PRODUCTION  OF  BENZOIC  ACID  FROM  NAPIITHALIN. 
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state,  can  be  got  for  less  than  one  cent  a  pound.  In  the  follow- 
ing I  will  proceed  to  describe  the  process,  but  first  mention 
something  about  naphthalin: — 
This  hydrocarbon  (formula  C20H8)  was  discovered  in  1820,  by 
Garden,  in  the  coal-tar  of  the  gas  works,  and  studied  by  Liebig, 
Faraday,  Woehler,  and  others.  It  is  a  colorless,  inflammable 
solid,  of  a  burning  aromatic  taste,  and  peculiar  smell.  Its  spe- 
cific weight  is  1*048,  its  melting  point  175°,  and  its  boiling 
point  428°  Fahr.  It  sublimes  unaltered  in  lamina,  and  can 
also  be  obtained  in  rhomboidal  crystals  from  its  alcoholic  solu- 
tion. It  is  inflammable,  and  burns  with  a  very  smoky  flame. 
Its  derivates  have  principally  been  studied  by  the  celebrated 
Laurent. 
The  process  now  by  which  this  hydrocarbon  is  transformed 
into  benzoic  acid  is  the  following : — 
(.1).  By  the  process  of  Laurent. — The  naphthalin  is  trans- 
formed into  the  the  a  modification  of  the  bi-proto-chloride  of  naph- 
thalin, C20  H8  2C12. 
(2)  .  The  bi-protochloride  of  naphthalin  is  converted  by  oxida- 
tion into  phtalic  acid,  C16  H4  0G  2HO,  and  the  latter  into  phta- 
late  of  ammonia,  C16  H4  06  2NH3. 
(3)  .  We  obtain  then  the  phtalamid,  C16  H5  N04,  simply  by 
subjecting  the  phtalate  of  ammonia  to  distillation. 
(4)  .  By  distilling  the  product  obtained  by  process  3  with 
hydrate  of  lime,  benzonitril,  C14H5N?  is  formed. 
C16H5N04-f2CaO-:C14H5]sr+2CaO,  C02. 
(5)  .  In  boiling  the  latter  with  a  solution  of  caustic  soda,  ben- 
zoate  of  soda  is  formed,  from  which  benzoic  acid  is  precipitated 
by  hydrochloric  acid. 
This  is,  in  short,  the  process  als  followed  by  John  Castelhay, 
of  Paris,  and  of  which  Menier,  the  Secretary  of  Class  44  of  the 
International  Exhibition  in  Paris,  says  that  it  is  the  most  im- 
portant discovery  made  in  technical  chemistry  since  the  London 
Exhibition  of  1862.— Chem.  News,  Pec.  13,  1867. 
