318 
INFLUENCE    OF  DRYING,  ETC. 
forming  a  dull  mirror,  but  does  not  effect  the  solution  of  cupric 
oxide  in  potassa ;  it  prevents,  like  all  nonvolatile  organic  acids, 
the  precipitation  of  ferric  oxide  by  ammonia  ;  all  its  salts  appear 
to  be  soluble  in  water  and  alcohol,  with  the  exception  of  the  basic 
lead  salt. 
The  author  used  pure  mannite  for  the  above  experiments,  and 
satisfied  himself  of  the  total  absence  of  glucose,  cane  sugar  and 
allied  compounds.  The  filtrate  from  the  insoluble  lead  salt 
yielded,  by  proper  treatment,  the  greatest  portion  of  the  mannite 
without  alteration. 
These  experiments  prove  that  to  distinguish  the  different 
kinds  of  sugar  by  their  behaviour  to  alkaline  solution  of  copper, 
is  correct  only  as  far  as  the  time  of  their  mutual  action  is  taken 
into  consideration. 
That  cane  sugar,  though  in  an  inferior  degree,  possesses  the 
power  of  reducing  cupric  oxide  from  its  alkaline  solution,  has 
been  known  for  some  years  ;  mannite  has  the  same  behaviour. 
The  close  relation  between  mannite  and  glucose  was  proven  by 
Linnemann's  discovery  in  1862,  that  grape  sugar  in  contact  with 
nascent  hydrogen  is  converted  into  mannite.  Ci2llj20i2+2H= 
C^2^ifii2  (mannite).-- C^Aem.  Centralhl.  1869,  iVb.  from  Zeitsch. 
d.  Ver.f.  Ruhenzueker  Indust.  xiv,  849,  xvi,  670. 
ON  THE  INFLUENCE  OF  DRYING  ON  THE  ACTIVE  PRIN- 
CIPLES OF  PLANTS  * 
By  Dr.  Leopold  Schoonbroodt,  Apothecary  at  Liege. 
The  author  extended  his  examination  to  29  plants,  selected 
for  the  importance  and  frequency  of  their  use  in  medicine.  The 
process  of  examination  was  based  upon  the  principles  of  Stas' 
method.  * 
The  carefully  selected  plants,  when  possible  collected  of  wild 
growth,  were  divided  into  two  equal  parts,  one  of  which  was 
dried,  if  necessary,  with  artificial  heat,  then  powdered,  the  loss 
in  drying  replaced  by  water,  after  maceration  for  24  hours  dis- 
*  Condensed  from  Wittstein's  Yierteljahresschr.  fiir  prakt.  Pharm.1869, 
p.  73-110.  The  author,  who  died  Dec.  1,  1866,  was  by  the  Societe  Royale 
des  Sciences  Medicales  et  Naturelles  de  Bruxelles,  awarded  a  gold 
medal  for  this  essay,  which  was  published  in  Journ.  de  Medic,  de  Brux. 
1867  and  1868. 
