ALOINE. 
143 
aloine  is  scarcely  obtainable  in  sufficient  quantity,  or  in  such  a 
state  of  purity  as  to  be  recognizable,  from  any  other  than  the 
Barbadoes  variety.  ¥ 
M.  Robiquet,  in  an  article  read  to  the  Acade'mie  de  Medecine, 
Feb.  26,  1856.  and  published  in  the  Chemist  of  July,  1856,  ar- 
rived at  the  same  conclusion  with  regard  to  Cape  and  Socotrine 
aloes,  but  gives  a  much  more  easy  and  productive  process  for  its 
preparation  from  Barbadoes  aloes. 
All  these  gentlemen  express  their  belief  that  the  opaque 
varieties  alone  contain  any  considerable  proportion  of  aloine 
in  a  crystallizable  state,  and  that  the  vitreous  or  translucent 
varieties  have  undergone  the  action  of  heat  subsequent  to  inspis- 
sation,  and  that  the  fusion  has  converted  the  aloine  into  an  amor- 
phus  substance,  quasi-resinous.  From  a  perusal  of  the  works  of 
the  two  first  experimenters,  and  a  consideration  of  what  had 
hitherto  been  published  respecting  the  manufacture  of  the  differ- 
ent varieties  of  aloes,  I  was  early  led  to  doubt  the  accuracy  of 
some  of  their  conclusions. 
For  instance,  Pereira  states  that  the  best  Barbadoes  aloes  is 
procured  by  evaporating  in  a  copper  vessel  over  a  naked  fire  the 
juice  that  spontaneously  exudes  from  the  transversely  cut  stems 
of  the  aloe  (the  decoction  of  the  leaves  is  not  unfrequently  used), 
and  that  the  evaporation  is  carried  to  such  a  point  that  the  ex- 
tract on  cooling  "  breaks  short"-— in  other  words,  has  been  re- 
duced to  dryness  and  incipient  fusion. 
The  Socotrine,  on  the  contrary,  appears  to  be  the  pure  spon- 
taneously exuded  juice  of  the  cut  leaves,  evaporated,  after  de- 
positing its  grosser  parts,  by  the  sole  agency  of  the  sun. 
If  it  be  true  then  that  aloine  is  so  readily  altered  by  contact 
of  air,  simultaneously  with  the  application  of  heat,  one  would 
scarcely  be  justified  in  attempting  its  preparation  from  the  for- 
mer kind,  without  first  applying  to  the  latter. 
Again,  aloine  is  proved  to  be  but  slightly  soluble  in  cold  water; 
then  why  use  cold  for  its  separation  ?  or  ether,  which  dissolves 
it  so  sparingly  ? 
I  shall  be  able  to  show  that  Socotrine  aloes  contains  a  con- 
siderable proportion  of  crystallizable  aloine,  to  be  obtained  from 
it  without  extraordinary  difficulty  or  precaution. 
The  following  circumstances  that  occurred  shortly  after  the 
