518 
Quinine  and  Homoquinine. 
<  Am.  Jour  Pharm. 
\        Oct.,  1884. 
0'5  to  0*6  per  cent.  According  to  Whiffen  the  cuprea  bark  examined 
shortly  before  the  publication  referred  to  contained  01  to  0*8  percent, 
of  the  alkaloid,  and  he  believed  that  in  greater  or  less  quantity  it  was 
to  be  met  with  in  every  cuprea  bark.  Paul  and  Cownley  first  observed 
it  very  frequently  four  months  before  their  communication  (con- 
sequently first  in  August,  1881).  D.  Howard,  who  appears  not  to 
have  observed  it  so  frequently  as  Paul  and  Cownley,  states  that  the 
quantity  of  homoquinine  in  the  barks  in  question  amounted  to  about 
10  per  cent,  of  their  quinine  contents,  consequently  to  about  0'2  per 
cent.  Finally  to  complete  the  history  of  our  alkaloid  it  may  be  men- 
tioned that  Wood  and  Barret1  were  unable  to  observe  this  alkaloid  in 
several  hundred  specimens  of  cuprea  bark  which  they  examined  specially 
for  the  purpose,  and  they  believed  that  it  might  be  a  compound  of 
quinine  with  conchinine. 
With  respect  to  this  latter  point,  my  examination  of  the  alkaloid 
prepared  by  Tod,  as  well  as  of  some  kindly  supplied  to  me  by  Paul 
and  Cownley,  has  shown  that  this  material  is  free  from  conchinine. 
Moreover  the  statement  made  by  Whiffen,  as  well  as  those  of  Howard 
and  Hodgkin,  point  to  the  same  conclusion,  so  that  the  opinion  of 
Wood  and  Barret  referred  to  would  appear  to  be  without  support, 
quite  apart  from  the  fact  that  I  have  been  unable  to  obtain  any  such 
compound  of  quinine  and  conchinine  in  working  according  to  the  direc- 
tions originally  given  by  those  chemists. 
All  the  above-named  chemists  who  have  indicated  the  existence  of 
homoquinine  in  one  way  or  another  are  unanimous  that  the  alkaloid  in 
question  forms  with  sulphuric  acid  a  neutral  salt  rather  difficultly  solu- 
ble in  cold  water;  it  is  presumed  consequently  that  it  would  be 
necessarily  mixed  with  quinine  sulphate  prepared  from  the  particular 
bark,  since  it  would  not  be  separated  or  altered  in  any  way  during  the 
manufacture  of  quinine. 
According  to  my  experience  the  best  method  of  separating  homo- 
quinine from  such  a  mixture  is  by  dissolving  it  in  dilute  sulphuric 
acid,  precipitating  the  alkaloids  with  ammonia  and  at  once  shaking 
them  out  with  ether,  from  which  after  a  short  time  the  homoquinine 
separates  out  in  crystals.  The  crystallized  homoquinine,  after  being 
separated  as  completely  as  possible  from  the  mother-liquor,  is  redis- 
solved  in  dilute  sulphuric  acid,  and  again  precipitated  with  ammonia 
1  Chemical  News,  xlv,  6;  Am.  Jour.  Phar.,  1882,  75. 
