142 
Aloes  in  Pharmaceutical  Preparations. 
J  Am  Jour.  Pharm. 
t      March,  1885. 
THE  DETECTION  OF  ALOES  IN  PHARMACEUTICAL 
PREPARATIONS.^ 
By  R.  a.  Cripps  and  T.  S.  Dymond. 
Among  the  difficult  problems  occasionally  met  with  by  a  chemist  is 
that  of  detecting  aloes  in  compound  mixtures.  This  involves,  by  all 
ordinary  methods,  a  considerable  amount  of  trouble  in  separating  the 
various  substances  by  means  of  solvents,  and  entails  the  use  of  a  large 
quantity  of  substance,  which  in  the  case  of  pills,  etc.,  cannot  always 
be  spared ;  the  results,  even  then,  are  often  unsatisfactory.  Perhaps 
the  test  proposed  by  Borntrager  {Zeitschrift  fur  anal.  Chem.j  xix,  165), 
is  the  best  of  those  hitherto  published.  It  consists  in  extracting  the 
substance  with  alcohol,  filtering,  shaking  the  filtrate  with  benzol, 
removing  the  benzol  layer  and  agitating  it  with  ammonia ;  on  standing 
the  aqueous  liquid  should  assume  a  pink  color  in  presence  of  aloes. 
This  test  was  applied  to  a  number  of  different  kinds  of  aloes,  for  most 
of  which  our  thanks  are  due  to  Mr.  Holmes,  but  the  results  were  not 
very  satisfactory,  some  of  the  specimens  requiring  twenty-four  hours 
to  develop  the  pink  color,  only  four  giving  it  at  all  distinctly  at  once. 
Mr.  R.  H.  Groves  has  pointed  out  [Pharm.  Journ.  [3],  xi,  1045)  that 
certain  precautions  are  necessary  to  render  the  test  trustworthy,  and 
that  the  color  reaction  is  not  due  to  the  aloin,  and  it  has  also  been 
shown  by  Lenz  (Zeitschrift  fur  anal.  Chem.,  xxi,  220)  that  any  sub- 
stance containing  chrysophanic  acid  also  gives  this  coloration,  and  it  is, 
therefore,  useless  for  distinguishing  aloes  from  rhubarb,  etc. 
The  following  test  has  been  proposed  by  Klunge  [Archiv  der  Pharm., 
1883,  363).  To  an  aqueous  solution  of  the  suspected  substance, 
diluted  with  water  till  nearly  colorless,  a  drop  of  copper  sulphate 
solution  is  added.  An  intense  yellow  coloration,  which  on  warming 
with  a  little  chloride  of  sodium  changes  to  a  deep  red  or  violet,  indi- 
cates the  presence  of  aloes.  This  test  is  also  unsatisfactory,  for  neither 
do  all  the  varieties  of  aloes  give  this  deep  red  color,  nor  is  the  yelloAV 
color,  though  distinctive  of  aloes,  seen  in  solutions  containing  already 
a  yellow  coloring  matter  such  as  saffron. 
In  view  of  this  unsatisfactory  state  of  the  detection  of  aloes,  we 
now  propose  a  test  depending,  first,  on  the  reaction  given  by  aloes  with 
sulphuric  acid  and  nitric  acid ;  secondly,  on  the  reaction  of  the  result- 
ing acid  mixture  with  water;  and  thirdly,  on  the  reaction  of  this  diluted 
1  Read  at  an  Evening  Meeting  of  tlie  Pharmaceutical  Society  of  Great 
Britain,  February  4,  1885. 
