CHEMICAL MICROSCOPY 



Numerous studies giving microcrystal 

 tests for various alkaloids and occasionally 

 other compounds can be found in the periodi- 

 cal literature of the last century and this one. 

 In 1932 and 1940 the present writer reviewed 

 the field of "alkaloidal" reagents used for 

 such tests, and began the work of extending 

 them to cover all compounds of basic ni- 

 trogen. 



In spite of the solid body of work on mi- 

 crocrystal tests cited above, and a consider- 

 able total of scattered work, largely on al- 

 kaloids, the general impression of past 

 history, and certainly the present situation, 

 is one of neglect. In most fields, the authors 

 who have contributed to the development of 

 microscopic chemistry are surprisingly out- 

 numbered by those others who do not recog- 

 nize any application of the microscope to 

 that field at all. 



This is most astonishing in toxicology, for 

 here the science of crystal tests began. Hel- 

 wig thought it strange that many toxicolo- 

 gists seemed unaware of the obvious advan- 

 tages of the use of the microscope in their 

 science, but this is still true nearly 100 years 

 later, as published works show. The neglect 

 is at least ec^ually great elsewhere. In most 

 colleges and universities, courses in ciuali- 

 tative analysis or analytical chemistry, 

 whether inorganic or organic, usually do not 

 even mention use of the microscope; if a 

 query about it is made, it is passed off as a 

 "specialty". 



How has this neglect come about? Un- 

 doubtedly one factor is simply that the field 

 underwent some development very early. It 

 has often happened that a subject developed 

 earliest is not developed best, for later re- 

 searchers hesitate to work in a field already 

 partly tilled. 



A most important factor, however, has 

 been the strangely long period through which 

 chemistry has passed, during which only 

 quantitative applications were considered to 

 have any value at all. The microscope is not 

 primarily a quantitative tool; this is one 



limitation on the tests. It has even happened 

 that reagents already well-known and useful 

 as alkaloidal precipitants for microcrystal 

 tests were renamed "Wagner's reagent" and 

 "Mayer's reagent", for example, for alleged 

 quantitative uses almost devoid of value. 



For three-quarters of a century or more 

 it was the use of the microscope in chemistry, 

 in one way or another, either purely obser- 

 vational, or a necessary aid in tests with 

 crystal-producing reagents, that was com- 

 monly known as "microchemistry". Then, 

 this name was appropriated for what is 

 merely chemistry on a small scale, often not 

 even on a "micro" scale at all; this new "mi- 

 crochemistry" had quantitative aspects, and 

 by about the 1920's it was enthusiasically 

 received. Emich himself spoke of the micro- 

 scope as indispensable, and described nu- 

 merous microcrystal tests, largely derived 

 from Behrens, in his "Lehrbuch der Mikro- 

 chemie" (1911), endorsing also the use of 

 optical crystallography; but since then the 

 microscope seems to have been lost in the 

 shuffle. 



The use of microcrystal tests in the or- 

 ganic field never has disappeared among 

 narcotic chemists, law-enforcement chemists 

 in general, drug analysts, and others. At the 

 present time E. G. C. Clarke in England is 

 doing very effective work in extending the 

 coverage of microcrystal tests, once again in 

 toxicology. The flood of new drugs in recent 

 years has vastly increased the demands and 

 difficulties for reliable identification tests. 

 The need of extended development of micro- 

 crystal tests was never greater than it is to- 

 day. 



Charles C. Fulton 



MIXED FUSION ANALYSIS 



Microscopic mixed fusion analysis consists 

 of the microscopical observation of the melt- 

 ing and solidification behavior of mixtures 

 of two or more fusible substances. Two main 

 methods of mixture preparation are em- 



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