56 
FORMATION  OF  RACEMIC  FROM  TARTARIC  ACID. 
at  which  cinchonicine  and  quinicine  are  produced,  the  modifying 
influence  of  the  heat  is  exerted  upon  the  tartaric  acid  itself.  Thus 
tartrate  of  cinchonine,  submitted  to  a  gradually-increasing  tempera- 
ture, becomes  first  of  all  converted  into  tartrate  of  cinchonicine. 
When  the  heat  is  continued,  the  cinchonicine  becomes  changed  ; 
it  loses  water,  acquires  a  color5  and  becomes  converted  intoquinoi- 
dine.  The  tartaric  acid  also  undergoes  important  modifications, 
and  after  five  or  six  hours'  exposure  to  a  heat  of  338°  F.,  a  portion 
of  it  has  been  changed  into  racemic  acid.  The  vessel  is  then 
broken,  and  the  black  resinous  mass  contained  in  it  treated  repeat- 
edly with  boiling  water ;  the  liquid  is  filtered  after  cooling,  and 
chloride  of  calcium  added  to  it  in  excess,  by  which  all  the  racemic 
acid  is  immediately  precipitated  in  the  form  of  racemate  of  lime, 
from  which  the  racemic  acid  is  readily  extracted. 
The  principal  part  played  by  the  cinchonicine  in  this  operation, 
is  to  give  a  little  stability  to  the  tartaric  acid,  and  to  enable  it  to 
support,  without  destruction,  a  temperature  which  would  change  it 
rapidly  in  a  free  state.  Cinchonine  and  cinchonicine,  although 
they  are  substances  which  act  upon  polarized  light,  play  no  part  in 
this  transformation.  Tartaric  ether,  for  example,  in  which  tartaric 
acid  is  in  combination  with  an  inactive  body,  which  is  capable  of 
supporting  an  elevated  temperature  without  destruction,  furnishes 
considerable  quantities  of  racemic  acid  by  the  action  of  heat. 
The  racemic  acid  thus  artificially  obtained  is  completely  identi- 
cal both  in  its  physical  and  chemical  properties,  with  natural  ra- 
cemic acid.  It  especially  possesses  the  important  character  of 
being  capable  of  resolution  into  dextro-  and  laevo-tartaric  acids,  ex- 
hibiting equal  rotatory  powers  in  opposite  directions  in  their  com- 
binations with  bases. 
This  resolution  of  artificial  racemic  acid  into  dextro-  and  lsevo- 
tartaric  acids,  leads  us  to  this  result, — that  ordinary  dextro-tartaric 
acid  may  be  artificially  converted  into  its  opposite,  laevo-tartaric 
acid  ;  a  result  which  is  particularly  remarkable  in  connexion  with 
this  extraordinary  fact,  which  will  no  doubt  be  explained  some 
day,  that  a  product  with  an  active  polarity  has  never  under  any 
circumstances  been  obtained  by  starting  from  an  inactive  substance, 
although  nearly  all  the  substances  elaborated  by  nature  in  the  vege- 
table organism  are  dissymmetric  in  the  same  manner  as  tartaric 
acid.    What  gives  to  this  fact  of  the  transformation  of  dextro-tar- 
