Am  Jour  Pharm.|  LUMcE  CitvaS.  321 
June,  1883.  J 
parts  of  nminoniated  water.  This  is  the  best  and  surest  method  of 
estimating  the  lithium. 
Another  process  is  to  separate  the  potassium  as  platino-potassium 
chloride,  then  shake  the  mixed  chlorides  of  sodium  aud  lithium,  dried 
at  120°  C,  with  a  mixture  of  ether  and  absolute  alcohol  for  twenty- 
four  hours,  until  the  salts  are  disintegrated,  decant  on  to  filter,  and 
treat  the  residue  again  with  several  smaller  portions  of  alcohol  and  ether. 
It  is  best,  in  order  to  be  as  accurate  as  possible,  to  distil  off  the  alcohol  and 
ether  and  again  treat  the  impure  lithium  salt  with  alcohol  and  ether,  a 
drop  of  hydrochloric  acid  being  added.  This  method  is  not  a  very 
reliable  one,  however. 
Bunsen,  seeing  the  difficulty  of  separating  the  lithium  and  sodium 
by  the  alcohol  treatment,  devised  an  indirect  method  of  determining 
the  potassium,  sodium  and  lithium.^ 
The  solution  of  the  chlorides  of  potassium,  sodium  and  lithium  is 
treated  with  nitrate  of  silver  and  the  total  amount  of  chlorine  present 
determined  ;  the  filtrate  is  freed  from  excess  of  silver  nitrate  by  hydro- 
chloric acid,  and  the  potassium  contained  in  the  filtrate  determined  by 
platinic  chloride.  The  potassium  thus  determined,  gives,  when  sub- 
tracted from  the  total  chlorides,  a  remainder:  A=x(LiCl)-l-y(NaCl) 
and  the  quantity  of  silver  chloride  equivalent  to  a  known  weight  of 
potassium  chloride  gives,  when  subtracted  from  the  total  weight  of 
silver  chloride,  a  weight  B.,  whence  quantity  of  lithium  chloride  is 
calculated  by  the  formula  x=l-0823  B— 2-6525  A 
As  the  citrate  of  litliium  in  crystals  has  been  shown  to  be  a  non- 
deliqttescent  body,  and  all  manufacturers  now  acknowledge  that  they 
can  make  it,  although  when  the  Pharmacopoeia  of  1867  was  brought 
out  they  were  dead  against  the  crystalliue  article,  it  is  to  be  hoped  that 
in  the  Pharmacopoeia  of  the  future  there  will  be  found  the  crystalline 
body  as  the  official  citrate. 
If  this  be  the  case,  there  will  not  be  much  fear  of  so  great  a  dissimi- 
larity between  the  commercial  article  and  the  official  article. 
1  cannot  close  my  paper  better  than  by  giving  Mr.  Umney^s  opin- 
ion on  the  crystalline  body^ : — 
"  The  crystals  are  quite  definite  and  reliable,  and  if  'indeed  it  were 
thought  necessary  to  have  a  citrate  containing  less  water,  then  let  it 
be  dried  at  100°,  which  will  be  quite  enough. 
^  Watt's  "Dictionary,"  vol.  iii. 
2  '<  Year-Book  of  Pharmacy,"  1875,  page  559. 
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