604 
Medicinal  Lithium  Carbonate, 
f  Am.  Jour.  Pharm. 
X   December,  1898. 
J.  Bewad,9  100  of  water  at  200  C.  dissolve  i'^2g,  and  the  same 
amount  of  water  dissolves  0*796  parts  or  0*955,  according  as  the 
solution  is  boiled  one-fourth  or  one-half  hour.  F.  A.  Fliickiger,1 
and  H.  Selzer11  confirm  Bewad's  results.  By  long  spontaneous 
evaporation  a  solution  can  be  obtained  which  contains  2  per  cent,  of 
lithium  carbonate. 
The  results  recorded  in  the  above  table  on  solubility  were 
obtained  by  the  digestion  method.  In  every  case  there  was 
present  a  small  amount  of  insoluble  residue  even  with  100  parts 
of  water.  The  impurity  also  manifested  itself  on  dissolving  the 
chemical  in  dilute  acetic  acid  or  other  acids.  This  is,  without  doubt, 
an  accidental  or  incidental  mechanical  impurity,  and  should  be  taken 
into  consideration  when  prescribing  limitations. 
One  gramme  of  lithium  carbonate  required  from  136  to  140  parts 
of  boiling  water  for  complete  solution.  The  samples  in  each  case 
were  finely  powdered,  so  that  all  lumpiness  was  eliminated. 
The  statement  that  the  salt  is  soluble  in  dilute  acids  is  somewhat 
sweeping.  It  might  be  well  to  state  that  lithium  phosphate  is 
somewhat  insoluble  and  considerable  excess  of  the  phosphoric  acid 
may  be  needed. 
On  cooling  fused  lithium  carbonate,  a  crystalline  mass  results, 
which  disintegrates  into  pearly  particles.  When  the  salt  is  heated 
to  a  high  temperature,  in  the  presence  of  air,  the  greater  part  of  the 
carbonate  is  converted  into  the  super  oxide  and  the  platinum  cru- 
cible (if  used)  is  attacked. 
A  glance  at  the  columns  headed  Impurities  and  Remarks,  of  the 
preceding  table,  will  render  comments  in  this  connection  unneces- 
sary. 
The  operation  given  in  the  Pharmacopoeia  for  detecting  excessive 
amounts  of  other  alkalies,  based  on  the  solubility  of  a  given  amount 
of  lithium  chloride  in  absolute  alcohol  and  ether,  is  rather  imprac- 
ticable. Absolute  alcohol  is  very  hygroscopic  and  lithium  chloride  is 
extremely  deliquescent,  making  a  combination  that  requires  skill 
and  apparatus  to  manage,  so  as  to  secure  reliable  results.  The 
writer  is  of  the  opinion  that  this  requirement  could  easily  be  dis- 
pensed with,  without  materially  affecting  the  standard  for  this 
chemical.  The  solubilities,  the  flame  test  and  the  sodium  cobaltic 
nitrite  practically  eliminate  other  alkalies.  The  test  might  be 
retained  for  information. 
