204     ON  THE  ACTIVE  PRINCIPLE  OF  CATALPA  BiaNONOlDES. 
tedious,  more  so  when  the  pores  of  the  filter  are  closed  with  an 
abundant  precipitate  of  gum,  etc.),  and  lastly  it  requires  the  use 
of  alcohol ;  this,  though  cheaper  now,  is  yet  worth  saving. 
Of  the  merits  of  the  following  process,  which,  in  my  humble 
judgment,  leaves  nothing  to  desire,  I  will  let  your  readers  judge. 
Take  of  Senega,  in  moderately  fine  powder,  eight  troy-ounces. 
Moisten  this  with  water,  pack  into  a  percolator,  and  pour  on  as 
much  water  as  it  will  absorb.  Close  lower  orifice  of  percolator 
and  allow  it  to  macerate  for  twenty-four  hours,  then  percolate 
until  one  pint  of  infusion  has  passed.  'Raise  this  to  the  boiling 
point,  filter  when  cold,  pass  enough  water  through  the  filter  to 
make  up  the  pint,  and  in  this  dissolve  24  troy-ounces  (or  in 
summer  26)  of  sugar,  and  strain. 
If  the  percolation  has  been  carefully  conducted,  the  drug  will 
have  been  exhausted  ;  if  found  otherwise,  the  percolation  may  be 
continued  to  exhaustion  and  the  resulting  infusion  evaporated. 
By  boiling  for  a  few  moments  the  albuminous  principles  coagulate, 
and  the  filtered  solution  and  syrup  are  perfectly  and  permanently 
clear.  The  small  amount  of  gum,  etc.,  held  in  solution  can 
hardly  be  objectionable;  it  does  not  induce  fermentation,  and 
the  syrup  as  made  above  will  be  found  as  stable  as  any.  I  have 
kept  it  on  a  high  shelf  in  a  heated  room  for  over  a  year,  and 
never  observed  signs  of  change  or  decomposition. 
Respectfully  yours,  A.  A.  K. 
Baltimore,  Md.,  March  5,  1870. 
ON  THE  ACTIYE  PRINCIPLE  OF  OATALPA  BIGNONOIDES. 
By  Eugene  A.  Rau. 
(From  an  Inaugural  Essay  presented  to  the  Philadelphia  College  of  Pharmacy.) 
This  well-known  ornamental  tree  is  the  largest  representative 
in  the  Northern  United  States  of  the  natural  order  Bignoniaceae, 
whither  it  has  strayed  from  the  Southern  States,  and  become  fully 
naturalized.  The  ample  size  of  its  cordate,  leaves  would  seem 
to  recommend  the  Catalpa  as  a  shade  tree,  but  owing  to  their 
being  rather  sparsely  disposed  and  early  deciduous,  together 
with  the  usual  uncouth  growth  of  the  tree,  it  is  but  seldom  culti- 
vated for  ornament.    In  the  months  of  June  and  July  the  tree 
