THE  MOST  CORRECT  METHODS  FOR  PREPARING  EXTRACTS.  233 
ON  THE  MOST  CORRECT  METHODS  FOR  PREPARING 
EXTRACTS* 
By  F.  Vielquth,  Jr.,  and  Julius  Nentwich. 
The  aim  of  the  authors  was  to  present  in  the  form  of  extracts, 
all  the  soluble  substances  of  the  medicinal  plants,  to  the  exclu- 
sion of  those  which  might  have  a  deteriorating  influence;  this 
they  believe  to  gain  by  the  proper  method  of  exhausting  the 
plants,  by  the  proper  temperature  during  evaporation,  and  by 
the  quickest  possible  dispatch  of  the  work.  The  best  form  for 
keeping  and  preserving  the  extracts  was  to  be  inquired  into, 
and  the  authors  think  the  dry  pulverulent  state  to  be  the  most 
advisable  to  preserve  extracts  from  the  change  induced  in  the 
presence  of  moisture  and  air. 
As  the  exhausting  menstruum,  water  is  used  for  plants  abound- 
ing in  sugar,  dextrin,  extractive,  tannin  and  bitter  principles, 
and  containing  no  resins,  volatile  oils  or  alkaloids  insoluble  in 
water  ;  albumen  and  starch,  if  present,  can  be  removed  by  mace- 
ration or  cold  displacement,  and  boiling  of  the  tincture.  Alco- 
hol and  water  are  used  when  principles  are  present  which  are 
soluble  in  alcohol ;  if  exhausted  by  a  boiling  temperature, 
Mohr's  apparatus  (M.  R.  k  Pr.  Pharmacy,  p.  264,)  may  be  ad- 
vantageously used,  and  the  lower  vessel  be  of  tin.  Alcohol 
alone  is  employed  for  the  extraction  of  alkaloids,  resins,  volatile 
oils  and  bitter  principles,  not  easily  soluble  in  water;  chloro- 
phyll and  vegetable  wax  detract  from  the  virtue  and  stability  of 
the  extract,  and  are  to  be  removed  by  the  addition  of  some 
water  to  the  evaporated  tincture,  and  the  employment  of  a 
weaker  alcohol  in  the  first  place.  Ether  is  used  when  it  is  a 
better  solvent  than  alcohol. 
To  determine  the  quantity  and  quality  of  the  narcotic  ex- 
tracts, prepared  from  the  fresh  and  the  dried  herb,  the  follow- 
ing experiments  were  made : 
*  Prize  essay  to  the  question  propounded  by  the  Moravian  Pharmaceu- 
tical Association,  for  1857,  as  published  in  Wittstein's  Vierteljahresschrift, 
1858,  p.  321-348  and  481  to  502.  The  essay  was  accompanied  with  speci- 
mens of  all  the  extracts  in  form  of  dry  powder  of  excellent  quality.  The 
above  is  a  short  abstract  of  that  lengthy,  very  interesting  essay. 
J.  M.  M. 
