PHOSPHOROUS  GLUE  AND  CHLORIDE  OF  AMMONIUM.  51 
ings  in  front,  for  charging  the  pans  and  stirring  the  contents, 
and  -with  flues  at  the  back,  communicating  with  the  chimney,  for 
drawing  off  the  vapors  of  sulphuric  and  sulphurous  acids.  The 
retorts  used  for  distilling  the  phosphorus  are  similar  to  those 
used  for  distilling  sulphuric  acid  from  sulphate  of  iron.  They 
are  made  of  fire  clay,  about  eighteen  inches  long,  and  four  inches 
wide  in  the  bulb.  The  furnace  used  for  the  distillation  is  like- 
wise constructed  in  the  same  manner  as  the  Saxon  furnaces  for 
distilling  sulphuric  acid.  Each  furnace  holds  twenty-four  re- 
torts, at  distances  of  four  or  five  inches  apart.  In  the  section 
A  Ar  are  the 
retorts ;  b  b, 
the  lateral 
walls  of  the 
fireplace  ;  <?, 
the  grate  fire 
bars  ;  c?,  the 
ash  pit ;  fg  h 
e  are  openings 
throughwhich 
the  retorts 
are  introduc- 
ed. They  are 
afterward  s 
closed  with 
loose  stones, 
covered  with 
mortar  at  the 
outside  only, 
so  that  they 
may  be  re- 
moved with- 
out injury  to 
the  furnace. 
A  slab  of  sandstone,  i  i,  covers  the  fireplace,  and  has  square 
holes  through  which  the  flame  passes  to  the  iron  plate,  I  I,  upon 
which  the  leaden  evaporating  pans  rest.  At  the  back  of  the 
furnace  the  channel  K  is  connected  with  the  chimney,  and  the 
draught  is  regulated  by  a  damper. 
