96 
Amount  of  Caffeine  in  Coffee. 
f  Am.  Jour.  Pharm. 
t       Feb.,  1887. 
samples  of  coffee  we  were  at  first  somewhat  perplexed  by  the  great 
discrepancy  of  the  published  statements  as  to  the  amount  of  this  con- 
stituent that  is  present,  as  will  be  seen  from  the  following  quota- 
tions : 
Caffeine  in  raw  coffee 
beans  per  cent. 
Robiquet   0'32  to  0'64 
Liebig   0"23  to  0  46 
Zenneck   0*75 
Graham,  Campbell  and  Stenhouse   0'88  to  1*00 
Dragendorff   0"99  to  1-22 
Squibb   l'OO  to  T03 
Bell   ro8torn 
Allen   0.50  to  2-00 
The  discrepancy  between  the  data  given  as  applying  to  roasted 
coffee  is  still  greater,  and  in  the  Allgemeine  Kaffee  Zeitung  for  1884 
the  amount  of  caffeine  in  roasted  coffee  is  stated  to  range  from  2*00 
to  3*64  per  cent. 
The  first  result  with  which  we  were  struck  on  carrying  out  a  number 
of  experiments  with  several  different  samples  of  raw  coffee  beans  was 
the  very  narrow  range  within  which  the  amount  of  caffeine  appeared 
to  vary.  Instead  of  being  a  varying  amount,  it  was  more  nearly  a 
constant  quantity  in  those  kinds  of  coffee  beans  we  had  an  opportunity 
of  examining,  which  were  the  following  : 
Caffeine 
per  cent. 
Coorg   riO 
Guatemala   1'18 
Travancore   1*16 
Liberian   1*20 
  1-28 
In  making  these  determinations  the  raw  coffee  berries  were  not 
dried,  but  taken  just  as  they  came  to  hand  and  powdered.  A  differ- 
ence in  the  amount  of  water  might  therefore  have  altered  the  amount 
of  caffeine  in  the  dry  material,  but  there  is  not  much  reason  for  ex- 
pecting that  the  foregoing  data  would  have  thus  been  materially  af- 
fected. It  would  be  desirable  to  extend  these  determinations  of  caf- 
feine to  a  number  of  other  samples  of  coffee  from  various  sources,  and 
it  is  to  a  great  extent  with  the  hope  of  obtaining  samples  for  examina- 
tion that  we  now  make  known  the  results  that  have  been  so  far  arrived 
at.  In  a  future  communication  we  propose  to  deal  with  the  determi- 
nation of  some  of  the  other  constituents  of  coffee. 
