ON  THE  COMPOSITION  OF  CREOSOTE. 
229 
none  of  them  are  to  be  regarded  as  rational  formulas  for  a  deter- 
minate creosote,  but  only  as  empirical  formulae  for  different  pro- 
ducts. The  author,  at  least,  thinks  that  the  facts  furnish  a 
proof  that,  by  Voickel's  process  of  purification,  two  different 
products  are  obtained  from  the  crude  wood  tar  creosote,  one  of 
which  is  of  the  composition  C24  H15  O4  (Von  Gorup-Besanez)  and 
the  other  C24  Hu  O5  (Volckel.)  They  are  distinguished,  as  far 
as  we  know,  only  by  the  small  difference  in  the  specific  gravity. 
The  author  also  obtained  a  lead  compound  from  his  creosote. 
He  mixed  the  solution  with  concentrated  liquid  ammonia,  and 
diluted  it  with  about  200  cub.  centims.  of  water.  On  the  addi- 
tion of  a  solution  of  neutral  acetate  of  lead,  also  diluted  and 
mixed  with  a  little  ammonia,  to  this  solution,  a  caseous  white 
precipitate,  separating  in  flakes  like  those  of  chloride  of  silver, 
was  produced.  This  was  washed  on  a  covered  filter,  pressed  be- 
tween blotting  paper,  and  dried  first  over  sulphuric  acid  and 
afterwards  at  212°  F.  It  contained  64-80  per  cent,  of  oxide  of 
lead,  which  corresponds  with  the  formula  C24  II14  O3,  PbO-j- 
2PbO.  But  the  amount  of  lead  is  different  according  to  the 
mode  of  treatment ;  in  partial  precipitations  it  was  found  that 
the  first  parts  of  the  precipitate  contained  less  oxide  of  lead. 
The  lead  precipitate  loses  creosote  even  at  ordinary  temperatures, 
and  undergoes  a  change  when  dried  at  a  temperature  between 
176°  and  212°  F. 
Although  it  appears  from  this  that  the  creosote  investigated 
by  the  author  was  different  from  Volckels,  the  author  tried,  fur- 
ther, whether  his  creosote  underwent  an  essential  change  by 
repeated  treatment  with  potash.  The  creosote  dissolved  com- 
pletely in  potash,  without  the  separation  of  any  body.  The  boil- 
ing was  continued  for  four  days,  each  time  five  hours,  without 
interruption.  The  solubility  of  the  distillate  in  dilute  solution 
of  potash  could  no  longer  serve  to  indicate  the  stopping  point, 
for  it  was  soluble  in  very  dilute  solution  of  potash  from  the  very 
commencement  of  the  operation. 
The  distillate  of  the  first  day  was  turbid,  exhibited  some  oil 
drops  on  the  surface,  and  did  not  acquire  any  color  by  standing 
in  the  air.  That  of  the  second  and  third  days  gradually  became 
violet-purple  in  the  air.  This  beautiful  violet-purple  color  was 
immediately  produced  when  one  or  two  drops  of  solution  of  potash 
