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ON  FERRATED  TINCTURE  OF  CINCHONA. 
ON  FERRATED  TINCTURE  OF  CINCHONA. 
By  Jno.  M.  Maisch. 
On  pages  193 — 197  of  this  volume  I  have  published  my 
observations  on  the  precipitates,  occurring  in  the  various  tinctures 
of  cinchona  bark,  prepared  with  diluted  alcohol.  It  is  evident 
that  such  tinctures  are  entirely  unsuited  for  the  preparation  of 
ferrated  tincture  of  bark,  and  the  following  experiments  were 
therefore  conducted  with  a  simple  tincture  of  calisaya  bark, 
obtained  by  percolation  with  alcohol  of  -877  spec.  grav.  This 
tincture  has  been  exposed  to  the  oxidizing  influence  of  atmos- 
pheric air  for  more  than  three  months,  care  being  taken  to 
prevent  the  evaporation  of  alcohol,  and  no  precipitate  has 
appeared  yet. 
Before  discussing  the  results  of  my  experiments,  it  will  be 
well  to  take  a  view  of  the  organic  constituents  of  bark,  those  of 
inorganic  nature  being  small,  not  exceeding  2J  per  cent.,  and 
mostly  insoluble  in  alcohol.  Besides  cellulose,  cinchona  bark 
contains  according  to  Dr.  E.  Reichardt,  alkaloids,  ammonia, 
kinic,  kinovic,  cinchotannic,  oxalic,  rufocinchotannic  and  humic 
acid,  sugar  and  wax.  Of  these  constituents  wax  and  humic 
acid  are  insoluble  in  alcohol  ;  oxalic  acid  is  combined  with  lime; 
sugar,  ammonia  and  kinovic  acid  are  not  important,  the  latter 
reaching  in  calisaya  bark  not  quite  -7  per  cent.  Only  the 
alkaloids  and  the  three  acids,  kinic,  cinchotannic  and  rufo- 
cinchotannic are  therefore  left. 
If  the  above  mentioned  tincture  of  bark  is  mixed  with  a 
solution  of  a  neutral  persalt  of  iron,  a  flocculent  or  voluminous 
precipitate  takes  place,  while  the  liquid  assumes  a  more  or  less 
inky  color.  The  precipitates  contain  besides  the  tannin  also 
kinic  acid,  while  a  small  portion  of  kinic  acid  remains  in  solution. 
Rufocinchotannic  acid  is  doubtless  precipitated  with  the  other ; 
but  its  quantity  in  calisaya  bark  is  insignificant,  reaching  only 
•722  per  cent.  No  alkaloids  are  found  in  the  precipitates  after 
they  have  been  washed  with  alcohol  of  -877. 
The  same  acids  are  found  in  the  residue  on  the  filter  after  the 
tincture  has  been  treated  with  freshly  precipitated  oxide  of  iron, 
but  a  larger  proportion  of  kinic  acid  remains  in  solution  and 
occasions  on  the  addition  of  a  neutral  ferric  salt  a  turbidity  and 
