400  EXAMINATION  OP  THE  SULPHATE  OP  QUINIA. 
Experiment  No*  4. 
From  the  impure  effloresced  sulphate  used  in  No.  3,  two  por- 
tions of  5  grams,  each  were  weighed  off,  and  marked  A  and  B. 
Portion  A  was  placed  in  a  beaker,  and  200  gram.,  or  about  7 
f.g.  of  distilled  water,  acidulated  with  14  drops  of  concentrated 
sulphuric  acid,  was  poured  upon  it,  and  the  whole  stirred  till  solu- 
tion was  effected. 
To  a  similar  quantity  of  water  in  another  beaker,  double  the 
quantity  of  sulphuric  acid  was  added,  and  this  dilute  acid  was 
then  carefully  saturated  from  a  measured  quantity  of  solution  of 
soda,  s.  p.  1-063,  and  the  quantity  thus  used  was  noted  as  5  f.j. 
From  the  same  solution  of  soda  5j  f.^.  was  then  measured  off 
and  thrown  at  once  into  the  quinia  solution,  and  the  whole  actively 
stirred  for  five  minutes.  The  beaker  was  then  covered,  and  al- 
lowed to  stand  five  hours.  This  standing  is  very  necessary,  for 
during  this  time  the  precipitate  slowly  contracts,  and  forces  out 
minute  quantities  of  undecomposed  sulphate,  which  otherwise 
would  render  the  filtered  mother  liquor  milky  after,  or  during  its 
separation  from  the  precipitate.  The  precipitate  also  becomes 
granular,  and  much  more  easily  managed  without  loss. 
The  supernatant  liquor  was  then  passed  through  a  dried  and 
weighed  filter  of  Swedish  paper,  and  then  the  precipitate  was 
thrown  into  the  filter  and  washed  till  the  washings  gave  no  re- 
action with  solution  of  chloride  of  barium.  The  drained  pre- 
cipitate was  then  carefully  transferred  to  a  weighed  capsule,  and 
the  filter  returned  to  the  funnel  for  farther  use. 
The  7  f.E  of  mother  liquor,  and  2f.§  of  washings,  were  then 
evaporated  together  to  about  3  f.3,  and  the  whole  residue  col- 
lected -upon  the  filter  and  washed  with  distilled  water  till  the 
residuary  liquor  amounted  to  about  7  f.3.  The  amount  of  colored 
precipitate  thus  obtained,  when  dried  and  fused,  was  -1252  gram, 
or  about  3-07  per* cent,  of  the  whole.  The  residuary  liquor  was 
very  slightly  bitter,  and  probably  contained  an  inappreciable 
portion  of  the  precipitate.  The  residue  from  the  washings  in  a 
weighed  watch  glass,  and  the  precipitate  in  the  capsule  were 
placed  in  an  air  bath  and  heated  till  they  fused  completely, 
when  they  were  transferred  to  the  bell  glass  over  sulphuric  acid. 
The  filter  was  then  dried  precisely  as  before  being  used,  and  also 
