554  OVER-HEATED  STEAM  IN  CARBONIZING  OF  WOOD. 
of  ammonia  under  the  influence  of  water,  as  shown  by  the  fol- 
lowing formulge  : — 
C20H~°N2  O4  +2HO=C20H22N2  O6  — C20H,9NO6  ,NH3 . 
<  ^  ;  v  f  , 
Sebamide.  Sebamate  of  ammonia. 
My  results  in  other  respects  are  completely  in  accordance  with 
those  of  the  English  chemist. — Chem.  Craz.,  Sept.  1,  1853,  from 
Comptes  HenduSy  July  25,  1853. 
OVER-HEATED  STEAM  APPLIED  TO  THE  CARBONIZING 
OF  WOOD. 
For  several  years  past,  over-heated  steam  has  been  used  in 
numerous  industrial  operations,  and  we  may  say  generally  that 
it  may  be  employed  in  all  processes  in  which  a  temperature  be- 
tween 100°  and  500°  C.  is  required.  Among  these  processes 
are  the  extraction  of  wood-spirit,  the  continuous  baking  of  bread, 
the  preparation  of  sea-biscuit,  the  drying  of  wood,  the  preserva- 
tion of  meats,  the  extraction  of  volatile  substances  insoluble  in 
water,  the  purification  of  fatty  acids,  by  MM.  Leplay  and  Du- 
brunfaut,  the  extraction  of  the  mercury  from  the  residues  of  zinc 
amalgam,  by  M.  Violette,  and  finally,  the  carbonizing  of  wood, 
by  the  same  chemist.  M.  Violette  is  a  member  of  the  Commis- 
sion on  Powder  and  Saltpeter,  and  in  this  situation  he  has  turned 
his  attention  to  the  ingredients  of  powder,  the  manufacture  of 
which  still  admits  of  much  improvement.  The  charcoal  em- 
ployed in  this  manufacture  is  of  a  quality  intermediate  between 
wood  and  ordinary  charcoal  (charbon  roux^  and  is  produced  at 
300°  C. ;  at  a  higher  temperature  it  becomes  black  charcoal, 
and  at  a  lower  the  carbonization  is  incomplete. 
By  the  old  process  of  heating  in  closed  cylinders,  10,000  kilo- 
grammes of  wood  furnished  2000  kil.  of  black  charcoal,  and 
1300  of  red.  The  new  process  with  steam  yields  a  better 
article  in  larger  quantity,  for  10,000  kil.  of  wood  give  4000. 
The  wood  immersed  in  the  vapor  is  readily  carbonized,  and  as  it 
is  easy  to  regulate  the  temperature  of  the  vapor,  charcoal  may 
be  obtained  of  a  constant  and  uniform  character.  It  is  some 
years  since  that  over-heated  steam  was  first  adopted  in  this  pro- 
cess, by  M.  Violette,  and  now  the  red  charcoal,  before  employed 
