■ 
478         CONTRIBUTIONS    TO  .ECONOMIC    GEOLOGY,   L906,   PART    T. 
The  phosphorus  in  some  ores  amounts  to  0.5  per  cent;  in  others 
reaches  1.5  per  cent.  At  Mount  Holly  Springs  the  wavellite  occu 
chiefly  in  nodular  form,  with  radiate  structure,  inclosed  in  the  win 
clay,  but  it  is  also  found  coating  pieces  of  quartzite  and  manganese  ore.. 
The  phosphorus  was  probably  associated  with  the  iron  in  its  origin* 
occurrence  and  in  the  process  of  redeposition  it  combined  with  the 
alumina,  but  it  is  possible  that  it  may  have  been  in  part  derived 
from  the  phosphatic  animal  remains  in  the  sediments.  It  is  known 
that  trilobites  and  other  fossils  with  phosphatic  skeletons  once  existej 
in  these  beds  in  considerable  abundance.  They  are  still  found  in 
the  limestones,  and  their  casts  are  occasionally  observed  in  the  sanol 
stones,  but  the  phosphatic  material  has  all  been  removed  from  the 
porous  beds  by  solution,  and  may  have  been  deposited  in  the  white 
clay  adjacent  to  the  iron  and  manganese. 
MANUFACTURE  OF  PHOSPHORUS. 
The  old  method  of  making  phosphorus,  which  has  been  in  use 
since  the  beginning  of  the  nineteenth  century,  is  as  follows:  Bona 
are  roasted  and  crushed,  and  the  powdered  hone  ash  (calcium  phosj 
phate)  is  treated  with  sufficient  sulphuric  acid  to  convert  all  or  part 
of  the  calcium  into  calcium  sulphate  and  the  phosphorus  into  calcium 
metaphosphate,  or  even  into  phosphoric  acid.  This  is  partialis 
evaporated,  mixed  with  powdered  charcoal,  and  reduced  in  a  fur- 
nace in  a  clay  retort.  Phosphorus  vapor  and  carbon  monoxide 
distill  off,  and  the  phosphorus  is  condensed  underwater  in  a  yellow, 
wax\   form.     Theoretically  the  reaction  would  be  as  follows: 
2Ca3(P04)2     t>II,S<>,  |-12C  =  6CaSO^  L2CO  P 2H2  +  P4  +  4H20. 
It    is  found   in   practice,  however,  that    the  following  is  more  nearly 
what  takes  place: 
:;Ca,(P()4),  •  6H2S04  •  LOC     6CaS04  •  Ca3(P04)2  •  L0CO  +  6H2O  +  P4. 
In  this  process  much  loss  results  from  t  he  dest  ruction  of  the  retorts 
by  the  acid  and  intense  heat,  and  only  about  one-half  of  the  phos- 
phorus in  the  charge  is  recovered.  There  is  also  danger  of  igniting 
the  phosphorus  when  removing  it,  and  the  greatest  care  is  required 
to  prevent  the  vapor  from  condensing  in  the  tubes  and  clogging  them. 
Many  improvements  and  modifications  of  this  process  have  been 
patented  in  recent  years.  Wohler  early  suggested  that  calcium  phos- 
phate, either  burnt  bones  or  rock  phosphate,  be  heated  with  sand 
and  carbon  without  the  sulphuric-acid  treatment,  and  the  Wing 
patent  (1891)  followed  the  same  general  method. 
