194 
Bitter  Aloes. 
Am.  Jour.  Pharm. 
April.  1887. 
be  natural  both  to  the  juice  of  the  leaf,  and  an  aqueous  solution  of  the 
drug  ;  also  by  the  well-known  practice  of  storing  a  certain  variety  of 
aloes,  whereby  it  is  believed  greatly  to  improve.  Prolonged  exposure 
to  moist  heat  is  said  by  Tilden  to  convert  aloin  into  a  brown  sub- 
stance, called  by  Craig  "  changed  99  aloin,  and  stated  by  him  to  retain 
its  therapeutic  activity,  since  numerous  experiments  on  human  beings 
and  rabbits  showed  that  1  or  2  grains  acted  as  a  mild  aperient.  So 
that  Aitken's  complaint  of  the  injury  done  to  the  extract  by  the 
employment  of  steam  heat  in  its  preparation  seems  hardly  well 
founded. 
Royle  and  Headland  state  that  aloin  heated  to  212°  F.  is  rapidly 
oxidized  and  decomposed,  but  Tilden  considers  the  presence  of  alkali 
essential  to  rapid  oxidation,  and  notes  that  potassium  carbonate  is 
-specially  conducive  to  this  change. 
In  Paris's  "  Pharmacologia  "  it  is  held  that  the  purgative  property 
of  an  alkaline  solution  diminishes,  pari  passu,  with  the  bitterness ; 
Branson  remarks  that  the  decoction  becomes  less  purgative  by  keep- 
ing, and  Tilden  states  that  the  oxidized  and  tasteless  alkaline  solution 
has  no  effect,  but  W.  Young  found  that  the  varying  degrees  of  bitter- 
ness did  not  affect  its  aperient  activity.  My  own  very  limited  ex- 
perience leads  to  a  doubt  whether  a  sample  of  concentrated  decoction, 
which  from  keeping  has  ceased  to  be  unbearably  nasty,  is  therefore 
necessarily  inefficient. 
Cathartic  remedies  excel  most  others  in  the  completeness 
with  which  their  action  is  demonstrated ;  that  such  clouds  of 
doubt,  therefore,  obscure  the  truth  with  regard  to  one  of  the  best 
known  of  this  class  lessens  our  wonder  at  the  virtues  alternately 
affirmed  and  denied  to  belong  to  those  whose  working  is  less  pal- 
pable. 
The  uncertainty  as  to  the  dose  of  aloin  will  illustrate  my  meaning. 
T.  and  H.  Smith  state  the  relative  proportion  as  1  to  5  of  aloes ;  but 
Tilden  took  \  to  1  grain  without  effect,  although  it  does  not  appear 
that  he  controlled  the  test  by  taking  5  grains  of  aloes.  Dr.  Craig 
gives  the  dose  as  J  to  1  grain,  the  B.P.  \  to  2  grains,  Squire  1  to  2 
grains,  Mitchell  1  to  3  grains,  and  Martindale  1  to  4  grains.  Stille 
and  Maisch  regard  aloin  as  probably  two  or  three  times  as  active  as 
good  aloes,  and  quote  Dr.  Harley  to  the  effect  that  1 J  grains  will  pro- 
duce two  or  three  copious  evacuations  in  a  strong  adult,  and  that  1\ 
grains  are  a  powerfully  cathartic  dose. 
