'94  Crystalline  Constituent  of  Jafferabad  Aloes.    { '^^eT'isss*'''"' 
aloes  and  a  portion  of  Dr.  Tilden^s  zanaloin,  which  he  kindly  gave  me 
for  the  pur])()se,  were  employed. 
There  is  no  distinguishable  difference  in  the  crystalline  form  of  the 
two  aloins. 
In  the  above  engravings,  which  are  from  photographs,  and,  there- 
fore, absolutely  trustworthy,^  la  and  lb  are  of  the  aloin  of  Jafferabad 
aloes,^  and  2  is  of  zaiialoin  of  Dr.  Tilden's  preparation.  Two  photo- 
graphs were  taken  of  my  aloin,  as  with  the  available  slide  it  was  not 
possible  to  get  good  pictures  of  both  the  large  and  small  crystals  at 
once. 
Neither  of  them  gives  any  change  of  color  in  the  cold  when  moist- 
ened with  ordinary  strong  nitric  acid ;  both  of  them  are  reddened  by 
fuming  nitric  acid.  And  the  Jafferabad  aloin,  by  prolonged  treatment 
with  nitric  acid,  yields  chrysammic,  aloetic,  picric,  and  oxalic  acids,  as 
^analoin  and  barbaloin  do. 
Jafferabad  aloin,  when  treated  with  potassium  chlorate  in  a  hydro- 
chloric acid  sokition,  yields  a  chloro-body  resembling  that  given  by 
zanaloin,  and  when  heated  with  acetic  anhydride  gives  an  acetyl  com- 
pound similar  to  acetyl-zanaloin. 
Both  of  them,  when  treated  with  strong ' sulphuric  acid  and  potas- 
sium bichromate,  give  a  violet  coloration  closely  resembling  that  given 
by  strychnia,  but  quickly  fading  to  green. 
These  results  seem  to  leave  no  doubt  that  the  aloin  of  Jafferabad 
aloes  is  identical  with  that  from  Zanzibar  aloes,  though  I  should  state 
that  the  color  of  ti.e  former  is  distinctly  a  lighter  shade  of  yellow  than 
that  of  the  latter. 
Up  to  the  present  time  four  aloins  have  been  examined  somewhat 
minutely,  viz.,  those  known  as  barbaloin,  zanaloin,  nataloin,  and  that 
which  is  the  subj'ect  of  the  present  communication.  In  addition,  soca- 
loin  has  been  partly  examined  and  is  believed  to  be  identical  with  zan- 
aloin. 
As  the  adoption  of  a  new  name  for  every  fresh  variety  of  aloin  ex- 
amined is  likely  to  be  a  source  of  some  inconvenience,  and  as  there  is 
an  obvious  advantage  in  adopting  a  nomenclature  which  will  group 
together  those  aloins  which  are  most  nearly  alike,  and  also  because  the 
aloins  seem  likely  to  fall  into  a  few  groups,  I  venture,  in  concluding 
^  These  were  kindly  taken  for  me  from  microscopic  .slides  by  Mr.  Woollet,  of  Col- 
•chester,  who,  with  my  brother,  has  lately  laken  a  good  deal  of  interest  in  such  work. 
^  The  magnification  in  each  is  about  180  diameters. 
