62  Lithium  Benzoate  and  Salicylate. 
ated  from  the  lithium  and  appears  to  volatilize  immediately,  since 
only  a  small  portion  is  carbonized.  That  the  sulphuric  acid  facili- 
tates the  combustion  is  well  known. 
If  the  ammonium  sulphate  should  contain  any  non-volatile  matter, 
this  can  be  estimated  and  an  allowance  made  in  the  calculation. 
This  chemical  can  easily  be  prepared  pure,  from  pure  ammonium 
carbonate  and  pure  sulphuric  acid.  The  salt  must  be  thoroughly 
dried,  so  as  to  eliminate  all  water. 
The  U.S.P.  requires  that  the  dry  salt  shall  be  99-6  per  cent.  pure. 
The  average  of  my  six  determinations  is  99*77  per  cent.  Accord- 
ing to  these  results,  the  U.S.P.  requirement  is  not  too  exacting. 
LITHIUM  SALICYLATE. 
Much  that  has  been  said  of  lithium  benzoate  applies  also  to 
lithium  salicylate.  It  must  be  remembered,  however,  to  keep  in 
mind  salicylic  instead  of  benzoic  acid.  Lithium  salicylate  is  recog- 
nized by  several  pharmacopoeias  besides  the  U.S.P.,  viz.:  the  Arznei- 
buch,  1895;  Pharmacopcea  Helvetica,  1893,  and  Pharmacopoea 
Norvegica,  1895. 
M.  Julliard,1  a  French  pharmacist,  examined  a  number  of  samples 
of  lithium  salicylate,  and  found  that  those  samples  which  produced 
permanent  colorless  solutions  were  either  acid  in  reaction  or  con- 
tained from  15  to  20  per  cent,  of  sodium  salicylate.  The  sam- 
ples examined  by  me  were  all  acid  in  reaction,  but  none  con- 
tained any  sodium  salt  beyond  that  introduced  by  the  lithium 
carbonate  used  in  their  manufacture.  The  results  of  this  inves- 
tigation are  embodied  in  the  accompanying  table : 
'  1887,  Bull.  Com.  June  ;  Abstr.  in  Am.  Jour.  Pharm.,  59,  400. 
