444 
The  Analysis  of  Wine. 
f  Am.  Jour.  Pharm 
t      Sept.,  1882. 
ANALYSIS  OF  WINE. 
By  J.  Nessler  and  M.  Barth. 
I.  Deteiiiiination  of  the  Amount  of  Extract. — The  methods  at  present 
in  use  for  the  determination  of  the  amount  of  extractive  in  wine  differ 
from  one  another  not  only  in  subordinate  details,  but  also  in  principle, 
according  as  extract  is  understood  to  mean  the  constituents  of  the  wine 
:absolutely  non-volatile  without  decomposition,  or  the  wine  deprived  of 
its  water,  alcohol  and  volatile  acids.  In  the  former  case  it  is  espe- 
•cially  necessary  to  volatilize  the  glycerin  completely  without  partially 
•decomposing  the  non-volatile  constituents  of  wine  through  submitting 
tliem  to  too  high  a  temperature.  Determinations  of  extract  in  this 
manner  are  usually  made  with  only  a  small  quantity  of  wine  (5  or  10 
^cc),  which  is  heated  upon  a  water-bath  so  long  as  water  is  percepti- 
bly driven  off,  and  the  drying  is  then  continued  in  an  air-bath  at  110° 
«C.,  or  preferably  hi  vacuo  until  the  weight  remains  constant.  The 
other  kind  of  determination  has  for  a  special  object  the  retention  of  the 
glycerin  as  completely  as  possible  in  the  extract.  This  can  be  effected 
'either  by  avoiding  raising  the  temperature  above  100°,  or  by  making 
an  addition  to  the  wine  which  will  prevent  the  volatilization  of  the 
glycerin  at  a  temperature  of  from  110°  to  115°C. 
In  estimating  a  wine  extract  the  authors  concentrate  50  c.c.  of  the 
wine  to  a  syrupy  consistence  on  a  water-bath,  and  then  further  dry  it 
for  three  hours  at  the  temperature  of  boiling  water.  In  order  to  main- 
tain this  temj)erature  exactly  they  used  a  jacketed  apparatus,  arranged 
like  a  paraffin  drying  chest,  the  interspace  being  filled  with  boiling 
water,  and  made  sufficiently  large  for  the  water  to  be  maintained  in 
vigorous  ebullition  during  four  hours  without  exhaustion. 
In  order  to  ascertain  whether  in  this  i)rocess  access  of  air  exercised 
an  essential  influence  upon  the  weight  of  the  extract  parallel  experi- 
ments were  made  in  which  25  cc.  of  wine  were  placed  in  each  of  two 
platinum  boats,  enclosed  in  test-tubes,  and  arranged  so  that  whilst  side 
by  side  in  the  above-mentioned  drying  chamber  a  current  of  dried 
•coal  gas  could  be  passed  over  one  and  a  current  of  dried  air  over  the 
other.  A  thermometer  fixed  in  the  drying  chest  showed  that  when 
the  water  was  boiling  vigorously  the  temperature  in  the  interior  was 
100°C.  After  heating  for  eight  and  ten  hours  the  residue  was 
weighed  with  the  following  results: 
