348        MICROSCOPICAL  RESEARCHES  ON  THE  ALKALOIDS. 
surprise  if  a  sap-fluid  containing  eleven  or  twelve  parts  of  salts 
of  the  alkaloids  in  a  hundred  should  then  at  least  (if  not  even 
whilst  maturing  on  the  tree,)  betake  itself  to  crystallization. 
"  In  order  to  observe  these  perfectly,  I  found  it  necessary 
that  the  section  of  bark  should  not  be  too  thin,  as  otherwise  the 
action  of  the  caustic  would  be  too  powerful,  leaving  only  the  ul- 
timate structure  of  the  cellular  tissue.  I  compared  the  crystals 
with  those  of  Cinchonine,  Quinidine,  and  Cinchonidine ;  but  the 
character  of  the  decoction  of  the  bark  being  always  acid,  seemed 
to  forbid  the  expectation,  which  indeed  was  not  realized,  of  find- 
ing the  crystals  coincide  with  these.  At  length  it  occurred  to 
me  to  compare  the  crystallized  compound  of  quinine,  formed,  as 
I  have  mentioned,  under  the  head  0.  succirubra,  by  adding  qui- 
nine to  the  ethereal  solution  of  the  mother-substance  from  the 
heartwood  of  the  tree.  I  found  the  crystals,  which  under  some 
circumstances  this  compound  forms,  to  agree  exceedingly  well  with 
those  seen  in  the  bark.  The  feeble  amount  of  polarization  in  the 
two  was  a  point  of  coincidence  that  could  not  be  passed  over ; 
and  on  the  whole,  it  is  almost  certain  that  the  quinine  is  in  this 
state  of  combination  in  Red  Bark,  since  the  decoction  abandons, 
by  cooling,  a  deposit  in  which  I  have  ascertained  the  presence  of 
quinine,  cinchona-red,  and  kinovic  acid,  and  after  this  has  been 
deposited,  no  trace  appears  to  exist  of  kinate  of  quinine,  the  only 
other  probable  form. 
"  I  therefore  conclude  that  the  crystals  seen  in  the  bark-section 
are  Kinovate  of  Quinine,  rather  than  kinova-tannate  or  cincho- 
tannate,  since  the  cincho-tannic  acid  oxidises  off  into  cinchona- 
red,  and  leaves  the  quinine  in  combination  with  kinovic  acid,  as 
an  almost  colorless  salt,  such  as  is  seen  in  the  section"  (as  pub- 
lished in  the  "  Quinologia").  It  is,  however,  not  improbable  that 
the  cincho-tannic  acid,  during  its  oxidation,  facilitates  the  combi- 
nation ;  and  as  the  kinovic  acid  in  the  different  parts  of  the  plant 
holds  the  exactly  inverse  proportion  to  the  amount  of  alkaloid 
obtained,  it  is  difficult  to  avoid  the  presumption  that  the  elements 
of  kinovic  or  kinova-tannic  acid  in  conjunction  with  ammonia, 
which  is  always  present,  may  give  rise  to  the  alkaloids  in  the 
bark.* 
*  See,  as  above,  under  head  C.  magnifolia. 
