860      PREPARATION  OF  NEUTRAL  SULPHATE  OF  ATROPIA. 
Supposing  that  the  chlorine  were  at  once  completely  evolved, 
seventy-eight  parts  of  sulphate  of  iron  would  correspond  with 
twenty  of  available  chlorine.  This,  however,  is  not  the  case, 
because  the  liberated  chlorine  does  not  escape  entirely  from  the 
solution  so  long  as  protosulphate  of  iron  is  present,  but  abstracts 
iron  forming  perchloride. 
(3.)  6  FeO  +  3  CI  =  2  Fe203  +  Fe2Cl3. 
The  smaller  the  quantity  of  chloride  of  lime  that  comes  in  con- 
tact with  the  sulphate  of  iron  in  a  given  time,  the  more  perfect 
is  the  conversion  of  this  liberated  chlorine  into  perchloride  of 
iron,  but  towards  the  end  of  the  experiment  .there  is  always  an 
escape  of  chlorine,  because  the  quantity  of  protoxide  of  iron  is 
then  very  small. 
It  follows,  therefore,  that  although  a  given  quantity  of  chloride 
of  lime  will  oxidize  much  more  protosalt  of  iron  than  is  supposed 
to  be  in  the  equation  (2),  still  it  is  impossible  to  oxidize  four 
equivalents  by  means  of  one  equivalent  of  hypochlorite.  It  is 
obvious  that  the  loss  of  chlorine  which  takes  place  in  this  man- 
ner, varies  according  to  the  circumstances  of  the  experiment. — 
Ibid,  from  Vierteljahresschrift  fur  Prakt.  Pharmacie,  iv.,  555. 
PREPARATION  OF  NEUTRAL  SULPHATE  OF  ATROPIA. 
By  M.  Ch.  Maitre. 
Take  of  crystallized  atropia  10  grammes,  (154-3  grs.,)  dis- 
solve in  it  a  sufficient  quantity  of  perfectly  pure  ether  free  from 
water,  and  of  the  sp.  gr.  66°  Baume.    Then  prepare  a  mixture 
of  pure  sulphuric  acid  and  alcohol  of  40°  Baume  in  the  propor- 
tion of  one  gramme  (15  J  grs.)  of  acid  to  10  grammes  of  alcohol, 
and  throw  the  mixture  drop  by  drop  into  the  solution  of  atropia. 
The  liquid  loses  its  transparency,  becomes  milky  and  deposits  on 
the  sides  of  the  vessel  a  voluminous  precipitate  having  a  viscid 
appearance.    When  this  precipitate  ceases  to  form,  the  super- 
natant ether  is  decanted  and  the  vessel  containing  the  residue 
put  in  the  drying  closet.    The  sulphate  of  atropia  soon  dries 
completely,  and  is  presented  in  the  form  of  a  white  powder,  per- 
fectly neutral,  very  soluble  in  water,  and  precipitates  chloride 
of  barium  abundantly. 
