of carbon disulphide to increase the 

 fluidity of oleic acid, and thus obviate the use of the hot 

 press. According to the specification, the carbon disulphide 

 may be added either before or after the cold pressing. The 

 crude fatty acids are melted in a suitable apparatus, and mixed 

 while fluid with twenty per cent, of the disulphide, then al- 

 lowed to cool, and expressed cold. The claim is made for 

 this process that the stearic acid obtained by it is free from 

 oleic acid. Inasmuch as by the old process, with the hot 

 press, much of the solid acid is lost by being pressed out 

 with the oil, the above may prove to be a valuable improve- 

 ment. 



IMPROVED PROCESS OF MAKING ALKALI. 



The usual method of manufacturing alkali by what is called 

 the Leblanc process consists in decomposing common salt 

 with sulphuric acid, roasting the resulting sulphate of soda, 

 technically known as salt-cake, with an admixture of ground 

 coke and limestone, and subjecting the crude mass thus ob- 

 tained to certain refining operations. It is now stated, on 

 the authority of Rudolph Wagner, that an entirely new 

 method has been elaborated, verified, and is about to be in- 

 troduced on a large scale simultaneously in England, Austria, 

 and Germany. Common salt in solution is mixed with bi- 

 carbonate of ammonia; the result is bicarbonate of soda 

 (which crystallizes out), and chloride of ammonium (sal am- 

 moniac), which remains in solution. The latter liquid is dis- 

 tilled along with limestone, the result being carbonate of am- 

 monia, which is collected, and chloride of calcium, which re- 

 mains in solution. Meantime the bicarbonate of soda, or such 

 part of it as is not required to be sold as such, is furnaced, 

 and thus converted into dry carbonate of soda, or soda-ash. 

 In this operation it loses half its carbonic acid, which, being 

 led into the carbonate of ammonia, is ready to use along 

 with a fresh lot of salt. The only materials thus consumed 

 will be common salt and chalk, or limestone, and the only 

 refuse yielded will be chloride of calcium, which is not inca- 

 pable of being utilized. The stock of bicarbonate of ammo- 



