386      DECOMPOSITION  OF  QUINIA  SALTS  BY  THE  ACETATES. 
acid ;  and  after  dissolving  some  in  muriatic  acid,  I  received,  to 
my  surprise,  a  considerable  precipitate  of  sulphate  of  baryta ; 
its  quantity  precluded  the  supposition  of  an  accidental  admixture 
of  sulphate  of  ammonia  or  magnesia  from  careless  washing  of 
the  crystals;  moreover,  they  burned  on  platina  foil  without 
leaving  any  stain,  and  caustic  potassa  evolved  no  ammonia  from 
their  solution,  and  thus  the  absence  of  magnesia  and  ammonia 
was  established.  Their  solution  in  sulphuric  acid  was  precipi- 
tated by  ammonia,  the  quinia  filtered  off,  the  filtrate  neutralized 
by  sulphuric  acid  and  mixed  with  nitrate  of  silver ;  the  forma- 
tion of  a  crystalline  precipitate  was  the  result,  dissolving  in 
boiling  water,  but  reappearing  on  cooling,  and  soluble  in  nitric 
acid ;  it  was  acetate  of  silver,  and  my  specimen,  therefore,  is  a 
mixture  of  sulphate  and  acetate  of  quinia. 
To  clear  up  this  seeming  mystery  I  undertook  a  series  of  ex- 
periments, of  which  I  here  give  the  results,  remarking  that 
sulphuric  and  acetic  acids  were  sought  for  in  the  above  indicated 
way  :  hydrochloric  acid  by  its  reaction  with  nitrate  of  silver,  and 
the  metallic  oxides  by  burning  the  substance  upon  platina  foil. 
If  the  solutions  of  sulphate  of  quinia  and  acetate  of  an  alkali 
are  so  diluted  that  a  precipitate  does  not  appear  until  after  a 
quarter  or  half  an  hour,  the  separated  and  washed  prismatic 
needles  are  pure  acetate  of  quinia. 
If  the  solutions  are  sufficiently  strong  to  form  a  precipitate 
within  a  few  seconds,  it  is  a  mixture  of  sulphate  and  acetate  of 
quinia,  if  the  solutions  had  not  been  well  mixed  or  stirred  before 
the  appearance  of  the  precipitate.  In  this  case,  doubtless,  the 
alkaline  acetate  is  decomposed  by  one  equivalent  of  sulphuric 
acid  of  the  dissolved  bisulphate  of  quinia,  whose  nearly  insoluble 
monosulphate  crystallizes  before  another  portion  of  the  acetate 
has  had  time  to  act  upon  it,  because  the  thus  liberated  acetic 
acid  is  unable  to  hold  an  equivalent  quantity  of  this  sulphate  in 
solution  ;  while  another  portion  of  the  quinia  salt  comes  in  suf- 
ficiently close  contact  with  the  acetate  to  be  decomposed  by  it. 
This  view  of  the  reaction  acquires  certainty  from  the  circum- 
stance that  if  a  mixture  of  the  two  solutions  is  well  stirred 
before  and  during  the  formation  of  the  crystalline  precipitate,  it 
will  contain  but  traces  of  sulphuric  acid,  and  if  the  mixed  ace- 
tate and  sulphate  of  quinia  be  dissolved  in  the  mother-liquor 
