ONE HUNDRED YEARS OF CHEMISTRY 333 



About 1866 the Solvay process appeared as a rival to 

 the Leblanc process. This depends upon the precipita- 

 tion of sodium bicarbonate from salt solutions by means 

 of carbon dioxide and ammonia, with the subsequent 

 recovery of the ammonia. It has displaced the older 

 process to a large extent, and it is carried on extensively 

 in this country, for instance, at Syracuse, New York. 



Other processes for soda depend upon the electrolysis 

 of sodium chloride solutions. In this case caustic soda 

 and chlorine are the direct products, and the chlorine 

 thus produced and liquified by pressure in steel cylinders, 

 has become an important commercial article. 



In earlier times wood-ashes were the source of potash 

 and potassium salts. Wurtz in the Journal (10, 326, 

 1850) suggested the availability of New Jersey green- 

 sand as a source of potash and showed how this mineral 

 could be decomposed, but it does not appear that this 

 mineral has ever been utilized for the purpose. About 

 1861 the German potash-salt deposits began to be devel- 

 oped, and these have since become the chief source of 

 this material. At present many efforts are being made 

 to obtain potassium compounds from other sources, such 

 as brines, cement-kiln dust, and feldspar and other min- 

 erals but thus far the results have not satisfied the 

 demand. 



Conclusion, 



This account of chemical progress has given only a 

 limited view of small portions of the subject, because the 

 amount of available material is so vast in comparison 

 with the space allowed for its presentation. Since the 

 Journal has published comparatively little organic chem- 

 istry, it was decided to make room for a better presenta- 

 tion of other things by giving only a brief discussion of 

 this exceedingly active and important branch of the 

 science. For similar reasons industrial and metallurgi- 

 cal chemistry, and other branches besides, in spite of 

 their great growth and importance, have been neglected, 

 except for some incidental references to them, and some 

 account of a few of the more important industrial 

 chemicals. 



It appears that we have much reason to be proud of the 



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