242  Method  of  Cleaning  Digitalis.      {Km' lgtim' 
screenings  apparently  contained  much  select  drug,  and  it  was 
deemed  an  unnecessary  waste  to  discard  the  same;  therefore,  they 
were  subjected  to  the  following  process: 
One  of  the  regular  sifting  frames  supplied  with  the  gyrator 
sifter  was  placed  on  the  machine.  This  frame  when  used  on  the 
machine  provides  for  the  separation  of  the  powder,  being  sifted 
into  three  degrees  of  fineness.  Approximately  three  fifths  of  the 
area  of  the  frame  used  is  covered  with  a  50-mesh  silk  bolting  cloth, 
one  fifth  with  a  17-mesh  linen  screen  and  the  remaining  area  is  open 
for  the  tailings  or  coarse  portion.  The  dust-proof  top  was  placed 
on  the  machine  and  the  17.138  Kg.  of  screenings  from  the  previous 
operation  run  through.  This  further  separation  yielded  5.97  Kg. 
of  coarse  tailings,  4.955  Kg.  of  middlings  and  5.805  Kg.  of  fine 
powder.  The  coarse  tailings  and  middlings  were  of  a  rich  green 
color  and  apparently  free  from  adhering  soil.  The  tailings  and 
middlings  were  returned  to  the  cleaned  drug  from  the  screening 
process,  after  samples  had  been  reserved  for  study.  The  fine  pow- 
der was  dark  gray,  faintly  tinged  with  green. 
The  fine  powder  above  referred  to  was  submitted  to  a  micro- 
scopical examination  which  revealed  the  presence  of  numerous 
typical  hairs  of  digitalis,  very  few  fragments  of  the  lamina  of  the 
leaf  and  numerous  particles  of  foreign  matter,  some  of  which  were 
opaque  and  black,  others  being  transparent  and  glasslike.  Upon  ex- 
amination with  the  micropolariscope  practically  all  of  the  trans- 
parent particles  of  foreign  matter  polarized  light,  the  larger  ones 
with  a  beautiful  display  of  colors  similar  to  those  produced  by 
feldspar. 
Ash  Determinations. — Ash  determinations  were  made  on  the 
original  drug  before  any  of  the  cleaning  processes  were  carried  out 
and  subsequently  on  the  various  separations  effected.  A  composite 
sample  carefully  selected  from  the  original  crop  yielded  on  three 
successive  determinations  11.368  per  cent.,  11.38  per  cent.,  and  H-59 
per  cent,  of  ash.  While  these  figures  are  considerably  below  the 
percentage  of  ash  permitted  by  U.  S.  P.  IX,  it  was  considered 
advisable  to  separate  all  of  the  foreign  matter  possible,  thus  pro- 
ducing a  drug  of  exceptional  cleanliness  and  probably  within  the 
two  per  cent,  limit  of  foreign  material. 
The  results  of  the  separation  by  the  two  methods  described 
together  with  ash  determinations  of  the  drug  taken  from  each  of 
the  seven  bins  are  given  in  the  following  two  tables : 
