Are'bSarryPi9i5m'}  Camphor— Natural  and  Synthetic/  57 
sium  bichromate  and  sulphuric  acid  are  used,  chrome  alum  is  obtained 
as  a  by-product. 
The  type  of  process  outlined  above  thus  involves  six  distinct 
stages  before  the  final  product  is  obtained : 
turpentine  — h*-  pinene  — >-  pinene  hydrochloride  — camphene  — > 
bornyl  acetate — >■  borneol  — >■  camphor. 
According  to  a  German  process,  the  anhydrous  rectified  oil  of 
turpentine  is  heated  directly  with  anhydrous  oxalic  acid.  Some 
camphor  is  formed,  and  the  oxalic  and  formic  esters  of  pinene,  which 
are  also  present,  are  saponified  and  oxidized.  Salicylic  acid  may 
also  be  employed  instead  of  oxalic  acid. 
The  crude  camphor  obtained  by  any  of  these  methods  is  refined 
by  steam  distillation  or  sublimation,  in  the  same  manner  as  the  crude 
natural  camphor  is  purified. 
Properties  of  Synthetic  Camphor. 
Synthetic  camphor  is  identical  with  the  natural  article  in  all  its 
chemical  and  physical  properties,  with  the  exception  (in  common 
with  other  synthetic  organic  compounds)  that  it  is  optically  inactive. 
The  question  of  the  differences  of  physiological  action  of  the  dextro, 
lsevo,  and  synthetic  modifications  appears  not  to  be  settled.14  The 
differences  seem  to  be  of  degree  and  not  of  kind.15  Johnston  16 
makes  a  plea  for  the  recognition  of  synthetic  camphor  in  the  British 
Pharmacopoeia,  on  the  ground  of  its  therapeutic  equivalence  to 
natural  camphor. 
As  regards  the  chemical  purity  of  synthetic  camphor,  celluloid 
manufacturers  state  that  it  must  be  quite  free  from  chlorine  for 
use  in  the  preparation  of  celluloid. 
History  and  Future  of  Camphor. 
The  short  history  of  synthetic  camphor  since  it  was  first  made 
about  10  years  ago  has  been  a  very  troubled  one,  and  the  future  of 
the  industry  still  seems  to  be  a  matter  of  great  uncertainty.  This 
checkered  career  has  been  caused,  largely  by  a  great  fluctuation  in 
the  price  of  natural  camphor.   Forty  years  ago  the  price  of  Japanese 
"Langgaard  and  Maass,  Therapeut.  Monatsh.  (1907),  20,  573.  Bruni, 
Gazz.  Chem.  Ital.  (1908),  38,  (II),  1.  Hamalainen,  Skan.  Arch,  fur  Physiol. 
(1908).  21,  64. 
15  See,  e.g.,  W.  E.  Grove,  Journ.  Pharmacol.,  1,  445. 
18  P harm.  Journ.,  83,  534. 
