VARIETIES. 
373 
2-62;  in  sample  3,  raw,  2-53,  roasted,  2-70 ;  in  sample  4,  raw,  2-71 ;  in 
simple  5,  raw,  2-50,  roasted,  2-49,  The  proportion  of  nitrogen  in  roasted 
coffee  appears  therefore  to  lie  between  two  and  a  half  and  three  per  cent. 
The  nitrogen  in  a  specimen  of  foreign  chicory  amounted  in  the  raw 
chicory,  to  1*51  per  cent. ;  in  the  same  roasted,  1-42  per  cent.  The  same 
of  English  growth  gave,  in  the  raw  state,  1*86  per  cent,  of  nitrogen  ;  and 
in  the  roasted  state,  1*74  per  cent. 
The  proportion  of  nitrogen  in  coffee  is  therefore  greater  than  in  chicory  ; 
but  the  difference  is  not  sufficiently  marked  to  distinguish  the  two  sub- 
stances easily  from  each  other.  The  conclusion  may,  however,  be  drawn, 
that  less  than  two  per  cent,  of  nitrogen  in  coffee  is  a  strong  presumption  of 
adulteration. 
We  may  now  advert  to  the  peculiar  and  characteristic  substances 
found  in  coffee,  and  the  aid  to  be  derived  from  them  in  the  discovery  of 
adulteration. 
Professor  Rochleder,  who  has  devoted  great  attention  to  the  analysis  of 
coffee,  gives  the  following  enumeration  of  the  substances  found  in  the  raw 
coffee-bean,  with  the  formula?  of  their  elementary  composition  : — 
C. 
H. 
0. 
Woody  fibre 
12 
10 
10 
Cane-sugar  . 
12 
11 
11 
C  Palmitic  acid 
32 
32 
4 
Fat  <  Oleic  acid 
36 
34 
4 
(  Glycerine 
6 
8 
6 
Legumin 
48 
36 
14 
Caffeic  acid  . 
16 
7 
6 
Caffeine       .  , 
16 
10 
4 
N. 
To  these  Rochleder  had  lately  added  citric  acid  (C12H5  On-|-3HO),  in 
the  small  proportion  of  two  grains  in  a  pound  of  coffee  ;  also  a  trace,  too 
small  to  be  estimated  by  weight,  of  viridic  acid  (C14H6  07  ).  This  last 
substance  is  the  acid  obtained  by  exposing  solutions  of  the  neutral  and 
basic  caffeates  to  the  influence  of  the  air.  The  green  color  of  raw  coffee 
is  believed  by  Rochleder  to  be  owing  to  a  small  quantity  of  viridate  of 
lime. 
The  evidence  upon  which  Rochleder  rests  the  existence  of  palmitic  and 
citric  acids  in  coffee  does  not  appear  to  us  quite  decisive.  The  formula? 
given  by  that  chemist  for  both  caffeic  and  viridic  acids  are  doubtful. 
It  is  also  stated  by  Rochleder,  that  when  dried  caffeic  acid  is  submitted 
to  destructive  distillation,  a  small  quantity  of  crystals  were  obtained,  which 
he  considered  to  be  pyrocatechine.  The  experiment  repeated  by  us  on  a 
considerable  scale  gave  a  negative  result. 
Rochleder  finds  caffeic  acid  in  Paraguay  tea  (Ilex  Paraguayensis^  as 
well  as  in  coffee.  This  statement  we  must  also  doubt.  The  acid  of  the 
Paraguay  tea  has  been  examined  by  us,  and  found  to  have  a  certain  re- 
semblance to  caffeic  acid,  but  not  to  be  identical  with  it.    Free  caffeic 
