EXAMINATION  OF  KINO. 
543 
alone  appearing  to  be  oxidized.  The  opinion  that  the  red  color- 
ing matter  is  a  product  of  the  alteration  of  the  tannic  acid,  is  ren- 
dered improbable  by  the  action  of  sulphurous  acid,  which  gives  to 
the  aqueous  infusion  a  yellow  color,  although  the  red  substance  is 
not  converted  into  anything  resembling  tannic  acid,  but  is  partial- 
ly precipitated  in  the  form  of  orange-colored  flocks,  which  redis- 
solve  in  alkalies  with  a  red  color;  the  tannic  acid  gave  the  same 
reactions  as  before,  and  in  the  evaporated  liquid  crystals  of  the 
sulphate  of  the  alkali  used  w7ere  formed.  Moist  chlorine  behaved 
in  a  similar  manner,  with  the  exception  that  the  yellow  precipitate 
floated  in  a  colorless  liquid,  and  the  tannic  acid  itself  appeared  to 
be  altered. 
The  products  obtained  by  the  action  of  caustic  potash  upon  raw 
kino,  and  those  obtained  by  treating  the  powdered  gum  with  hy- 
drochloric acid  for  the  purpose  of  separating  the  earthy  bases, 
were  submitted  to  analyses  and  found  to  correspond  closely  with 
the  substance  called  kino  red  by  Gerding. 
Strong  nitric  acid  decomposes  all  the  constituents  of  kino,  espe- 
cially when  heat  is  applied  ;  nitric  oxide  and  hydrocyanic  acid  are 
evolved;  and  the  liquid  contains  nitropikric  acid  and  oxalic  acid. 
Hennig  attempted  to  separate  the  tannic  acid  of  kino  by  taking 
advantage  of  the  fact  that  ordinary  tannic  acid  is  dissolved  by  ace- 
tic acid,  and  remains  in  solution  even  on  the  addition  of  water, 
while  the  red  substance  of  kino  is  at  first  completely  precipitated 
on  diluting  the  solution  in  acetic  acid  with  water.  Raw  kino  in 
fine  powder  was  digested  for  some  days  with  concentrated  acetic 
acid,  the  liquid  evaporated,  and  the  residue  digested  with  very  cold 
water  until  it  began  to  acquire  color.  The  product  obtained  in  this 
way  was,  however,  too  small. 
The  fractional  precipitation  of  the  solution  of  kino  by  means  of 
metallic  salts,  especially  acetate  of  lead,  yielded  larger  quantities  of 
tolerably  pure  tannic  acid.  This  salt  first  combines,  apparently 
in  substance,  with  the  "  kino  red  ;"  subsequent  precipitates  al- 
ways contain  larger  percentages  of  lead  and  larger  quantities  of 
tannic  acid,  but  the  acetic  acid  set  free  somewhat  disturbs  the  re- 
sult. For  the  reason  the  aqueous  infusion  of  kino  was  treated 
with  successive  portions  of  hydrated  oxide  of  lead,  but  still  the  tan- 
nic acid  obtained,  though  large  in  quantity,  was  impure.  Finally, 
Hennig  found  that  the  most  advantageous  process  was  to  precipi- 
