ON  THE  RESIN  OF  JALAP. 
353 
alcohol,  and  partly  decolorized  by  treatment  with  water  and  animal 
charcoal,  is  but  partly  soluble  in  ether;  and  it  is  the  insoluble 
part  which  Mayer  has  examined. 
Rhodeoretine. — The  rhizomes  were  treated  with  boiling  water 
until  no  more  coloring  matter  was  extracted.    They  were  then 
dried,  coarsely  powdered,  and  digested  three  times  with  twice  their 
weight  of  alcohol  (0*833  sp.  gr.)    The  alcoholic  extract  was 
mixed  with  water  until  it  began  to  become  turbid,  and  treated 
twice  with  bone-charcoal.    The  alcohol  was  then  distilled  off  from 
the  pale  yellowish  filtrate  ;  a  yellow  brittle  resin  remained,  which 
was  powdered,  digested  with  ether  four  or  five  times,  dissolved 
three  times  in  the  least  possible  quantity  of  absolute  alcohol,  and 
precipitated  by  ether  in  order  to  effect  the  perfect  separation  of  a 
minute  quantity  of  the  resin  soluble  in  ether.    Owing  to  the 
neglect  of  this  purification,  Kayser  estimated  the  per-centage  of 
carbon  nearly  1.5  per  cent,  too  high.    Thus  prepared,  and  dried 
at  212°  F.,  rhodeoretine  resembles  in  appearance  the  finest  gum- 
arabic  ;  it  is  odorless,  tasteless,  brittle,  colorless,  and  transparent 
in  thin  pieces,  perfectly  white  when  powdered.    When  it  contains 
but  a  small  amount  of  water,  it  becomes  soft  below  212°  F.,  and 
may  be  drawn  out  into  fine  threads  having  a  pearly  lustre.  It 
softens  at  265°.8  F.  melts  at  302c  F.  to  a  yellowish  liquid  ;  above 
311°  F.  it  begins  to  decompose.  Its  alcoholic  solution  has  a  feeble 
acid  reaction.  It  appears  to  be  the  active  principle  of  jalap  ;*  3  or 
4  grs.  caused  repeated  and  violent  purging.  It  bi^rns  with  difficulty, 
and  its  analysis  could  only  be  effected  by  means  of  a  mixture  of  9 
parts  of  chromate  of  lead  and  1  part  bichromate  of  potash,  the  front 
part  of  the  tube  being  charged  with  chromate  of  lead  alone. 
Analysis  gave — 
Carbon    -    -    -    -  55*01  54*56  54-53  54* 57  72  54*75 
Hydrogen    -    -   -     7*89    8*07    7*89    7-89  60  7-73 
Oxygen    -    -    -    -  37-10  37-37  37*58  37-54  37  37*52 
On  the  analysis  of  rhodeoretine,  which  had  not  been  precipitated 
by  ether,  56*76  carbon  and  8- 16  hydrogen  were  obtained.  Kayser 
obtained — 
Carbon  -  -  56*06  55*87  42  56-37 
Hydrogen  -  -  7*94  7*89  35  7*84 
Oxygen     -       -      -  36*00    36*24    20  35*79 
*  Schlossberger  is  not  of  this  opinion.    See  his  Organ.  Chemie,  2nd  edition, 
p.  280. 
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