ADecimbef.hi898m'}        Medicinal  Lithium  Carbonate.  601 
the  bases,  except  alkalies,  precipitated  by  carefully  adding  a  solution 
of  sodium  carbonate  to  the  boiling,  moderately  dilute  liquid.  The 
precipitate  is  removed  by  filtration  or  otherwise,  and  the  filtrate 
concentrated  to  remove  a  small  amount  of  foreign  carbonates  still 
present.  The  lithium  chloride  solution  is  finally  concentrated,  the 
lithium  carbonate  precipitated  by  means  of  a  solution  of  sodium 
carbonate,  collected,  washed  and  dried. 
M.  H.  Mlillei3  devised  a  method  for  working  the  phosphates, 
some  years  ago,  and  the  same  process  is,  probably,  in  use  at  pres- 
ent. The  powdered  mineral  is  treated  with  hydrochloric  acid,  the 
iron  oxidized  by  means  of  nitric  acid,  the  phosphoric  acid  precipi- 
tated with  a  ferric  salt,  the  mixture  evaporated  to  dryness  and 
the  residue  extracted  with  water.  The  resulting  solution  con- 
tains the  alkaline  chlorides,  manganous  chloride  and  some  iron 
chloride.  The  manganese,  etc.,  are  removed  with  barium  sulphide. 
The  excess  of  barium  is  removed  with  sulphuric  acid  and  filtration. 
The  lithium  carbonate  is  precipitated  from  the  filtrate  by  means  of 
sodium  carbonate  or  carbon  dioxide  gas.  For  other  useful  litera- 
ture on  the  manufacture  of  lithium  carbonate  see  reference  at  end 
of  this  article.4 
From  the  above  information  we  can  readily  judge  what  impurities 
are  likely  to  be  met  with  in  lithium  carbonate,  viz.:  traces  of  the 
powdered  mineral  itself,  any  of  the  bases  associated  with  the  lithium 
and  impurities  introduced  through  the  solvents  or  precipitants. 
The  1890  U.S.P.  describes  lithium  carbonate  as  a  light,  white 
powder,  odorless,  of  an  alkaline  taste  and  reaction,  and  permanent 
in  the  air.  It  is  soluble  in  80  parts  of  water  at  15 0  C.  and  140 
parts  of  boiling  water,  much  more  soluble  in  water  impregnated 
with  carbon  dioxide  gas,  soluble  in  acids  with  active  effervescence, 
insoluble  in  alcohol,  fuses  at  a  low  red  heat,  and  at  a  higher  tem- 
perature is  partially  converted  into  the  oxide,  with  evolution  of 
carbon  dioxide  gas.  One  gramme  treated  with  40  c.c.  of  dilute  acetic 
acid  should  produce  a  clear  solution,  separate  portions  of  which 
should  not  be  affected  with  solutions  of  silver  nitrate,  hydrogen  sul- 
phide, barium  chloride,  ammonium  oxalate,  ammonium  sulphide  or 
sodium  cobaltic  nitrite.  The  dried  chloride  from  one  half  gramme  of 
lithium  carbonate  should  be  completely  soluble  in  3  c.c.  of  absolute 
alcohol,  and  the  addition  of  3  c.c.  of  ether  should  not  produce  a 
turbidity.    The  salt  should  contain  98  98  per  cent,  of  pure  lithium 
