152 ELEMENTS OF APPLIED MICROSCOPY. 



group, unaffected by acetic acid but volatilized by. sul- 

 phuric acid, includes nitrates, acetates, chlorates, chlo- 

 rides, bromides, iodides, cyanoferrates, cyaniferrates, and 

 borates. The third group of non-volatile acids com- 

 prises the sulphates, phosphates, arsenates, and arsenites 

 (colorless solutions), the permanganates, bichromates, 

 and chromates (colored solutions), and the silicates, 

 molybdates, and tungstates (precipitates). 



In each case' specific confirmatory tests are made 

 for each of the acids indicated. In the two first groups 

 the volatilization is repeated twice, once with silver 

 nitrate and once with lead acetate on the upper watch- 

 glass. Nitrates yield negative results with the first and 

 octahedral crystals of lead nitrate with the second. Ace- 

 tates show the long white prisms with rhombic ends 

 characteristic of silver acetate, and. no reaction with 

 the second reagent. Chlorides are characterized by 

 thick rhombic prisms of lead chloride and minute cubical 

 crystals of silver chloride. In each case comparison 

 with known substances makes it possible to identify the 

 compound present without serious difficulty. 



REFERENCES. 



Behrens, H. a Manual of Microchemical Analysis. Trans, 

 by J. W. JuDD. London, 1894. 



CoHN, A. O. Tests and Reagents, Chemical and Microscopical. 

 New York, 1903. 



Hanausek, T. F. Lehrbuch der technischen Mikroskopie. 

 Stuttgart, 1 90 1. 



HiNRicHS, C. G. Microchemical Analysis. St. Louis, 1904. 



Lehmann, O. Die Krystallanalyse. Leipsic, 1891. 



WoRMLEY, T. G. The Microchemistry of Poisons. Phila- 

 delphia, 1885. 



