Am  ju°ner,'i898frm"}    Atropine  Periodides  and  I odomer curates.  301 
In  the  following  estimation  of  the  strength  of  atropine  solutions 
both  the  iodine  solution  and  the  sodium  thiosulphate  solution  were 
strictly  decinormal.  Of  the  iodine  solution  20  or  25  c.c.  were  put 
into  a  100  c.c.  measuring  flask  and  atropine  solutions  of  known 
strength  run  in  from  a  burette  and  the  operation  continued  as 
described  above.  When  the  supernatant  liquid  was  perfectly  trans- 
parent, the  flask  was  filled  up  to  100  c.c.  and  50  c.c.  were  filtered  off. 
In  these  50  c.c.  the  excess  of  iodine  was  determined  by  means  of  the 
tenth-normal  thiosulphate  solution  and  the  strength  of  the  atropine 
solutions  calculated  by  using  the  factor  o  0036048  for  every  cubic 
centimeter  of  decinormal  iodine  used  up. 
Number  of  c.c.  Number  of  c.c.  of  Calculated  '  Actual 
of  the  atropine  the  tenth-normal  strength.  strength. 
No.  of  sample.     solution  taken.  iodine  used  up.  Per  cent.  Per  cent. 
1  12  15-6  0-47  0.50 
2  15  14-9  C36  0-40 
3  17  13*2  0*28  0*30 
4  12  io"o  0*28  0*25 
We  shall  try  to  determine  experimentally  whether  this  method  is 
also  applicable  to  other  alkaloids  and  their  galenical  forms. 
The  above-mentioned  factor  for  every  cubic  centimeter  of  the 
decinormal  iodine  solution  was  deduced  as  we  said  upon  the  ground 
that  only  eight  atoms  of  iodine  of  every  molecule  of  the  atropine 
enneaiodide  are  furnished  by  the  free  iodine  of  the  iodine  solution — 
the  ninth  atom  forming  the  normal  iodine  of  the  enneaiodide  coming 
from  the  potassium  iodide. 
That  this  is  really  so  has  been  admitted  by  almost  all  chemists  in 
the  case  of  all  other  periodides  whose  constitution  is  similar  to  that 
of  the  atropine  enneaiodide.  It  would,  therefore,  seem  to  be  super- 
fluous to  prove  experimentally  the  correctness  of  this  view  with 
regard  to  the  enneaiodide  of  atropine.  But  owing  to  the  fact  that 
Kippenberger  in  the  above-cited  articles  advances  a  different  view, 
we  thought  it  advisable  to  prove  irrefutably  that  the  iodide  of  potas- 
sium of  the  iodide  solution  takes  an  active  part  in  the  reaction  by 
which  the  atropine  enneaiodide  is  formed  and  gives  off  an  amount 
of  iodine  which  is  just  equal  to  the  amount  of  the  normal  iodine  of 
the  enneaiodide. 
We  proceeded  in  the  following  manner :  We  first  determined  the 
strength  of  our  iodine  solution  with  regard  to  free  iodine ;  this  was 
done  by  means  of  a  sodium  thiosulphate  solution  of  known  strength. 
We  then  took  10  c.c.  of  this  iodine  solution  and  determined  the  total 
