Am.  |our.  Pharm  \ 
Dec,  1878.  J 
Sodium  Salicylate. 
57* 
process  in  which  sodium  hydrate  is  used  to  saturate  the  salicylic  acid. 
He  gives  it  as  his  experience  that  u  the  sodium  salicylate  made  from 
the  artificial  salicylic  acid  is  liable  to  be  more  or  less  impure  and  indefi- 
nite in  composition."  It  certainly  will  be  unless  great  care  is  taken  to 
employ  pure  salicylic  acid,  yet  I  consider  that  the  best  crystallized  acid 
of  the  market  is  sufficiently  free  from  impurities  to  insure  a  pure  and 
uniform  product.  The  principal  arguments  against  the  employment  of 
sodium  hydrate  for  the  saturation  are  the  high  price  of  the  pure  article 
and  the  solubility  of  any  accidental  excess  in  alcohol  if  purification  is- 
attempted  by  recrystallization.  The  recrystallization  from  alcohol, 
owing  to  its  ready  solubility,  is  difficult,  entailing  a  considerable  loss  of 
alcohol  as  well  as  time,  and  is  usually  regarded  as  rather  an  unsatis- 
factory process. 
Mr.  G.  W.  Kennedy  ("Am.  Jour  of  Pharm.,"  1877,  p.  592) 
saturates  an  indefinite  quantity  of  a  20  per  cent,  solution  of  sodium 
hydrate  with  salicylic  acid,  by  adding  it  until  it  is  no  longer  dissolved 
(italics  mine),  filters  and  evaporates  to  dryness.  The  addition  of  the 
acid  thus  indefinitely  would  be  liable  to  insure  a  greater  excess  of 
salicylic  acid  than  was  desirable,  and  thus  impair  the  purity  of  the  salt. 
Mr.  Pennypacker  ("  Am.  Jour,  of  Pharm.,"  1878,  p.  114,)  employs 
the  acid  sodium  carbonate,  adding  it  to  the  acid  mixed  with  water,  as 
long  as  there  is  effervescence ,  evaporates  to  dryness  upon  a  water-bath, 
dissolves  in  alcohol,  pours  off  the  clear  liquid,  and  evaporates  the  alco- 
holic solution  to  dryness. 
The  indefiniteness  of  the  terminal  reaction  is  apparent,  and  will, 
unless  very  carefully  manipulated,  result  in  an  unsatisfactory  product. 
The  existence  of  any  residue  insoluble  in  alcohol  indicates  either  the 
unsuitable  character  of  the  materials  employed  or  else  an  avoidable 
excess  of  the  sodium  dicarbonate,  in  which  case  the  salt  would  be  to  a 
greater  or  less  extent  colored.  If,  on  the  other  hand,  salicylic  acid 
were  present  in  excess,  it  would  be  readily  dissolved  by  the  alcohol  and 
be  mixed  with  the  supposedly  purified  salicylate.  The  process  also 
necessitates  a  loss  of  alcohol,  or  the  labor  necessary  for  its  recovery. 
The  process  which  the  author  recommends  has  been  employed; 
practically  for  some  time,  and  has  been  found  to  be  the  most  economi- 
cal and  satisfactory  of  any  which  have  been  tried  for  the  manufacture 
of  the  salt  upon  a  large  scale,  and  it  will  doubtless  be  equally  satisfac- 
tory in  the  hands  of  careful  pharmacists. 
Brooklyn,  N.  T.,  Nov.  18,  1878. 
