HISTORY 



The new science of microcrystal identifica- 

 tion tests came of age in the 1860's. Perhaps 

 it may be said that the idea had crystalhzed 

 with the issuance of the prospectus of Worm- 

 ley's book in the United States in 1861. This 

 pubhcation was delayed by the Civil War, 

 and actually the honor of the first book of 

 this science, at least the first findable by the 

 writer, goes to Helwig, whose "Das Mikros- 

 kop in der Toxikologie" was published in 

 Germany in 1864 and 1865. Chamot and 

 Mason have also mentioned a similar book 

 by Erhard, "Die giftige Alkaloide u. d. Aus- 

 mittelung auf Mikroskopischen Wege", 

 1866. 



Wormley's great book, "Microchemistry 

 of Poisons", was fuially published in 1867 

 (1869). He gave attention to sensitivities 

 and established the science on a firm basis. 

 His book is a landmark; the tests are still 

 good but, of course, the number of com- 

 pounds covered has now become quite inade- 

 quate. A second edition was issued, without 

 very much change, in 1885. 



In those days, most poisons were inorganic 

 or else natural plant alkaloids, and crystal 

 tests were developed for both kinds. Later, 

 such tests were extended over the whole 

 field of inorganic chemistry, but their ex- 

 tension to other organic compounds besides 

 the alkaloids has been \'ery slow and meager. 



Inorganic tests were further developed by 

 Haushofer in "Mikroskopische Reaktionen" 

 (1885), and by Klement and Renard in 

 "Reactions Microchimiques" (Brussels, 

 1886). 



Behrens' outstanding work, with some 

 publication as early as 1882, culminated 

 near the end of the century in "Anleitung 

 zur Mikrochemischen Analyse", 1895-97. He 

 brought the inorganic part to a high level, 

 and made a strong effort to develop the 

 science throughout the organic field, with 

 many examples of reactions and descriptions 

 of crystals suitable for microscopic identifi- 

 cation tests. 



In spite of this, the majority of chemists 



even today think of such tests as suitable 

 only for alkaloids, if they use them at all. 



A new edition of Behrens' work, by Kley, 

 in 1921-22, represented the fourth edition 

 for the inorganic part, the second for the 

 organic part. 



The inorganic field has been developed 

 further, and admirably, by Chamot and 

 Mason, especially in volume II of the second 

 edition of their "Handbook of Chemical Mi- 

 croscopy" (1940). 



The work on alkaloids was carried on in 

 excellent fashion by Stephenson, "Some 

 Microchemical Tests for Alkaloids", 1921, 

 and Amelink, "Schema zur mikrochemischen 

 Identifikation von Alkaloiden", 1934. Ame- 

 link gave attention to just a few compounds 

 besides alkaloids, reacting with the same 

 reagents. 



"Toxikologische Mikroanalyse", by Ro- 

 senthaler, 1935, included tests for various 

 inorganic and other organic compounds as 

 well as alkaloids and their modern analogs, 

 and is very valuable although it often seems 

 not too well based on the best preceding 

 work. (It was reissued in the United States 

 in 1946, and is still "in print".) 



While Behrens was especially influential, 

 "microchemistry" usually meant the use of 

 the microscope in making chemical identifi- 

 cations, especially by means of reactions pro- 

 ducing characteristic crystals. However, in 

 the last 40 years, to most chemists the term 

 "microchemistry" has come to mean merely 

 small scale chemistry. Meanwhile the oldest 

 type of microchemistry, i.e., the chemistry 

 of things observed through the microscope, 

 also survived and was further developed by 

 botanist-chemists, Tunmann and Molisch in 

 particular; it now includes considerable use 

 of crystal-forming reagents, but is not lim- 

 ited to them. 



Only the beginning of optical crystallog- 

 raphy has been noted above, and no attempt 

 has been made to trace the development of 

 micro-sublimation, or micro-melting-points 

 and the modern fusion microscopj'. 



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