448 
Ana/i/sis  of  Wine. 
f  Am.  Jour.  Pharni. 
t      Sept.,  1882. 
But  a  larger  proportion  of  extract  than  1  per  cent,  after  deduction 
of  total  acids  may  be  expected — 
(1)  In  wines  which  contain  much  sngar  still  unferniented,  but  in 
which  from  any  cause  fermentation  is  stopped.  The  fully  fermented  (h'v 
wines  usually  still  contain  a  small  quantity  of  sugar,  which  may  varv 
between  OOl  and  O'OOl  per  cent.  The  minimum  of  extract  free  from 
acid  to  be  expected  in  a  natural  wine  would  exceed  1  per  cent,  by  as 
much  as  the  quantity  of  sugar  as  ascertained  under  suitable  precau- 
tions by  means  of  Fehling's  solution  exceeds  O'l  per  cent. 
(2)  In  wines  from  certain  districts  which  are  known  by  experience 
to  produce  in  their  best  years  a  relatively  full-bodied  wine. 
(3)  In  red  wines.  In  these  the  smallest  amount  of  acid-free  extract 
is  usually  1*2  per  cent.  ;  but  in  ^n)erry  wines/'  and  in  such  red  wines 
as  have  stood  only  for  a  very  short  time  over  the  husks  and  stalks,  the 
minimum  is  exceptionably  1  per  cent. 
^Yines  rich  in  ash  also  stand  higher  in  respect  to  amount  of  extract. 
If  a  wine  yields  much  ash  and  gives  relatively  little  extract,  and  if  in 
addition  the  ash  is  easily  fusible  and  not  blackened  by  incineration, 
then  the  authors  think  there  is  reason  to  suspect  that  the  wine  consists 
partially  of  the  product  of  fermentation  of  a  solution  of  sugar  over 
wine  residues. 
Provided  that  the  total  amount  of  extract,  free  from  ash  and  sugar, 
does  not  sink  below  a  certain  quantity,  it  may  vary  very  consiclerabl}' 
in  composition  according  to  the  quality  of  the  wine.  For  instance, 
since  glycerin  is  a  by-product  of  fermentation,  and  may  amount  to 
from  7  to  10  per  cent,  of  the  weight  of  alcohol  produced,  a  clear 
natural  wine,  rich  in  alcohol,  would  evidently  contain  more  glycerin 
than  one  poor  in  alcohol.  Another  portion  of  wine  extract  consists  of 
pectin  bodies,  which  occur,  however,  in  less  quantity  in  proportion  to 
the  ripeness  of  the  grapes  used  in  making  the  w4ne.  Very  ripe  grapes,, 
rich  in  sugar,  leave  after  fermentation  relatively  much  glycerin  and 
little  pectin  substance,  while  with  unripe,  very  acid  grapes,  poor  in 
sugar,  the  contrary  is  the  case. 
The  ash  constituents  amount  on  the  average  to  about  10  per  cent,  of 
the  entire  weight  of  the  extract,  l)ut  this  amount  is  not  an  indispensable 
characteristic  of  a  pure  wine,  since  it  may  be  aifected  by  various  con- 
ditions. For  instance,  a  wine  may  be  rich  in  extract,  but  not  in  ash, 
when  it  contains  a  considerable  ({uantity  of  unfermented  sugar;  or  the 
ash  may  be  low  through  separation  of  tartar  not  only  when  a  wine 
