Am.  Jour.  Pharm. 
May,  18&4. 
Saponin  from  Saponaria. 
275 
a  small  quantity  of  alcohol.  A  boiling  aqueous  solutiou  of  saponin 
dissolves  barium  carbonate  (up  to  10  per  cent.),  which  may  be  precipi- 
tated by  sulphuric  acid;  nevertheless  barium  sulphate  is  slightly 
soluble  in  aqueous  saponin.  This  property  of  dissolving  salts  throws 
great  difficulty,  as  already  observed,  in  the  way  of  purifying  saponin. 
This  substance  likewise  dissolves  gases  and  incloses  them  mechanically. 
A  dilute  aqueous  solution  of  saponin  forms  on  agitation  a  very  per- 
sistent froth. 
An  aqueous  solution  of  saponin  mixed  with  hydroxide  of  potassium, 
barium,  or  strontium,  yields  precipitates  of  the  corresponding  compounds. 
The  barium  compound  has  the  composition — 
C,32H53018.BaC32H52018.BaC32H53018. 
Products  of  Decomposition  of  Saponin. — An  aqueous  solution  of 
saponin  was  heated  on  a  water-bath  with  dilute  sulphuric  or  hydro- 
chloric acid,  the  liquid  being  filtered  after  two  hours,  in  order  to  remove 
the  flocculent  substance  which  separated,  and  thereby  prevent  its  further 
decomposition  by  the  acid  ;  the  filtered  solution  was  then  again  boiled, 
the  new  precipitate  separated,  and  these  operations  were  repeated  a 
third  time.  The  three  precipitates  thus  obtained  agreed  very  closely 
in  composition,  giving  as  the  mean  result  of  their  analysis,  60*65  per 
cent,  carbon  and  8*22  hydrogen,  numbers  agreeing  nearly  with  the 
formula  C40H66O18,  which  requires  61*06  carbon,  8*38  dydrogen,  and 
3*56  oxygen.  The  decomposition  of  saponin  by  dilute  acids  may  there- 
fore be  represented  by  the  equation 
2C32H54018  +  3H20  =  C10H66O15  +  406H12O6. 
The  compound  C40H66O15  is  called  by  the  author  saponetin,  to  distin- 
guish it  from  the  sapogenin  of  Rochleder  and  others,  which  was  not 
of  constant  composition.  Saponetin  is  a  whitish  microcrystalline  sub- 
stance, insoluble  in  water,  alcohol,  and  ether, 
The  glucose  formed  by  the  action  of  dilute  acids  on  saponin  is  dex- 
trogyrate, its  specific  rotatory  power  being  [«]b=  +  52*48.  It  is 
fermentable,  has  a  saccharine  taste,  and  has  not  yet  been  crystallized, 
its  solution,  after  concentration  to  a  syrup,  having  remained  for  six 
months  without  giving  any  sign  of  crystallization.  Further  experi- 
ments are,  however,  required  to  determine  whether  it  is  a  peculiar 
sugar  distinct  from  dextrose,  or  whether  the  difference  between  its 
optical  rotatory  power  and  that  of  the  latter  is  due  to  some  other  cause. 
—  Gazzetta,  xiii.,  422-430;  Jour.  Chem.  Soc,  March,  1884,  p.  332. 
