150 
REMARKS  ON  POLYGALIC  ACID, 
striction  of  the  throat.  When  its  dust  is  inhaled  through  the 
nostrils,  irritation  and  violent  sneezing  occur.  It  is  not  volatile ; 
when  burnt  in  a  tube  it  affords  no  nitrogen,  andiswholly  com- 
bustible. Polygalic  dissolves  slowly  in  cold  wTater,  but  readily 
in  hot  water,  forming  a  solution  which  reddens  litmus  paper, 
and  froths  strongly  by  agitation.  It  is  soluble  in  boiling  alco- 
hol, but  the  larger  part  separates  on  cooling.  It  is  soluble  in 
diluted  alcohol,  but  the  solution  has  a  tendency  to  deposit  it  on 
standing.  It  is  absolutely  insoluble  in  ether,  and  in  acetic  ether, 
the  fixed  and  volatile  oils.  It  is  soluble  in  alkaline  solutions, 
with  the  production  of  a  greenish  yellow  coloration.  It  is  pre- 
cipitated in  its  free  state  by  subacetate  of  lead,  and  proto  nitrate 
of  mercury,  but  by  no  other  salts ;  various  salts  throw  it  down 
from  solution  when  it  is  combined  with  an  excess  of  potassa  or 
soda.  When  heated  with  nitric  acid  it  affords  oxalic  and  picric 
acids,  and  sulphuric  acid  decomposes  it  with  a  rose  and  violet 
color.  The  acid  character  of  this  substance  is  so  slight  that  it 
will  not  decompose  the  carbonates,  yet  it  forms  amorphous  salts 
with  alkaline  and  metallic  bases.  Quevenne  suspected  a  close 
relationship  between  polygalic  acid  and  saponin.  More  recently 
(Annl.  der  Chemie,  and  Amer.  Jour.  Pharm.  vol.  xxvii.,  43)  M. 
Bolley  has  resumed  the  inquiry,  and  believes  that  both  saponin 
and  polygalic  acid  are  glucosides,  like  salicin,  resolved  by  hydro- 
chloric acid,  into  sugar  and  a  derivative  body  sapogenin,  and 
that  their  formula  is  the  same. 
Preparation  of  Polygalic  Acid,  The  particular  object  of  this 
paper  is  the  preparation  and  administration  of  this  substance. 
The  original  process  of  Quevenne  required  precipitation  by 
acetate  of  lead,  and  the  action  of  sulphuretted  hydrogen  ;  but 
he  afterwards  greatly  simplified  the  process,  but  retained  some 
complications  not  necessary  to  obtain  the  acid  sufficiently  pure 
for  medicinal  use.  The  following  process  I  have  tried  several 
times,  and  it  has  the  merit  of  great  simplicity. 
Take  of  Senega,  in  powder,  (50  meshes  to  the  inch)  10000  grs. 
Alcohol, 
Ether,  and  water,  each,  a  sufficient  quantity. 
Moisten  the  senega  with  half  a  pint  of  a  mixture  of  two  parts 
of  alcohol  and  one  part  of  water,  pack  it  in  a  large  glass  funnel ; 
cover  the  surface  with  a  piece  of  muslin,  or  paper,  and  pour  on 
