Am.  Jour.  Pharm. 
Oct.,  1884. 
Quinine  and  Homoquinine. 
517 
cinchona  barks.1  The  possibility  is  not,  however,  excluded  that  the 
commercial  sulphate  obtained  from  cuprea  bark  may  contain  somewhat 
less  than  eight  molecules  of  water  of  crystallization,  not  only  because 
it  has  effloresced  more  or  less,  but  also  because  it  contains  an  admix- 
ture of  homoquinine. 
II.  Homoquinine. 
The  occurrence  in  cuprea  bark  of  a  special  alkaloid,  similar  in  many 
respects  to  quinine,  was  announced  simultaneously,  in  December,  1881, 
by  D.  Howard  and  Hoclgkin,  Paul  and  Cownley,  and  G.  Whiffen,2 
the  alkaloid  being  named  by  the  first  two  chemists  "  homoquinine," 
and  by  Whiffen  "  ultraquinine."  The  name  "  cupreine"  has  also  been 
suggested  for  it.  This  same  alkaloid  was  also  observed  by  one  of  my 
colleagues  a  year  earlier ;  but  he  considered  it  to  be  cinchonidine  until 
June,  1881,  when  he  became  aware  of  the  error. 
According  to  Tod  the  alkaloid  in  question  first  appeared  in  cuprea 
bark  in  September,  1880,  but  only  in  a  few  specimens  of  bark;  its 
occurrence  first  became  almost  general  in  May,  1881,  The  amount  of 
homoquinine  in  the  bark  in  many  cases  reached  0*3  per  cent.,  in  some 
1  With  respect  to  the  remark  of  Fliickiger  upon  this  salt  ("  Die  China- 
rinden,"  1883,  p.  55),  that  "  it  is  not  established  whether  this  salt  contains 
seven  or  eight  molecules  of  water  of  crystallization,  or  possibly  a  quantity 
lying  between  the  two,"  I  may  say  that  more  than  twenty  years  since 
(Annalen,  cxix,  361)  it  was  shown  by  Jobst  and  myself  that  the  formula 
(CMH24N202)2,  S04H2+7H20,  for  quinine  sulphate,  is  incorrect.  On  the 
other  hand,  it  is  not  so  easy  to  say  whether  the  sulphate  in  question  con- 
tains seven  and  a  half  or  eight  molecules  of  H2  O.  A  series  of  experiments, 
however,  carried  out  by  me  with  every  precaution,  showed  that  pure  un- 
effloresced  sulphate  may  actually  contain  eight  molecules  of  water  of  crystal- 
lization. In  that  case  the  formula  attributed  to  quinine  sulphate  by 
Robiquet  about  fifty  years  ago  would  be  correct. 
Undoubtedly  the  commercial  sulphate  may  contain  generally  less  watei 
than  is  required  by  the  formula  (C20H24N2O2)2,SO4H2H-8H2O,  and  for  this 
reason,  that  in  manufacturing  operations  it  is  almost  impossible  to  prepare 
it  dry  and  avoid  at  the  same  time  the  occurrence  of  a  partial  efflorescence 
of  the  salt.  Quite  apart  'from  the  fact  that  in  certain  quarters  a  smaller 
amount  of  water  (for  instance,  14*4  per  cent.)  in  quinine  sulphate  is  re- 
quired, it  should  not  be  overlooked  that  a  commercial  sulphate  correspond- 
ing to  the  legally  prescribed  tests  of  the  German  Pharmacopoeia  may  some- 
times contain  quite  a  considerable  quantity  of  .cinchonidine  sulphate  (An- 
nalen,  ccv,  222),  upon  which  a  deficiency  in  water  of  crystallization  may 
equally  depend. 
2  Pharm.  Journ.,  [3],  xii,  497,  528,  565;  Am.  Jour.  Phar.,  1882,  75. 
