372 
MANUFACTURE  OF  PHOSPHATE  OF  SODA,  ETC. 
this  experiment  of  M.  Schiitzenberger's,  it  is  proved  that  melted 
sulphur  crystallizes  below  100°  in  octahedra  of  the  fourth  sys- 
tem, without  the  aid  of  any  solvent.  The  facts  will  probably  be 
turned  to  account  in  the  study  of  the  formation  of  natural  cryst- 
als.— Lond.  Chem.  Neivs,  May  22,  1868. 
ON  THE  MANUFACTURE  OF  PHOSPHATE  OF  SODA  AND 
FLUORIDE  OF  SODIUM. 
By  M.  Jean. 
A  note  on  the  manufacture  of  phosphate  of  soda  and  fluoride 
of  sodium  has  been  published  by  M.  Jean.  The  process  usually 
adopted  in  the  fabrication  of  neutral  phosphate  of  soda  consists 
in  attacking  the  tribasic  phosphate  of  lime,  either  in  the  form  of 
nodules  or  calcined  bones,  with  sulphuric  acid ;  thus  a  solution 
of  acid  phosphate  of  lime  containing  some  sulphate  and  excess 
of  sulphuric  acid  is  obtained.  This  solution  of  acid  phosphate  of 
lime  is  treated  with  carbonate  of  soda,  when  phosphate  of  soda 
and  carbonate  of  lime  result,  but  a  large  quantity  of  sulphate  of 
soda,  or  otherwise  of  sulphate  of  lime,  and  free  sulphuric  acid 
requires  separating :  repeated  and  carefully  conducted  crystalli- 
zations are  therefore  necessary.  M.  Jean  made  experiments 
with  a  view  to  founding  a  better  process. 
The  following  are  notes  of  experiments :- — (I.)  In  fusing  a 
mixture  of  one  equivalent  of  tribasic  phosphate  of  lime,  two 
equivalents  of  sulphate  of  soda  and  carbon  in  excess,  and  ex- 
tracting with  cold  water,  a  strongly  sulphurous  liquor  containing 
phosphate  of  soda  was  obtained.  The  residue,  chiefly  oxysul- 
phide  of  calcium,  contained  about  two-thirds  of  the  phosphate  of 
calcium  unattacked.  (2.)  A  second  experiment  made  with  three 
equivalents  of  sulphate  gave  soluble  acid  phosphate  14  per  cent., 
acid  in  an  insoluble  form  13-71  percent. :  with  three  equivalents, 
then,  about  half  the  phosphate  is  obtained  in  the  form  of  neutral 
phosphate  of  soda.  (3.)  By  increasing  the  amount  of  sulphate 
to  six  equivalents,  20*6  per  cent,  was  the  yield  of  soluble  phos- 
phate, while  the  residue  contained  1*933  per  cent,  of  acid  com- 
bined with  lime.  M.  Jean  attributes  this  small  quantity  of 
phosphoric  acid  to  the  action  of  caustic  lime,  always  present  to 
a  slight  extent  in  the  residue,  upon  the  phosphate  of  soda  after 
