ON  THE  BERRIES  AND  BARK  OF  RHUS  GLABRUM. 
195 
Starch. — A  decoction  was  made  by  boiling  a  portion  of  the 
bark  in  water,  for  fifteen  minutes,  and  allowed  to  cool ;  to  the 
filtered  decoction  a  few  drops  of  tincture  of  iodine  were  added, 
which  produced  a  precipitate  characteristic  of  starch. 
Gallic  Acid. — An  infusion  was  made  with  cold  water,  and  de- 
prived of  its  tannin  by  means  of  gelatine,  filtered,  and  the  filtrate 
evaporated  to  an  extract.  This  was  treated  with  ether,  and  when 
the  ethereal  solution  was  allowed  to  evaporate  spontaneously,  it 
yielded  crystals  of  a  light  yellow  color,  which,  when  dissolved  in 
water,  gave  an  acid  reaction  with  litmus  paper ;  and  solution  of 
sesquisulphate  of  iron  added  to  it,  caused  a  greenish  black  colora- 
tion, entirely  dissipated  by  heat. 
Caoutchouc. — An  alcoholic  extract  was  made,  and  a  portion  of 
it  was  taken  and  rubbed  up  with  water,  giving  a  dark  and  opaque 
liquid;  this  was  then  filtered,  and  a  residue  was  left  on  the  filter, 
which  had  the  appearance  and  consistence  of  caoutchouc,  and  was 
entirely  soluble  in  recently  distilled  oil  of  turpentine. 
Soft  Resin — The  remainder  of  the  alcoholic  extract  was  treated 
with  ether,  and  the  ethereal  solution  shaken  up  with  water,  when 
a  light  gray  resinous  precipitate  was  thrown  down,  which  was 
acid  to  litmus  paper,  had  a  soft  consistence,  and  was  entirely 
soluble  in  solution  of  caustic  potash,  with  the  effect  of  neutralizing 
the  solution,  which  would  seem  to  indicate  an  acid  resin. 
Volatile  Oil. — Water  distilled  from  the  bark,  had  a  strong  dis- 
agreeable odor,  and  was  slightly  milky,  as  if  due  to  the  presence 
of  volatile  oil. 
Coloring  Matter. — The  bark  contains  a  small  portion  of  brown 
coloring  matter,  which  is  dissolved  out  by  both  alcohol  and  water. 
It  was  not  isolated. 
From  the  foregoing  experiments  the  bark  of  the  root  contains 
albumen,  gum,  starch,  tannic  acid,  gallic  acid,  caoutchouc,  soft 
resin,  coloring  matter,  and  probably  a  volatile  odorous  principle. 
Analysis  of  the  (rails. 
Sumach  galls  are  of  a  reddish  brown  color  externally,  grayish 
white  internally,  having  a  very  astringent  and  slightly  bitter 
taste,  and  vary  much  in  size  and  appearance,  being  generally 
very  irregular  in  their  outline,  hollow,  and  sometimes  consist  of 
a  mere  shell,  of  a  line  or  less  in  thickness. 
