248 ELEMENTARY CHEMICAL MICROSCOPY 



Table VI. 



REFRACTIVE INDICES AND CHARACTER OF DOUBLE 

 REFRACTION OF TYPICAL CRYSTALS. 



Name. 



Ammonium nickel sulphate 



Ammonium oxalate 



Ammonium persulphate 



Barium chloride 



Copper sulphate 



Magnesium sulphate 



Mercuric chloride 



Mercuric cyanide 



Potassium antimonyl tartrate . . 



Potassium arsenate 



Potassium bichromate 



Potassium nickel sulphate 



Potassium nitrate 



Potassium persulphate 



Potassium sulphate 



Silver nitrate 



Sodium borate (tetra) 



Sodium nitrate 



Sodium phosphate (tertiary) 



Sodium phosphate (secondary) . 



Sodium thiosulphate 



Strontium antimonyl tartrate.. 



Sucrose 



Tartaric acid 



Urea 



Zinc sulphate 



Formula. 



(NH 4 ) 2 Ni (SO,), • 6 H 3 



(NH 4 ) 2 C 2 4 -H 2 



(NH^jSjO, 



BaCl 2 • 2 H 2 



CuS0 4 • 5 H 2 



MgS0 4 • 7 H 2 



HgCl 2 



Hg (CN), 



K (SbO)C 4 H 4 6 -H 2 



H 2 KAs0 4 



K 2 Cr 2 7 



K-.NKSOJj-eHjO 



KNO3 



K 2 S 2 Oj 



K 2 S0 4 



AgN0 3 



Na 2 B 4 7 • 10 H 2 



NaNO, 



Na 3 P0 4 • 12 H 2 



HNa 2 P0 4 -i2H 2 



Na 2 S,0 3 • S HoO 



Sr (SbO) 2 (C 4 H 4 O a ) 2 



Ci 2 H 22 O u 



H 2 C 4 H 4 0j 



CO(NH 2 ) 2 



ZnS0 4 • 7 H,0 



Double 



refrac- 

 tion. 



+ 



+ 

 + 



+ 



+ 



+ 

 + 

 + 



+ 

 + 



+ 

 + 



1 Values for n have been taken from Groth's tables and checked in the laboratory. For uni- 

 axial crystals the first column is u and the second e. For biaxial crystals the first column is a, 

 the second fi and the third y. 



REFERENCES. 



Tables of refractive indices in the following articles will be found by the analyst 

 of great value in the identification of compounds by means of the immersion 

 method. 

 Schroeder van der Kolk — Tabellen zur mikroskopischen Bestimmung der 



Mineralien nach ihren Brechnungsindex, Zeit. anal. Chem., 38 (1899), 615. 

 Kley — Ein Beitrag zur Analyse der Alkaloide, Zeit. anal. Chem., 43 (1904), 160. 

 Bolland — Die Brechnungs indices der weinsauren Alkaloide nach Einbettungs- 



methode. Monats., 29 (1908), 991. Die Brechnungsindices krystallinischer- 



chemischer Individuen nach der Einbettungsmethode von Standpunkte der ana- 



lytischen Praxis. Monats., 31 (1910), 387. 

 Fry — Microscopic Identification of Inorganic Salts. Bui. 110S, U. S. Depart. 



Agric. 1922. 

 Larsen — Microscopic Determination of Nonopaque Minerals. Bui. 679, U. S. 



Geolog. Surv. 1921. 

 Behrens-Kley — Mikrochemische Analyse. 3 Auf. Voss, Leipzig. 1915. 



