302 Wells & Foote — One Hundred Years of Chemistry. 



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 

 advances in chemistry that have been made during the 

 Journal's period, and of the part that the Journal has 

 taken in connection with them, and there seems to be no 

 doubt that this progress has not diminished during more 

 recent times. 



The present tendency of chemical research is evidently 

 towards a still greater development of organic chemis- 

 try, and an increased application of physics and mathe- 

 matics to chemical theory and practice. 



The very great improvements that have been made in 

 chemical education, both in the number of students and 

 the quality of instruction, during the period_ under dis- 

 cussion, and particularly in rather recent times, gives 

 promise for excellent future progress. 



