An.  Jour  Pharm.,1.      Extmdion  of  AJkaloids  fvom  Cinchona.  623 
Dec,  1883.       j  J  ^ 
consider  the  influence  of  quantity  in  chemical  reactions  (I'influence  des 
masses),  as  propounded  by  Berthollet  in  his  "Stalique  Chimique/'  the 
necessity  for  a  preponderating  quantity  of  acid  will  require  no  further 
demonstration. 
A  series  of  observations  on  bark  of  C.  officinalis  and  succirubra 
showed  that  four  molecules  of  HCl  (4x36-6)  sufficed  for  one  mole- 
cule of  total  alkaloids,  of  which  the  molecular  weight  may  be  taken 
to  be  310.  Supposing,  therefore,  that  the  total  alkaloids  of  the  bark 
to  be  operated  upon  do  not  exceed  10  per  cent.,  17  grammes  of  strong 
HCl,  containing  30  per  cent,  of  real  HCl,  will  be  sufficient  for  the 
complete  extraction  of  100  grammes  of  finely-powdered  bark.  Mere 
acid  must  be  used  in  those  rare  cases  in  which  the  alkaloids  exceed  10 
per  cent. 
The  method  of  applying  the  quantity  of  acid  thus  determined  is 
also  important  to  the  success  of  the  operation.  The  acid  should  be 
mixed  with  a  portion  of  water  equal  to  the  quantity  of  bark,  and  the 
bark  should  then  be  added  so  as  to  form  a  thick  paste,  which  is  to  be  left 
for  some  hours.  More  water  is  then  stirred  in  until  the  whole  is  suffi- 
ciently fluid  to  pour  freely.  Much  foan:i  is  formed  at  this  stage,  and 
it  is  necessary  to  postpone  the  next  operation  until  the  foam  has 
entirely  disappeared.  Percolation  is  then  efi^ected  in  a  cylindrical  glass 
tube  with  constricted  exit,  which  is  closed  by  a  loose  plug  of 
^^charpie."  ^  As  soon  as  the  percolate  begins  to  run  clear  it  is 
collected,  percolation  being  kept  up  by  pouring  on  distilled  water 
until  excess  of  caustic  soda  ceases  to  produce  a  precipitate  in  the 
passing  percolate. 
I  must  now  allude  to  two  matters,  one  of  which  has  been  publicly 
advanced  as  an  objection  to  the  above  process,  whilst  the  other  has 
been  communicated  to  me  privately. 
J .  It  has  been  objected  that  after  the  percolate,  as  above,  has  ceased 
to  be  acted  upon  by  caustic  soda,  the  addition  of  the  well-known 
reagent  iodide  of  mercury  and  potassium  shows  a  distinct  alkaloidal 
reaction,  and  percolation  must  be  carried  much  farther  before  this 
reaction  ceases.  Although  not  myself  attaching  importance  to  this 
objection,  I  have  thought  it  right  to  ascertain  by  actual  experiment 
i"Charpie"  is  the  French  name  for  threads  of  old  linen.  Upon  this 
apparently  insignificant  agent  the  success  of  the  operation  largely  depends, 
whether  it  shall  be  completed  in  a  few  hours,  or  whether  it  may  be 
prolonged  for  days. 
