ISO         CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   L906,  PART    I. 
as  a  carbon  rod,  placed  above  the  charge.  The  rod  becomes  incandes- 
cent, and  the  fool',  which  is  arched  over  the  grate,  reflects  the  heat  as 
in  a  reverberatory  furnace. 
The  Keadman  process  was  modified  by  the  Irvine  patent  in  1901 
Tin1  charge  is  tin1  same  as  in  the  earlier  method,  although  either 
aluminum  or  calcium  phosphate  can  he  used  with  the  silica  or  basis 
salt  flux.  The  two  carbon  electrodes  are  suspended  vertically  from 
above  and  are  connect ed  below  at  the  start  by  coal,  through  which 
the  current  passes.  After  the  charge  is  melted  the  slag  forms  on  top, 
and  thereafter  the  current  passes  through  it  as  the  conductor  between 
the  electrodes.  Fusion  is  continuous,  and  the  excess  of  slag  is  tapped 
oil'  gradually  so  as  not   to  expose  the  ends  of  the  electrodes. 
A  process  patented  in  L903  by  Duncan  takes  77  parts  of  powdered 
phosphate,  eil  her  organic  <>r  mineral,  and  23  parts  of  powdered  carbon, 
mixed  with  tar  as  a  binder.  This  i>  dried,  and  after  a  preliminary 
heat  ing,  a-  a  matter  of  economy,  in  a  hydrogen  Maine,  a  by-producl  in 
the  manufacture,  it  is  put  into  an  electric  furnace  and  calcium  phos- 
phide is  continuously  produced.  This  is  put  into  a  chamber  sub- 
merged in  hydrogen,  and  after  adding  water  it  forms  phosphorus 
hydrides.  On  heating,  the  hydrides  are  reduced  to  phosphorus  in 
pure  state,  either  red  or  yellow,  depending  mi  the  degree  of  heat  at 
which  it  is  allowed  to  deposit. 
In  1902  Parker  patented  a  process  in  England  for  the  reduction  of 
aluminum  phosphate,  which  is  treated  with  sulphuric  acid  and  then 
with  an  alum-forming  sulphate,  all  1  he  alumina  being  removed  by  the 
crystallization  of  the  alum  previous  t<>  the  electric  treatment.  The 
residual  liquor  is  mixed  with  coal  and  other  carbonaceous  materia] 
and  reduced  in  an  elect  ric  furnace. 
The  American  Phosphorus  Company,  through  (1.  C.  Landis,  its! 
chemist,  secured  a  patent  in  January,  L907,  on  certain  improvements 
in  its  furnace  that  were  designed  to  prevent  the  escape  of  fumes, 
vapors,  and  gases,  or  their  absorption  by  the  furnace  lining.  This  is 
accomplished  by  an  outer  lining  of  nonabsorbenl  brick  and  by  a  sealing 
device  for  all  openings  into  the  furnace,  whereby  the  projecting 
flanges  of  the  joints  are  inclosed  in  a  moat  of  water.  The  furnace 
has  an  inner  lining  of  carbon  bricks  that  act-  as  one  elect  rode,  and  one  1 
or  more  vertical  carbon  rods  are  used  for  the  other  elect  rode,  which 
may  be  adjusted  either  to  furnish  a  continuous  current  through  the 
charge  or  to  produce  with  it  an  electric  arc. 
The  phosphorus  obtained  by  most   commercial  processes  is  a  crude 
form  of  the  white  or  yellowish  waxy  variety,  containing  sand,  carbon, 
clay,  and  other  impurities.     These  are  removed  in  various  ways     by 
filtering  while    molten    and   submerged    in    water  through    powdered  I 
canvas;    by  forcing   the   molten  mass  through  1 
charcoal   or  through 
