2l8 
Proximate  Analysis  of  Plants. 
Am.  Jour.  Pharm, 
April  1880. 
Stance  In  a  flask  or  graduated  cylinder,  and  then  adding  a  measured  volume  of  cold 
water.  Allow  to  macerate,  with  frequent  agitation,  for  from  6  to  iz  hour.s,  then- 
filter  through  fine  washed  linen,  and  evaporate  an  aliquot  portion  of  the  solution. 
In  this  residue  determine  total  organic  matter  and  ash.  This  residue  usually  con- 
tains little  but  gum  ,•  in  analysis  of  fruits  and  fleshy  roots  pectin  bodies^  salts  of  organic 
acids,  rarely  a  substance  resembling  dextrin,  and  small  amounts  of  albuminous  sub- 
stances and  coloring  matter.  Usually  the  separation  of  these  substances  is  very  diffi- 
cult. The  unevaporated  liquid  should  be  used  for  such  qualitative  reactions  as  are 
necessary  to  show  the  nature  of  the  substances  extracted.  The  insoluble  residue 
should  be  well  washed  with  water,  transferred  to  a  crucible,  and  completely  dried 
atiio^C.    This  residue  should  be  then  weighed. 
VIII.  Estimation  of  Acid  Extracts. 
The  dried  residue  insoluble  in  cold  water  should  be  transferred  to  a  beaker  con- 
taining 500  cc.  of  water  and  5  cc.  of  concentrated  sulphuric  acid  (sp.  gr.  i"84). 
Boil  for  6  hours,  on  a  gauze  support,  adding  water  to  keep  the  volume  of  liquid 
unchanged  5  if  the  substance  be  very  starchy  a  longer  boiling  may  be  necessary. 
This  treatment  will  convert  starch  and  its  amorphous  isomers  to  dextro  glucose,  and 
will  occasionally  remove  some  salt  of  an  organic  acid,  with  usually  traces  of  albu- 
minous and  indeterminate  substances. 
The  total  amount  extracted  may  be  found  by  washing,  drying  at  iio°C.,  and 
weighing  the  yet  insoluble  residue,  and  subtracting  the  weight  from  the  one  taken 
after  extracting- with  cold  water.  The  amount  of  starch  and  isomers'  may  be  found 
by  determining  in  a  given  valume  of  the  acid  filtrate  the  amount  of  glucose,  using 
Fehling's  solution  ;  the  glucose  thus  found  multiplied  by  "9  equals  starch  and  iso- 
mers. The  total  extract  minus  starch  and  isomers  equals  acid  extract  not  starch. 
This  includes  a  small  amount  of  ash,  which  may  be  approximately  determined  by 
evaporating  and  igniting  a  known  volume  of  the  solution. 
Where  it  is  wished  to  separate  the  extracted  matter  from  the  sulphuric  acid,  boil 
the  liquid  with  an  excess  of  powdered  barium  carbonate  until  no  acid  reaction 
remains.  Filter  and  evaporate  to  dryness.  The  residue  consists  chiefly  of  hydiated 
dextro  glucose  (CgH^,Og.H.,0),  with  some  ash. 
IX.  Estimation  of  Alkali  Extract. 
Wash  well  and  dry  at  iio°C.  the  lesidue  from  treatment  with  acid,  and  record  its 
weight.  Boil  this  residue  for  two  hours  with  500  cc.  of  a  solution  containing  20 
grams  of  sodic  hydrate  to  the  liter.  Filter  through  fine  washed  linen,  and  wash  the 
residue  thoroughly  with  hot  water,  alcohol  and  ether.  Transfer  it  to  a  weighed 
crucible,  dry  at  no  to  120'^C.,  and  weigh  the  residue  as  crude  fibre  and  ash  ^  this 
weight  subtracted  from  the  previous  one  shows  the  total  alkali  extract.  This  extract 
is  largely  alhuminous  matter  and  various  modifications  oi  pectic  acid,  Fremy's  '•'■cutose^ 
and  various  coloring,  humus  and  decomposition  compounds  in  small  amounts.  Most  of 
the  extracted  substances  may  be  precipitated  by  excess  of  an  acid  with  or  withou 
the  presence  of  alcohol. 
X.  Cellulose. 
The  crude  fibre  from  IX  should  be  treated  with  from  50  to  100  c.  c.  of  U.  S.  P 
solution  of  chlorinated  soda  and  allowed  to  stand  twenty-four  hours.  If  not  ther 
bleached  white,  slightly  acidulate  with  hydrochloric  acid  and  set  aside  for  anothe 
