4io 
Natural  Salicylates. 
(  Am.  Jour.  Pharm. 
I  September,  1908. 
slight  excess  of  oil  after  saponification  is  complete,  also  in  not  losing 
any  hydrochloric  acid  by  excessive  ebullition  while  it  is  being  added. 
All  measurements  must  be  made  accurately.  One  indication  of  a 
genuine  oil  of  birch,  is  the  formation  of  a  transient  pink  color  when 
about  half  the  hydrochloric  acid  has  been  added,  also  the  character- 
istic woody  odor  at  the  same  time.  It  is  true  that  irregular  results 
are  sometimes  met  with,  but  no  doubt  they  are  often  due  to  some 
little  fault  in  manipulation. 
(g)  General.  It  has  been  suggested  that  the  natural  salicylates 
are  more  loosely  combined,  or  have  a  different  structural  arrange- 
ment, than  the  synthetic  product,  and  this  may  lead  to  a  positive 
means  of  identification.  The  natural  oils  are  undoubtedly  formed 
from  the  decomposition  of  glucosides,  by  either  water  or  ferments, 
or  both,  while  the  synthetic  product  is  made  in  a  very  different  man- 
ner. It  would  seem  from  their  different  action,  that  there  was  a 
more  important  factor  than  the  small  difference  in  composition  would 
indicate.  Physicians,  as  a  rule,  prefer  the  salicylates  made  from  true 
oil  of  birch  or  gaultheria  and  are  perfectly  willing  to  pay  the  cor- 
responding higher  price,  as  many  state  positively  that  clinically  sali- 
cylates from  true  oils  give  better  results. 
Another  distinction  of  natural  salicylates  is  that  they  are  slippery 
when  ground  in  a  mill,  while  salicylates  made  from  synthetic  methyl 
salicylate  are  dry  and  irritating. 
One  of  our  main  difficulties  was  in  obtaining  a  supply  of  oils  of 
birch  and  gaultheria  for  experimental  work,  that  we  were  positive 
was  authentic.  We  personally  distilled  some  oil  of  gaultheria  and 
obtained  undoubtedly  genuine  oil  of  birch  from  several  sources. 
Oil  of  birch  frequently  comes  to  us  of  dark  red  color.  This  is 
supposed  to  indicate  the  genuineness  of  the  sample,  but  frequently 
it  is  thus  colored  by  the  addition  of  a  very  small  quantity  of  ferric 
chloride.  A  trace  of  tartaric  acid  will  remove  this  color.  Some 
samples  are  said  to  be  colored  with  red  sanders,  but  we  were  unable 
to  color  the  oil  by  this  means,  as  the  coloring  matter  does  not  appear 
to  be  soluble  in  the  oil. 
We  are  indebted  for  much  of  the  information  here  presented  to 
many  who,  like  ourselves,  are  anxious  to  solve  the  problem  of  the 
detection  of  spurious  "  Natural  Salicylates." 
Research  Laboratory, 
Smith,  Kline  &  French  Co.,  July,  1908. 
