66 
Terebene. 
Am.  Jour.  Pharm. 
Feb.,  1887. 
several  bodies  which  could  be  separated  by  repeated  fractional  distil- 
lation. They  found  that  the  greater  part  distilled  between  173°  and 
180°  with,  however,  a  considerable  fraction,  about  160°.  This  latter 
fraction  was  supposed  to  be  the  terebene  described  by  Biban,  but  in- 
stead of  remaining  liquid  at  — 27°  it  crystallized  in  ice,  and  when  care- 
fully fractioned  proved  to  be  the  inactive  solid  camphene  which  small 
amounts  of  impurities  prevented  from  crystallizing.  The  fraction  boil- 
ing from  170°  to  180°  was  cymol  mixed  with  a  hydrocarbon  (terpi- 
lene)  boiling  at  about  178°  and  having  the  same  composition  as  the 
original  oil  o"f  turpentine.  By  using  dilute  sulphuric  acid  they  found 
the  reaction  somewhat  different,  no  camphene  was  formed,  the  result- 
ing mixture  being  mostly  composed  of  terpilene. 
The  correctness  of  these  views  is  doubted  by  Biban,  as  Armstrong 
and  Tilden  did  not  follow  the  method  of  preparation  proposed  by  him. 
For,  while  the  latter  distilled  over  his  terebene  in  the  presence  of 
sulphuric  acid,  Armstrong  and  Tilden  carefully  avoided  high  heat  and 
removed  all  traces  of  acid  before  distilling.  In  considering  the  above 
it  seems  quite  possible  that  Armstrong  and  Tilden  had  quite  a  different 
material  under  investigation  from  that  described  by  Biban.  For,  as 
the  latter  justly  remarks,  while  his  terebene  was  a  very  mobile  liquid, 
their  material  was  a  solid  body  only  liquefied  by  the  presence  of  some 
trifling  impurities,  and  thus  should,  he  thinks,  present  the  appear- 
ance of  a  more  or  less  viscous  oil. 
There  are  numerous  substances  that  can  be  substituted  for  sul- 
phuric acid  in  this  reaction  on  oil  of  turpentine,  notably  among  these 
the  fluoride  of  boron,  the  former,  however,  is  usually  employed. 
When  this  acid  is  dropped  into  oil  of  turpentine  the  mass  becomes 
heated,  and  if  great  care  is  not  taken  the  turpentine  boils  with  evolu- 
tion of  large  quantities  of  sulphurous  anhydride.  In  extreme  cases 
the  reaction  becomes  so  intense  that  the  turpentine  bursts  in  flames. 
When  the  reaction  is  completed  the  acid  is  separated  from  the  oil  and 
the  latter  distilled  with  live  steam.  In  the  distillate  an  oily  layer 
separates  which  is  collected  and  rectified.  A  thick  greenish  residue  is 
left  in  the  still.  This  consists  principally  of  colophene.  An  inactive 
camphor  boiling  about  200°  C.  is  also  present.  This  body  has  been 
shown  to  be  identical  with  borneol. 
As  terebene,  scientifically  considered,  seems  to  offer  such  a  lati- 
tude of  opinion  it  is  to  be  supposed  that  the  commercial  article  bear- 
ing this  name  would  vary  very  much  in  its  composition.    For  the 
