21 
Ammonio-nitrate  of  Silver. 
Am.  Jour.  Pharm. 
Jan.,  1887. 
ultimate  analysis  might  be  just  as  well  left  unattempted.  But  some  of 
the  results  obtained  (notes  by  the  way,  so  to  speak),  affecting  as  they 
do  the  relations  between  two  so  familiar  bodies  as  silver  and  ammonia 
are  I  think  quite  interesting  enough  to  be  noted.  It  is  true  that  I 
have  sometimes  found  after  a  tiresome  search  into  the  literature  of  the 
subject  that  they  had  been  observed  before ;  but  they  were  so  unfa- 
miliar to  myself,  and  are  so  persistently  ignored  by  the  ordinary  text- 
books, that  I  venture  to  think  there  may  be  others  for  whom  also  they 
may  have  interest.  I  propose  to  state  these  results  in  the  form  of 
memoranda  and  as  concisely  as  possible. 
When  ammonia  is  added  to  solution  of  neutral  silver  nitrate,  the 
first  drop  produces  a  precipitate  which  is  brownish-ivhite.  As  more 
ammonia  is  added,  the  precipitate  becomes  darker,  and  just  before  the 
point  of  final  solution  is  reached,  it  is  dark  brown. 
This  precipitate  is  slightly  soluble  in  water. 
The  smallest  addition  of  nitric  acid  to  a  neutral  solution  of  silver 
nitrate  completely  prevents  its  precipitation  by  ammonia. 
The  first  addition  of  ammonia  to  a  solution  of  silver  nitrate  renders 
it  alkaline  to  turmeric  paper  and  phenol phthalein,  but  the  solution 
does  not  smell  of  ammonia. 
Silver  oxide,  freshly  precipitated  by  KHO  and  thoroughly  washed, 
strongly  browns  turmeric  paper. 
Freshly  precipitated  silver  oxide  is  readily  soluble  in  a  neutral  solu- 
tion of  ammonium  nitrate  and  the  solution  is  strongly  alkaline  to  tur- 
meric paper. 
In  the  following  experiments  a  solution  of  ammonia  was  used  of 
which  10  cc.  required  for  neutralization  16*37  cc.  of  standard  solu- 
tion of  oxalic  acid.  100  cc.  therefore  contained  27  grammes 
NH3. 
To  the  solution  of  8*5  grammes  silver  nitrate  in  70  cc.  water  the 
standard  ammonia  solution  was  added  from  a  burette  until  the  precip- 
itate at  first  formed  was  redissolved. 
The  quantity  of  ammonia  solution  required  Was  6.  6  cc.  (theory  re- 
quires 6 '3  cc). 
Ten  test  tubes,  each  containing  the  solution  of  1*7  grammes  silver 
nitrate  in  17  cc.  of  water  (the  solution  having  been  made  neutral  by 
digestion  with  precipitated  silver),  were  arranged  in  series.  To  tube 
10  was  added  just  so  much  of  the  standard  ammonia  as  was  necessary 
to  redissolve  the  precipitate  at  first  formed.    This  quantity  was  1*3 
