Am.  Jour.  Pharru.\ 
October,  1897.  / 
Powdered  Vegetable  Drugs. 
529 
i 
1 
4 
i 
1 
jo 
14  =  0*500  gramme. 
3^=0-250 
#  =  0-125 
XV  =  0-0625  " 
3L  =  0-03125  " 
:h  =  °'°°78  " 
rk  =  °'°°39  " 
(5)  The  cover-glasses  used,  whether  round  or  square,  should  be 
uniform  in  siz.e  and  thickness  for  comparison  of  the  mounts  of  the 
standard  with  those  of  the  specimen  to  be  tested. 
(6)  The  amount  of  reagent  employed  in  making  a  mount  must  be 
just  sufficient  to  float  the  cover-glass,  and  as  few  air-bubbles  as  pos- 
sible are  permitted  to  be  formed. 
(7)  A  homogeneous  mixture  of  powder  with  reagent  must  be  formed 
before  the  cover-glass  is  put  down.  This  is  best  done  by  taking  the 
edge  of  the  cover-glass  in  a  pair  of  forceps  and  distributing  the 
powder  in  the  mounting  media  or  reagent. 
(8)  After  the  mount  has  been  made  and  the  powder  examined 
previously  qualitatively,  the  quantitative  estimation  of  the  powder  is 
determined.  This  is  based  on  one  or  more  of  the  structures  or  con- 
stituents that  are  characteristic  of  the  drug  or  drugs  that  may  be 
present.    A  few  examples  may  be  given  : 
In  Cinchona,  the  bast  fibres  are  best  selected. 
In  Quillaja,  the  monoclinic  calcium  oxalate  crystals  are  most 
characteristic. 
In  Belladonna  folia,  the  pieces  of  tissues,  with  some  cells  contain- 
ing the  characteristic  grayish  sand-like  crystals  of  calcium  oxalate, 
are  selected. 
In  Hyoscyami  folia,  the  pieces  of  tissues,  with  some  cells  con- 
taining the  characteristic  cubical  or  tetragonal  crystals  of  calcium 
oxalate,  are  used. 
In  £ tram onii  folia,  the  pieces  of  tissues,  with  some  cells  containing 
the  characteristic  "rosette-shaped"  crystals  of  calcium  oxalate, are 
most  characteristic. 
In  Zingiber,  the  estimation  is  based  on  the  starch  grains,  or  better, 
the  oil-secreting  cells. 
