THE  ANIMAL  CHARCOAL  USED  IN  SUGAR  REFINING^  425 
THE  ANIMAL  CHARCOAL  USED  IN  SUGAR  REFINING. 
(Transactions  Philosophical  Society  Glasgow,  May  4.) 
Dr.  Wallace  stated  that  his  communication  to  the  Section  was 
not  fo  be  dignified  by  the  name  of  a  research,  but  as  his  name 
had  been  associated  with  the  chemistry  of  sugar-refining  during 
the  last  ten  years,  he  thought  it  likely  that,  as  a  result  of  his 
observations  and  experiments,  he  might  be  able  to  mention  some 
things  not  contained  in  books.  He  stated  briefly  the  mode  of 
making  animal  charcoal  from  bones,  and  mentioned  the  princi- 
pal Scottish  manufacturers  of  the  substance.  All  the  bone  char 
made  in  Glasgow,  Paisley,  and  Greenock,  in  addition  to  a  large 
quantity  imported  from  France  and  Russia,  is  used  in  the  Clyde 
refineries.  A  large  amount  of  it  is  manufactured;  for  not- 
withstanding the  fact  that  the  charcoal  lasts  a  considerable  time, 
it  has  to  be  occasionally  renewed,  owing  to  the  stock  gradually 
dwindling  down  from  various  causes.  The  author  calculates  that 
the  quantity  of  animal  charcoal  in  actual  use  in  the  Clyde  re- 
fineries is  probably  well  nigh  5,000  tons,  and  that  the  annual  re- 
newal is  probably  about  1,500  tons. 
The  carbonisation  of  the  bones  is  usually  continued  for  twelve 
hours,  that  length  of  time  generally  giving  better  charcoal  than 
when  the  bones  are  only  carbonised  for  six  hours,  even  though 
in  the  latter  case  the  heat  is  made  stronger.  After  the  bones 
are  charred  they  are  crushed  between  rollers,  and  the  charcoal 
is  ready  for  use  when  the  dust  is  removed.  The  quality  of  the 
char  varies  with  the  kind  of  bones  employed,  and  the  care  ob- 
served in  the  charring  operation.  Hand-picked  home-collected 
bones  make  the  best  charcoal.  Besides  these  there  are  the 
shank  bones  from  the  saladeras  of  Brazil  and  Buenos  Ayres  ; 
camp  bones  dug  up  from  old  battle  fields,  and  bearing  evidence 
of  having  been  buried  for  a  long-time,  and  the  charcoal  from  which 
may  be  easily  distinguished  from  that  prepared  from  home-col- 
lected bones ;  and  there  are  also  large  shipments  from  Italy 
and  Turkey,  including  the  bones  of  the  camel  along  with  those 
of  cattle,  antelopes,  sheep  and  horses. 
In  the  analysis  of  the  best  charcoal  from  home-collected  bones, 
carbon  usually  occurs  to  the  extent  of  about  ten  per  cent.,  the 
the  remainder  being  the  phosphates  and  other  mineral  ingredi- 
