634 The Philippine Journal of Science 3923 



When a fragment of potassium iodide is added to the test 

 drop containing the bismuth salt and hmt there is immediately 

 produced an amorphous yellow precipitate which gradually 

 changes into tiny, yellow octahedra. This is an exceedingly 

 delicate test for bismuth. See precautions noted under anti- 

 mony. 



Bismuth may be readily distinguished from tin by adding to 

 a test drop a fragment of cesium chloride and then a fragment 

 of potassium iodide. Bismuth yields orange-red hexagonal 

 plates, while tin yields yellow octahedra. 



Deniges 6 states that the compound of bismuth and hexamethy- 

 lenetetramine has the formula 



3(C e H 12 N 4 .HCl).BiCl 3 



3(C 6 H ]2 N 4 .HI)BiL, 2(C 6 H 12 N 4 .HI)BiI,, or C 6 H J2 N 4 .HI.BiL. 



strong hydrochloric acid hmt forms with solutions of tin 

 octahedra (an amorphous precipitate is obtained in 

 solutions which are neutral or only slightly acidified). The 

 crystals are usually smaller than those formed with bismuth and 

 the test is not so delicate. 



The addition of potassium iodide gives rise to exceedingly 

 tiny yellow octahedra gradually crystallizing from a yellow 

 amorphous precipitate. See precautions under antimony. 



Concentrated hydrochloric acid solutions of cadmium salts give 

 with hmt thin, colorless plates belonging to the hexagonal system. 



If potassium iodide is added to the test drop, highly refractive, 

 square-ended, colorless prisms and hexagonal plates appear 

 (Plate 2, fig. 9) . These crystals belong to the hexagonal system 

 and are very characteristic. See precautions under antimony. 



