MOLECULAR  DISSYMMETRY  OF  ORGANIC  PRODUCTS.  Ill 
purely  mineral,  artificial,  and  we  all  know  how  prudent  we  should 
be  in  the  application  of  results  in  our  laboratories  to  the  phe- 
nomena of  life.    Therefore  I  have  reserved  almost  all  the  views 
presented  in  this  lecture  until  I  recognised  in  the  most  certain 
manner,  that  molecular  dissymmetry  offers  itself  as  a  modifier 
of  chemical  affinities,  not  only  in  the  re-actions  of  inorganic  na- 
ture, but  in  those  of  a  physiological  order,  in  fermentations. 
This  is  the  remarkable  phenomenon  to  which  I  allude. 
It  has  long  been  known,  through  the  observation  of  a  manu- 
facturer of  chemical  products  in  Germany,  that  the  impure  tar- 
trate of  lime  of  the  factories,  soiled  by  organic  matters,  and 
abandoned  under  water  in  the  spring,  may  ferment  and  yield 
different  products. 
That  stated,  I  place  in  fermentation  the  common  right  tar- 
trate of  ammonia  in  the  following  manner: — I  take  the  very 
pure  crystallized  salt,  dissolve  it,  adding  to  the  liquid  a  very 
limpid  solution  of  albumenoid  matters.  One  gramme  of  dry 
albumenoid  matters  is  enough  for  100  grammes  of  tartrate. 
Very  often  the  liquid,  placed  in  a  stove,  spontaneously  ferments: 
I  say  very  often  ;  I  might  add,  that  it  always  takes  place,  if  care 
is  taken  to  mix  with  the  liquid  a  very  small  quantity  of  one  of 
those  liquids  in  which  spontaneous  fermentation  has  been  ob- 
tained. 
Thus  far  there  is  nothing  remarkable;  it  is  a  tartrate  which 
ferments.    The  fact  is  known. 
But  apply  this  mode  of  fermentation  to  the  paratartrate  of 
ammonia;  and,  in  the  preceding  conditions,  it  ferments.  The 
same  yeast,  or  leaven,  is  deposited.  All  indicates  that  things 
go  on  absolutely,  as  in  the  case  of  the  right  tartrate.  If,  how- 
ever, we  follow  the  steps  of  the  operation  with  the  aid  of  the 
polarizing  apparatus,  we  very  soon  perceive  marked  differences 
between  the  two  operations.  The  liquid,  at  first  inactive,  pos- 
sesses a  rotary  power  sensibly  to  the  left,  which  augments  little 
by  little,  and  attains  a  maximum.  Then  the  fermentation  is 
suspended.  There  is  no  longer  a  trace  of  right  acid  in  the 
liquid,  which,  evaporated  and  mixed  with  its  volume  of  alcohol, 
immediately  furnishes  a  fine  crystallization  of  left  tartrate  of 
ammonia. 
We  remark  at  first  in  this  phenomenon  two  distinct  things  ;  as 
