146 
The  Study  of  Drugs. 
Am.  Jour.  Pharm. 
March,  1919. 
Some  of  them  have,  since  the  beginning  of  the  war,  been  among 
the  list  of  scarce  drugs,  and  we  have  been  sorely  tried  with  supplies 
of  doubtful  origin  and  usefulness.  At  times  we  have  been  com- 
pelled to  look  for  substitutes.  We  may  with  profit  ask — Which 
of  our  preparations  best  exhibit  the  physiological  and  therapeutic 
properties  of  the  drug?  If  a  drug  has  more  than  one  action,  what 
preparation  represents  these  separate  actions?  In  making  a  phar- 
maceutical preparation  of  these  drugs  do  we  take  into  account  all  of 
the  constituents  of  the  drug? 
The  solvent  now  most  commonly  used  for  vegetable  drugs  is 
alcohol.  Alcohol  is  becoming  a  very  expensive  solvent  and  difficult 
to  procure.  It  may  be  that  there  is  a  better  solvent  for  many  drugs. 
Workers  have  become  convinced  that  a  substance  other  than  alcohol 
should  be  found  for  use  as  a  solvent  for  many  vegetable  principles. 
Possibly  we  are  following  precedence  rather  than  actual  knowledge 
in  the  percentage  of  alcohol  which  we  use  for  the  extraction  of 
drugs.  Here  are  a  few  of  the  problems  which  will  occur  to>  every 
worker  in  drugs :  Alcohol  of  95  per  cent,  is  a  solvent  for  a  certain 
range  of  constituents.  Alcohol  50  per  cent,  strength  gives  us  an 
entirely  different  range  of  substances.  Which  percentage  is  best 
adapted  to  each? 
If  we  moisten  a  pound  of  the  drug  with  our  menstruum,  and 
pack  in  a  tall,  narrow  percolator  and  proceed  to  percolate  in  the  con- 
ventional manner,  by  pouring  on  the  drug  a  pint  of  alcohol,  we  will 
see  that  when  it  proceeds  through  the  drug  it  becomes  loaded  with 
extractive,  and  its  solvent  power  changes.  Its  solvent  power  at  the 
last  inch  is  quite  different  from  its  solvent  power  at  the  first  inch. 
The  second  pint  of  menstruum  will  be  brought  in  contact  with  the 
drug  and  constituents  left  behind,  or  perhaps  only  partly  carried 
over  with  the  first  pint  which  passed  through.  With  every  step 
every  new  addition  of  menstruum,  and  every  new  percolate  you 
will  have  a  different  action.  When  we  have  finally  reached  the 
point  where  we  can  say  we  have  extracted  all  of  the  principles,  we 
find  that  the  menstruum  will  still  dissolve  something. 
If  we  take  our  percolate  from  the  drug  made,  say  with  80  per 
cent,  alcohol,  and  put  the  liquid  in  an  evaporating  dish  and  set  the 
dish  over  a  flame  and  evaporate  the  menstruum,  the  result  will  be  a 
sticky  mass  which  we  call  the  solid  extract.  This,  we  say,  repre- 
sents the  drug.  Now,  if  instead  of  evaporating  the  liquid  over  the 
fire  we  pour  it  into  thin  films  and  allow  warm  air  to  drive  off 
