878 
llic  Theory  of  Percolation . 
(  Am.  Tour.  Pliarni. 
I     Dt'ccml-,er.  l'>2n. 
devoted  by  pharmacists  to  a  prevention  of  changes  which  are, 
for  pharmaceutical  purposes,  often  wholly  unimportant.  If  pro- 
teins are  coagulated,  starch  precipitated,  carbohydrates  caramelized, 
and  non-medicinal  tannins  oxidized  what  does  it  matter?  The 
essential  purpose  is  the  preservation  of  therapeutic  value  and  if 
this  is  accomplished  the  important  part  of  the  process  is  successful. 
And  that  precipitation,  oxidation,  and  other  phenomena  to 
which  evaporation  is  liable  to  lead  are  not  usually  fatal  the  following 
evidence  is  offered:  Diehl'  stated  that  the  moderate  heat  required 
in  the  preparation  of  fiuidextracts  does  not  injure  them.  Maisch 
was  of  the  same  opinion  and  a  fluidextract  of  Ipecac  made  by 
him  about  1864  by  an  evaporation  process  was  analyzed  by  Lawall 
in  1897-  and  found  to  be  aboA^e  U.  vS.  P.  strength  even  after  thirty 
years. 
An  investigation  of  the  nature  of  precipitates  in  tinctures  was 
reported  by  Cripps'^  who  found  the  following:  the  deposit  in  Tr. 
Calumba  contained  none  of  the  active  principles;  that  in  Tr.  Car- 
damom Comp.  was  almost  wholly  calcium  tartrate :  tinctures  of 
cinchona  (B.  P.)  exhibited  precipitates  which  contained  varying 
amounts  of  alkaloids  in  combination  with  tannoids;  the  deposit  in  Tr. 
Gentian  Comp.  was  starch,  gentian  sugar,  and  albuminous  matter,  that 
in  a  concentrated  Tr.  Ipecac  did  not  contain  emetine ;  a  deposit  in  a 
tincture  of  quinine  was  calcium  sulphate;  one  in  tincture  of  rhubarb 
contained  gummy  matters,  calcium  oxalate,  with  a  little  magnesium 
and  chrysophanic  acid.  It  may  thus  be  seen  that  in  a  great  num- 
ber of  cases  a  precipitate  contains  nothing  of  therapeutic  impor- 
tance. If  an  active  ingredient  separates  the  fault  is  with  the  sol- 
vent or  the  associated  compounds. 
PRECIPITATION  IN  FLUIDEXTRACTS. 
This  subject,  because  of  its  great  importance,  has  received  much 
attention  from  pharmacists.  Maisch, Lilly, ^  Diehl,*'  Lloyd, and 
others  have  given  careful  consideration  to  the  causes  of  precipitation. 
1  Proc.  A.  Ph.  A.  1879,  727. 
-  This  Journal,  Vol.  69,  619,  (1897). 
Pharm.  Jour.  Trans.  43,  483,  (1883);  This  Journal,  Vol.  56,  lor,  (1884). 
^  This  Journal,  Vol.  31,  113,  (1859). 
Pharm.  Rec.  1888,  233.  • 
«  Proc.  A.  Ph.  A.  1878,  681. 
'  Proc.  A.  Ph.  A.  Vol.  1881,  408,  421;  1882,  508;  1883,  336;  1884,  410;  1885 
411;  This  Journal,  Vol.  56,  499,  (1884). 
