Am.  Jour.  Pharm, ") 
August,  1898.  j 
The  Chemistry  of  Aloes. 
401 
which  was  obtained  from  the  latter,  or  from  aloin  obtained  from  the 
first  three  kinds  of  aloes  just  mentioned.  It  is  emodin,  the  great 
laxative,  to  which  rhubarb,  senna,  cascara,  frangula,  owe  their  laxa- 
tive properties.  It  can  be  obtained  from  aloin  by  extracting  this 
with  ether,  from  which  it  will  crystallize,  and  can  be  purified  by 
sublimation.  Hence  the  so-called  Borntraeger's  reaction  for 
aloin  is  not,  correctly  speaking,  a  reaction  for  aloin  but  for  emodin ; 
aloin  that  has  been  deprived  of  emodin  not  giving  the  reaction.  A 
test  of  the  emodin  obtained  from  Barbadoes  aloes  showed  that  in 
doses  of  half  to  one  grain  it  possesses  marked  purgative  proper- 
ties, and  in  smaller  doses  quite  marked  laxative  properties,  and 
it  was  shown  that  this  property  is  due  to  increased  per- 
istalsis of  the  intestine.  It  was  further  shown  that  solutions 
of  pure  aloin,  when  allowed  to  stand  exposed  to  the  air,  de- 
velop in  a  very  short  time  quantities  of  emodin  which  were 
isolated  and  analyzed.  The  same  result  can  be  obtained 
by  heating  aloin  with  a  1  per  cent,  solution  of  caustic  potash. 
Whether  the  reaction  is  one  of  oxidation  or  of  saponification  has  not 
yet  been  determined,  but  it  is  believed  that  the  laxative  properties  of 
aloin  are  due  to  emodin,  and  that  even  if  our  aloin  that  has  been 
deprived  of  all  emodin  is  taken  into  the  system  the  conversion  of 
the  same  into  emodin  in  its  passage  through  the  system  is  the  cause 
of  its  laxative  property.  While  this  does  not  detract  from  the 
value  of  aloin,  it  much  increases  our  interest  in  this  substance,  and 
accounts  for  the  unusual  efficacy  and  popularity  of  cascara  sagrada, 
whose  active  principle,  the  glucoside  purshianin,  which  it  was  my 
good  fortune  to  be  the  first  to  isolate,  does,  as  we  know  easily  by 
saponification,  split  up  into  sugar  and  this  same  emodin.  The 
result  of  this  valuable  contribution  to  pharmaceutical  science  of  Pro- 
fessor Tschirch  and  his  pupil,  G.  Pedersen,  will  be  to  stimulate  the 
interest  in  emodin,  and  probably  to  give  us  a  ready  means  of  making 
it  on  a  large  scale.  To  sum  up  the  points  brought  out  in  this 
paper:  (1)  That  Curacoa  aloes  is  as  efficient  and,  being  much  cheaper, 
should  be  used  in  preference  to  Socotrine  aloes,  the  greater  portion 
of  which  as  sold  to-day  is  made  up  anyway  of  Curacoa  aloes.  (2) 
That  the  resin  of  aloes  is  an  ester  or  organic  salt,  and  varies  accord- 
ing to  the  kind  of  aloes,  and  that  the  varying  constituent  is  the 
acid,  the  alcoholic  constituent  being  aloresinotannol  and  being  the 
same  in  both  Barbadoes  and  Cape  aloes,  the  only  two  thus  far  ex- 
