PHOSPHORUS    ORE    AT    MOUNT    HOLLY    SPRINGS,  PA.  481 
porous  pottery  by  means  of  steam;  or  by  redistillation  in  iron  retorts. 
The  best  method  of  purification,  however,  is  to  treat  the  crude  phos- 
phorus, when  molten,  with  a  mixture  of  potassium  dichromate  and 
sulphuric  acid,  or  with  sodium  hypobromite,  some  of  the  impurities 
being  dissolved  and  others  rising  to  the  surface  as  scum. 
Because  ordinary  white  phosphorus  is  very  poisonous  and  injurious 
to  handle,  other  forms  of  the  element  have  been  sought.  Red 
amorphous  phosphorus,  which  is  not  poisonous,  is  readily  prepared 
by  heating  the  ordinary  variety  to  250°  C.  in  a  closed  vessel  under 
pressure  or  excluded  from  air  and  water.  It  has  not  the  same  quali- 
ties, however,  as  the  white  crystalline  variety.  A  red  crystalline 
form,  recently  discovered  in  Germany,  is  made  by  heating  to  boiling 
a  10  per  cent  solution  of  white  phosphorus  in  phosphorus  tribromide. 
This  form  is  not  only  nonpoisonous  but  is  an  efficient  substitute  for 
white  phosphorus  in  making  matches. 
PRODUCTION. 
The  industry  in  this  country  is  so  young  that  statistics  are  diffi- 
cult to  obtain;  in  faet,  general  information  on  the  subject  is  lacking. 
The  world's  production  of  phosphorus  has  been  variously  estimated 
to  be  from  1,000  to  3,000  tons  a  year,  and  until  very  recently  this 
was  almost  entirely  a  foreign  industry.  The  greater  part  of  the 
world's  supply  is  made  in  the  Albright  &  Wilson  factory,  Wednes- 
field  (Oldbury),  England,  where  the  Readman  process  originated. 
This  plant  is  said  to  produce  500  tons  a  year.  Other  large  factories 
are  located  at  Lyons,  France,  and  at  Griesheim  and  Frankfort,  Ger- 
many. There  is  also  a  plant  in  Sweden  and  numerous  smaller  ones 
in  Russia,  six  of  which,  located  near  Perm,  had  an  output  of  about 
140  tons  in  1890. 
In  the  United  States  the  first  phosphorus  works  were  built  about 
forty  years  ago  in  Philadelphia  by  Moro  Phillips,  and  this  factory 
has  continued  in  operation  until  very  recently.  J.  J.  Allen's  Sons' 
plant  was  established  in  Philadelphia  in  1891,  and  they  supplied  the 
Diamond  Match  Company,  the  largest  match  manufacturer  in  the 
United  States,  in  competition  with  imported  phosphorus.  In  1897 
the  English  firm  of  Albright  &  Wilson,  under  the  firm  name  of  the 
Oldbury  Electro-Chemical  Company,  built  at  Niagara  Falls  a  300- 
horsepower  factory  of  the  Readman  type,  which  has  since  supplied 
the  Diamond  Match  Company  and  furnished  the  major  portion  of 
the  domestic  product.  This  company  has  recently  made  a  further 
improvement  in  its  plant  by  introducing  the  Irvine  patent  furnace, 
and  it  is  reported  that  by  this  method  80  to  90  per  cent  of  the  phos- 
phorus is  extracted  from  the  raw  material,  a  high-grade  phosphate 
rock.     This  is  similar  to  the  results  obtained  in  the  English  works, 
