PHOSPHAT  OF  LIME.
132
who  were  making  a  ſet  of  experiments  in  company.  They  made
some  on  the  earthy  part  of  bones  and  horns,  commonly  called  boneaſhes, ¬
  that  is,  the  white  matter  which  remains  from  bones  and  horns,
when  all  the  inflammable  matter  has  been  completely  burnt  out  of
them.  This  white  matter  was  formerly  kept  in  our  apothecaries
ſhops,  under  the  name  of  cornu  cervi  calcinatum,  and  it  was  supposed  to
be  an  alkaline  earth.  I  gave  a  few  experiments  on  it  in  the  essay  of
magneſia,  which  ſhewed  that  it  had  very  little  of  an  alkaline  quality.
But  the  Swedish  chemists,  having  examined  it  with  different  views,
and  in  a  quite  different  way,  found  it  to  be  compounded  of  calcareous
earth  and  phosphoric  acid.  Their  first  process  for  decompounding  it
has  been  reduced  to  greater  simplicity  by  other  chemists.  This  simpler ¬
  process  is  given  very  distinctly  in  the  last  edition  of  the  Edinburgh
Pharmacopœia,  as  a  step  in  the  process  for  preparing  the  foda  phospborata, ¬
  which  is  a  phosphat  of  foda,  recommended  lately  by  Dr.
Pearson  at  London,  as  a  pleasant  and  effectual  laxative  and  purgative. ¬

Since  Scheele  and  Gahn  publifhed  their  process  for  analysing  bone
aſhes,  a  fimilar  compound,  or  phosphat  of  lime,  has  been  found  in
vaſt  abundance  among  the  foffil  productions  of  nature.  The  first
example  of  this  was  communicated  by  a  letter  from  Mr.  Proust,  an
able  chemist,  in  the  fervice  of  the  King  of  Spain,  to  Mr.  Darcet  of
the  late  French  Academy  of  Sciences,  and  publifhed  in  the  Journal
de  Physique  June  1788,  informing  him  that  in  Estremadura  it  constituted ¬
  extensive  rocky  strata.  Mr.  Proust  found  it  in  a  stone  so
abundant  in  the  province  of  Estremadura,  that  it  is  quarried  and
employed  in  building.  In  appearance,  it  resembles  a  stone  composed
of  felt  spar;  but  it  consists  of  the  calcareous  earth  saturated  with
phoſphoric  acid,  or  at  leaſt  containing  it  in  the  fame  proportion  with
the  earth  of  bones,  that  is,  nearly  one-fifth.  It  is  highly  phosphorescent
when  heated.  It  is  also  found  in  Saxony  and  in  Bohemia.  Mr.
Werner  discovered  it  similar  to  the  Spanish  in  Saxony.  At  Schlack¬