A  *MmZmt™'}  Old  and  New  Reagents  for  Common  Phenol.  281 
ored  red  by  alcoholic  potash.  When  the  acid  is  heated  to  120°,  it  is 
resolved  into  santonin  and  water  ;  the  same  decomposition  is  pro- 
duced by  adding  sulphuric  acid  to  its  aqueous  solution  ;  hydrochloric 
acid  acts  in  the  cold  in  a  similar  way,  but  more  slowly,  while  by  add- 
ing either  of  these  acids  to  a  hot  solution  of  a  salt,  santonin  is  at  once 
precipitated. 
Cannizzaro  and  Sestini  have  lately  shown  that  when  santonin  is 
heated  for  some  time  with  an  alkali,  it  is  converted  into  the  stable 
santonic  acid,  which  is  isomeric  with  santoninic  acid,  but  cannot  be 
reconverted  into  santonin. — Jour?i.  Chem.  Soc,  March,  1874,  from 
Deut.  Chem.  Ges.  Ber.,  vi,  1280—1282. 
OLD  AND  NEW  REAGENTS  FOR  COMMON  PHENOL. 
By  Egidio  Polacci. 
The  author  points  out  the  distinctions  between  the  blue  color  pro- 
duced by  phenol  and  hydrochloric  acid  with  a  chip  of  fir-wood  and 
that  given  by  hydrochloric  acid  alone.  The  violet  coloration  given 
by  perchloride  of  iron  is  indecisive  as  being  common  to  all  the  phenols. 
The  blue  coloration  given  by  the  successive  action  of  ammonia  and  a 
hypochlorite  is  less  general.  As  this  method  turns  on  the  conversion 
of  the  phenol  into  anilin  by  the  action  of  ammonia,  the  test  is  only 
available  where  the  absence  of  anilin  is  satisfactorily  demonstrated. 
Cresylic  acid  and  thymol  yield  similar  results.  In  complex  organic  fluids 
the  reaction  may  fail.  The  conversion  of  phenol  into  picric  acid  by  the 
action  of  nitric  acid  cannot  be  used  for  the  detection  of  the  first  men- 
tioned body,  since  the  same  result  is  obtained  with  a  great  variety  of 
bodies.  The  author  pours  into  a  narrow  test-tube  concentrated  sul- 
phuric acid  to  the  height  of  four  or  five  centimetres,  and  adds  cau- 
tiously the  aqueous  solution  containing  the  phenol,  in  such  a  manner 
that  the  two  liquids  may  not  mix.  A  formation  of  three  colors  is 
soon  perceived  at  the  line  of  contact  of  the  two  liquids.  These  three 
are  soon  reduced  to  one,  a  vermillion  red,  which,  setting  out  from  the 
plane  of  division,  diffuses  itself  through  the  entire  mass  of  the  phenol 
solution.  This  color  is  stable,  and  remains  unaltered  for  months. 
If  the  red  liquid  is  removed  from  the  acid  and  treated  with  an  alkali, 
it  becomes  yellow  without  losing  its  transparency.  This  reaction 
serves  to  detect  one  part  of  phenol  in  about  2000  of  water.  Another 
method  is  as  follows  : — In  a  well  glazed  porcelain  crucible  is  put  a 
