Am.  Jour.  Pharm. 
April,  1887. 
Bitter  Aloes. 
193 
been  prepared  by  boiling;  but  it  is  questionable  whether  the  two. 
classes  differ  essentially  in  their  operation,  or  merely  in  degree,  need- 
ing onlv  readjustment  of  doses  to  overcome  it.  A  more  important 
question,  indeed  the  cardinal  point  in  discussing  the  thereapeutics  of 
aloes,  is,  whether  aloin  is  the  true  active  principle  or  measure  of  value 
-  of  the  drug.  In  spite  of  the  boiling,  it  is  the  Barbadoes  variety  which 
has  generally  been  used  as  the  source  of  this  principle.  Tilden,  how- 
ever, regards  Barbaloin,  Socaloin  and  Nataloin  as  unmistakably  dif- 
ferent substances.  In  the  hands  of  Plenge,  Tilden's  process  gave 
yields  of  3  per  cent,  from  Socotrine  and  9  per  cent,  from  Barbadoes 
respectively.  An  alternative  process,  in  which  Socotrine  was  treated 
by  boiling  in  alcohol  for  two  hours,  gave  10  per  cent,  of  aloin  ;  but  it 
is  difficult  to  reconcile  this  method  of  separation  with  Squibb's  state- 
ment that,  with  the  exception  of  about  6  or  7  per  cent,  of  impurities, 
the  whole  of  the  drug  is  soluble  in  alcohol. 
Tilden  considers  that  all  varieties  owe  their  bitterness  to  the  aloin 
they  contain,  and  he  obtained  20  per  cent,  from  Barbadoes  by  treating 
it  as  for  extract,  evaporating  the  liquid  resulting  from  1  lb.  of  aloes  to 
32  fluidounces,  which  must  consequently  have  been  a  10  per  cent,  so- 
lution of  aloin. 
Craig  states  that  aloin  constitutes  25  per  cent,  of  aloes,  yet  Mitchell 
obtained  only  between  8  and  9  per  cent,  from  Barbadoes,  and  oddly 
enough,  states  that  the  residual  liquid  from  1  lb.  yielded  10  oz.  of 
"  very  good  "  extract.. 
It  appears  then  that  the  boiling,  which  is  so  strongly  deprecated 
both  in  obtaining  the  crude  drug  and  in  making  its  galenical  prepara- 
tions, is  consistent  with  a  larger  yield  of  aloin  and  greater  purgative 
power  in  the  aloes  so  prepared. 
Most  curious  is  it  also  to  note  that  while  the  sun-dried  Socotrine  is 
generally  regarded  as  the  standard  quality  and  described  by  Tilden 
and  Rammell  as  consisting  mainly  of  crystallized  aloin  with  some  resi- 
noid,  the  authentic  specimen  procured  by  Professor  Balfour,  when  ex- 
amined by  Dott,  yielded  only  2  per  cent,  of  the  former  to  55  per  cent, 
of  the  latter,  and  was  regarded  as  more  historically  interesting  than 
medicinally  valuable. 
If  the  reason  for  this  be  sought  for  in  the  fact  that  it  had  been  kept 
for  three  years,  we  are  confronted  by  the  statement  of  Tilden 
that  aloin  is  not  easily  decomposed  by  heat  in  neutral  or 
slightly  acid  solution,  which  latter  condition  is  stated  by  Branson  to 
13 
