524 
Quinine  and- Homoquinine. 
Am.  Jour.  Pharm. 
Oct.,  1884. 
In  other  respects  also  no  difference  could  be  recognized  from  the 
known  pure  sulphate. 
IV.  Concluding  Remarks. 
The  foregoing  results  justify  the  conclusion  that  Barret  and  Wood 
in  their  investigation  converted  the  homoquinine  into  quinine  and  that 
it  thus  escaped  observation  by  them.  I  myself  also  had  previously 
fruitlessly  endeavored  to  prepare  the  alkaloid  in  question  from  cuprea 
bark.  It  was  only  after  a  series  of  English  chemists  had  simulta- 
neously affirmed  the  existence  of  homoquinine  that  I  felt  I  ought  to 
drop  my  doubts  as  to  the  peculiarity  of  the  alkaloid,  which  was  at  any 
rate  first  prepared  by  Tod ;  but  up  to  that  time  I  had  considered  the 
substance  in  question  to  be  none  other  than  crystallized  quinine. 
Upon  the  grounds  stated  my  original  opinion  as  to  the  nature  of 
this  substance  might  still  be  correct.  It  is  true  that  at  present  I  have 
not  yet  succeeded  in  preparing  homoquinine  from  cinchona  bark,  and 
it  may  be  there  is  no  present  prospect  that  it  is  obtainable  from  that 
bark,  so  that  this  substance  may  still  pass  as  characteristic  of  the 
Remijia  pedunculata,  which  yields  the  cuprea  bark.  But  I  might 
maintain  to  the  contrary  that  I  formerly  had  the  opportunity  of  being 
able  to  point  out  that  quinine  under  certain  conditions  would  become 
modified,  in  that  it  passed  into  the  anhydride,  and  that  this  substance 
also  behaved  as  a  special  alkaloid.  At  that  time  also  I  succeeded  in 
reconverting  this  substance  into  ordinary  quinine  through  prolonged 
treatment  with  dilute  sulphuric  acid,  though  not  through  precipitation 
wTith  soda  lye.1 
Besides  this  modification  of  quinine  there  exists  at  least  one  more, 
which  forms  with  sulphuric  acid  a  neutral  sulphate  that  separates  from 
a  hot  aqueous  solution  as  a  jelly,  only  subsequently  assuming  a  crys- 
talline form,2  I  was  formerly  inclined  to  place  this  peculiarity  of  the 
sulphate  in  question  to  the  account  of  a  coloring  substance,  concerning 
which  not  much  was  known.  Nevertheless,  exactly  those  solutions 
from  which  quinine  sulphate  separates  at  first  in  a  gelatinous  form  are 
so  very  little  colored  that  the  cause  of  the  gelatinization  might  far 
rather  be  sought  in  the  absence  of  coloring  matter.  I  may  also  add 
that  in  the  cases  mentioned,  if  the  alkaloid  be  taken  up  in  ether,  the 
ethereal  solution  gelatinizes  relatively  easy.    These  peculiarities  of  the 
1  Annalen,  clxxxvi,  207. 
2  Annalen,  clxvi,  262. 
