OBTAINING  PRODUCTS  FROM  TAR. 
animal  substances  is  submitted  to  the  same  processes,  to  extract 
therefrom  the  crude  oil,  to  purify  it,  and  to  separate  from  it 
the  purified  oils  and  the  denser  substances  contained  therein.  In 
order  to  carry  into  effect  the  first  series  of  processes,  forming 
part  of  this  invention,  the  patentees  take  coal  or  gas  tar,  and  put 
it  into  a  still  of  any  suitable  construction,  with  a  worm  and  con- 
densing apparatus  attached  thereto,  and  by  means  of  steam 
passed  into  the  still  from  a  steam-boiler,  the  crude  or  rough 
naphtha  is  distilled  over  in  the  usual  way  until  the  crude  naphtha 
coming  over  from  the  still  becomes  of  the  specific  gravity  of 
about  910°  (water  being  considered  1000°).  The  steam  is  then 
shut  off,  and  by  the  application  of  heat  from  a  fire,  a  quantity  of 
water  is  distilled  over,  as  well  as  the  previously-mentioned  naph- 
thaline oil,  which  is  commonly  called  pitch  oil,  tar  oil  or  creosote 
oil.  The  distillation  is  still  continued  until  the  oil  reaches  the 
specific  gravity  of  about  990°;  the  fire  is  then  withdrawn,  and 
the  residue  of  the  pitch  in  the  still  is  run  off  in  a  heated  state 
and  allowed  to  cool  in  the  usual  way.  A  further  quantity  of  oil 
may  be  extracted  from  the  pitch  by  subjecting  it  to  a  strong  fire- 
heat  in  a  retort,  with  a  worm  and  condensing  apparatus  attached 
thereto. 
The  second  part  of  the  process  relates  to  the  purification  of  the 
crude  naphthaline  oil,  and  the  extraction  therefrom  of  the  naph- 
thaline and  oils  which  it  contains.  For  this  purpose  the  crude 
naphthaline  oil  is  put  into  a  leaden  vessel,  and  to  every  100  gal- 
lons thereof  about  15  gallons  of  sulphuric  acid,  of  the  specific 
gravity  of  about  1-830,  is  gradually  added,  the  mixture  being 
continually  stirred  until  the  acid  has  become  mixed  with  all  the 
impurities  with  which  it  can  combine.  The  contents  of  the  ves- 
sel are  then  allowed  to  settle,  and  the  clear  liquor  is  drawn  off 
into  another  vessel.  To  every  100  gallons  of  oil  about  10  gallons 
of  caustic  alkali,  having  the  specific  gravity  of  about  1-350,  is  next 
gradually  added  ;  and  this  mixture  is  kept  continually  stirred,  un- 
til any  excess  of  acid  left  in  the  oil  is  neutralized,  and  all  other 
impurities  with  which  the  alkali  can  combine  are  taken  up.  The 
contents  of  the  vessel  are  then  allowed  to  settle,  and  the  clear  li- 
quor is  drawn  off  and  put  into  a  still  of  any  convenient  construc- 
tion, with  a  worm  and  condensing  apparatus  attached. 
The  process  of  distillation  is  carried  on  until  the  oil  coming 
over  reaches  the  specific  gravity  of  about  940°.    The  oil  from 
