40O 
The  Chemistry  of  Aloes. 
f  Am.  Jour.  Pharm. 
t      August,  1898. 
exclusion  of  the  Soeotrine,  especially  as  it  costs  only  about  one- 
eighth  as  much.  So  much  for  the  commercial  side  of  aloes.  T. 
and  H.  Smith,  in  185 1,  and  Stenhouse,  Fliickiger,  Tilden,  E. 
Schmidt,  Liebelt  and  Groenewald  since  have  studied  aloes  as  to 
the  aloin  obtained  therefrom.  The  Smiths  operated  on  Barbadoes 
aloes,  and  obtained  what  they  called  barbaloin,  formula  C17H1807  -f- 
H20.  Fliickiger,  in  1871,  decided  that  the  aloin  he  and  Histed 
obtained  from  Soeotrine  aloes  was  not,  as  Pareira  had  stated,  identi- 
cal with  barbaloin,  but  was  C15H1607.  From  these  aloins,  notably 
barbaloin,  Tilden  had  obtained  by  the  action  of  strong  oxidizing 
agents  such  as  potass,  bichromate,  alaxanthin  or  methyl- tetra- 
oxyantryaquinone,  thus  indicating  that  aloin  was  a  derivative  of 
anthraquinone.  As  we  all  know,  aloes  contains  besides  the  aloin, 
quite  a  quantity  of  resin,  which  has,  however,  as  yet  not  been 
investigated.  Tschirch  and  his  pupils  at  Bern  have  been  these  past 
four  or  five  years  investigating  in  order  the  various  resins,  beginning 
with  tolu,  benzoin,  peru,  etc.  He  has  recently  taken  up  the  resin 
of  aloes,  and  finds  it  to  be  like  the  other  resins,  an  ester  or  organic 
salt,  made  up  in  case  of  Barbadoes  aloes  of  cinnamic  acid,  and  one 
of  that  peculiar  and  characteristic  class  of  resin  alcohols,  which  he 
finds  in  all  resins  and  has  named  "  resinotannols  "  and  which  he 
has  named  "  aloresinotannol."  It  is  a  gray-brown  powder  of 
formula  C22H26G6,  and  contains  two  hydroxyl  groups,  as  he  obtained 
from  it  a  di-benzoyl  derivative.  The  resin  of  Cape  aloes  was  similarly 
treated,  and  yielded  the  same  aloresinotannol  ;  but  to  demonstrate 
that  the  resin  was  different  from  that  of  Barbadoes  aloes,  he  found 
that  the  acid  in  combination  with  it  was  not  cinnamic  but  para- 
cumaric  acid.  The  resin  of  Soeotrine  aloes  has  not  been  taken  up 
as  yet,  but  the  aloin  from  the  three  aloes  was  next  considered.  Here 
some  most  unexpected  valuable  and  interesting  observations  were 
made,  and  as  the  result  of  close  observation  of  a  certain  color 
reaction  of  aloe,  known  as  Borntraeger's  test  for  aloes.  It  is  this  : 
aloes  or  aloes  solutions,  when  treated  with  either  benzin  or  benzene, 
yield  to  these  solvents  a  yellow  substance  which  turns  cherry-red 
on  the  addition  of  ammonia.  It  was  noticed  that  Cape,  Barbadoes 
and  Curacoa  aloes  gave  the  reaction,  while  Natal  and  liquid  or  true 
Soeotrine  aloes  did  not.  The  color  was  not  due  to  the  aloin  or  to 
the  resin,  as  both  of  these,  when  pure,  did  not  give  it,  but  to  another 
substance  which  no  one  ever  thought  was  contained  in  aloes,  and 
