2 1 4  Proximate  Analysis  of  Plants,       { ^%J°iK  xs^so""" 
through  paper.  The  filtrate  should  be  tested  for  alkaloids  ?iX\d  glucosides.  The 
amount  extracted  by  acid,  if  any,  may  be  determined  by  weighing  the  still  undis- 
solved residue.  Treat  this  residue  with  several  considerable  portions  of  eighty  per 
cent,  alcohol  (sp.  gr.  "8483  at  i5'6°C.),  allowing  at  least  an  hour  for  each  treatment. 
Filter  through  paper  and  determine  by  evaporation  the  matter  dissolved  ;  this  usu- 
ally consists  of  chlorophyll  with  one  or  more  resins,  which  may  sometimes  be  sepa- 
rated by  use  of  petroleum  naphtha,  chloroform  or  similar  solvents  Purified  animal 
charcoal  removes  chlorophyll  and  some  resins  from  alcoholic  solution,  while  certain 
other  resins  are  not  removed,  camphors  wqvq  present  in  the  plant,  the  greater 
portion  will  be  found  in  the  alcoholic  liquid. 
The  substances  undissolved  by  eighty  per  cent,  alcohol  may  be  fixed  oil,  solid  fat, 
ivax,  and  very  rarely  a  resin  :  their  separation  may  be  attempted  by  refrigeration  and 
pressure,  or  by  use  of  ether,  chloroform,  etc. 
Recapitulation. 
1.  Loss  by  evaporation,  with  precautions  :  volatile  oil. 
2.  Soluble  in  water:  alkaloids,  glucosides,  organic  acids. 
f  Insoluble  in  water.         1        ah   1  •  1  -i  1      /      ■  i 
3.  ■{  o  1  ui    •    j-i  .       -J     \    '•  Alkaloids,  y^os.'ivoi'Sf  plucosides. 
^     y  Soluble  m  dilute  acids,  j  »  r         j  6 
f  T      ,  ,  ,    .        ,  1  (Removed  by  animal  charcoal  r 
Insoluble  in  water:  \  a.      \       11     ^1  ,1 
T      I  ,  ,    .       -  ,  '  [     chlorophyll,  some  resins. 
4.  Insoluble  in  acids.  \  :  y  •  1         •     1  u 
c  1  ui    •    o  .111  /        S  Not  removed  by  animal  char- 
Soluble  in  80  per  cent,  alcohol.     \      b.      <  ^  • 
1^  *  J  (     coal :  some  resins. 
(  Insoluble  in  water.  "] 
5.  <  Insoluble  in  dilute  acids.  V  :  ^ax,  fats,  fixed  oils. 
(  Insoluble  in  80  per  cent  alcohol.  J 
It  is  frequently  advantageous  to  extract  the  plant  with  petroleum  naphtha  (sp.  gr. 
66  to  "]o,  boils  at  about  50°C.,  wholly  volatile)  before  treatment  with  benzol  5  hj 
reference  to  the  accompanying  table  of  comparative  solubilities  it  will  be  seen  that 
this  treatment  may  serve  to  separate  fixed  and  volatile  oils,  and  some  resins  and  col-  _ 
ors,  from  certain  solid  fats,  wax,  other  rcNins  and  colors. 
Where  benzol  of  sufficient  purity  cannot  be  had,  pure  chloroform  is  the  best- 
substitute.  The  use  of  ether  is  objectionable  in  this  place,  as  its  solvent  properties 
are  less  distinctly  marked  than  are  those  of  naphtha,  chloroform  and  benzol;  in 
other  words,  more  plant  constituents  are  sparingly  soluble  in  ether  than  in  the  above 
mentioned  solvents.  Consequently  many  substances  which  should  properly  be 
extracted  by  80  per  cent,  alcohol  will  be  sparingly  dissolved  if  ether  were  used^ 
while  benzol,  chloroform  and  naphtha  would  have  no  perceptible  solvent  action, 
upon  them;  tannic  acids  may  be  cited  as  instances  illustrating  this  point. 
VI.    Estimation  of  eighty  per  cent.  Alcohol  Extract. 
That  part  of  the  plant  not  dissolved  by  benzol  should  be  dried  at  ioo°C.,  and  then> 
completely  exhausted  by  80  per  cent,  alcohol  (sp,  gr.  '8483  at  15-60.).  This 
requires  from  12  to  14  hours'  continuous  treatment  with  the  solvent.  Remove,  dry^ 
and  weigh  any  crystals  or  powder  that  may  separate  upon  concentrating  and  cool- 
ing the  alcoholic  percolate.  Make  the  clear  liquid  to  a  definite  volume  by  adding; 
more  80  per  cent,  alcohol.  In  an  aliquot  part  of  this  liquid  determine  total  organic 
matter  und  ash  ^  in  another  equal  portion  determine  total  organic  matter  and  asb 
soluble  in  njoater,  and,  by  difference,  total  organic  matter  insoluble  in  ivater. 
The  remaining  clear  alcoholic  liquid  should  bs  evaporated  cirefully  to  dryness^ 
