Am.  Jour.  Pharm.  j 
March,  1919-  > 
D  ig  it  alls  L  e  aves. 
177 
fibrin ;  0.52  mgrm.  of  the  original  solution  liquefied,  and  0.56  mgrm. 
filtered  through  paper  liquefied,  i.  e.}  my  purified  preparation  is  2% 
times  as  strong  as  Griibler's  trypsin.  It  may  be  noted  that  about  20 
per  cent,  of  the  Griibler  trypsin  was  insoluble  in  water. 
I  do  not  suppose  for  a  moment  that  the  preparation  I  have  made 
is  a  pure  enzyme,  and  I  have  not  been  able  to  ascertain  how  far  the 
purification  can  be  carried  by  the  above  method,  but  I  have  reason 
to  believe  that  the  purer  the  enzyme  the  less  colloidal  is  its  character, 
and  that  it  will  pass  through  a  membrane.  Professor  Kipping  has 
kindly  examined  a  solution  of  the  purified  enzymes  with  the  polari- 
scope  in  order  to  ascertain  if  it  is  optically  active.  The  solution  con- 
tained 0.1 184  Gm.  of  solids  per  100  Cc,  which  was  a  strong  solu- 
tion from  the  point  of  view  of  enzyme  activity,  being  about  three 
times  as  strong  as  those  I  have  usually  employed.  No  rotation  of 
the  plane  of  polarization  could  be  detected  in  a  200  Mm.  tube.  The 
following  are  the  minimum  quantities  of  material  required  to  liquefy 
the  gelatin  in  the  test  described: — Griibler's  pancreatin  (unfiltered) . 
0.56  mgrm.;  do.  (filtered),  0.52;  safranine  precipitate  from  pan- 
creas extract,  0.30 ;  pancreas  extract  on  paper,  0.34 ;  purified  enzyme, 
0.23  mgrm. 
From  the  above  facts  I  draw  the  conclusion  that  the  enzyme  itself 
is  extremely  soluble,  whereas  the  protein  matter  with  which  it  is 
associated  is  difficultly  soluble,  and  this  difference  in  solubility  may  y 
be  used  to  purify  the  enzyme. 
DIGITALIS  LEAVES :  EFFECT  ON  ACTIVITY  OF 
TEMPERATURE  IN  DRYING.1 
By  Herbert  C.  Hamilton. 
Since  the  first  attempt2  to  standardize  digitalis 'leaves  and  the 
extracts,  it  has  been  observed  that  they  vary  greatly  in  activity. 
Bennefield,3  in  1881,  using  a  method  almost  identical  with  that 
suggested  in  the  9th  Rev.  U.  S.  P.  for  standardizing  the  digitalis 
series  of  heart  tonics  found  a  variation  of  about  500  per  cent,  in  the 
1  Reprinted  from  The  Journal  of  the  American  Chemical  Society,  Jan- 
uary, 1919.   Contribution  from  the  Research  Laboratory  of  Parke,  Davis  &  Co. 
2  Ber.,  40,  4586,  1907.  » 
3  Bennefield,  "  Ueber  Digitalis  Tincturen,"  Inaug.  Diss.,  Gottingen,  1881. 
