544 
Crystalline  Constituents  of 
[Am.  Jour.  Pharm. 
t       Dec.  1875. 
FURTHER   RESEARCHES    ON    THE    CHRYSTALLINE  CONSTITU- 
ENTS OF  BARBADOES  AND  SOCOTRINE  ALOES."-- 
BY   WILLIAM   A.  TILDEN,   D.SC.  LOND.,  F.C.S. 
The  names  employed  in  the  following  pages  to  designate  the  crys- 
talline principles  obtained  from  the  several  varieties  of  aloes  are  to  be 
understood  as  folloes  : — 
Barhaloin. — From  Bardadoes  aloes.  Discovered  by  Smith  and  Co. 
of  Edinburgh,  and  analyzed  by  Stenhouse,  1851. 
Socaloin. — Isolated  from  Socotrine  aloes  in  1856,  by  T.  B.  Groves. 
Natalo'in. — Discovered  by  Fl'dckiger,  1871. 
Zanaloifi. — Prepared  by  Histed,  from  a  variety  of  socotrine  aloes  im- 
ported by  way  of  Zanzibar.     Analyzed  by  Fllickiger,  1871. 
Before  proceeding  to  the  comparison  of  the  properties  of  these 
bodies,  and  the  discussion  of  their  chemical  constitution,  I  propose  to 
describe  briefly  some  additional  experiments  lately  conducted  in  my  lab- 
ratory  upon  the  aloin  from  Zanzibar  aloes.  All  the  new  analyses  in- 
cluded in  the  following  account  were  made  for  me  by  Mr.  W.  A. 
Shenstone,  to  whose  care  and  patience  I  take  this  opportunity  of  ex- 
pressing my  obligations. 
Zanaloin. — I  am  indebted  to  Messrs.  Hanbury,  of  Plough  Court,  for 
liberal  supplies  of  very  fine  Zanzibar  aloes,  from  which  the  specimens 
of  aloin  now  produced  were  prepared.  Without  such  aid,  in  fact,  the 
experiments  must  have  come  to  an  end  prematurely,  as  I  found  it  im- 
possible to  obtain  appreciable  quantities  of  the  crystalline  constituent 
from  commercial  samples  of  the  drug  produced  from  other  sources. 
The  process  employed  for  its  isolation  was  devised  by  Mr.  Histed,  and 
although  rather  troublesome  and  not  very  productive,  I  have  not  suc- 
ceeded in  improving  upon  it.  It  consists  in  macerating  the  coarsely 
powdered  aloes  with  a  sufficient  quantity  of  proof  spirit  to  make  a 
paste,  and  afterwards  gradually  expressing  the  liquid  from  the  mass. 
The  yellow  cake  which  remains  is  purified  by  crystallization  from 
water,  and  then  from  rectified  spirits. 
The  aloin  obtained  in  this  way  has  already  been  described  by  Dr. 
Fllickiger  (Year-Book  of  Pharmacy,  1871),  and  in  the  main  my  ob- 
servations agree  with  his.  I  have  found  that  when  dried  by  exposure 
to  air  at  the  ordinary  summer  temperature  the  quantity  of  water  it  con- 
tains varies  perceptibly  from  day  to  day,  and  it  is  difficult  to  get  it  into 
Read  before  the  British  Pharmaceutical  Conference. 
