54  PHOSPHORUS  AND  MATCH  MANUFACTURES. 
When  we  consider  that  1000  parts  of  urine  contain  scarcely 
one  part  of  phosphorus,  and  of  this  probably  only  a  portion  was 
obtainable  by  the  processes  first  in  use,  we  shall  not  be  surprised 
at  the  statement  of  Boyle  that  "  the  liquor  yields  but  a  small 
proportion  of  the  desired  quintessence,"  or  at  the  price  of  50s. 
an  ounce  charged  by  Hanckwitz  for  his  product.  Even  an  im- 
proved process,  purchased  and  published  by  the  French  Govern- 
ment in  1737,  yielded,  under  the  direction  of  Hellot,  Geoffroi, 
Dufay,  and  Duhamel  only  four  ounces  of  phosphorus  for  every 
five  hogsheads  of  the  liquid. 
After  the  death  of  Hanckwitz,  in  1741,  some  experiments 
were  made  by  Margraaf,  Fourcroy,  Vauquelin,  and  others  ;  but 
no  great  improvement  in  the  production  of  phosphorus  appears 
to  have  been  effected  until  1769,  when  Gahn  made  the  impor- 
tant discovery  of  phosphoric  acid  in  bones.  Margraaf  had  al- 
ready demonstrated  the  individuality  of  this  acid  as  early  as  the 
year  1740,  and  it  only  now  remained  to  devise  a  process  for 
extracting  it.  Scheele  immediately  did  this,  and  various  emi- 
nent chemists  quickly  succeeded  in  making  various  improve- 
ments in  the  method  of  working,  and  bequeathed  unto  us  sub- 
stantially the  same  process  of  manufacture  as  that  now  in  opera- 
tion. 
The  present  sources  of  phosphorus  are  the  bones  of  buffaloes 
and  other  animals,  slaughtered  in  the  great  hunting-grounds  of 
South  America  (the  Pampas  bordering  the  La  Plata),  where 
bones  are  used  as  fuel;  exhausted  "bone-black,"  or  "animal 
charcoal"  of  sugar  refineries  ;  calcareous  deposits  of  phosphate 
of  lime,  or  "mineral  guano"  from  the  coast  of  Yucatan;  and 
similar  deposits  from  the  Island  of  Sombreros  ;  but  the  chief  of 
these  sources  is  the  burnt  bones  from  Monte  Video,  Rio  Janeiro, 
Rio  Grande,  &c,  and  the  animal  charcoal  of  the  sugar  refine- 
ries. These  various  substances  contain  from  60  to  90  per  cent, 
of  their  weight  of  phosphate  of  lime,  or  from  12  to  18  per  cent, 
of  phosphorus. 
The  phosphorus-yielding  material,  of  whatever  kind,  having 
been  suitably  ground,  a  weighed  quantity  of  the  powder  is  placed 
in  a  large  circular  tub,  lined  with  lead,  with  a  mixture  of  oil  of 
vitriol  and  water,  and  stirred  by  means  of  a  revolving  wooden 
stirrer,  driven  by  a  steam-engine,  steam  being  admitted  by  a 
