56 
PHOSPHORUS  AND  MATCH  MANUFACTURES. 
their  mouths,  and  arranged  nearly  close  together  in  a  horizon- 
tal row  in  a  furnace,  somewhat  similar  to  the  retorts  in  a  gas- 
works. They  are  placed  in  a  nearly  horizontal  position,  with 
their  open  ends  slightly  raised,  and  in  a  furnace  so  constructed 
as  to  subject  them  to  nearly  a  white  heat. 
The  black  powder  is  introduced  into  the  retorts  when  the 
latter  are  comparatively  cool,  and  the  retorts  are  about  half 
filled  with  the  mixture.  Bent  pipes,  open  at  both  ends,  are  in- 
serted, air-tight  by  means  of  clay,  into  the  mouths  of  the  retorts, 
and  their  outer  ends  dip  into  warm  water,  in  cast-iron  basins, 
placed  to  received  the  distilled  phosphorus.  I  may  now  inci- 
dentally remark  that  all  the  manipulations  with  ordinary  phos- 
phorus in  its  simple  and  separated  state  are  performed  under 
the  surface  of  water,  otherwise  it  would  quickly  inflame  and  be 
reconverted  into  phosphoric  acid. 
The  heat  of  the  furnace  is  gradually  raised,  and  in  the  course 
of  some  hours  phosphorus  begins  to  distil  over,  and  accumulates 
in  a  melted  state  in  the  basins  of  water.  The  fire  is  still  further 
raised,  by  gradual  means,  until  a  most  intense  heat  is  obtained ; 
the  phosphorus  then  distils  rapidly.  The  heat,  after  being  thus 
continued  as  long  as  any  more  phosphorus  appears,  is  gradually 
decreased,  and  the  basins  containing  the  crude  phosphorus  are 
removed.  The  time  occupied  in  the  distillation  is,  in  some  cases, 
protracted  from  forty-eight  to  seventy-two  hours. 
In  this  operation  the  charcoal,  at  a  high  temperature,  com- 
bines with  the  oxygen  of  the  phosphoric  acid,  forming  therewith 
carbonic  oxide  and  carbonic  acid  gases,  which  escape  through 
the  nose-pipe,  and  the  phosphorus  thus  set  free  is  converted  into 
vapor  by  the  heat  and  distils  over  into  the  receiving  basins.  At  the 
same  time,  the  portion  of  water  not  extracted  by  the  preceding 
process  is  also  decomposed,  and  its  hydrogen  set  free,  combines 
with  some  of  the  phosphorus  and  forms,  phosphuretted  hydrogen 
gas.  The  inflammable  gases,  carbonic  oxide,  and  phosphuretted 
hydrogen,  are  conducted  away  from  the  phosphorus  basins  by 
means  of  a  pipe,  and  consumed. 
When  the  distillation  is  at  an  end  the  furnace  is  cooled  down 
and  the  residuary  contents  of  the  retorts  extracted.  The  resi- 
due consists  chiefly  of  charcoal  (of  which  there  is  always  an 
excess),  and  of  undecomposed  phosphate  of  lime,  together  with  a 
