TESTS  FOR  THE  CINCHONA-ALKALOIDS. 
341 
statements  about  the  origin  of  the  barks,  which  was  scarcely  pos- 
sible. All  my  experiments  refer  only  to  commercial  barks,  by  the 
names  under  which  they  occur  in  commerce,  and  I  have  described 
their  physical  characters.  Weddell,  on  the  other  hand,  had  quite 
another  object  in  view,  namely,  the  origin  of  the  barks;  and  he  made 
no  comparative  chemical  investigations  of  them.  Nevertheless, 
he,  like  his  predecessors,  has  left  us  in  uncertainty  about  the  origin 
of  many  commercial  barks  ;  for  I  can  never  persuade  myself  that 
Loxa  bark  and  the  woody  Carthagena  bark  are  derived  from  the 
same  mother-plant,  Cinchona  condaminea  ;  and  every  one  who 
knows  and  has  chemically  examined  both  barks,  will  perfectly 
agree  with  me. 
We  ought,  therefore,  while  fully  acknowledging  Weddell's 
merits,  not  to  overlook  the  difficulties  of  the  subject.  It  would 
be  unjust  to  expect  that  a  traveller  struggling  with  hardships  of 
every  kind  should  perform  chemical  experiments  on  the  spot. 
This  would  be  contrary  to  the  purpose  of  so  great  an  undertaking. 
My  object  has  hitherto  been  to  arrange  the  commercial  barks 
according  to  the  specific  proportion  of  alkaloid  which  they  con- 
tain, as  I  have  already  done,  in  a  small  treatise. 
There  is  indeed  nothing  that  could  materially  obstruct  such 
an  arrangement,  especially  as  by  the  discovery  of  the  kinates 
we  are  enabled  easily  to  distinguish  similar  spurious  barks  from 
genuine  ones,  whilst  every  uncertainty  may  be  removed  by  one 
single  experiment.  Discrepancies  like  that  which  Reigel  has 
noticed  with  regard  to  the  chemical  constitution  of  Pitaya  or  bi- 
colorata  bark,  depend  on  the  mistaking  of  one  bark  for  another, 
which  frequently  arises  from  the  employment  of  erroneous  names. 
The  bark  which  Peretti  examined  as  Cinchona  bicolorata,  cannot 
be  identical  with  that  whose  alkaloid  richness,  Muratori  deter- 
mined. According  to  Peretti,  and  his  experiments  agree  with 
mine,  the  bark  which  he  examined  contained  a  peculiar,  amor- 
phous, uncrystallizable  alkaloid  (Peretti's  Pittayin}  and  is 
decidedly  no  cinchona. 
As  regards  the  testing  of  cinchona  barks  for  the  alkaloids,  no 
notice  has  hitherto  been  taken  of  the  proportion  of  kinovic  acid, 
but  as  the  very  bitter  taste  of  the  spurious  cinchona  barks  depends 
exclusively  on  this  acid,  and  in  some  of  the  genuine  barks  kinovic 
acid  is  found,  a  mistake  may  be  easily  made  by  the  taste.  I  have 
