5io  Poison  Sumac.  {^2S£w? 
far  exceeding  that  of  acacia.  Its  aqueous  solution  rapidly  changes 
freshly  prepared  tincture  of  guaiac  to  a  deep  blue  color ;  with 
naphthol  it  produces  a  purplish-blue  color,  and  with  guaiacol  a  red 
color  in  30  minutes  ;  no  effect  was  produced  with  vanillin  and  hy- 
drochloric acid.  An  aqueous  solution  of  the  gum-enzyme  does  not 
convert  starch  paste  into  reducing  sugars  even  by  standing  at  400 
for  96  hours.  An  emulsion  prepared  from  the  gum-enzyme,  water 
and  the  separated  resins,  blackens  on  standing  like  the  fresh  lac. 
An  aqueous  solution  of  the  gum-enzyme  is  rendered  inactive  by 
boiling,  though  the  fresh  lac  may  be  boiled  in  95  per  cent,  alcohol 
for  twenty  minutes  without  becoming  completely  inactive.  By 
boiling  for  eight  hours  with  2  per  cent,  sulphuric  acid  the  purified 
gum  yields  a  non-crystallizable,  non-fermentable,  dextro-rotatory 
sugar,  which  reduces  Fehling's  solution,  but  has  no  effect  on  Bar- 
fold's  solution  of  cupric  acetate.  The  purified  gum  contained 
appreciable  quantities  of  nitrogen,  which  could  not  be  removed  by 
repeated  precipitations  with  alcohol. 
It  was  found  that  the  portion  insoluble  in  water  could  not  be  com- 
pletely freed  from  gumming  or  mucilaginous  matters  even  by 
repeatedly  triturating  with  cold  water  or  by  long-continued  boiling 
with  the  same  solvent.  After  the  most  thorough  washing  with 
water  the  insoluble  residue  (if  unboiled)  still  produced  a  blue  color 
when  kept  for  several  hours  in  contact  with  water  to  which  a  few 
drops  of  tincture  of  guaiac  have  been  added.  It  was  of  a  rich, 
chocolate-brown  color,  odorless  and  tasteless.  When  boiled  for  five 
hours  with  2  per  cent,  sulphuric  acid  it  yielded  only  the  merest 
traces  of  reducing  sugars  without  appreciable  change  in  bulk. 
Probably  these  traces  of  sugar  were  derived  from  minute  quantities  of 
gummy  matters  remaining  in  the  sample,  which  had  failed  to  be 
removed  by  previous  boiling  and  washing  with  water.  When  exam- 
ined by  the  Lassaigne  test  and  by  the  Kjeldahl  quantitative  method 
the  substance  was  found  to  be  rich  in  nitrogen.  When  boiled  with 
dilute  potassium  hydroxide  it  darkened,  forming  a  hard,  brown-black 
substance  which  could  not  be  powdered  readily.  Neither  the  gum 
nor  the  portion  insoluble  in  water  was  poisonous. 
CRUDE  RESINS. 
On  evaporation  the  alcoholic  filtrate  from  the  lac  gave  a  dark, 
amber-red,  oily,  non-volatile  liquid,  having  a  peculiar,  not  unpleasant 
