oSoK'ig^o^'"'- }    Samples  of  ''Grey''  Cinchona  Bark.  733 
In  order  to  confirm  the  cinchonine  value,  the  separated  alka- 
loid was  examined  by  the  optical  test,  and  gave  exactly  the  correct 
value  for  a. 
The  bark  was  then  submitted  to  Mr.  E.  M.  Holmes  for  his 
opinion,  and  was  reported  as  Grey  Bark  of  Huanuco.  The  bulk 
of  the  sample  consisted  of  Cinchona  nitida  (Pereira,  "Mat.  Med.," 
Vol.  II,  Pt.  II,  p.  98,  fourth  edition)  and  Cinchona  Peruviana 
(J.  E.  Howard),  together  with  a  small  amount  of  Cinchona  officinalis. 
As  mentioned  above,  grey  bark  as  known  on  the  market  in  the  sixties 
and  seventies  usually  contained  the  first  two  varieties,  together 
with  Cinchona  micrantha,  which  was  absent  in  the  sample  under 
examination.  There  would  seem  to  have  been  some  doubt  in  the 
past  as  to  whether  or  not  the  Peruviana  of  J.  E.  Howard  was  identi- 
cal with  Cinchona  nitida  of  Ruiz  and  Planchon,  and  in  order  pos- 
sibly to  throw  some  light  on  this  point  the  first  two  varieties,  as 
sorted  out  of  the  bulk  sample  by  Mr.  Holmes,  were  again  examined 
analytically : 
Cinchona  Nitida. 
Per  Cent. 
Cinchona 
Peruviana, 
Per  Cent. 
0.28 
j  0.20 
*Cinchonine  Alkaloid  
  5 -08 
5-04 
Trace 
  0.82 
1.28 
Total  Alkaloid  
  6.10 
6.60 
*The  cinchonine  was  again  checked  by  optical  test,  and  gave  a  specific  rota- 
tion of  208°  and  212°,  respectively,  which  is  sufficiently  close  to  Allen's  figure  of 
226°  for  identification  purposes. 
The  average  of  two  tests  (6.35  per  cent.)  confirms  the  first  re- 
sult of  the  samples  as  a  whole  (6.302  per  cent.). 
From  the  analytical  point  of  view,  therefore,  the  alkaloidal 
contents  of  the  Peruviana  was  practically  identical  with  the  Nitida. 
It  therefore  remained  to  compare  the  two  barks,  microscopically, 
and  Mr.  Holmes  kindly  undertook  to  have  this  examination  carried 
out. 
The  authors  feel  that  they  cannot  do  better  than  give  this  re- 
port in  full: 
The  microscopic  examination  of  the  bark  indicates  that  it  is 
in  all  probability  a  form  of  Cinchona  Peruviana,  Howard,  remark- 
ably rich  in  cinchonine,  bearing  somewhat  the  same  relation  to  that 
species  that  Cinchona  Ledgeriana  does  to  Cinchona  Calisaya  Wedd. 
