600  Medicinal  Lithium  Carbonate.  {ADeimbe^bi89™' 
MEDICINAL  LITHIUM  CARBONATE. 
By  Lyman  F.  Kkbler. 
Research  Committee  E,  Pharmacopoeia  Revision. 
Before  considering  the  properties  of  lithium  carbonate  it  might 
be  well  to  briefly  review  its  sources  and  methods  of  manufacture. 
Lithium,  although  widely  diffused  in  small  quantities,  is  found  availa- 
ble for  economical  extraction  in  only  a  lew  localities.  The  minerals 
containing  it  most  abundantly  are  the  bisilicates  of  petaiite  and 
spodnmene,  the  unisilicate  lepidolite  and  the  phosphates  o\  triphilite, 
amblygonite  and  lithiophilite. 
Lepidolite  is  (or  probably  better,  has  been)  the  source  of  much 
lithium  carbonate,  which  is  extracted  by  E.  Schering's1  process  as 
follows  :  The  finely-ground  lepidolite  is  mixed  with  warm  sulphuric 
acid  to  the  consistence  of  a  thin  paste,  which  is  then  heated  and 
stirred  until  agglomeration  results.  The  resulting  lumps  are  then 
calcined  in  a  reverberatory  furnace,  cooled,  and  while  yet  warm  are 
lixiviated  with  water.  From  this  solution  most  of  the  aluminum  is 
removed  as  potassium  alum  and  the  bases  are  farther  removed  by 
means  of  milk  of  lime.  The  remaining  bases  are  converted  into  chlor- 
ides by  precipitation  with  a  solution  ol  barium  chloride,  and  the  clear 
solution  evaporated  to  dryness.  The  dry  residue  is  next  digested 
with  absolute  alcohol,  which  removes  lithium  and  calcium  chlorides. 
The  alcohol  is  distilled  off,  the  residue  taken  up  with  water  and  the 
calcium  removed  as  an  oxalate.  The  small  amount  of  foreign 
metals  still  present  is  removed  by  treating  the  filtrate  with  am- 
monia and  ammonium  sulphide.  The  filtrate  is  now  evapo- 
rated to  dryness,  the  pure  lithium  chloride  taken  up  with  a  suitable 
quantity  of  water  and  converted  into  the  carbonate  by  adding  the 
proper  quantity  of  a  concentrated  solution  of  ammonium  carbonate. 
The  lithium  carbonate  is  finally  collected,  washed  with  60  per  cent, 
alcohol  and  dried. 
A.  Schrotter's2  method,  for  similar  minerals,  is  probably  the  best 
commercially,  but  does  not  give  as  pure  an  article.  By  this  method 
the  minerals  are  fused  at  a  red  heat  and  while  molten  are  ladled 
out  into  water.  When  cold,  the  mass  is  powdered,  mixed  with  a 
suitable  quantity  of  water  and  treated  with  hydrochloric  acid  (sp. 
gr.  1-2).  After  standing  twenty-four  hours  the  whole  is  heated  to 
nearly  boiling,  and  in  a  few  hours  most  of  the  silica  will  be  separ- 
ated.   The  iron  is  then  oxidized  with  a  little  nitric  acid  and  most  of 
