Am  AJp°rnr'  i^lrm'  }    Content  of  Ash  of  Certain  Drugs.  273 
centration  of  manganese  in  certain  working  cells  might  leave  behind 
in  the  older  bark  a  higher  uniform  residue.  In  any  case  it  seems 
evident  that  definite  amounts  of  manganese  may  be  found  present 
in  all  or  any  of  the  different  parts  of  plants. 
Manganese  Fraction  Soluble  in  Water. 
By  methods  of  percolation,  and  by  boiling  the  powdered  barks  in 
water,  it  was  found  that  about  one  quarter  of  the  total  manganese 
present  may  be  extracted  from  members  of  the  Rhamnaceae  family 
by  this  means. 
Table  II. 
Total  Manganese  in  the   Manganese  Extracted, 
Bark  Examined.  Bark,  Per  Cent.  Per  Cent. 
Rhamnus  Frangula    0.0242  0.0058 
Rhamnus  Purshiana    0.0137  0.0029 
Rhamnus  Californica    0.0033  0.0008 
The  numbers  are  based  on  dry  samples  as  above  and  are  the 
average  results  of  several  good  duplicate  determinations,  showing 
the  uniformity  with  which  manganese  is  extracted  from  such  mate- 
rials. Manganese  thus  extracted  does  not  appear  to  have  the  prop- 
erties of  inorganic  manganese  and  is  not  removed  from  these  solu- 
tions by  ordinary  means.  This  at  once  leads  to  a  new  method  for 
distinguishing  between  these  closely  related  species  and  it  follows 
from  this  that  the  development  of  a  "  Manganese  Number "  for 
commercial  extracts  of  such  drugs  would  seem  to  be  a  quite  reason- 
able and  practical  method  of  procedure  in  their  examination.  It  is 
our  hope  to  develop  such  an  application  in  the  near  future. 
Method  of  Estimation. — The  analytical  work  reported  was  ac- 
complished by  a  simple  application  of  the  ammonium  persulphate 
method  for  the  determination  of  small  amounts  of  manganese. 
The  work  was  done  in  two  ways,  depending  on  the  manganese  found 
present  by  initial  trials.  ■ 
Wherever  10  Gm.  samples  are  available,  the  following  procedure 
may  be  recommended :  If  the  presence  of  manganese  is  known  to  be 
of  the  order  of  0.015  per  cent,  or  higher,  it  is  possible  to  titrate 
directly  the  permanganate  formed  with  standard  sodium  arsenite 
solution.  If  the  percentage  is  lower  than  this  it  is  more  feasible 
to  compare  the  color  developed  with  solutions  of  known  perman- 
ganate content  which  have  been  carefully  prepared  and  correspond 
