62 
ON  ALCOHOLIC  FERMENTATION. 
the  dyeing  properties  depend,  may  probably  be  procured  by  a 
similar  process  by  which  it  is  extracted  from  the  different  Cur- 
cumas. A  consideration  of  the  preceding  details  would  lead  to 
the  supposition  that  this  product  may  comprehend  one,  among 
other  varieties  of  turmeric  imported  into  England  from  the  East 
Indies,  and  the  subject  is  therefore  worthy  of  careful  investiga- 
tion.— London  Pharm.  Jour.  Nov.  1859. 
ON  ALCOHOLIC  FERMENTATION. 
By  L.  Pasteur. 
When  the  accurate  analyses  of  Gay-Lussac  and  Thenard  and 
those  of  De  Saussure  had  definitely  established  the  composition 
of  sugar  and  alcohol,  it  became  easy  to  show  theoretically  that 
by  mixing  alcohol  and  carbonic  acid,  the  composition  of  sugar 
might  be  reproduced.  This  was  indicated  by  Gay-Lussac  in  a 
letter  addressed  by  him  to  M.  Clement  in  1818,  which  concludes 
thus  :  "  If  we  suppose  now  that  the  products  furnished  by  the 
ferment  may  be  disregarded  in  relation  to  the  alcohol  and  car- 
bonic acid  which  are  the  only  sensible  results  of  fermentation, 
we  shall  find  that  100  parts  of  sugar,  51.34  are  converted  into 
alcohol,  and  48-66  into  carbonic  acid  during  fermentation." 
This  deduction  of  Gay-Lussac  coincided  with  the  views  pro- 
mulgated twenty-five  years  before  by  Lavoisier  upon  alcoholic 
fermentation,  and  it  removed  all  the  doubts  which  sooner  or 
later  must  have  been  raised  by  the  inaccurate  experiments  of 
that  illustrious  chemist. 
It  was  admitted,  however,  that  experiment  could  not  in  all 
points  confirm  Gay-Lussac's  theories,  for  Lavoisier  had  rightly 
indicated  that  a  small  portion  of  sugar  was  transformed  into  an 
organic  acid,  which  he  supposed  to  be  acetic  acid,  but  which  has 
long  since  been  identified  with  lactic  acid. 
The  results  of  the  author's  experiments  are  at  variance  with 
the  general  opinions  upon  the  products  of  fermentation  : — 
1.  The  acid  of  alcoholic  fermentation  is  never  either  acetic 
or  lactic  acid. 
2.  Alcoholic  and  carbonic  acid  are  not  the  only  products  of 
the  splitting-up  of  sugar.  They  are  always  ^accompanied  by 
succinic  acid  and  glycerine.    The  proportion  of  succinic  acid 
