352 
Synthetic  Camphor. 
f  Am.  Jour.  Pharru. 
I      August.  1907. 
turpentine  and  hydrochloric  acid,  the  yield  being  markedly 
diminished  by  the  presence  of  moisture.  Anhydrous  turpentine  is 
produced  by  treating  the  article  of  commerce  with  finely  granulated 
dry  calcium  chloride  and  with  subsequent  decantation.  Hydro, 
chloric  acid  is  prepared  by  the  action  of  sulphuric  acid  on  dry  sea 
salt,  the  associated  impurities  removed  by  cooling  and  subsequently 
passing  the  gas  through  calcium  chloride.  When  the  turpentine  is 
thoroughly  saturated  with  the  hydrochloric  acid  gas,  the  bornyl 
chloride  will  crystallize  out  and  can  be  separated  from  the  liquor 
either  by  centrifugalizing  or  by  means  of  a  filter  pump.  The  crys- 
tals so  obtained  should  be  recrystallized  from  benzin  or  washed 
with  alcohol. 
The  patentee  found  that  bornyl  chloride  can  be  converted  into 
camphor  by  the  following  simple  operation  :  The  purified  crystals 
are  mixed  with  lime  in  the  proportion  of  about  three  parts  of  the 
former  with  one  part  of  the  latter,  by  weight,  and  submitted  to  dis- 
tillation. This  procedure  results  in  the  formation  of  camphene, 
which,  when  heated  with  nitric  acid  at  a  moderate  heat,  is  converted 
into  camphor.  Other  oxidizing  agents,  such  as  potassium  perman- 
ganate, chromic  acid  or  ozone,  can  also  be  used. 
The  apparatus  used  in  the  manufacture  of  camphor  by  this  process 
is  elaborately  illustrated  and  described.  The  process  for  purifying 
the  crude  camphor  is  dismissed  by  saying  :  "  This  product  will  be 
found  usually  somewhat  dirty  and  may  be  cleaned  in  any  suitable 
manner." 
Nearly  five  years  later,  April  29,  1902,  U.  S.  patent  No.  698,761, 
on  a  process  of  producing  camphor,  was  granted  to  N.  Thurlow. 
The  method  consists  in  treating  anhydrous  turpentine  with  anhy- 
drous oxalic  acid  at  a  suitable  temperature  with  subsequent  oxida- 
tion and  purification.  The  oxalic  acid  supplies  the  carboxyl  group, 
thus  forming  an  ethereal  compound.  The  method  is  carried 
out  by  mixing  five  parts  by  weight  of  anhydrous  turpentine  with 
one  part  by  weight  of  anhydrous  oxalic  acid  and  heating  to 
about  1 20-1 30  degrees  centigrade.  This  results  in  the  formation 
of  "  penyl  oxylate,  formate,  camphor,  and  waste  polymerization 
products."  The  mixture  is  then  treated  with  lime  in  excess  to 
break  up  the  ethereal  salts  of  borneol  into  borneol.  The  camphor 
and  borneol  are  separated  from  the  mass  by  submitting  to  steam 
distillation.    The  distillate  contains  not  only  the  borneol  and  cam- 
