132     IMPROVED  PROCESS  FOR  BLUID  EXTRACT  OF  BUCHU. 
It  follows,  from  these  observations,  that  specific  gravity  is  a  good 
and  sufficient  indication  of  the  strength  of  the  percolate,  and 
therefore  of  exhaustion  of  the  drug.  And  it  also  follows,  from 
a  crude  but  practical  calculation  or  estimate,  based  on  the  specific 
gravities  and  the  inert  residues,  that  the  first  pint  of  weak  per- 
colate cannot  contain  more  of  the  medicinal  properties  of  the 
drug  than  would  be  contained  in  two  and  a  half  ounces  of  the 
powdered  buchu;  and  that  the  second  pint  could  not  contain 
more  than  one  seventh  of  this.  The  medicinal  properties  of  the 
drug  would  thus  be  distributed  in  the  percolate  as  follows  : 
First  12  Q,  or  reserved  percolate,  represents  13-14  g 
First  pint  of  weak  percolate  "  2*50  M 
Second   "        "  '  "  0-36  " 
16.00  " 
From  this  it  appears  that  the  process  might  be  terminated  at 
the  end  of  the  first- pint  of  weak  percolate  with  the  loss  of  thirty- 
six  hundreths  of  the  medicinal  strength  of  one  troyounce  of 
buchu,  but  with  the  saving  of  one  *pint  of  alcohol;  always  pro- 
vided the  percolation  be  skilfuly  conducted. 
The  next  point  to  be  noticed  is  that  the  evaporation  of  the  1 
two  pints  of  weak  percolate  to  four  fluidounces,  much  of  the 
medicinal  portion  is  sacrificed, — first  by  being  driven  oif,  and 
second  by  oxidation  and  other  changes.  A  very  considerable 
portion  of  the  deposit  which  occurs  during  this  evaporation  is 
insoluble  in  the  original  menstruum. 
Finally,  the  filtration  through  paper  is  tedious  and  wasteful. 
Even  when  accomplished  through  a  covered  funnel  into  a  bottle, 
the  loss  by  evaporation  in  moderately  warm  weather  was  two 
fluidounces;  and  the  portion  which  refused  to  pass  through 
measured  nearly  one  fluidounce  more. 
The  cost  of  a  pint  of  this  fluid  extract  by  the  officinal  pro- 
cess is  nearly  as  follows, — the  pint  weighing  a  little  over  fourteen 
ounces  avoirdupois : 
16  troy  ounces=l  lb.  If  oz.  avoirdupois. 
of  Buchu,  powdered,  .  .  $  .90 
SJ  pints  Alcohol,  .       .  1.79 
$2.69 
