ON  THE  DRIED  COFFEE-LEAF  OF  SUMATRA. 
253 
so  characteristic  of  solutions  of  kinone.  Kinone  is  so  exceedingly 
soluble  in  water,  that  unless  a  considerable  amount  of  it  is  evolved, 
and  proper  precautions  are  employed,  a  deep-colored  solution  of 
it  only  is  obtained,  either  from  the  coffee-leaf,  the  berry  or  the 
leaves  of  the  holly.  The  comparatively  small  amount  of  the 
kinone  yielding  substance,  or  perhaps  we  should  say  substances, 
present  in  such  plants  as  the  privet,  the  oak,  &c.,  is  most  probably 
the  only  reason  why  crystals  of  kinone  have  not  likewise  been 
obtained  from  these  plants. 
In  order  to  assist  in  forming  an  estimate  of  the  comparative 
value  of  coffee-leaves  as  a  beverage  as  compared  with  the  bean,  I 
determined  the  amount  of  soluble  matter  which  each  of  them 
yielded  to  boiling  water.  6.048  grms.  of  dried  coffee-leaves  and 
6.038  grms.  of  roasted  and  ground  coffee-beans  were  repeatedly 
treated  with  precisely  similar  quanties  of  boiling  water,  till  the 
liquid  which  came  off  from  them  was  nearly  colorless.  The 
6.048  grms.  coffee  leaves  were  found  to  have  lost  2.348  grms.  — 
38.8  per  cent.,  while  the  6.038  grms.  roasted  coffee-beans  had 
lost  1.759  grms.  —  29.1  per  cent.  From  this  determination  it 
is  clear  that  coffee-leaves  yield  to  boiling  water  near  10  per  cent, 
more  soluble  matter  than  the  bean.  In  this  respect,  therefore, 
the  coffee-leaf  has  an  advantage  over  the  berry. 
So  far  as  regards  the  two  characteristic  principles  of  coffee, 
viz.,  caffeic  acid  and  theine  or  caffeine,  these  are  common  both 
to  the  leaf  and  to  the  bean,  the  leaf  being  decidedly  rich  in  both. 
In  other  respects,  however,  they  differ  considerably.  The  coffee- 
leaf  contains  some  tannin,  and  scarcely  any  sugar  or  fat.  The 
coffee-bean  contains  about  12  per  cent,  of  fat  and  "  8  per  cent, 
of  cane-sugar."    (See  Joint  Report.) 
So  far  as  I  can  judge,  the  infusion  of  the  coffee-leaf  has  a  much 
greater  resemblance  to  that  of  tea  than  to  a  decoction  of  the 
coffee-bean  ;  so  that  should  the  coffee-leaf  ever  come  into  general 
use  in  European  countries,  it  will  be  rather  as  a  substitute  for  tea 
than  for  coffee.  If  the  coffee-leaves  were  only  dried  at  a  some- 
what lower  and  better  regulated  temperature,  I  have  little  doubt 
that  they  would  yield  a  much  more  agreeable  beverage  than  can 
be  made  with  the  present  roughly-roasted  and  partially  empyreu- 
matized  product — Lond.  Pharm.  Jour.  Feb.  1854,  from  Philo- 
sophical Magazine. 
