Arosept'  i8«)!'rnQ'}     Quinine,  Cinclionidine  and  Isomers.  453 
the  uncorrected  melting  point  of  cinchonidine  determined  according 
to  the  method  then  adopted,  while  Skraupand  Vortmann  give  210-5° 
as  the  corrected  melting  point  of  their  cinchonidine  that  was  in 
fact  homocinchonidine.  In  several  handbooks  both  substances  have, 
in  consequence  of  the  statement  of  Skraup,  de  Vrij  and  others,  been 
confused  together  under  the  name  of  cinchonidine,  and  thus  there 
have  naturally  been  great  differences  between  the  statements  as  to 
melting  point.  Dr.  Hesse,  however,  disclaims  responsibility  for 
these  discrepancies,  since  he  has  repeatedly  insisted  upon  the  differ- 
ence between  the  two  bases  and  their  melting  points. 
The  above-described  conversion  of  cinchonidine  into  homocin- 
chonidine calls  to  mind  the  ^3-cinchonidine  which  Dr.  Hesse  obtained 
under  similar  conditions  from  cinchonidine  by  means  of  hydrochloric 
acid.  It  had  a  melting  point  from  206°  to  207°  C,  but  then  became 
brown,  polarized  in  acid  solution  rather  more  strongly  than  homo- 
cinchonidine, and  gave  a  neutral  sulphate  having  great  similarity  to 
homocinchonidine  sulphate,  but  much  more  soluble  in  water  than 
it  is.  A  small  quantity  of  this  base  that  still  remains  has  meanwhile 
become  yellow-colored.  Both  cinchonidine  and  homocinchonidine 
prepared  at  the  same  period  have  remained  for  ten  years  quite 
colorless ;  and  it  is  therefore  probable  that  the  discoloration  was  due 
to  some  admixture  which  was  not  removed.  Lenz  also  observed 
that  his  cinchonidine  became  somewhat  brown  on  melting,  though 
this  is  never  the  case  with  the  pure  base.  If  the  above-mentioned 
j§-cinchonidine  was,  as  Dr.  Hesse  conjectures,  chiefly  homocinchon- 
idine, it  would  be  possible  to  reconvert  it  into  cinchonidine  as 
already  described,  and  that  was  found  to  be  the  case,  nearly  three- 
fourths  of  the  substance  separating  in  the  form  of  tetrasulphate, 
which  could  easily  be  recognized  as  a  cinchonidine  salt.  From  this 
observation  it  must  therefore  be  inferred  that  by  heating  cinchon- 
idine with  hydrochloric  acid  of  1-125  SP-  gr-  to  I4°°  C.  the  base  is 
at  first  converted  into  homocinchonidine,  which  is  then  further 
changed  into  apocinchonidine.  When  sulphuric  acid  of  the  suitable 
strength  is  used  this  alteration  does  not  proceed  beyond  the  first 
stage. 
The  behavior  of  these  bases  strikingly  recalls  that  of  the  mutually 
convertible  bromtetraethyl  pholoroglucines  which  Hirzig  and  Zeisel 
obtained  by  the  action  of  bromine  upon  tetraethyl  phloroglucine. 
