'^'^'leh^mf^^'}         Mercurammonium  Chlorides.  85 
acid;  the  addition  of  ammonium  hydrate  after  the  separation  of  tlie 
mercurous  trace,  caused  only  a  faint  turbidity,  but  potassium  iodide 
yielded  a  copious  precipitate,  showing  the  presence  of  mercuric  salt 
in  the  acetic  acid  solution,  and  the  solubility  of  ammoniated  mercury 
in  ammonium  acetate  solution.  III.  and  IV.  did  not  dissolve  in  the 
acid,  but  after  boiling  for  a  few  minutes  and  filtering,  the  filtrate  with 
KI  indicated  the  presence  of  mercuric  salt.  The  insoluble  portion 
was  yellow,  and  on  addition  of  hydrochloric  acid  the  greater  part  dis- 
solved, leaving  a  small  quantity  of  a  white  powder  which,  on  addition 
of  potassium  and  ammonium  hydrates,  blackened,  the  tests  for  calomel. 
Mercuric  chloride  boiled  with  acetic  acid  for  a  few  minutes  becomes 
turbid,  and  a  precipitation  of  calomel  occurs,  and  for  this  reason  the 
mercurammonium  chloride  acts  in  the  same  way. 
The  analysis  of  the  specimens  was  first  attempted  by  boiling  with 
KOH,  which  was  supposed  to  liberate  ammonia ;  this  could  be  estimated 
volumetrically,  the  residue  weighed  as  mercuric  oxide,  while  the  filtrate 
contained  the  chlorine  which  could  be  precipitated  by  silver  nitrate 
after  acidification  with  nitric  acid.  III.  and  IV.  failed  to  yield  ammo- 
nia by  heating  witli  potassium  hydrate,  and  as  nitrogen  could  be  detected 
by  other  reagents,  as  potassium  iodide  and  sodium  thiosulphate  libera- 
ting ammonia,  this  scheme  was  supplanted  by  the  following  one,  even 
more  simple : 
1  gm.  of  the  sample  is  mixed  with  20  c.c.  water  and  1  c.c.  hydro- 
chloric acid,  hydrogen  sulphide  is  then  passed  through  the  mixture 
until  this  smells  strongly  of  the  gas,  after  slight  warming  and  allowing 
to  stand  for  half  an  hour.  This  part  can  be  expressed  by  the  reac- 
tions : 
1.  NH^  Hg  Cl-f  H^S^NH^  Cl+HgS. 
•  2.  (NH3  Cl)2  Hg-f-H2S=2         Cl-f  HgS. 
3.  ]SrHg2  ClH-2  H2S=NH4Cl-j-2  HgS. 
The  sulphide  of  mercury  is  transferred  to  a  weighed  filter,  the  fil- 
trate collected  in  a  tared  beaker  and  after  evaporation  on  a  water-bath, 
both  filtrate  and  filter  are  dried  at  100°  C,  and  weighed. 
The  percentages  of  Hg,  HgS  and  NH^  CI  obtainable  from  the  different 
compounds  follow  : 
NH,HgCl     (NH3Cl),Hg    NHg.ClHp  NHg^Cl 
Hg        79.53  65.61  85.56  88.99 
Hgs       92.27  76.09  99.27  103.25 
NH4CI   21.26  35.07  11.44  11.90 
