252 
ON  RACEMIC  ACID. 
the  crude  tartar.  The  racemate  of  lime  itself  is,  indeed,  but  little 
soluble  in  bitartrateof  potash. 
Having  been  informed  by  M.  Fikentscher  that  there  were  ex- 
tensive refineries  of  tartar  at  Trieste  and  at  Venice,  M.  Pasteur 
started  for  those  places,  with  a  view  to  examine  the  mother  liquors 
of  the  refineries;  but  whilst  stopping  at  Vienna  to  visit  some  manu- 
factories of  tartaric  acid,  the  question  as  to  the  origin  of  racemic 
acid  became  so  clear  to  his  mind,that  he  at  once  decided  on  consi- 
dering it  as  a  purely  natural  product.  In  the  course  of  his  visits 
to  several  tartaric  acid  manufactories,  in  company  with  M.  Red- 
tenbacher,  he  at  first  thought  that  no  appearance  of  racemic  acid 
presented  itself,  but  on  examining  the  different  qualities  of  tartaric 
acid  in  the  stores  of  M.  Nach,  he  soon  recognized  the  small  crys- 
tals of  racemic  acid  present ;  the  quantity,  however,  was  so  small, 
that  it  took  more  than  three  hours  to  collect  a  few  decigrammes. 
It  has  previously  been  supposed  that,  as  M.  Nach  decomposed  the 
tartrate  of  potash  by  means  of  sulphate  of  lime,  these  crystals  were 
sulphate  of  potash.  A  circumstance,  however,  which  militated 
against  this  supposition  was,  that  it  was  only  within  about  a  year 
that  these  needle-shaped  crystals  had  made  their  appearance  in  his 
manufactory,  and  that  it  was  only  during  the  last  two  years  that 
M.  Nach  had  employed  the  crude  Austrian  tartars.  When  par- 
tially refined  tartars  had  been  used,  no  racemic  acid  showed  itself. 
Hence  M.  Pasteur  concluded  : — 
1.  That  the  crude  Austrian  tartars  contain  racemic  acid  ready 
formed ;  for  it  is  evident  that,  if  this  acid  were  an  artificial  pro- 
duction, it  would  always  make  its  appearance  in  the  same  manu- 
factory, the  mode  of  operating  in  which  was  not  changed,  but  in 
which  the  quality  only  of  the  tartars  used  had  varied. 
2.  That  the  crude  Austrian  tartars  should  contain  this  acid  in 
less  quantity  than  the  crude  Neapolitan  tartars,  since  the  latter, 
when  partially  refined,  still  furnish  some  racemic  acid,  and  that, 
too,  when  the  liquors  are  comparatively  new. 
Besides,  as  the  mother  liquors  remained  upwards  of  one  year 
before  giving  indications  of  racemic  acid,  this  acid  does  not  appear 
until  it  has  been  accumulated  by  successive  operations,  which 
have  gradually  concentrated  into  a  small  compass  the  acid  con- 
tained in  a  large  quantity  of  tartar  ;  the  mother  liquors  of  one 
being  used  in  the  treatment  of  new  crude  tartar.    This  result  was 
