Am.  Jour.  Pharm,  ) 
Jan.  2, 1871.  J 
A  few  Notes  oil  Aloes, 
37 
boiled  and  tested  as  above.  Both  gave  gas  in  about  half  an  hour 
nearly  equally.  A  portion  of  the  same  sample  of  yeast  was  used  in 
all  these  cases.  There  is  consequently  no  sugar  produced  by  boiling 
aloin  with  acids,  and  the  aloin  undergoes  practically  no  change. 
The  copper  test  is  inapplicable,  inasmuch  as  pure  aloin  which  has 
ungergone  no  manipulation  reduces  alkaline  copper  solution  rapidly 
and  freely.* 
Aloin  gives  no  apparent  change  with  tartar  emetic  nor  with  ferrous 
salts,  but  with  ferric  salts  it  strikes  an  olive  coloration,  which  is  de- 
stroyed by  reducing  agents. 
III.  The  substance  termed  resin,  which  abounds  in  all  kinds  of 
aloes,  is  not  very  happily  so-called,  for  it  is  soluble  in  considerable 
quantity  in  hot  water.  It  is  said  to  yield  chrysammic  acid  by  treat- 
ment with  nitric  acid,  and  is  therefore  related  in  some  way  to  the 
soluble  part  of  aloes ;  but  this  is  a  point  upon  which  nothing  is  known 
at  present. 
IV.  There  can  be  no  doubt  that  the  "  aloesic  acid,"  supposed  to  be 
present  in  aloes,  has  no  existence.  The  reaction  with  iron  salts, 
ascribed  to  it  is  due  to  the  crystallizable  aloin,  and  the  acidity  to  test- 
paper  presented  by  an  infusion  of  aloes  is  a  property  cf  the  half- 
oxidized  substance  contained  in  the  uncrystallizable  ^'aloetin." 
y.  In  addition  to  those  bodies,  there  is  in  all  aloes  a  small  but  nota- 
ble proportion  of  vegetable  albumen.  It  is  left  when  either  kind  is 
exhausted  with  rectified  spirit.  Its  presence  probably  promotes  the 
change  to  which  solutions  of  aloes  are  always  subject. 
Pure  aloin,  then,  in  pure  solutions,  is  liable  only  to  very  tardy  al- 
teration. Exposed  to  the  air,  it  gradually  absorbs  oxygen,  and  the 
solution  deepens  in  color ;  but  the  change  which  is  thus  slow  under 
such  circumstances,  is  very  rapid  indeed  if  a  small  quantity  of  any 
alkali  is  introduced.  The  solution  then  becomes  in  a  few  hours  of  a 
deep  brown  color ;  and  after  the  lapse  of  three  or  four  days,  if  the  air 
be  admitted,  the  aloin  entirely  disappears,  and  is  transformed  into  a 
substance,  or  mixture  of  substances,  which  no  longer  possesses  any  bit- 
terness, but  is  perfectly  insipid.  An  experiment  was  made  by  dissolv- 
ing pure  aloin  in  water  with  an  equal  weight  of  carbonate  of  potas- 
sium ;  the  solution,  left  in  an  imperfectly  closed  flask  for  about  a  week, 
*I  have  found  that  many  other  bodies  besides  the  glucoses  do  this  ;  amongst 
others  tannin  and  orcin. 
