AmMan'i87h6!rm'}        Iodo-Sulphate  of  Chinioidin.  127 
pose  of  applying  it  to  the  quantitative  determination  of  quinia.  After 
some  experiments  with  the  iodo-sulphate  of  chinioidin  (wrongly  called 
amorphous  quinia,)  I  found  that  this  compound  is  perfectly  adapted 
for  the  required  purpose,  as  its  solubility  in  cold  alcohol  is  great  enough 
to  make  a  concentrated  alcoholic  solution  containing  16  per  cent,  or 
even  more  of  it.    This  reagent  is  made  as  follows  : 
Two  parts  of  sulphate  of  chinioidin,1  are  dissolved  in  8  parts  of 
water,  containing  5  per  cent,  of  sulphuric  acid.  To  this  clear  solution, 
contained  in  a  large  capsule,  a  solution  of  one  part  of  iodine  and  two 
parts  of  iodide  of  potassium  in  100  parts  of  water,  is  slowly  added  under 
continuous  stirring,  so  that  no  part  of  the  solution  of  chinioidin  comes 
into  contact  with  an  excess  of  iodine.  By  this  addition,  an  orange- 
colored  flocculent  precipitate  is  formed  of  iodo-sulphate  of  chinioidin, 
which  either  spontaneously  or  by  a  slight  elevation  of  temperature,  col- 
lapses into  a  dark  brown-red  colored  resinous  substance,  whilst  the 
supernatant  liquor  becomes  clear  and  slightly  yellow-colored.  This 
liquor  is  poured  off,2  and  the  resinous  substance  is  washed  by  heating 
it  on  a  water-bath  with  distilled  water.  After  washing,  the  resinous 
substance  is  heated  on  the  water-bath  till  all  the  water  has  been  evap- 
orated. It  is  then  soft  and  tenacious  at  the  temperature  of  the  water- 
bath,  but  becomes  hard  and  brittle  after  cooling.  One  part  of  this 
substance  is  now  heated  with  6  parts  of  alcohol  of  92  or  94  per  cent, 
on  a  water-bath,  and  is  thus  dissolved,  and  the  solution  allowed  to 
cool.  In  cooling,  a  part  of  the  dissolved  substance  is  separated.  The 
clear  dark-colored  solution  is  evaporated  on  a  water-bath,  and  the  resi- 
due dissolved  in  5  parts  of  cold  alcohol.  This  second  solution  leaves 
a  small  part  of  insoluble  substance.  The  clear  dark  colored  solution 
obtained  by  the  separation  of  this  insoluble  matter,  either  by  decanta- 
tion  or  filtration,  constitutes  the  reagent  which  I  have  now  used  since 
the  beginning  of  1875,  under  the  name  of  iodo-sulphate  of  chinioidin, 
both  for  the  qualitative  and  quantitative  determination  of  crystallizable 
quinia. 
To  determine  the. quantity  of  quinia  contained  in  the  mixed  alkaloids 
1  Identical  with  "  Sulphate  of  Amorphous  Quinia,  prepared  according  to  Dpt  de 
Vrij's  process,  by  Messrs.  Howard  &  Sons,  Stratford. 
2  To  prevent  the  use  of  an  excess  of  iodine,  I  have  prescribed  on  purpose  not 
enough  iodine  to  precipitate  all  the  chinioidin  in  the  form  of  iodo-sulphate.  There- 
fore this  liquor  contains  still  chinioidin  which  can  be  obtained  in  a  very  pure  state, 
if  a  little  sulphurous  acid  is  added  before  precipitating  the  alkaloid  by  caustic  soda. 
