AMAugUi,iP8?tRM }   ^nls  Venenata,  or  Poison  Sumach.  355 
tained  above,  and  the  result  is,  approximately,  the  weight  of  resin  in 
forty  grams.  Divide  by  four,  and  the  quotient  is  the  weight  of  resin 
(approximate). 
(3).  Find  fusing  point  of  fatty  acids. 
d.  Take  ten  grams,  dissolve  in  alcohol,  add  alcoholic  solution  of 
sulphuric  acid  until  precipitation  ceases,  and  filter.  Add  baric  car- 
bonate and  filter  again.  Evaporate  until  the  alcohol  is  all  expelled, 
and  weigh  sweet  residue  as  glycerin. 
e.  Add  together  the  amount  found  of  carbonate,  salts  and  foreign 
matter,  alkali  (free),  alkali  (combined),  fatty  acids,  resin,  glycerin, 
and  the  difference  between  that  sum  and  ten  grams  is  the  weight  of 
water. 
University  of  3fic1iigan,  June,  1874, 
EHUS  VENENATA,  OR  POISON  SUMACH— DESCRIPTION  AN  I) 
PARTIAL  ANALYSIS. 
By  Robert  M.  Cotton. 
This  is  a  low,  smooth,  branching  shrub,  growing  from  six  to  eighteen 
feet  high,  and  always  inhabiting  swamps,  especially  tamarack  swamps. 
Its  leaves  are  compound,  dotless,  alternate,  odd  pinnate  and  stipulate, 
with  from  seven  to  thirteen  obovate-oblong,  entire  leaflets.  It  is  most 
widely  known  under  the  common  name  of  poison  sumach,  though,  in 
some  localities,  it  is  known  as  poison  elder. 
It  is  not  necessary  to  give  the  details  of  the  analysis,  as  Rochie- 
der's  process  for  the  analysis  of  plants  was  quite  closely  followed. 
It  is  sufficient  to  say  that  an  acid  was  obtained  from  the  decoction, 
which  remained  after  subjecting  a  quantity  of  the  powdered  leaves 
to  distillation  for  several  days.  This  acid  crystallizes  in  congregated 
clusters  of  minute,  transparent,  triangular  prisms  ;  non-volatile  and 
decomposed  by  a  high  temperature.  The  water  solution  of  these 
crystals  has  a  moderately  sour  taste,  and  reddens  blue  litmus  quite 
distinctly.  With  neutral  acetate  of  lead,  it  gives  a  white,  flocculent 
precipitate  ;  with  chloride  of  barium,  a  white,  granular  precipitate, 
which  is  increased  in  amount  by  heat ;  with  calcic  hydrate  a  white 
precipitate  is  produced  after  standing  a  short  time.  A  large  number 
of  other  reagents  were  added,  such  as  nitrate  of  silver,  phosphate  of 
magnesium,  chloride  of  mercury,  etc.,'  without  producing  any  precipi- 
tates. 
