Mar  1883*™" }        Turpentine:  its  Natv/re  and  Adulterations.  151 
answers  admirably— all  that  is  volatile  is  distilled  off'.  The  distillate  is 
mixed  with  about  lialf  its  bulk  of  4 : 1  acid,  and  treated  in  a  precisely  simi- 
lar manner. 
The  product  from  this  second  operation  should  only  consist  of  a  mixture 
of  cymene  and  the  paraffinoid  hydrocarbon  ;  in  bulk  it  should  not  be  more 
than  4  to  5  per  cent,  of  the  original  hydrocarbon.  This  is  the  result  of  a 
very  large  number  of  estimations;  as  little  as  3  per  cent.,  however,  has 
been  obtained  in  experiments  conducted  with  special  care.  If  much  more 
than  about  5  per  cent,  be  obtained,  it  is  desirable  to  repeat  the  treatment 
with  4 : 1  acid. 
If,  from  the  result  of  this  treatment,  it  appears  probable  that  petroleum 
spirit  is  present,  the  product  is  placed  in  a  well-stoppered  bottle,  together 
with  several  times  its  volume  of  concentrated  sulphuric  acid,  heated  to  50° 
to  60°,  with  which  it  is  violently  agitated.  This  treatment  is  rejieated  if 
desirable  (weak  Nordhausen  acid  being  with  advantage  substituted  for  the 
concentrated  sulphuric  acid),  and  the  residual  hydrocarbon  is  separated, 
steam  distilled,  and  then  measured.  The  amount  thus  obtained  should  not 
exceed  from  ^  to  1  per  cent,  of  the  original  bulk  of  turpentine.  This  treat- 
ment with  concentrated  acid  affords  a  check  on  the  previous  determination. 
If  American  petroleum  spirit  be  thus  treated  it  suffers  comparatively 
little  loss,  so  that  the  amount  of  hydrocarbon  above  1  per  cent,  represents 
the  minimum  amount  of  petroleum  spirit  in  the  turpentine.  The  spirit 
from  Scotch  petroleum  contains  a  very  much  higher  proportion  of  hydro- 
carbons alterable  by  sulphuric  acid,  and  therefore  cannot  be  satisfactorily 
estimated. 
To  confirm  the  presence  of  petroleum  spirit,  the  turpentine  should  be 
distilled.  Petroleum  spirit  commences  to  distill  at  a  temperature  which 
may  be  above  or  below  that  at  which  turpentine  boils,  according  to  its 
i|uality,  but  always  distills  within  comparatively  wide  limits  of  tempera- 
ture; turpentine  commences  to  boil  near  160°,  and  almost  entirely  passes 
over  below  180°. 
The  presence  of  resin  spirit  also  affects  the  boiling-point  in  a  similar 
manner.  Evidence  of  the  presence  of  this  adulterant  is  also  afforded  by 
the  increased  yield  of  hydrocarbons  on  treatment  both  with  4:1  and  con- 
centrated sulphuric  acid,  as  resin  spirit  also  yields  a  cymene  and  paraffinoid 
hydrocarbon  on  treatment  with  4 : 1  acid.  The  cymene  from  resin  spirit 
being  isomeric  with  that  from  turpentine,  proof  of  the  presence  of  resin 
spirit  can  be  obtained  by  the  detection  of  its  cymene,  but  this  is  a  some- 
what delicate  operation. 
Addendum. — The  method  above  described  is  also  available  for  the  analy- 
sis of  solvent  naphtha  from  coal  tar  and  similar  products ;  it  is,  in  fact,  the 
only  method  which  is  capable  of  affording  results  which  approach  exact- 
ness. The  problem  is  by  no  means  so  simple,  however,  as  the  coal  tar  pro- 
duct itself  contains,  besides  benzene  and  its  homologues,  basic  bodies, 
hydrocarbons  alterable  by  diluted  sulphuric  acid,  and  paraffins.  Until, 
therefore,  a  considerable  number  of  genuine  samples  have  been  examined, 
the  method  is  chiefly  of  value  as  a  qualitative  test. —  The  Pharm.  Jour,  and 
Trans.,  Jan.  20,  1883. 
