MERCUROUS CHLORIDE BY HAROLD S. KING 121 



to a very large number of ammonia mercury compounds by 

 assuming that they are more or less complex derivatives of the 

 hypothetical HO-Hg-NH^. Ih this system, infusible white 

 precipitate is the chloride of the above base, i. e., Cl-Hg-NH,. 

 This formula has the advantage of fitting into a scheme con- 

 sistent with a large group otherwise difficult to account for. 



Franklin's formula expresses the chemical properties of the 

 compound sufficiently well. For instance it is readily acted 

 upon by hydrochloric acid with the formation of mercuric and 

 ammonium chlorides. Moreover all its nitrogen is liberated 

 as ammonia when treated with potassium hydroxide. Amido- 

 mercuric chloride, as we may now call it, reacts with ammonium 

 chloride to give fusible white precipitate. This substance is 

 generally considered as being HgCl2.2NH3, that is, mercuric 

 chloride with two molecules of ammonia of crystallization. It 

 would be better to represent the two ammonia molecules as 

 sharing their free electron pairs with the mercury to give 



CI 



H3N:Hg:NH3. 



CI 



Here we have an additional octet formed about the mercury as 

 in HgClT^or Hg^HgClj. The reaction is reversible because in 

 the presence of aqua ammonia, fusible white precipitate or 

 dichloro diammine mercury, loses ammonium chloride with the 

 formation of amido-mercuric chloride: 



CI— Hg— NH, + NH,-^ +C1— ;! CL = Hg = (XH,).. 



This reaction therefore supports the view that the mercury in 

 amido-mercuric chloride is not surrounded by an additional 

 octet,' at least not by a stable one. Actually the molecule 

 may be some polymerization product, because the simple formula 

 does not account for the infusibility of the compound. 



It has been suggested that the formation of infusible white 

 precipitate proceeds through the intermediate formation of 

 dichloro diammine mercury 



