CHAPTER XIII. 



THE METHODS OF MICROCHEMICAL QUALITATIVE 

 ANALYSIS. 



In order that success may follow our efforts in the application 

 of tests resulting in the production of characteristic microscopic 

 crystals, it is essential that reagents be always applied in the best 

 possible manner and in concentrations and under conditions such 

 as will lead to the separation of a solid crystalline phase in a very 

 short period of time. It is. therefore necessary that we first 

 ascertain the best method of procedure for each particular re- 

 agent. Most of the failures to obtain satisfactory results when 

 attempting microchemical reactions are due to a lack of apprecia- 

 tion of the importance of this fact. Manuals of microchemical 

 analysis usually neglect to state definitely the best manner of 

 adding a reagent to a drop to be tested, assuming that the in- 

 vestigator will ascertain for himself the conditions which will 

 yield him products most easily identified. 



Under similar conditions as to concentration, acidity and 

 manner of reagent application, the crystalline phase will not only 

 almost invariably separate with the same habit, but the crystals 

 will usually develop to the same size and will lie upon the object 

 slide in each experiment in the same positions with respect to 

 faces. 



The following methods for performing microchemical reactions 

 involve different manipulations and can be considered as typical 

 procedures, each applicable to the detection of a number of dif- 

 ferent elements or compounds. The student should perform 

 them until he is sufficiently proficient to invariably obtain an 

 unequivocal test and one yielding each time similar crystals of a 

 similar size. The more insoluble the compound, the more 

 rapidly the crystals will separate and the smaller they will be. 



For convenience for future reference these methods are here 

 numbered and described in detail. 



250 



