Am.  .Tour.  Pharm. 
Oct.,  1889. 
Mer 'dur 'ammonium  Chlorides. 
519 
Tables  are  given  in  the  original  showing  the  solubility  as  deter- 
mined by  digestion  with  boiling  water  for  five  hours,  of  various  glasses 
commonly  found  in  commerce,  and  the  chemical  composition  of  the 
same  glasses. 
MERCUR  AMMCXNT UM  CHLORIDES.1 
By  G.  Andre. 
The  solutions  employed  contained  33*875  grams  of  mercuric  chloride 
and  4.25  grams  of  ammonia  respectively  per  litre,  and  the  compounds 
were  obtained  by  precipitation  in  the  cold. 
When  equal  volumes  of  the  two  solutions  are  mixed,  and  the  pre- 
cipitate is  collected  after  several  hours  or  days,  washed  with  a  small 
quantity  of  water,  and  dried  at  110°,  it  has  not  exactly  the  composi- 
tion of  mercurammonium  chloride,  NH2HgCl. .  This  result  is  due  to 
the  decomposing  action  of  the  water,  which  at  once  becomes  evident  in 
dilute  solutions,  and  which,  as  Kane  has  shown,  results  ultimately  in 
the  formation  of  Millon\s  dimercurammonium  chloride,  NH^Hg'O- 
HgCl.  If,  however,  mercuric  chloride  is  added  to  an  excess  of 
ammonia  and  the  precipitate  is  washed  rapidly  with  a  small  quantity 
of  water,  the  compound  NH2HgCl  is  obtained  in  a  pure  condition. 
The  presence  of  Millon's  compound  in  the  precipitates  formed  in  dilute 
solutions  is  readily  detected  by  the  fact  that  after  these  precipitates 
have  been  dried  at  110°,  they  evolve  water,  if  heated  at  a  higher  tem- 
perature. 
With  solutions  of  the  strengths  given  above,  the  precipitate  after 
one  hour  contained  0T1  mol.,  after  12  days  0.25  mol.  of  Millon's 
compound  for  each  molecule  of  mercurammonium  chloride.  With 
6  mols.  of  ammonia  to  each  molecule  of  mercuric  chloride,  de- 
composition  proceeds  further,  and  the  precipitate  contains  the  two 
compounds  in  equal  molecular  proportions.  With  an  increasing 
amount  of  ammonia,  the  precipitate  eventually  consists  solely  of 
the  compound  NH^Hg'O'HgCl.  Variations  in  the  proportion  of 
mercuric  chloride  have  no  influence  on  the  composition  of  the  precipi- 
tate. 
If  the  two  solutions  are  mixed  in  equal  proportions,  allowed  to 
remain  24  hours,  the  liquid  decanted  off,  the  precipitate  treated  with 
xCompt.  rend.,  cviii,  233,  290,  1108  and  1164  ;  reprinted  from  Jour.  Chem.  Soc,  ' 
June,  1889,  p.  570,  and  Sept.,  p.  827. 
