462 
FABRICATION  OF  SUGAR. 
undergoes  all  the  modifications  which  reagents  exert  upon  the 
solutions  of  albumen  and  casein.  The  salts  of  lime,  and  lime 
coagulate  it.  But  this  latter,  whether  by  its  own  proper  alka- 
line action  it  dissolves  a  portion  of  the  vegetable  substance,  and 
holds  it  in  combination,  as  M.  Frenay  has  lately  shown  ;  or 
whether  it  liberates  potassa  or  soda,  causes  the  juices  treated  by 
it  to  remain  always  alkaline  after  the  action  of  carbonic  acid. 
These  two  effects  are  even  found  united,  and  there  results  from 
them  a  subsequent  change  of  the  syrups,  which  is  especially  felt 
in  the  low  products  of  the  manufacture  of  sugar. 
The  second  substance  is  a  matter  generally  colorless  as  long 
as  it  remains  in  the  cells  of  the  plant ;  but  very  greedy  for 
oxygen,  coloring  rapidly  under  the  action  of  the  air,  modified 
very  easily  by  oxidizing  agents,  so  as  to  be  either  transformed 
into  that  well  known  brown  substance  which  appears,  when  vege- 
table juices  are  evaporated,  or  entirely  destroyed.  This  sub- 
stance, indeed,  when  it  is  deprived  of  all  the  albumenoid  mat- 
ter, reduces  by  heat  the  salts  of  silver,  the  binoxide  of  mercury, 
&c.  By  the  action  of  this  last  material,  the  solution  even  takes 
the  natural  tint  which  the  juice  possesses  after  long  exposure 
to  air. 
These  facts  being  established,  the  data  of  the  problem  of  the 
simplification  of  the  making  of  sugar  may  thus  be  stated  :  We 
must  find,  1st,  a  substance,  generally  but  slightly  soluble,  having 
the  power  of  coagulating  all  albumenoid  substances,  without  any 
injurious  action  either  on  the  sugar,  or  on  the  health  ;  which 
can  easily  be  withdrawn  from  the  juice  in  case  a  certain  quantity 
should  remain  in  solution  ;  and  finally  shall  be  of  low  price. 
2d,  Another  substance,  of  an  oxidating  power,  so  to  speak, 
limited ;  which  may  by  its  action  either  destroy  the  coloring 
matter  or  transform  it  into  the  brown  substance  and  then  absorb 
it ;  in  short,  shall  add  to  this  absorbing  action  the  inriocuousness 
and  the  low  price  of  the  former. 
Sulphate  of  lime  in  whatsoever  state  it  may  be,  natural  or 
artificial  (raw  or  calcined  plaster),  is  the  substance  which  ap- 
pears to  me  to  fulfil  all  the  above  indications  better  than  any 
other  material  which  I  have  studied.  It  is  neutral,  a  condition 
which  I  regard  as  indispensable :  without  action  on  the  sugar, 
but  slightly  soluble  :  it  unites  to  the  conditions  of  harmlessness 
and  low  price,  a  most  remarkable  property  of  coagulating  the 
