Am.  Jour.  Pharm.l 
ApriJ,1891.  j 
Arts  to  I . 
179 
ing  on  the  water-bath,  determined  above  as  about  6  4  per  cent., 
must  be  due  mainly  to  water.  Allowing  two  equivalents  of  water 
to  be  in  combination,  there  would  be  present  6-14  per  cent,  of  water 
and  41-96  per  cent,  of  iodine,  figures  that  closely  agree  with  the 
results  obtained  by  me,  the  average  of  the  three  determinations 
of  iodine  being  41-36  per  cent.  From  these  experiments  we  are 
compelled  to  accept  the  statement  that  aristol  is  a  biniodide  of 
dithymol,  in  which  the  hydrogen  of  the  hydroxyl  groups  is  replaced 
by  iodine  and  is  represented  by  the  formula  C20H24T2O2.2H2O. 
A  formula  based  upon  the  experiments  of  Messinger  and  Vort- 
mann  would  be  : 
Thymol,  15  gm. 
Soda,  20  " 
Iodine,  .  .  .  .  50  8  " 
Potassium  iodide,  66  4  " 
The  thymol  and  soda  are  dissolved  in  250  cc.  water.  The 
iodine  and  potassium  iodide  in  1,000  cc,  and  gradually  added 
to  the  first  solution,  continually  stirring.  The  precipitate  is 
collected,  washed  and  dried.  The  precipitate  obtained  by  this 
formula  was  at  first  of  a  purple-brown  color,  but  while  drying 
gradually  became  lighter  in  color,  until  when  dry  it  was  of 
the  same  yellow-red  color  as  the  commercial  article.  The  filter 
on  which  the  precipitate  was  collected  and  dried  was  stained 
with  iodine.  The  filtrate  gave  no  indication  of  free  iodine,  and  a 
portion  acidulated  and  extracted  with  ether  yielded  no  thymol, 
showing  that  the  reaction  was  complete.  It  is  not  believed  that 
this  is  the  process  adopted  by  the  manufacturers,  as  it  requires  the 
use  of  a  large  amount  of  iodide  of  potassium  and  iodine.  The 
greater  portion  of  the  latter  being  lo>t  in  the  drying  of  the  pre- 
cipitate. 
The  following  formula  is  offered  as  an  economical  process: 
Thymol,   15  gm. 
Soda,  20  " 
Iodine,  •.   .   .  .    6-35  <l 
Potassium  iodide,  8*3  iL 
Solution  of  chlorinated  soda,  a  sufficient  quantity. 
The  thymol  and  soda  are  dissolved  in  250  cc.  of  water.  The  iodine 
and  iodide  of  potassium  are  also  dissolved  in  250  cc.  of  water  and  the 
two  solutions  mixed,  resulting  in  an  opalescent  solution  with  a  dis- 
