1 80  Aristol.  {Am'l^mi^' 
tinct  green  tint,  the  slight  precipitate  first  formed  being  redis- 
solved.  Solution  of  chlorinated  soda  is  now  added  gradually  while 
stirring  until  no  further  precipitation  is  produced,  and  a  slight  excess  is 
indicated  'by  the  odor.  About  650  to  700  cc.  will  be  required. 
The  precipitate,  a  light  red  brown  in  color,  is  collected,  washed  and 
dried,  by  spreading  on  bibulous  paper  in  a  suitable  room  where  it 
can  be  protected  from  the  light,  at  a  temperature  not  exceeding  500  C. 
The  filtrate  showed  the  absence  of  iodides  in  any  quantity,  and 
a  portion  acidified  and  extracted  with  ether  yielded  no  thymol. 
The  yield  by  this  and  the  preceding  formula  was  about  29  grm., 
corresponding  in  color,  melting  point  and  solubilities  with  the 
aristol  in  the  market  and  closely  approximating  the  theoretical 
yield  29  285  grm.  calculated  from  the  formula  C20H2J2O2.2H2O. 
The  thymol  used  in  this  formula  must  be  free  from  essential  oil 
or  thymene  or  there  is  produced  some  iodoform  in  the  reaction 
which  remains  as  a  contamination  of  the  finished  product.  As  most 
of  the  commercial  thymol  contains  a  small  portion  of  hydrocarbon 
it  must  be  first  purified,  which  is  easily  accomplished  by  percolating 
the  powdered  thymol  with  a  small  quantity  of  purified  benzin 
which  dissolves  of  course  a  portion  of  the  thymol  as  well  as  the 
thymene,  but  it  can  be  recovered  by  evaporation  of  the  solvent  and 
used  for  other  purposes.  The  solution  of  chlorinated  soda  used 
should  contain  no  excess  of  chlorinated  lime,  and  in  its  preparation 
for  this  purpose,  it  is  advisable  to  use  an  excess  of  sodium  carbonate 
as  an  excess  of  this  latter  salt  does  not  affect  the  product. 
In  Repertoire  de  Pharmacie,  1890,  page  355,  M.Louis  Boule  fur- 
nishes the  following  formula  for  the  preparation  of  aristol :  Crystal- 
lized thymol,  caustic  soda  and  potassium  iodide  each  5  grams,  dis- 
solved in  50  cc.  of  water  and  then  poured  into  250  cc.  concentrated 
solution  hypochlorite  of  soda.  It  will  be  observed  on  calculating 
the  quantities  used  that  there  is  an  insufficient  amount  of  iodine 
supplied  by  the  potassium  iodide  to  furnish  a  product  of  the 
above  composition.  In  the  absence  of  sufficient  iodine  a  cer- 
tain amount  of  the  thymol  combines  with  the  chlorine.  Upon 
adding  solution  of  chlorinated  soda  to  an  alkaline  thymate  solution 
there  is  precipitated  a  compound  of  a  pinkish  tint  soluble  in  ether, 
alcohol  and  chloroform  and  precipitated  from  its  alcoholic  solution 
by  water.  The  filtrate  from  this  precipitate  yields  but  a  slight  trace 
of  thymol  upon  acidifying  and  extracting  with  a  solvent.    A  similar 
