Am.  Jour.  Pharna.  1 
May,  1914.  / 
Chemistry  of  a  Cup  of  Coffee. 
217 
the  "  grounds."  It  is  the  infusion  with  which  the  following  labora- 
tory notes  deal,  and  certain  fresh  indications,  we  believe,  have  been 
obtained  which  are  worth  presenting  in  view  of  their  medical  in- 
terest. The  story  is  far  from  complete,  but  there  are  interesting 
incidents  in  it  which,  as  far  as  it  goes,  are  worth  recording. 
A  Comparison  between  Coffee  and  Tea. 
From  a  pharmacological  or,  what  should  amount  to  the  same,  a 
dietetic  standpoint  tea  or  coffee  ought  in  certain  ways,  at  all  events, 
to  act  similarly,  since  both  contain  the  alkaloid  caffeine  which  has  a 
well-known  and  marked  effect  of  stimulation  upon  the  central 
nervous  system.  It  is  generally  admitted,  however,  that  the  two 
beverages,  though  having  one  thing  in  common,  afford  different 
results.  Tea,  it  is  well  to  point  out,  contains  a  much  larger  propor- 
tion of  the  alkaloid  than  coffee,  but  in  the  preparation  of  tea  in 
ordinary  domestic  practice  a  much  smaller  quantity  of  material  is 
used  than  is  the  case  with  coffee.  A  common  formula  enjoined  in 
the  making  of  tea  amounts  to  the  preparation  of  1.25  per  cent,  in- 
fusion of  the  leaf.  Similarly,  in  the  preparation  of  coffee  the  quan- 
tity of  coffee  usually  directed  to  be  used  signifies  a  6  per  cent,  decoc- 
tion. Since  tea  contains  from  3  to  4  per  cent,  of  caffeine,  and 
coffee  seldom  more  than  1  per  cent.,  it  follows  that  as  regards  this 
alkaloid  both  infusions  of  coffee  and  tea  made  on  common  domestic 
lines  will  contain  practically  the  same  amount  of  caffeine  volume  for 
volume  of  fluid.  The  inference  is  that  whether  it  be  a  cup  of  coffee 
or  of  tea,  the  dose  of  alkaloid  will  be  the  same.  But  according  to 
the  present  investigation  the  caffeine  in  coffee  infusion  has  quite 
different  associates  from  those  in  tea.  This  would  appear  to  be  the 
case,  inasmuch  as  while  little  caffeine  is  extracted  from  tea  by  cold 
water,  we  find  that  practically  the  whole  of  the  caffeine  in  coffee  is 
taken  out.  There  seems  to  be  little  doubt,  as  we  have  shown  in  pre- 
vious articles  upon  tea,1  that  the  caffeine  in  tea  is  for  the  most  part 
combined  with  tannin  in  the  form  of  caffeine  tannate,  which  is  not 
very  soluble  in  cold  water,  but  is  easily  soluble  in  hot  water.  We 
think  this  is  an  important  observation,  for  it  points  to  the  proba- 
bility of  caffeine  existing  in  coffee  in  a  quite  different  form  which  is 
1 "  The  Chemistry,  Physiology,  and  ^Esthetics  of  a  Cup  of  Tea,"  The 
Lancet,  Jan.  7th,  191 1,  and  Dec.  2nd,  191 1. 
