}  Analytical  Researches  and  Investigations.  357 
ash  in  flour,  wine,  beer,  extracts,  etc.,  may  be  much  facilitated  by- 
perfecting  the  combustion  of  the  previously  carbonized  residue  in  a 
•current  of  oxygen.  The  oxygen  apparatus  may  consist  of  a  test- 
tube,  in  which  is  placed  a  mixture  of  potassium  chlorate  and  man- 
ganese dioxide,  and  the  upper  portion  of  which  is  filled  with  glass- 
wool,  in  order  to  prevent  the  escape  of  dust-like  particles.  The  oxy- 
:gen  is  conveyed  through  the  perforated  lid  of  a  Rose  crucible,  the  lat- 
ter being  first  heated,  and  finally  the  test  tube.  As  soon  as  oxygen 
passes  over,  a  violent  combustion  is  produced,  and  the  ash  is  very 
soon  burned  to  whiteness. — Ibid,,  p.  474,  from  Pharm,  Centralhalle, 
3,  p.  188. 
Reactions  of  Aloes.  By  Dr.  Wilhelm  Lenz. — By  the  examination 
'of  a  number  of  specimens  of  authentic  varieties  of  aloes,  and  a  com- 
parison of  their  reactions  with  those  of  extracts  of  rhubarb,  senna, 
frangula  bark  and  buckthorn  berries,  th^  author  found  that  the  reac- 
tion of  Borntrager,  appearance  of  a  red  coloration  by  the  addition  of 
ammonia  to  the  benzin  extract  of  the  liquid,  is  not  characteristic  for 
aloes,  as  the  other  named  substances,  when  treated  in  the  same  man- 
ner, also  produce  red  colorations  which  cannot  be  plainly  distin- 
guished from  those  obtained  with  aloes.  The  behavior  toward  fer- 
xic  chloride  and  iodinized  potassium  iodide,  which  Klunge  has  recom- 
mended, the  author  also  considers  unreliable  for  the  detection  of 
aloes.  The  reaction  of  Borntrager,  which  is  attributed  to  the  pres- 
ence of  aloetin,  is  also  produced  by  chrysophanic  acid,  and  the  for- 
mer and  the  latter,  according  to  their  reactions  with  solution  of  potas- 
sium hydrate  and  sulphuric  acid  (which  produce  first  a  red  and  then 
an  orange  coloration),  and  by  fusion  with  caustic  potassa,  which  is 
•colored  blue  by  both  aloetin  and  chrysophanic  acid,  would  appear 
to  be  identical. 
Reliable  results  for  the^  detection  of  aloes  are  obtained  by  the  pro- 
cedure of  Dragendorif,  which  consists  in  the  precipitation  of  the  solu- 
tions by  neutral  acetate  of  lead,  removal  of  the  excess  of  lead  by  sul- 
phuric acid,  purification  of  the  solution  by  agitation  with  ether,  and 
•extraction  of  the  aloin  with  amylic  alcohol.  In  the  residue  obtained 
by  the  subsequent  evaporation  of  the  amylic  alcohol  the  aloes  may  be 
detected  with  certitude;  the  corresponding  residues  from  rhubarb, 
senna,  frangula  bark  and  buckthorn  berries  are  much  smaller  in 
amount  and  show  none  of  the  reactions  which  characterize  aloin. — 
Ibid.,  J).  475,  from  Ztschr.  Anal.  Chem.,  21,  p.  220. 
