Am.  Jour.  Pharm. 
July,  1895. 
Some  Commercial  A/oms. 
369 
/9-Barbaloin  to  the  similar  principle  existing  alike  in  Socotrine, 
Zanzibar  and  Jafferabad  aloes. 
During  the  time  of  these  discoveries  and  for  some  years  after- 
ward many  prominent  investigators  instituted  researches  for  the 
purpose  of  clearing  up  the  confusion  which  seemed  to  exist  among 
these  similar  principles  and  also  to  investigate  their  therapeutical 
activity  which  some  writers  believed  to  be  of  little  or  no  value. 
Among  the  names  of  writers  who  accomplished  much  in  this  respect 
are :  T.  and  H.  Smith,  Stenhouse,  Groves,  Fliickiger,  Histed, 
Pareira,  Tilden,  Dobson  and  Craig. 
Three  distinct  aloins  were  acknowledged  to  exist,  Nataloin,  Bar- 
baloin  and  Socaloin.  Nataloin  is  seldom  found  in  commerce,  and  at 
the  last  revision  of  the  U.  S.  P.,  Barbaloin  and  Socaloin  were  given 
official  recognition. 
In  1870,  W.  A.  Tilden1  made  a  thorough  investigation  of  the 
subject  in  which  he  ascertained  the  following  facts  :  Aloin  in  pure 
solutions  is  liable  only  to  tardy  alteration ;  exposed  to  the  air  the 
solution  deepens  in  color  by  absorption  of  oxygen ;  this  change  is 
hastened  by  the  addition  of  a  small  quantity  of  alkali  to  the 
solution. 
Preparations  of  aloes  upon  standing  for  a  long  time,  lose  their 
bitterness  without  sensibly  impairing  their  therapeutical  activity 
and,  in  his  opinion,  aloin  could  not  be  considered  the  active  con- 
stituent of  aloes,  as  it  possessed  very  little  action. 
He  was  immediately  contradicted  by  T.  and  H.  Smith,2  who  con- 
tended that  the  dose  of  aloin  bore  a  simple  ratio  to  the  dose  of  the 
drug  itself  and  was  of  unvarying  effect. 
Dr.  Wm.  Craig3  in  1875,  m  an  a^e  article,  summed  up  his  con- 
clusions regarding  aloin  in  the  following  words: 
"(1)  Aloin  may,  by  exposure  to  air,  undergo  considerable  chemi- 
cal change  without  losing  its  physiological  activity  as  an  active 
aperient. 
"  (2)  The  resin  when  thoroughly  freed  from  aloin  possesses  no 
purgative  properties  and,  therefore,  cannot  be  the  active  principle  of 
aloin. 
1  Pharm.  Jour.  ^rans.  (3),  1,  375. 
2  Pharm.  Jour.  Trans.  (3),  1,  402. 
3  Am.  Jour.  Pharm.,  47,  349. 
