368 ELEMENTARY CHEMICAL MICROSCOPY 



8. Add to a drop a little CsCl and KI presence or absence 

 ofPb,Sn,Hg,Ag,Sb,Bi,(Cu). 



9. Add to HC1 solution H 2 PtCl6 presence or absence of K, 

 NH4, Na. 



10. Add zinc-sulphide-fiber, then at once a drop of NELtOH 

 - presence or absence of Pb, Ag, Hg, Cu, Bi, Cd, As, Sb, Sn, 



Ni, Co, Fe, Al, Cr, Mn, Au, and salts insoluble in NELtOH. 



11. Or instead of proceeding as in 10, add HKC 2 O 4 pres- 

 ence or absence of Ca, Sr, Ba, (Mg), Zn, Cd, Sb, Sn, Pb, U, Mn, 

 Fe, Ni, Co, Cu, Ag, (Hg), (Cr). 



12. Test for the acids. 



13. From the solubility tests, optical behavior and above 

 reactions make a list of the elements which are probably absent 

 and proceed to make identity tests for those which can be 

 present. In all tests applied observe carefully the precautions, 

 notes and interferences given in the discussion of the test. 



14. Make special tests for silicates, titanates, etc. 



THE COMMON ACIDS. 



The detection of the acid radicals (anions) by microchemical 

 reactions is much more difficult than the identification of the 

 bases (cations). This is largely due to the relatively high 

 concentrations employed, to rapid evaporation taking place 

 during manipulations and to the fact that through the addition 

 of reagents many complex salts are formed of lower solubilities 

 than those originally existing in either unknown or reagent. 



In the elementary course whose outline is covered by this 

 textbook the identification of the acid radicals in simple salts 

 or simple mixtures alone is undertaken. With materials of this 

 nature the qualitative analysis is comparatively easy and no 

 elaborate directions or schemes of procedure are necessary. 

 Most of the tests for the acids have already been studied and it 

 is merely necessary in most cases to reverse the test for the 

 bases to enable us to properly identify the acids. 



The behavior of the crystals, obtained in a test, toward polar- 

 ized light will be found to be of great value in identifying the 



