324        MEANS  OF  RENDERING  TIMBER  INCOMBUSTIBLE. 
the  acid  treatment.    I  thought  that  if  beams  of  timber  were 
prepared  in  this  way  there  would  be  less  chance  of  the  protect- 
ing crust  washing  out  by  use,  rain,  or  sea  carriage,  in  consequence 
of  the  silica  being  rendered  insoluble  by  the  acid  treatment. 
The  pieces  of  wood  being  finally  all  dried,  were  placed  in  a  heap, 
and  a  gas  jet  lighted  beneath  them ;  the  result  was,  as  might  be 
anticipated,  the  coating  of  silicate  of  potassa,  and  silica  prevents 
the  wood  actually  "  adding  fuel  to  the  fire,"  except  only  in  this 
way: — when  a  body  of  heated  matter  surrounds  it  the  wood  be- 
comes subject  to  destructive  distillation — it  cracks,  exposes  nu- 
merous fissures  in  its  surface,  from  which  inflammable  gas  is 
given  out,  and  then  in  many  instances  the  pieces  of  wood  sepa- 
rate into  smaller  fragments,  and  combustion  goes  on  to  a  consider- 
able extent,  though  I  never  found  any  result  which  would  justify 
me  in  saying  that  silica  does  not,  to  a  certain  extent,  prevent 
combustion  ;  at  the  same  time  I  can  only  repeat  the  sentiments 
I  uttered  in  the  Manchester  Guardian,  in  January  last,  on  this 
subject  (as  to  a  statement  that  M.  Carteron  had  done  something 
wonderful  in  France  in  this  matter)  that  the  mere  fact  of  a  sub- 
stance being  of  an  organic  nature  like  wood,  capable  of  being 
made  to  yield  large  quantities  of  inflammable  gas  by  destructive 
distillation,  which  gas  is  itself  practically  employed  in  heating 
the  retorts  from  which  acetic  acid  is  distilled,  must  necessarily 
go  to  prove  that  even  a  near  approach  to  perfection  in  this 
matter  can  never  be  reasonably  expected ;  moreover  it  is  ques- 
tionable whether  the  aqueous  vapor  driven  off  is  not  decomposed 
by  the  surrounding  particles  of  incandescent  carbon  into  water 
gas.    But  it  may  be  said  that  the  timber  does  not  itself  blaze, 
and  so  that  a  screen  or  partition  of  wood  prepared  in  this  way 
would  effectually  prevent  the  spread  of  flame ;  this  I  can  safely 
grant  to  be  correct  within  certain  limits;  but  considering  the  im- 
mense heat  generated  in  the  conflagration  of  a  single  house,  I 
do  not  see  how  the  timber  could  escape  the  action  of  destructive 
distillation.  But  here,  again,  I  am  ready  to  admit,  that  if  every 
fabric,  even  to  the  dresses  of  the  inmates  were  fire-proofed,  nay, 
if  every  individual  article  of  an  organic  nature  were  treated 
with  some  substance  of  this  sort,  fires  could  not  produce  such 
devastating  effects  as  we  are  frequently  horrified  at  reading ;  and 
surely  if  the  subject  were  properly  taken  up,  the  matter  would 
