2 1 6  Proximate  Analysis  of  Plants.  {^"aS'xsso^'"- 
pulverized  and  treated  with  several  considerable  portions  of  absolute  alcohol  (sp.  gr. 
•7938  at  I5-6C.). 
A.  Soluble  in  Absolute  Alcohol. 
a.  Soluble  in  njjater. 
a^.  Precipitated  by  subacetate  of  lead. 
Tannin  and  most  organic  acids  5  some  extractives  5  some  inorganic  acids  of 
the  ash.     Weigli  in  Gooch's  filter,  ignite  cautiously,  and  again  weigh;  loss 
equals  organic  matter  precipitated. 
a\  Not  precipitated  by  subacetate  of  lead. 
Alkaloids,  glucosides,  some  extractives  and  colors.     Determine  by-difter- 
ence  between  a  and  a^. 
b.  Insoluble  in  ^ater. 
b^.  Soluble  in  dilute  hydrochloric  acid. 
Alkaloids,  glucosides  (rarely),  some  extractives.    Determine  by  difference 
between  b  and  b'^. 
b^.  Insoluble  in  dilute  hydrochloric  acid, 
b^.  Soluble  in  dilute  amnionic  hydrate. 
Most  acid  resins,  some  colors.    Determine  by  difference  between  b'  and  b^. 
bK  Insoluble  in  dilute  amnionic  hydrate. 
Neutral  resins,  some  colors,  albuminoids  (in  some  seeds).    Re-dissolve  in 
alcohol,  evaporate  and  weigh. 
B.  Insoluble  in  Absolute  Alcohol. 
c.  Soluble  in  njoater. 
c^.  Precipitated  by  subacetate  of  lead. 
Some  colors,  extractives,  albuminoids  (rarely),  organic  acids,  and  inor- 
ganic acids  of  the  ash.  Weigh  in  Gooch's  filter,  ignite  cautiously,  and 
again  weigh  ;  loss  equals  organic  matter  precipitated. 
<:'-.  Not  precipitated  by  subacetate  of  lead. 
Alkaloids,  glucosides,  glucose,  sucrose,  some  extractives.  Determine  by 
diftVrence  between  c  and  c'^.  Remove  Pb  by  H.S,  H^SO^,  Na.^COg,  or  other 
means,  and  titrate  for  sucrose  and  glucose. 
d.  Insoluble  in  njoater. 
d^.  Soluble  in  dilute  hydrochloric  acid. 
Some  alkaloids  and  glucosides.     Determine  by  difference  between  d  and  d^ 
d-.  Insoluble  in  dilute  hydrochloric  acid. 
Few  resins,  some  extractives  'and  color  substances.    Dissolve  in  alcohol, 
evaporate  and  weigh  in  a  tared  dish. 
In  some  cases  it  may  be  preferable  to  use  the  following  method  for  analysis  of  the 
80  per  cent,  alcohol  extract;  it  is  more  desirable  when  the  plant  examined  contains 
a  considerable  amount  of  sugars,  tannic  acid,  etc. 
Alcohol  Extract,  dilute  to  200  cc.  with  80  per  cent,  alcohol. 
1.  In  20  cc.  determine  total  organic  matter  and  ash. 
2.  In  20  cc.  determine  total  organic  matter  3.r\d  ash  that  are  soluble  in  nvater^  and, 
by  difference,  total  organic  matter  insoluble  in  ^ater. 
3.  Evaporate  the  remaining  160  cc.  to  dryness,  treat  with  water,  filter,  and  make 
the  filtrate  measure  160  cc.  Reserve  the  insoluble  matter  on  the  filter  for  examina- 
tion (10). 
