222 
On  JResorcin. 
j  Am.  Jour.  Pharm. 
t      May,  1881. 
at  first  a  watery  distillate  with  the  odor  of  butyric  acid,  and  afterwards 
an  oily  quickly  crystallizing  body.  The  latter,  which  consists  of  im- 
pure resorcin,  is  repeatedly  distilled  in  order  to  remove  the  volatile 
fatty  acids,  or,  after  saturation  with  caustic  baryta,  it  is  again  dissolved 
in  ether  and  purified  by  recrystallizaiion.  It  was  afterwards  obtained 
by  a  similar  process  from  ammoniacum,  asafoetida,  sagapenum,  acaroid, 
and  other  resins,  and  would  seem  to  be  produced  by  all  resins  which 
by  destructive  distillation  furnish  umbelliferon,  CgHgOg,  the  latter 
also  yielding  it  by  fusion  with  caustic  potassa.  It  is  likewise  readily 
obtained  by  the  destructive  distillation  of  brasilin  or  dry  extract  of 
brazil  wood. 
Since  the  more  exact  determination  of  its  chemical  characters  and 
constitution  these  methods  of  formation  have,  however,  been  super- 
ceded by  its  direct  production  from  other  closely  related  benzol  deriva- 
tives, such  as  meta-chlor-  or  meta-brom-benzolsulphonic  acid,  meta- 
clilor-  and  meta-iodophenol,  and  phenolmeta-sulphonic  acid,  or  their 
potassium  salts,  by  fusion  with  caustic  potassa,  the  latter  acid  being 
decomposed  as  follows  :  . 
The  most  reasonable  and  best  method  for  its  formation,  however, 
and  that  which  is  now  technically  employed,  is  from  the  benzoldisul- 
phonic  acid  (formed  by  the  action  of  fuming  sulphuric  acid  on  benzol), 
subsequently  preparing  therefrom  the  potassium  salt,  and  fusing  this 
with  caustic  potassa,  when  it  is  resolved  into  resorcin  and  potassium 
sulphite,  as  follows : 
Resorcin,  CgHg02,  or  CgH4(OH)2,  is  a  diatomic  phenol,  isomeric  with 
hydroquinone  and  pyrocatechin,  the  distinction  in  its  physical  and 
chemical  characters  from  the  two  latter  being  due  simply  to  the  differ- 
ent relative  position  of  the  hydroxy  1  groups  in  the  benzol  nucleus. 
Its  name  is  derived  from  resinay  resin,  and  orcin,  CgIl3CB[3(OII)2,  a 
handsomely  crystallizable,  homologous  body,  which  appears  to  exist 
ready  formed  in  many  lichens,  and  was  first  isolated  therefrom  by 
Robiquet  in  1829. 
Resorcin  is  odorless  and  colorless  when  perfectly  pure,  but  by  expo- 
sure to  the  air  assumes  a  reddish  color.  It  crystallizes  in  short  thick 
prisms  of  the  rhombic  system,  as  represented  by  the  subjoined  figure, 
