MOLECULAR  DISSYMMETRY  OF  ORGANIC  PRODUCTS.  13 
V. 
The  announcement  of  the  preceding  facts  naturally  placed  me 
in  relation  with  M.  Biot,  who  was  not  without  doubts  about  their 
exactness.    Charged  with  reporting  upon  it  to  the  Academy,  he 
caused  me  to  go  to  his  place  to  repeat  the  decisive  experiment 
under  his  eyes.    He  sent  to  me  the  paratartaric  acid  which  he 
had  previously  studied  with  particular  care,  and  found  to  be  per- 
fectly neutral  to  polarized  light.    I  prepared  in  his  presence  the 
double  salt  of  soda  and  ammonia,  which  he  also  desired  me  to 
procure.    The  liquor  was  left  in  one  of  his  closets  to  slowly 
evaporate,  and  when  it  had  furnished  about  80  or  40  grammes 
of  crystals,  he  requested  me  to  go  to  the  college  of  France  for 
the  purpose  of  collecting  and  isolating,  under  his  eye  by  ex- 
amining their  crystallographic  characters,  the  right  and  left 
crystals,  desiring  me  to  declare  anew,  if  I  affirmed  that  the  crys- 
tals which  I  should  place  to  his  right  would  deviate  to  the  right 
and  the  others  to  the  left.    That  done,  he  said  he  would  take 
charge  of  the  rest.    He  prepared  the  solutions  in  strong  pro- 
portions, and  at  the  moment  of  observing  them  in  the  polarizing 
apparatus  he  again  invited  me  into  his  cabinet.    He  first  placed 
in  the  apparatus  the  most  interesting  solution,  that  which  ought 
to  deviate  to  the  left.    Even  without  any  measuring,  he  saw, 
from  the  aspect  alone  of  the  tints  of  the  two  images,  ordinary 
and  extraordinary,  of  the  analyser,  that  there  was  a  strong 
deviation  to  the  left.    Then,  with  very  visible  emotion  the  illus- 
trious sage  took  my  arm  and  said  ; — "  My  dear  child,  I  have  loved 
science  so  much  all  my  life  that  this  makes  my  heart  beat." 
You  will  excuse,  gentlemen,  these  personal  recollections,  which 
will  never  be  effaced  from  my  mind.  In  our  times,  with  our 
habits,  they  should  be  excluded  from  a  scientific  memoir,  but 
they  seem  to  me  proper  in  an  oral  exposition ;  and  perhaps  the 
biographic  interest  of  similar  recollections  will  constitute  one  of 
the  advantages  of  the  kind  of  teaching  which  the  Chemical  So- 
ciety now  inaugurates. 
Besides,  there  is  more  here  than  personal  recollections.  The 
emotion  of  the  sage  in  M.  Biot  was  mingled  with  the  internal 
pleasure  of  beholding  his  own  anticipations  realized.  For  more 
than  thirty  years  M.  Biot  had  vainly  endeavored  to  induce 
chemists  to  participate  in  his  conviction,  that  the  study  of  rotary 
