248         IODO-SULPHATES  OF  THE  CINCHONA  ALKALOIDS. 
color,  but  if  exposed  over  sulphuric  acid  at  62°  Fahr.,  or  if  at- 
tempted to  be  dried  at  212°  Fahr.,  they  lose  5.32  per  cent, 
water  =  6  atoms,  and  become  a  dark  greenish-black  residue, 
which  is  a  tri-hydrate. 
If  this  olive- colored  residue  be  boiled  in  dilute  spirit,  the  opti- 
cal crystals  deposit  on  cooling. 
The  author's  more  recent  analyses  of  the  iodo-sulphates  of 
the  cinchona  alkaloids  have  induced  him  to  suggest  the  following 
formulae  for  them  :— 
Sulphate  of  iodo-quinine        C57H33N2O5  ^  2SQ3HO+5HO=  840 
Sulphate  of  iodo-cinchonidin  f  C57H33N0O5  )  9Qn  TTn  1  zjjf\  op^ 
(optical  salt.)  {  I3  j  *jbU3tlU+0ilU=  ')bl 
Sulphate  of  iodo-cinchonidin  f  C57H33N2O5  )  9Q,n  tta  i  nnn  mno 
(silky  salt.)  {  I3  5  2»02HO+9HO=  100o 
Sulphate  of  iodo-quinidin        C35H19N2O4  ^   gQ  HO-f  5HO—  637 
Sulphate  of  iodo-cinchonine     C35H19N0O2?    on  TTa  i  ^tta 
IS     bU3JtlU-j-OliU=  Ivt 
From  this  it  appears  that  the  optical  salt  of  quinine  differs  in 
chemical  atomic  numbers  merely  in  the  possession  of  1  atom  less 
iodine,  the  cinchonidin  salt  having  3,  the  quinine  salt  2  atoms 
iodine  ;  but  in  each  case  2  atoms  of  sulphuric  acid,  and  5  water, 
with  an  organic  base  of  C57  H33  N2  05  common  to  both.  How 
this  is  derived  from  C40  H24  N2  04  in  the  one  case,  or  C40  H24  N2 
02  in  the  other,  it  is  difficult  to  point  out  in  the  present  state 
of  the  question. 
Closely  as  the  quinine  and  cinchonidin  salts  agree  amongst 
themselves,  they  differ  widely  from  the  quinidin  and  cinchonine 
compounds. 
The  quinidin  salt,  after  recrystallization,  presents  itself  as 
long  quadrilateral  acicular  prisms,  having  a  deep  ruby  or  garnet- 
red  color,  with  a  bluish-violet  or  light  purplish  reflexion-tint ;  it 
is  sometimes  deposited  in  thin  flat  plates,  or  long,  flat,  acicular 
prisms  ;  these,  when  thin,  transmit  a  pure  yellow  color,  but  in 
thicker  plates  it  becomes  reddish,  with  a  tinge  of  brown. 
There  is  scarcely  any  appearance  of  double  absorption  in  this 
salt ;  the  thicker  crystals  alone  exhibit  it,  when  their  usual  tint 
becomes  darkened  on  analysis  with  a  Nichol. 
This  salt  requires  31  parts  of  boiling  spirit,  and  121  part 
