CHAPTER XIV. 



CHARACTERISTIC MICROCHEMICAL REACTIONS OF THE 

 COMMON ELEMENTS WHEN IN SIMPLE MIXTURES. 



The methods of applying reagents and of performing the neces- 

 sary manipulations arising in qualitative analysis have already 

 been discussed at length in Chapter XIII, as well as the applica- 

 tion of the simple polarizing microscope to the differentiation 

 of chemical compounds in Chapter VIII. 



In the directions which follow it is assumed that the student 

 is thoroughly familiar with these topics. As an aid to the 

 recognition of common salts which may be met with, there has 

 been given under each element the crystal system to which its 

 common salts are to be referred. This has been done in the 

 hope that the student will learn to employ the polarizing micro- 

 scope and come to appreciate its many advantages as an invalu- 

 able aid and great saver of time and labor. In these tabulations 

 the following abbreviations have been used: (I) Isometric; 

 (H) Hexagonal; (T) Tetragonal; (O) Orthorhombic; (M) 

 Monoclinic; (Tr) Triclinic; and the salts arranged in the order 

 named. 



SODIUM. 



Crystal Forms and Optical Properties of Common Salts 

 of Sodium. 1 



A. ISOTROPIC. 



Isometric. — Chlorate. 2 



The alums (double sulphates of Na and Al, Fe, Cr) 



(I); chloride (I); bromide (I); iodide (I); 3 



molybdate (I or O). 



1 In the following tabulations the data given have largely been obtained from 

 Groth's Chemical Crystallography. 



2 NaC10 3 although belonging to the isometric system exhibits circular polari- 

 zation in crystals. Its solution is inactive. 



3 Nal forms hydrates optically active. 



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