528  Powdered  Vegetable  Drugs.  { ^ ocfobS.!?^"1, 
(A.Ph. A.  Proc,  1 896) and  Kebler ( Amer.  Jour.  Pharm.,  i  897,  p.  244) — 
as  well  as  the  labors  of  some  students  during  the  past  year,  indicate 
that  the  principle  of  the  process  suggested  is  satisfactory,  whatever 
the  modifications  recommended.  The  following  are  the  important 
points  embracing  the  principles  of  the  process  as  developed  thus 
far: 
(1)  The  same  reagents  and  mounting  media  are  employed  in  doing 
quantitative  work  as  were  considered  in  the  qualitative  examination 
of  the  powder.  In  quantitative  work,  not  only  some,  but  all  of  the 
important  characteristic  tissues  and  contents  are  to  be  rendered 
visible. 
(2)  The  quantity  of  powder  to  be  examined  by  means  of  the 
microscope  must  represent  the  sample  in  every  particular ;  in  other 
words,  the  sampling  must  be  done  properly  and  in  accordance  with 
the  methods  used  in  the  assay  of  ores.  While  the  quantity  to  be 
examined  may  consist  of  but  a  few  grammes,  it  must  thoroughly 
represent  the  lot  of  powder  on  which  value  is  to  be  given. 
(3)  The  standard  powders,  with  which  the  powder  under  investi- 
gation is  to  be  -compared,  must  thoroughly  represent  the  drug  in  the 
various  ways  in  which  it  may  be  treated.  The  degree  of  fineness 
must  especially  be  carefully  borne  in  mind.  A  sample  of  a  drug  of 
No.  40  powder  cannot  be  compared  with  one  of  No.  60.  If  the  sam- 
ple of  a  drug  to  be  examined  is  of  a  No.  40  powder,  the  standards 
must  also  be  of  the  same  degree  of  fineness.  If  extraction  of  active 
principles  is  suspected  in  the  powder,  it  must  be  compared  with  a 
standard  that  has  been  extracted.  .  In  fact,  every  treatment  that  is 
possible  in  a  sample  to  be  analyzed  must  be  given  to  a  standard,  if  pos- 
sible, with  which  the  comparison  is  made. 
(4)  The  amount  of  powder  used  in  the  examination  is  generally 
about  2-j-g  gramme  (==  0-0039  gramme  =  006  grain).  In 
some  cases  twice  this  quantity  (T-i-g-  gramme)  or  but  one-half  this 
amount  (-g-l^  gramme)  may  be  used  to  greater  advantage.  The 
quantity  of  powder  may  be  weighed  out,  or,  what  is  more  conven- 
ient, with  practice  a  gramme  is  weighed  out  and  divided  with  a 
spatula  with  the  eye,  as  follows  : 
