COMMERCIAL  VALUE  OF  ANIMAL  CHARCOAL. 
153 
this  so  much  the  more  because  this  very  property  is  undoubtedly  the 
one  most  important  to  the  manufacturer,  since  it  frees  the  syrups 
of  a  substance  which  is  hurtful  in  the  baking,  and  which  prevents 
the  crystallization  of  a  certain  quantity  of  saccharine  matter. 
This  settled,  it  is  easy  to  find  a  method  by  which  every  one  may 
determine  the  value  of  animal  charcoal.  A  solution  of  saccharate 
of  lime  is  prepared;  the  number  of  degrees  of  the  solution  of  sul- 
phuric acid  employed  in  alkalimetric  analyses  required  to  saturate 
a  given  volume  (say  50  cub.  centims.)  of  this  succharate  is  then  de- 
termined. 
This  done,  the  samples  of  animal  charcoal  are  reduced 
as  nearly  as  possible  to  the  same  degree  of  fineness  ;  equal  quanti- 
ties (say  50  grms.)  of  samples  are  then  put  into  separate  flasks, 
and  an  equal  quantity  (say  I  decilitre)  of  the  saccharate  added  to 
each,  and  left  in  contact  for  about  an  hour.  The  liquids  are  then 
filtered  separately;  and  the  quantity  of  the  normal  solution  of  sul- 
phuric acid  required  to  complete  the  saturation  of  50  cub.  centims. 
of  each  of  them  determined;  the  difference  will  show  the  quantity 
of  lime  which  has  been  absorbed  by  each  sample  of  animal  black. 
That  which  absorbs  the  most  is  undoubtedly  the  best  for  the  con- 
sumer, and  that  to  which  he  should  give  the  preference. 
The  sacharate  of  lime  and  the  solution  of  sulphuric  acid  may  be 
prepared  in  the  following  manner  : — 
An  acid  liquid  is  first  prepared,  composed  of  20  grms.  of  pure 
monohydrated  sulphuric  acid  diluted  with  water  to  exactly  1  litre. 
A  solution  of  saccharate  of  lime*  is  then  prepared,  of  such  a 
nature  that  it  will  be  exactly  saturated  by  the  same  volume  of  the 
dilute  sulphuric  acid.  By  adding  the  latter  to  50  cub.  centims.  of 
the  liquid  filtered  from  the  animal  charcoal,  it  is  easy  to  see  how 
*  If  any  given  weight  of  lime  would  dissolve  in  a  saccharine  solution,  it 
would  require  11-40  grms.  of  pure  lime  to  saturate  20  grms.  of  pure  sulphu- 
ric acid  ;  but  as  this  is  not  the  case,  it  is  necessary  to  operate  in  the  follow- 
ing manner : — 
From  125  to  130  grms.  of  white  sugar  are  dissolved  in  water,  and  15  to 
20  grms.  of  quick  lime  added  thereto  ;  the  liquid  is  then  boiled,  and  filtered 
to  separate  the  undissolved  lime.  It  is  then  necessary  to  ascertain  how 
many  degrees  of  the  normal  acid  are  required  to  saturate  50  cub.  centims.  of 
this  solution;  if  it  takes  125,  we  get  the  following  proportion  : — 125  :  100  :  : 
100:  x  =  80.  Consequently  by  taking  80  centilitres  of  the  prepared  sac- 
charate, and  diluting  them  with  water  to  the  volume  of  1  litre,  a  solution  of 
saccharate  of  lime  is  obtained,  which  saturates  exactly  its  volume  of  the  nor- 
mal acid  solution. 
