352 ELEMENTARY CHEMICAL MICROSCOPY 



EXPERIMENTS. 



a. Test by Method A the following: solutions of As 2 O 3 ; of NaAsO 2 ; of 

 H^AsOaj one drop of commercial E^SO^ one drop of commercial HC1; trying 

 first the AgNO 3 crystal and then the HgBr 2 fiber. 



b. Test the above compounds by Method B. 



c. Test the same compounds with AgNOa; and finally with ZnCl 2 . 



ANTIMONY. 



Crystal Forms and Optical Properties of Common Salts 

 of Antimony. 



A. ISOTROPIC. 



B. ANISOTROPIC. 



Hexagonal. Red tri-iodide; strontium-antimonyl 

 tartrate; lead-antimonyl tartrate. 



Tetragonal. Barium-antimonyl tartrate (T or 0). 



Orthorhombic. Yellow tri-iodide (O or M) ; ba- 

 rium-antimonyl tartrate; potassium-anti- 

 monyl tartrate; sodium-antimony 1 tartrate. 



Monoclinic. Antimonyl chloride. 



Tridinic. 



DETECTION. 



A . By Means of Cesium Chloride. 



Apply reagent by Method /, page 251, to the drop acidi- 

 fied with hydrochloric acid. 



A double chloride of cesium and antimony of the formula 

 2 CsCl SbCls 2^ H 2 separates in hexagons and elongated six- 

 sided plates. Many of the hexagons show a system of straight 

 or curving ribs extending from the center to the angles of the 

 hexagons. 



Bismuth yields rhombs or long plates showing an hexagonal 

 outline, and having a lower solubility than the antimony salt. 



Copper yields a series of double chlorides varying in color from 

 bright yellow to deep red. These salts usually separate in rec- 

 tangular prisms, but the red compound sometimes assumes forms 

 closely resembling the iodo-compounds referred to below. 



Tin causes the immediate precipitation of tiny regular octa- 

 hedra of the formula C^SnCle, a salt of chlorostannic acid. 



