Ana.  Joiir.Pharm.  [ 
Sept.,  1882.  '  j 
Aiiali/sfs  of  Wine. 
contains  much  alcohol,  but  when  it  has  been  exposed  for  a  long  time 
to  a  low  temperature,  which  causes  a  separation  of  the  tartar  in  crys- 
tals that  do  not  redissolve  on  the  normal  temperature  being  restored. 
The  total  amount  of  ash  found  by  the  authors  in  genuine  wines  did 
not  fall  below  0*14  per  cent. 
II.  A  Modification  of  Neuhauer^s  Tent  for  Potato  Sugar  in  Wine, 
and  the  Optical  Behavior  of  Pure  and  Saccharated  Wines. — Neu- 
bauer's  method  for  the  recognition  of  an  addition  of  potato  sugar  to 
wine  or  must  is  based  upon  the  optical  behavior  of  the  wine  in  a 
polarimeter.  Whilst  pure  natural  wine,  which  contains  unfermented 
fruit  sugar^  rotates  the  plane  of  polarized  light  to  the  left,  and  com- 
pletely fermented  wine  is  quite  neutral  in  its  behavior  or  rotates  the 
plane  only  a  few  tenths  of  a  degree  of  Wild's  scale  to  the  right,  a  fer- 
mented potato  solution  has  a  considerable  residue  of  strongly  dex- 
trogyre  constituents,  w^hich  are  not  sugar.  According  to  recent  experi- 
ments by  the  authors  with  various  kinds  of  commercial  potato  sugar, 
even  the  best  qualities,  pure  white  and  in  crystalline  granules,  contain 
from  15  to  18  per  cent,  of  unfermentable  substance,  each  1  per  cent, 
of  which,  in  200  mm.  tubes,  has  a  dextrogyre  action  of  1*5°  (Wild). 
Consequently  1°  of  rotation  by  the  fermented  wine  due  to  this  cause 
would,  on  the  average,  correspond  to  an  addition  of  4  kilos  of  potato 
sugar  to  the  hectoliter  of  wine.  In  the  presence  of  unfermented  sugar 
this  result  would  be  modified  :  1  |)er  cent,  of  sugar  rotates  about  1*25° 
to  the  right,  so  that  1°  of  rotation,  due  to  unfermented  potato  sugar, 
would  correspond  to  about  800  grams  of  chemically  pure  grape  sugar 
in  the  hectoliter.  But  inferior  kinds  of  potato  sugar  contain  from  26 
to  30  per  cent,  of  the  unfermentable  substances,  which  do  not  reduce 
Fehling^s  solution. 
As  before  mentioned,  wine  frequently  contains  a  small  quantity  of  a 
dextrin-like  constituent,  capable  of  exercising  a  slight  dextrogyre 
action  amounting  to  0"03°  to  0*6°  (Wild).  But  this  substance  is  almost 
completely  nisoluble  in  alcohol,  whilst  the  greater  portion  of  the  dex- 
trogyre residue  from  fermented  ])otato  sugar  is  soluble  in  90°  alcohol. 
Upon  this  fact  Ncubauer  based  a  method  of  distinguishing  between 
the  slight  dextrogyre  action  of  a  normal  wine  and  that  of  one  conhiin- 
ing  potato  sugai*.  I'he  method,  however,  has  the  defect  of  admitting 
the  possibility  of  the  result  being  affected  by  the  presence  in  the  test 
solution  of  free  tartaric^  acid,  which  also  has  a  dextrogyre  action.  It 
is,  therefore,  proposed  by  the  authois  to  modify  it  as  follows: 
