AmsJeptr;i87h9a,m}  Walnut  Leaves  and  Extract  of  Walnut  Leaves.  457 
If  walnut  leaves  collected  at  the  proper  time  and  recently  dried  be 
compared  with  those  met  with  in  commerce,  the  difference  in  the  char- 
acters is  striking.  After  some  months,  in  fact,  the  dried  leaves,  exposed 
to  the  open  air,  turn  brown,  and  at  the  same  time  lose  their  aromatic 
odor  and  bitterness.  This  physical  change,  produced  under  the  influ- 
ence of  moi&ture  and  air,  is  the  index  of  a  chemical  transformation 
that  takes  place  after  the  drying.  The  prolonged  action  of  air  and 
moisture  gradually  converts  the  juglandin  into  an  insoluble  and  insipid 
black  substance,  and  the  tannin  becomes  partially  insoluble  or  decom- 
posed. 
Experiments  were  made  with  preparations  from  (1)  leaves  collected 
in  June;  (2)  leaves  collected  in  October;  (3)  leaves  collected  at  the 
proper  time,  but  which  had  been  kept  one  year.  Tannin  being  one  of 
the  most  active  principles  of  the  leaves,  this  was  estimated  as  indicative, 
to  a  certain  extent,  of  the  value  of  the  respective  preparations.  The 
method  adopted  was  that  of  Lowenthal,  based  upon  the  oxidation  of 
the  tannin  by  permanganate  of  potash  in  the  presence  of  indigo  car- 
mine. A  gram  of  each  extract  was  dissolved  in  100  cc.  of  distilled 
water,  and  20  cc.  of  each  solution  were  submitted  to  the  action  of  the 
permanganate. 
(a.)  An  extract  prepared  from  the  juice  of  leaves  collected  in  June, 
clarified  by  heat  and  evaporated.  Taste,  bitter  and  astringent;  odor, 
aromatic  ;  solution,  limpid  ;  tannin  in  1  gram  of  extract,  019  gr. 
(b.)  Similar  leaves  were  submitted  to  distillation,  and  the  residue  fil- 
tered and  evaporated  to  an  extract.  Taste,  slightly  bitter  ;  odor,  very 
slight;  solution,  turbid  ;  tannin  in  1  gram,  0*19  gr. 
(c.)  The  remainder  of  the  June  leaves  were  dried  in  the  open  air  and 
an  extract  prepared  from  them  according  to  the  Belgian  Pharmacpoeia. 
Taste,  bitter  and  astringent  ;  odor,  aromatic  ;  solution,  limpid  ;  tannin 
in  1  gram,  0  20  gr. 
(d.)  Leaves  collected  in  October  were  drred  directly  and  converted 
into  extract.    The  product  resembled  (c)  in  every  respect. 
(e.)  Extract  prepared  from  leaves  one  year  old.  Taste,  slightly 
astringent  and  slightly  bitter  ;  odor,  none  ;  solution,  very  dark  ;  tannin 
in  1  gram,  o*io  gr. 
(/*.)  Extract  of  commerce.  Similiar  to  (<?)  with  the  exception  of 
solution  being  limpid. 
It  appears,  therefore,  that  the  full  grown  leaves  may  be  collected  at 
