316 
Lithice  Citras. 
f  Am.  Jour.  Pharni. 
X     June,  1883. 
be  accei)tecl  as  correct,  then  100  parts  of  carbonate  of  lithium  will  be 
required  to  neutl'alize  189*2  parts  of  citric  acid,  the  product  of  anhy- 
drous lithium  citrate  being  identical  with  the  amount  of  citric  acid 
originally  employed  in  the  operation.  But  as  the  best  commercial 
<jarbonate  of  lithium  does  not  contain  more  than  98*5  per  cent  of  real 
carbonate,  the  proportion  will  be  100  parts  of  carbonate  to  186*5  parts 
of  citric  acid.^ 
Lithium  citrate,  according  to  Mr.  Umney,  when  prepared  from 
these  proportions  and  dried  until  anhydrous,  is  neutral  to  test  paper. 
According  to  the  1864  Pharmacopoeia,  lithium  citrate  is  a  white, 
-amor])hous  powder,  deliquescent,  and  soluble  in  water  without  leaving 
any  residue.  Heated  to  redness,  it  blackens,  evolving  inflammable 
gases,  and  the  residue,  neutralized  by  hydrochloric  acid,  yields  with 
rectified  spirit  a  solution  wliich  burns  with  a  crimson  flame.  Twenty 
grains  of  the  salt  burned  at  a  low  red  heat,  with  free  access  of  air, 
leave  10*6  grains  of  white  residue. 
The  U.  S.  P.  of  1870  gives  the  following  characters  and  tests  by 
which  this  salt  may  be  recognized  ; — 
^'A  wh  ite  j)0wder,  deliquescent  and  soluble  in  25  parts  of  water ; 
upon  ignition  it  leav^es  a  residue  which  if  dissolved  in  dilute  muriatic 
acid  gives  a  solution,  which  burns  with  a  crimson  flame,  showing  the 
presence  of  lithium.  The  citric  acid  is  indicated  by  the  solution  be- 
coming turbid  when  heated  with  lime-water  and  clear  again  on  cool- 
ing. Twenty  grains  of  this  salt  burned  at  a  low  red  heat,  with  free 
access  of  air,  should  leave  lOj^^j-  grains  of  white  residue."  The  revised 
edition,  before  alluded  to,  gives  a  much  fuller  account  of  the  characters 
and  tests. 
"A  white  powder,  deliquescent  on  exposure  to  air,  odorless,  having  a 
slight  cooling,  faintly  alkaline  taste,  and  of  a  neutral  reaction,  soluble 
in  5*5  parts  of  water  at  15°  C.  and  in  2*5  parts  boiling  water;  only 
slightly  soluble  in  alcohol.  When  exposed  to  a  red  heat,  the  salt 
chars,  emits  inflammable  vapors,  and  finally  leaves  a  black  residue 
having  an  alkaline  reaction,  which  imparts  a  crimson  color  to  a  non- 
luminous  flame.  The  aqueous  solution  of  the  salt  mixed  with  test 
solution  of  calcium  chloride  deposits  a  white  precipitate  on  boiling. 
On   dissolving  the  residue  left  on  ignition  in  diluted  hydrochloric 
^  In  some  formulse  for  new  medicaments  adoped  by  the  Paris  Pharmaceu- 
tical Society,  it  is  recommended  to  use  100  parts  of  carbonate  of  lithium  to 
186  parts  citric  acid. — iPharm.  Journ.,  July  21,  1877). 
