22 ' 6 Cole: Hexamethylenetetramine 537 



In concentrated solution they are usually feathery, appearing 

 black by transmitted light and white by reflected light. In 

 hydrochloric acid solution there are formed colorless plates and 

 needles. 



When free hydrochloric acid is absent the compound J1 has 

 the formula C 6 H 12 N 4 .2HgCl 2 -f H 2 0. When hydrochloric acid is 

 present the compound formed is C 6 H 12 N 4 .HC1.2HgCL + H 2 0. 



Sensitivity with hmt, 1 : 200. 



Silver salts in nitric acid solution form with hmt colorless 

 needles or plates belonging to the monoclinic system. The plates 

 usually appear only when the preparation is scratched. They 

 often show high polarization colors (Plate 2, fig. 7). 



Palladium may interfere with the test for silver. 



SUMMARY 



Hexamethylenetetramine can be used as a reagent in micros- 

 copic qualitative chemical analysis for the identification of salts 

 of antimony, bismuth, tin, cadmium, gold, iridium, platinum, pal- 

 ladium, mercury, and silver. It can also be used as a group 

 test for calcium, magnesium, iron, and manganese. The crys- 

 tal forms and the best method of applying the test have been 

 described. The sensitivities of the various tests have been 

 determined. 



