CHAPTER XI. 



MICROCHEMISTRY. 



I. The Application of Microchemical Analysis. — In 



few fields have the possibilities of the microscope been 

 less fully realized than in pure and applied chemistry. 

 A science which deals with the character and behavior 

 of chemical substances should surely take into account 

 the characteristic crystals of which, under certain con- 

 ditions, many such substances are composed. Yet 

 chemists trained to study gross color reactions and 

 precipitates have too often regarded the microscope as 

 a strange and impracticable instrument. ■ Systems of 

 recondite and elaborate secondary tests have been built 

 up, while the direct study of fundamental physical char- 

 acters has been neglected. Although the toxicologist and 

 the medical microscopist have used microchemical tests 

 with such good results that in those special fields they 

 are of importance, in general the adoption of these 

 methods by chemists is slow; and only the develop- 

 ment of petrography, the microscopic study of rock 

 sections, has at last, during very recent years, called 

 general attention to their importance. 

 The study of microchemistry is by no means limited 



to the examination of crystalline forms alone, as might 



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