138         VALUES  OF  SOCOTRINE  AND  BARBADOES  ALOBB. 
(including  Hepatic),  is  fairly  represented  by  the  positions  they 
respectively  occupy  in  our  Pharmacopoeia.  In  my  opinion  it  is 
not  fairly  represented,  but,  on  the  contrary,  so  far  as  my  obser- 
vation goes,  the  Barbadoes  is  a  better  description  of  aloes  for 
medical  purposes,  acting  in  a  preferable  manner  as  a  purgative 
to  the  Socotrine.  This  opinion  has  been  held  by  some  medical 
practitioners,  including  apparently  the  late  Dr.  Marshall  Hall, 
from  whose  original  and  favourite  formula  known  as  Pii.  Aloes 
Diluta,  our  Pharmacopoeia  has  borrowed  the  directions  for  the 
preparation  already  spoken  of  under  the  name  of  Pil.  Aloes  c. 
Sapone. 
It  is  well  known  that  many  patients  have  a  strong  objection 
to  the  use  of  ordinary  aloes,  and  we  must  all  have  noticed  the 
solicitude  manifested  by  such  persons  to  have  their  prescriptions 
dispensed  with  the  veritable  aqueous  extract  instead  of  the  crude 
drug.  Now  it  is  worthy  of  remark  that  the  per-centage  of  aque- 
ous extract  in  Socotrine  aloes  is  about  56,  and  in  Barbadoes 
about  80  ;  and  it  almost  follows  that  if  the  aqueous  extract  is 
really  preferable  in  its  operation,  according  to  the  concurrent 
belief  of  the  faculty  and  their  patients,  that  description  of  aloes 
must  be  the  best  which  contains  the  largest  proportion  of  aque- 
ous extract. 
But  in  addition  to  this,  Messrs.  Smith  of  Edinburgh  by  their 
discovery  of  aloin,  seem  to  me  to  have  supplied  a  further  a 
priori  argument  in  favor  of  Barbadoes  aloes.  From  their  ex- 
periments {Ph.  Journal,  vol.  xi.,  p.  23)  it  appears  that  aloin  is 
at  all  events  obtained  with  greater  facility  from  Barbadoes  aloes 
than  from  any  other  description  :  and  although  the  contradic- 
tory statements  which  have  been  published  with  reference  to 
this  substance  are  somewhat  perplexing,  we  may  safely  conclude 
that  the  purgative  properties  of  aloes  are  due  to  it  in  part,  if 
not  wholly,  and  that  the  facility  with  which  it  is  obtained  from 
the  Barbadoes  variety,  indicates  its  abundant  presence  in  a  con- 
dition unaltered  by  the  process  of  inspissation,  which  cannot  be 
said  with  equal  confidence  of  Socotrine  aloes.  (  Vide  Dr.  Perei- 
ra's  paper  on  Aloe  Juice,  Ph.  Journal,  xi.,  439.) 
The  favorable  estimate  of  Barbadoes  aloes,  deducible  from  its 
relation  both  to  the  aqueous  extract  and  to  aloin  as  above  de- 
scribed, has  been  confirmed  by  my  own  experience,  for  after 
