Am.  Jour.  Pharm.  \ 
March,  1899.  / 
Lithium  Citrate. 
139 
that  after  .the  samples  had  taken  up  a  certain  amount  of  moisture, 
they  became  brittle  and  non-deliquescent. 
Those  which  possessed  the  highest  per  cent,  of  water  of  crystal- 
lization appeared  to  be  the  most  deliquescent,  after  having  been 
dried  as  above.  That  these  dried  products  possessed  considerable 
avidity  for  water  was  manifested  from  the  rise  of  temperature,  de- 
veloped when  the  dried  articles  were  added  to  water,  or  vice  versa. 
Just  why  the  various  makes  of  lithium  citrate,  dried  side  by  side, 
behaved  so  differently,  when  exposed" to  the  atmosphere  is  difficult 
to  say.    They  were  all  of  the  same  degree  of  fineness. 
The  degree  of  solubility  is  another  factor  that  depends  on  the  kind 
of  salt  considered.  The  anhydrous  salt,  according  to  W.  A.  Puckner,1 
is  soluble  in  2-38  parts  of  water  at  150  C.  The  results  obtained  in 
this  investigation  indicate  that  lithium  citrate  is  somewhat  less  solu- 
ble, on  the  average,  than  this;  or  one  part  of  lithium  citrate  re- 
quires 2-434  parts  of  water  at  150  C.  The  solubility  of  the  hydrous 
article,  based  on  the  results  obtained  for  the  anhydrous,  is  one  in  1-91 
parts  of  water  at  150  C.  This  is  exactly  what  was  obtained  by 
experiment.  The  solubility  as  given  by  the  British  Pharmacopoeia, 
for  this  article,  is  about  correct,  viz.:  that  it  is  entirely  soluble  in 
twice  its  weight  of  cold  water. 
The  anhydrous  lithium  citrate  is  soluble  in  about  one-fourth  its 
weight  of  boiling  water.  This  is  equivalent  to  the  water  of  crystal- 
lization of  the  hydrous  product.  On  taking  the  melting-point  of 
the  salt  containing  four  molecules  of  water  of  crystallization,  in  a 
capillary  tube,  it  became  pasty  at  ioo°  C,  and  at  1 1 5 0  C.  a  perfect 
solution  was  obtained.  The  boiling-point  of  a  saturated  solution  of 
the  anhydrous  article  varied  from  1 1 5 0  C.  to  1 20°  C.  Neither  the 
hydrous  nor  the  anhydrous  salts  are  soluble,  to  any  appreciable  ex- 
tent, in  either  alcohol  or  ether. 
The  aqueous  solutions  were  either  neutral  to  litmus  or  slightly 
acid. 
On  ignition  there  is  left  a  blackish  residue,  consisting  of  a  mix- 
ture of  carbon,  lithium  carbonate  and  the  oxides  of  lithium. 
In  estimating  the  amount  of  water  of  crystallization  some  unex- 
pected results  were  obtained. 
After  drying  some  of  the  products  at  1 1 50  C.  for  eight  hours, 
then  estimating  the  amount  of  pure  lithium  citrate,  it  was  surprising 
1  1892,  The  American  Druggist,  page  65. 
