^"•^:c.^^75""■}      Barbadoes  and  Socotrine  Aloes,  545 
such  a  condition  as  to  retain  a  constant  weight.  By  exposure  in  a 
vacuum  over  sulphuric  acid  it  loses  weight  rapidly,  and  two  determina- 
tions made  in  this  way  gave  14*06  and  13*9  per  cent,  respectively. 
The  loss  of  weight  experienced  upon  exposure  to  a  temperature  of 
115°  to  120°  C.  was  somewhat  greater  than  this — 14*46  and  15*95 
per  cent,  in  two  recorded  instances — but  this  greater  loss  is  in  all  prob- 
ability due  to  partial  decomposition,  the  aloin  fusing  and  becoming 
darker  in  color. 
Two  determinations  of  carbon  and  hydrogen  made  upon  the  air- 
dried  substance  gave  these  results  : 
I.  II. 
Twice  Crystallized  Mean. 
Crystallized.  Three  Times. 
C    .       .     5270  .       .  52-87     .       .  5278 
H.       .       .  6-42      .        6*39  .      .       .  6-40 
No  great  importance,  however,  attaches  to  these  numbers  in  conse- 
quence of  the  uncertainty  regarding  the  hygroscopic  condition  of  the 
substance. 
After  drying  in  a  vacuum  over  sulphuric  acid  three  combustions 
were  made  with  the  results  indicated  below.  In  all  these  and  subse- 
quent analyses  the  substance  was  burnt  with  a  mixture  of  lead  and  po- 
tassium chromates,  all  the  usual  precautions  being  observed  : 
I.  '2926  gram  of  anhydrous  zanaloin  gave  '6379  of  CO2  and 
.1528  of  H2O. 
II.  -2650  gram  gave  '5792  CO2  and  '1370  H2O. 
III.  -2606  gram  gave  *5678  CO2  and  *i38o  H2O. 
I.  II.  III.  Mean  Percentage. 
C  59'45  59-6o  59-42  59-49 
H  5-80  574  5-87  5-80 
Dr.  FlUckiger  gives  59*20  and  5*94  as  the  percentages  of  carbon  and 
hydrogen  in  zanaloin  dried  over  sulphuric  acid,  but  the  slight  discrep- 
ancy may  be  accounted  for  by  the  more  complete  dryness  of  the  sub- 
stance operated  upon  by  us. 
Bromoxanaloin. — The  aloin  upon  which  I  have  been  operating  was 
prepared  from  aloes,  taken,  I  am  informed,  from  she  same  sample  upon 
which  FlUckiger  made  his  experiments.  I  have  also  been  careful  to 
prove  by  repeated  application  of  the  test,  that  my  zanaloin  gives  the 
same  reaction  with  nitric  acid  and  other  oxidizing  agents  as  the  zana- 
loin examined  in  the  laboratory  at  Bern.  We  have  been  more  fortu- 
nate than  Professor  FlUckiger  in  the  production  of  definite  brominated 
and  chlorinated  derivatives  from  this  body.     By  dissolving  zanaloin  in 
35 
