KM       MOLECULAR  DISSYMMETRY  OF  ORGANIC  PRODUCTS. 
question,  and  in  the  anticipation  even  of  the  results  which  I  am 
about  to  have  the  honor  to  lay  before  you,  that  I  immediately 
made  a  journey  to  Vendome,  where  I  submitted  my  doubts  to 
M.  Dessaignes,  who  at  once  presented  me  with  a  specimen  of 
his  aspartic  acid.  On  my  return  to  Paris,  I  found  immediately, 
in  fact,  that  the  acid  of  M.  Dessaignes  was  only  an  isomeric  of 
the  natural  aspartic  acid,  that  is,  the  acid  derived  from  aspara- 
gine,  and  that  it  differed  from  it,  as  I  had  foreseen,  by  the  rotary 
property,  entirely  absent  in  the  artificial  acid,  not  at  all  doubt- 
ful in  the  natural  acid.  But  all  the  other  physical  and  chemi- 
cal properties  possessed  the  greatest  analogies,  so  great  that  M. 
Dessaignes,  who  was  not  put  on  his  guard  by  any  pre-conceived 
idea,  had  concluded  that  the  two  substances  are  really  identical. 
What  attracted  me  most  in  the  examination  of  the  new  com- 
pound, (which  by  itself  offers  no  very  remarkable  crystallizable 
combinations,)  was  its  transformation  into  malic  acid.  It  is 
indeed  known  that  M.  Piria,  just  mentioned,  long  ago  gave  the 
means  of  obtaining  malic  acid  from  asparagine  and  aspartic 
acid ;  and  I  was  assured  by  the  most  exact  proofs  that  this 
malic  acid  was  identical  with  that  of  the  service,  [sorbus,^  the 
apple,  the  grape,  and  tobacco. 
I  then  treated  the  new  acid  in  the  manner  discovered  by  M. 
Piria,  and  transformed  it  into  a  new  malic  acid  very  similar  to 
the  natural  acid,  so  close  to  the  latter,  that  a  chemist  would  have 
great  difficulty  in  distinguishing  them,  even  if  warned  of  their 
real  dissimilarity;  only  this  malic  acid  had  no  action  on  polarized 
light,  and  it  was  the  same  with  all  its  saline  combinations. 
There  are  certain  derivations  of  these  two  malic  acids,  the 
comparison  of  which  does  not  very  clearly  manifest  the  true  mu- 
tual dependence  of  the  molecular  arrangements  of  these  curious 
isomerics,  but  there  are  others  in  which  it  is  plainly  seen.  Let 
us  consider,  for  example,  the  ordinary  active  bimalate  of  lime, 
and  the  corresponding  inactive  bimalate.  Their  chemical  com- 
position is  exactly  the  same,  and  their  crystalline  forms  are  alike, 
with  this  difference  that  the  form  of  the  active  bears  four  small 
hemihedric  faces,  always  absent  in  the  form  of  the  inactive. 
Whence  it  results  that  placed  before  a  glass,  the  image  of  the 
active  cannot  be  superposed  on  it,  while  the  image  of  the  inactive 
is  absolutely  identical  and  superposable  to  the  reality  which  gives 
