FABRICATION  OF  SUGAR. 
463 
albumenoid  matters  of  vegetable  juices,  of  that  of  the  beet  in 
particular.  This  property  is  such  that  it  requires  but  a  rela- 
tively very  small  quantity  of  its  solution  to  produce  this  effect. 
The  operation  of  defecation  can  therefore  be  performed  under 
these  excellent  conditions,  and  with  but  a  small  quantity  of 
matter ;  the  head  is  very  firm,  collects  well,  and  the  juice  can 
be  drawn  off  in  a  proper  state  of  clearness.  The  sulphate  of  lime 
therefore  removes  perfectly  all  coagulable  matter,  but  does  not 
touch  the  coloring  matter,  so  that  after  the  separation  of  the 
head,  the  juice  soon  colors  deeply. 
Animal  charcoal  is  almost  without  effect  immediately  after  de- 
fecation ;  it  removes  only  the  matter  which  is  already  oxidized, 
for  after  its  action,  the  juice  whose  coloration  is  much  lessened, 
soon  colors  again.  We  want  therefore  an  oxidizing  agent 
which  shall  do  in  a  short  time  that  which  the  air  produces  at 
length,  or  which  may  so  modify  this  substance  as  to  destroy  or 
absorb  it.  Among  the  numerous  bodies  which  I  have  examined 
in  reference  to  this  point,  and  which  I  shall  not  now  enumerate, 
the  hydrated  peroxide  of  iron  presents  superior  advantages  in 
all  respects. 
Thus,  after  having  removed  by  the  sulphate  of  lime  all  the 
coagulable  matters  of  a  saccharine  juice,  if  we  agitate  it  either 
cold  or  heated  to  a  temperature  which  must  never  reach  ebulli- 
tion with  hydrated  peroxide  of  iron,  the  filtered  liquor  passes 
altogether  decolored,  and  purified  from  almost  all  the  foreign 
matters  which  it  contained.  Besides  this,  the  peroxide  of  iron, 
by  that  property,  which  all  chemists  know  it  to  possess,  of  ab- 
sorbing the  alkaline  and  earthly  salts,  removes  the  small  quantity 
of  sulphate  of  lime  which  remained  in  solution.  Thus  the  juice 
which,  after  the  defecation  by  the  sulphate  of  lime,  reduced  the 
nitrate  of  silver,  &c,  causes  no  change  in  them  after  its  contact 
with  the  peroxide  of  iron. 
This  juice,  when  it  comes  from  a  plant  in  the  normal  condi- 
tion, is,  after  this  purification,  perfectly  neutral  to  test-papers, 
and  may  be  kept  in  contact  with  the  air  for  several  days  without 
undergoing  the  slightest  alteration  or  coloration,  which  proves 
that  all  the  matters  which  could  act  as  ferments  have  been  re- 
moved. It  boils  very  well,  and  does  not  color  even  by  the  ac- 
tion of  heat.    The  syrup  when  concentrated  to  the  proper  point 
