ON  ALCOHOLIC  FERMENTATION. 
63 
varies  between  5  and  7  thousandths,  and  that  of  glycerine  be- 
tween 25  and  36  thousandths  of  the  weight  of  sugar  set  in  fer- 
mentation. 
3.  The  alcohol  and  carbonic  acid  do  not  equate  with  a  de- 
finite weight  of  sugar  ;  that  is  to  say,  the  alcohol  and  carbonic 
acid  are  not  in  the  proportions  indicated  by  the  theoretical 
equation ;  more  carbonic  acid  is  evolved  than  is  required  by 
the  weight  of  alcohol  produced. 
4.  More  than  1  per  cent.  (1*2  to  1-5)  of  the  weight  of  sugar 
is  fixed  upon  the  yeast  in  the  form  of  various  matters,  amongst 
which  are  cellulose  and  fatty  substances. 
Thus  of  100  grms.  of  sugar  which  are  fermented,  5  to  6  grms. 
do  not  follow  the  equation  of  Lavoisier  and  Gay-Lussac  ;  and 
this  portion  of  sugar  is  transformed  by  assimilating  water  in 
such  a  way  as  to  furnish  in  ordinary  cases — 
grm.  grm. 
Succinic  acid,  0-6  to  0.7 
Glycerin,  3-2  «  3-6 
Carbonic  acid,  0-6  "  0-7 
Cellulose,  fatty  matters,  and  other  products 
still  undetermined,       ...        1-2   "  1-5 
Total.        5-6  to  6-5 
The  remainder  of  the  sugar  appears  to  correspond  with  the 
whole  of  the  alcohol  and  the  rest  of  the  carbonic  acid,  in  accord- 
ance with  the  equations  of  Lavoisier  and  Gay-Lussac. 
The  question  here  arises  whether  the  succinic  acid  and  gly- 
cerin with  the  carbonic  acid  which  accompanies  them,  may  not 
be  the  results  of  a  secondary  and  accidental  action.  This  the 
author  cannot  admit,  as  in  more  than  a  hundred  analyses  of 
fermentations  effected  under  the  most  different  conditions, 
these  products  were  always  obtained. 
In  wine  also  he  found  that  succinic  acid  and  glycerine  are 
present  in  considerable  quantity;  1  litre  of  wine  contains  6 
to  8  grms.  of  glycerine,  and  1  to  1-5  grm.  of  succinic  acid. 
The  solid  residue  of  the  evaporation  of  a  litre  of  wine  being 
from  15  to  25  grms.,  it  will  be  seen  that  more  than  a  third,  and 
often  more  than  half  of  the  solid  materials  of  wine  have  been 
unknown  to  the  present  day. — Lon.  Qhem.  Graz.  Oct.  15,  1859, 
from  Oomptes  Bendus,  June  27,  1859. 
