602  Medicinal  Lithium  Carbonate.        { A^cimbef  hmt 
carbonate  when  titrated  with  normal  sulphuric  acid  and  methyl 
orange  as  indicator. 
The  Arzneibuch  fur  das  Deutsche  Reich,  3d  ed.,  1895,  contains 
almost  the  same  requirements,  but  omits  the  rigid  ammonium  sul- 
phide test. 
The  English  Pharmacopoeia  of  1898  is  somewhat  less  exacting. 
An  examination  of  the  lithium  carbonate  available  in  the  United 
States  shows  that  not  a  single  sample  complies  with  the  U.S. P. 
requirements.  The  results  of  the  eight  samples  examined  are  con- 
tained in  the  table  opposite  : 
Let  us  now  examine  the  U.S.P.  requirements  seriatim.  Lithium 
carbonate  is  a  light,  white  powder,  odorless,  of  an  alkaline  reaction 
and  taste. 
Sample  number  one  differed  materially  from  all  the  others  in 
physical  appearance ;  being  bulkier,  notably  free  from  agglutina- 
tion, and  smooth  and  soft  like  starch.  This  difference  is  probably 
due  to  the  method  of  manufacture.  If  lithium  carbonate  is  pre- 
pared from  lithium  sulphate,  by  the  use  of  potassium  carbonate,  a 
harsh,  sandy  powder  is  the  result;  but  on  dissolving  the  lithium 
carbonate  thus  formed,  in  hydrochloric  acid,  and  then  precipitating 
with  ammonium  carbonate,  a  beautiful  voluminous  product  is  the 
result.    No.  1. 
It  will  be  noticed,  under  microscopical  examination,  that  crystals 
are  frequently  present.  This  point  ought  to  be  noted  in  the  de- 
scription. These  crystals  are  produced  in  several  ways.  On  boiling 
a  solution  saturated  with  carbon  dioxide  gas ;  by  spontaneous  evap- 
oration of  a  similar  or  other  solutions  ;  the  lithium  carbonate  sepa- 
rates as  prismatic  crystals,  or  as  crystalline  crusts. 
Lithium  carbonate  is  soluble  in  80  parts  of  water  at  I5°C,,  and 
in  140  parts  of  boiling  water.  Much  more  soluble  in  water  impreg- 
nated with  carbon  dioxide.  Soluble  in  acids,  with  active  efferves- 
cence.   Insoluble  in  alcohol. 
The  data  on  the  solubility  of  this  chemical  are  greatly  at  vari- 
ance. P.  Kremers5  states  that  100  parts  of  water  at  130  C.  dissolve 
0769  parts,  while  the  same  quantity  at  1020  C.  dissolves  0778  parts 
of  the  salt.  L.  Troast6  says  100  parts  of  hot  or  cold  water  dissolve 
1-2  parts  of  lithium  carbonate.  E.  Schmidt,7  75  parts  of  water  at 
20°  C.  dissolve  1  part  of  the  salt.  C.  N.  Draper,8  100  parts  of 
water  will  dissolve   1-4787  at   150  C,  and  07162  at   I00c  C. 
