320 
Lithice  Citras. 
j  Am.  Jonr.  Phann, 
t      June,  1883. 
sii^,  sodium,  and  of  the  lithium  present  in  the  samples.  There  are 
four  processes  for  this,  all  starting  with  the  salts  as  chlorides  ;  there- 
fore a  weighed  quantity  of  the  citrate  is  to  be  taken,  incinerated  in  a 
platinum  crucible,  and  the  greyish-white  mass  dissolved  up  in  as  small 
a  quantity  as  possible  of  dilute  hydrochloric  acid,  and  then  having  the 
salts  present  as  chlorides,  either  one  of  the  following  four  processes 
may  be  proceeded  with. 
1.  Kobell  separates  the  potassium  by  precipitation  as  plat i no-potas- 
sium chloride,  and  separates  the  sodium  and  lithium  by  heating  the 
mixed  chlorides  to  incipient  fusion  in  a  platinum  crucible  (care  must 
be  taken  not  to  raise  the  temperature  too  high,  or  else  some  of  the 
sodium  chloride  will  be  volatilized),  then  weighs  the  residue;  he  leaves 
it  exposed  for  twenty-four  hours  to  an  atmosphere  not  moist  enough 
to  attack  the  sodium  chloride,  till  the  lithium  chloride,  which  is  very 
deliquescent,  has  absorbed  water,  drenches  the  partly  deliquesced  mass 
with  alcohol,  decants  carefully,  repeats  the  washing  and  decantatiou  a 
second  time  and  weighs  the  residual  sodium  chloride. 
According  to  the  author  this  process  gives  exact  results. 
2.  Mayer^s  process,  as  given  by  Fresenius.  Add  to  the  solution  (of 
the  chlorides  before  mentioned)  a  sufficient  quantity  of  sodium  phos- 
phate (which  must  be  perfectly  free  from  phosphates  of  the  alkaline 
earths — this  is  very  important),  and  enough  soda,  either  carbonate  or 
hydrate,  to  keep  the  solution  alkaline;  evaporate  the  mixture  to  dry- 
ness, pour  water  over  the  residue,  in  a  sufficient  quantity  to  dissolve 
the  soluble  salts  by  the  aid  of  a  gentle  heat.  Add  an  equal  volume  of 
a  solution  of  ammonia,  digest  at  a  gentle  heat,  filter  after  standing  for 
twelve  hours,  and  wash  the  precipitate  Avith  a  mixture  of  equal  volumes 
of  water  and  ammonia.  Evaporate  filtrate  and  first  and  second  washing 
to  dryness,  and  treat  the  residue  the  same  way  as  before.  If  any  phos- 
phate is  obtained  add  it  to  that  previously  obtained.  The  phosphate 
is  then  dried  and  weighed. 
The  formula  of  the  phosphate  is  LisPO^.  Rammelsberg  asserted 
that  a  variable  quantity  of  lithium  sodium  phosphate  was  formed. 
Fresenius,  however,  confirmed  Mayer's  work,  and  showed  that  no 
double  phosphate  was  formed. 
According  to  Mayer  this  process  gives  99'61  for  every  one  hundred  of 
lithium,  and  Fresenius  obtained  99*8  per  cent.  The  phosphate  is  not 
a  very  soluble  body,  1  part  dissolving  in  2,539  parts  of  pure,  and  3,920 
