154  TARTARIC  ACID  WITH  SACCHARINE  MATTERS. 
Alumina  therefore  gives  us  a'method  of  separating  the  one  class 
from  the  other.  The  precipitates  are  less  gelatinous  than  alumina 
and  more  easily  washed  out.  In  many  cases  a  solution  of  alum 
may  be  added  directly  to  the  extract  of  the  plant,  and  the  alumina 
then  precipitated  in  combination  with  the  organic  matter  by 
means  of  ammonia.  As  an  example  of  the  method,  an  aqueous 
decoction  of  horse-chestnut  bark,  treated  with  a  solution  of  alum 
and  then  with  ammonia,  gives  a  fawn-colored  precipitate.  The 
filtered  solution  is  wine-yellow.  The  solution  neutralized  with 
acetic  acid  and  evaporated  to  dryness  in  a  water-bath  gives  a 
mass  containing  the  sulphates  of  potash  and  ammonium,  a  little 
acetate  of  ammonia  and  all  the  aesculin.  This  may  be  separated 
by  boiling  with  a  little  strong  alcohol  and  filtering.  The  sesculin 
crystallizes  on  evaporation  and  after  a  single  recrystallization 
is  perfectly  pure.  The  tannic  acid,  if  easily  separated  from  the 
fawn-colored  precipitate  by  solution  in  water  containing  acetic 
acid,  filtration,  precipitation  with  a  salt  of  lead,  and  decomposi- 
tion of  the  lead  salt  with  sulphydric  acid.  In  conclusion  the 
author  suggests  that  the  employment  of  the  hydrate  of  alumina 
will  permit  us  to  prepare  many  substances  at  a  cheap  rate  which 
have  hitherto  found  no  application  in  consequence  of  their  high 
price. — American  Journal  of  Science  and  Arts,  January,  1858, 
from  Sitzungs  berichte  der  h.  k.  Acad,  zu  Wien. 
ON  THE  COMBINATIONS  OF  TARTARIC  ACID  WITH  SACCHARINE 
MATTERS. 
By  M.  Berthelot. 
In  pursuing  his  investigations  into  the  compounds  formed  by 
saccharine  matters,  Berthelot  has  been  led  to  produce  acid  com- 
pounds of  a  peculiar  nature  with  mannite,  dulcine,  and  glucose. 
These  compounds  establish  the  constitution  of  a  great  number  of 
natural  compounds  analogous  to  tannin,  and  capable,  by  taking 
up  water,  of  splitting  into  glucose  and  a  corresponding  acid.  In 
the  present  communication  the  author  points  out  the  combinations 
of  tartaric  acid  with  glucose,  milk  sugar,  cane  sugar,  sorbine, 
pinite,  quercite,  and  erythroglucine,  as  well  as  a  compound  of 
glucose  and  citric  acid.  All  these  bodies  may  be  prepared  and 
purified  by  the  following  process.  Equal  weights  of  tartaric  acid 
and  saccharine  matter  are  mixed  intimately  and  heated  for  a  day 
