Am.  Jour  Pharni. 
Oct.,  1884. 
Aloin. 
507 
ALOIN. 
By  Henry  Charles  Plenge,  Ph.G. 
From  an  Inaugural  Essay. 
The  only  published  process  which  a  priori  seemed  practicable  for  all 
varieties  of  aloes  is  that  of  Tilden,  which  was  followed.  25  grams 
of  aloes  were  dissolved  in  250  cc.  of  boiling  water  acidulated  with 
hydrochloric  acid  and  allowed  to  cool.  The  liquid  was  then  decanted 
from  the  precipitated  resinous  matter,  evaporated  to  about  50  cc,  and 
set  aside  two  weeks  for  .crystals  to  form.  The  liquid  portion  was 
poured  off,  the  crystals  were  pressed  between  folds  of  bibulous  paper  to 
remove  as  much  as  possible  of  the  adhering  resin,  and  then  purification 
by  various  means  was  tried. 
The  mixture  of  crystals  and  resin  was  dissolved  in  diluted  alcohol, 
the  solution  filtered  and  set  aside  to  crystallize.  The  crystals  were 
still  contaminated  with  a  considerable  amount  of  resinous  matter. 
Other  solvents  were  used,  of  which  acetic  ether  proved  to  be  the  best. 
The  resin  is  apparently  more  soluble  in  ether  than  the  aloin,  and  when 
the  impure  aloin  was  treated  with  this  solvent  and  allowed  to  stand, 
with  occasional  agitation,  the  liquid  acquired  a  brown  color,  and  the 
yellowish  color  of  the  crystals  could  be  distinguished.  The  liquid  was 
then  quickly  and  carefully  poured  off  and  the  crystals  dried. 
Five  commercial  varieties  of  aloes  were  experimented  with :  Soco- 
trine, Barbadoes,  Cape,  Cura$ao  and  Bonare.  The  two  latter  were 
very  similar  in  appearance  and  yielded  about  the  same  amount  of  aloin. 
From  Cape  aloes  no  aloin  was  obtained. 
In  the  first  experiment  Socotrine  yielded  3  per  cent,  of  aloin;  in 
subsequent  trials  none  was  obtained.  Barbadoes  aloes,  to  which  this 
process  is  specially  adapted,  averaged  9  per  cent. ;  Curacao  averaged 
7*5  per  cent.,  and  Bonare  7  per  cent.  The  cause  of  variation  in  the 
yield  of  aloin  from  different  portions  of  the  same  sample  treated  by 
the  same  process  is  evidently  due  to  variation  in  the  degree  of  heat 
used  in  evaporating  the  infusion  and  probably  also  to  the  length  of 
time  at  which  the  heat  was  applied.  By  the  use  of  a  vacuum  appa- 
ratus the  yield  would  undoubtedly  have  been  greater  and  the  aloin  of 
a  better  quality.  The  aloin  finally  obtained  was  not  in  distinct  crys- 
tals but  in  small  crystalline  crusts. 
Aloin  was  obtained  from  Socotrine  aloes  by  the  following  process: 
One  part  of  Socotrine  aloes  was  digested  in  3  parts  of  alcohol  for  24 
