404  Salicylic  Acid  and  Sodium  Salicylate.  {^tS^hann' 
1903. 
Further,  it  was  shown  that  the  difference  was  due  to  an  impurity 
in  the  artificial  acid — not  a  trace  of  which  existed  in  the  natural 
salicylic  acid.  Dr.  Charteris  from  these  experiments  concluded  that 
artificial  salicylic  acid  contained  an  impurity  or  impurities,  and  that 
until  this  or  these  could  be  extracted  by  the  aid  of  chemistry,  the 
internal  administration  of  the  acid  or  its  salt  should  be  discounte- 
nanced. Large  and  repeated  doses  of  the  sodium  salt  were  necessary 
in  the  treatment  of  acute  rheumatism,  and  hence  the  restlessness, 
the  confusion  and  the  delirium  attendant  at  times  on  their  use.  He 
observed  that  the  retarded  convalescence  also,  which  occurred  in 
-  some  cases  of  acute  rheumatism  after  the  salicylate  treatment,  was 
due  in  all  probability  to  the  great  and  protracted  prostration  to 
which  the  impurity  gave  rise.  In  connection  with  these  symptoms 
it  was  noted  that  prescriptions  for  the  salicylate  of  sodium  were 
invariably  made  up — unless  otherwise  indicated — from  the  artificial 
and  not  the  natural  salt.  In  a  paper  read  before  the  Royal  Medico- 
Chirurgical  Society,  Dr.  Charteris's  attention  was  called  to  a  method 
of  purifying  salicylic  acid  by  the  late  M.  Williams,  and  following 
along  lines  laid  down  by  M.  Williams  an  acid  was  made  by  repeated 
'crystallization  from  water  instead  of  rectified  spirit,  and  an  artificial 
acid  was  obtained  identical  in  its  chemical  form,  its  solubility,  its 
melting-point  and  its  physiological  action  with  that  of  the  natural 
acid.  It  was  also  shown  that  if  the  form,  the  solubility  and  the 
melting-point  varied  from  that  of  the  natural,  no  uniform  physio- 
logical result  could  be  obtained. 
In  October,  1890,  Professor  Dunstan  sent  Dr.  Charteris  a  sample 
of  artificial  salicylic  acid  and  samples  of  these  substances  extracted, 
labeled  O-acid,  P-acid  and  M-acid,  the  several  creosotic  acids. 
These  were  examined  in  their  physiological  action  by  dissolving  2 
grains  in  rectified  spirit  and  injecting  into  a  rabbit  weighing  \  y2 
pounds.  The  O-acid  produced  death  in  thirty  hours,  the  P-acid  in 
forty-two  hours,  while  the  M-acid  did  not  produce  any  unhealthy 
action. 
The  results  of  these  investigations  proved  that  an  impurity  existed 
in  the  artificial  acid  that  was  a  poison,  and  that  poison  was  not  found 
in  the  acid  from  vegetable  origin.  We  are  therefore  interested  in 
securing  a  source  from  which  a  pure  acid  and  its  salts  can  be  made, 
and  we  find  in  oil  of  wintergreen  such  a  source.  At  present  a  very 
large  percentage  of  the  oil  of  wintergreen  on  the  market  is  adul- 
