ON  THE  PREPARATION  OF  LARD. 
347 
acid,  there  remains  a  body  with  the  composition  of  the  carbo- 
hydrates : — 
Saccharic  acid  ....  C12H10O16 
Tartaric  acid         ....       C8  H6  Ol2 
C,H404 
The  elements  of  the  last  subtracted  from  tartaric  acid  leave 
oxalic  acid : — 
Tartaric  acid         ....  C8H6012 
Carbohydrates       ....  C4H404 
Oxalic  acid  ....  C4H208 
Liebig  believes  that  oxalic  acid  is  the  first  acid  product  formed 
in  a  plant  from  carbonic  acid,  and  that  tartaric  and  malic  acids 
are  derived  from  oxalic.  By  exchanging  two  equivalents  of 
oxygen  for  two  of  hydrogen,  oxalic  acid  becomes  malic  ;  by  ex- 
changing four  of  oxygen  for  four  of  hydrogen,  it  produces  alde- 
hyde. Malic  acid  therefore  may  be  considered  as  oxalic  acid 
half  changed  into  aldehyde. 
To  become  tartaric  acid,  malic  acid  has  only  to  fix  two  equiv- 
alents of  oxygen : — 
Malic  acid  .  .  .  C8H6O10 
Tartaric  acid       .  .  .  C8H6012 
Tartaric  acid  then  is  only  a  product  of  the  oxidation  of  malic 
acid  ;  and  this  explains  the  constant  presence  of  malic  acid  in 
unripe  grapes. — Chem.  News,  London,  March  31,  1860,  from 
Ann.  der  Chem.  und  Pharm. 
ON  THE  PREPARATION  OF  LARD. 
Mr.  Hills  stated,  that  having  been  requested  by  Dr.  Redwood 
to  give  his  experience  on  the  preparation  of  lard,  he  begged  to 
make  the  following  remarks  : — 
Having  experienced  great  difficulty  in  obtaining  lard  perfectly 
fresh  and  free  from  smell.,  and  having  tried  a  variety  of  plans, 
such  as  getting  it  as  a  favor  from  wholesale  houses,  or  inducing 
farmer  friends  to  make  it  expressly,  and  also  having  it  made  on 
our  own  premises,  none  of  which  succeeded  to  my  satisfaction, 
I  at  last  thought  of  a  plan  of  preparing  it  in  the  same  manner 
