PHOSPHORUS  GLUE  AND  CHLORIDE  OF  AMMONIUM.  53 
The  improvements  that  still  remain  to  be  made  in  the  prepa- 
ration of  phosphorus,  relate  only  to  the  distillation.  The  cost  of 
the  material  prepared  for  distillation  does  not  amount  to  one- 
fourth  the  price  of  the  phosphorus  it  yields,  while  the  cost  of  the 
distillation  amounts  to  one-half  the  price  of  the  phosphorus.  Hr. 
Gentele  is  therefore  of  opinion  that  there  cannot  be  any  advan- 
tage in  attempting  to  prepare  phosphorus  with  a  mixture  of 
charred  bones,  (2  CaO,  P05>)  carbon,  and  silica,  because  a  much 
higher  temperature  is  requisite ;  and  to  obtain  a  given  quantity 
of  phosphorus  from  this  mixture,  containing  less  than  one-third 
as  much  phosphorus  as  that  generally  used,  a  very  much  larger 
consumption  of  fuel  would  be  necessary. 
The  chief  disadvantage  of  the  present  distillation  method,  con- 
sists in  the  circumstance  that  the  furnace  cannot  be  worked  con- 
tinuously, and  therefore  attempts  should  be  made  to  effect  the 
distillation  in  larger  retorts,  which,  like  those  used  for  distilling 
zinc  by  the  Altenburg  method,  may  be  emptied  and  charged 
without  interfering  with  the  fire.  If  this  were  effected,  it  is 
probable  that  there  would  be  a  saving  of  one-half  the  fuel  at 
present  used,  and  one  cylinder  would  work  as  much  of  the  mix- 
ture as  a  whole  furnace  does  now  ;  and  although  this  alone  would 
-very  materially  reduce  the  cost  of  production,  yet  it  would  be 
necessary  to  increase  the  size  of  all  the  other  parts  of  the  plan, 
and  this  could  not  be  done  at  a  factory  without  a  certain  pros- 
pect of  their  being  a  demand  for  the  increased  supply. 
The  crude  phosphorus,  obtained  as  above  described,  is  purified 
by  distillation  from  a  large  cast-iron  retort,  the  neck  of  which 
only  just  dips  into  water,  contained  in  a  flat  earthen  pan,  which 
is  so  full,  that  as  phosphorus  distils  over,  some  of  the  water  runs 
over  the  edge. 
The  phosphorus  to  be  distilled  is  cut  in  pieces  under  water, 
mixed  with  some  wet  sand,  and  put  into  the  retort  in  quantities 
of  ten  or  twelve  pounds.  The  wet  sand  serves  to  prevent  the 
ignition  of  the  phosphorus  while  charging  the  retort.  The  ap- 
plication of  heat  to  the  retort  requires  great  caution.  In  the 
first  instance  the  water  adhering  to  the  phosphorus  evaporates, 
and  drives"  out  a  portion  of  the  air,  then  bubbles  of  gas  issue, 
which  sometimes  ignites  when  escaping  from  the  water,  and, 
lastly,  drops  of  phosphorus  pass  over,  and  condense  in  the  neck 
