618 
Action  of  Alkaline  Phosphates. 
Am.  Jour.  Pharm. 
Deo.,  1888. 
phosphate  yields  two  products  according  to  the  proportion  of  oxide 
employed,  namely,  9P2O5,10CaO,8Na2O,  which  was  previously 
obtained  by  Wallroth,  under  the  same  conditions,  and  forms  mono- 
clinic  lamellse,  and  P205,2CaO,Na20,  which  has  been  described  by 
Ditte,  and  forms  transparent  hexagonal  rosettes.  Sodium  pyrophos- 
phate and  orthophosphate  yield  the  salt  P205,2CaO,Na20,  and  also  the 
salt  2P205,3CaO,3Na20,  which  crystallizes  in  slender,  transparent  mo- 
noclinic  needles  melting  to  a  white  enamel  at  a  red  heat.  With  the 
carbonate,  phosphate,  sulphate,  chloride,  and  fluoride,  the  same  pro- 
ducts are  obtained  as  with  the  oxide.  With  sodium  or  calcium  chlo- 
ride in  excess,  chlorophosphates  corresponding  to  apatite  and  wagner- 
ite  are  formed. 
Strontium  oxide  and  salts  with  potassium  meta-  or  pyro-phosphate 
yield  the  compound  P205,SrO,K20,  identical  in  form  with  the  corres- 
ponding calcium  salt.  Tripotassium  phosphate  produces  the  compound 
P205,2SrO,K20,  identical  in  form  with  the  analogous  barium  and  cal- 
cium compounds.  Sodium  meta-  and  pyro-phosphates  yield  first  the 
compound  P205,2SrO  in  small,  rhombic  prisms  similar  to  those  of  the 
barium  salt,  and  then  the  compound  P20.5,2SrO,Na20  analogous  to 
the  product  obtained  with  calcium.  Sodium  orthophosphate  yields 
only  the  salt  P205,2SrO,]S[a20  ;  strontium  sulphate  is  not  decomposed 
by  the  sodium  phosphates. 
Barium  is  not  readily  displaced  by  alkalis,  and  therefore  does  not 
readily  form  double  salts.  Calcium  forms  double  phosphates  only^ 
and  strontium  occupies  an  intermediate  position. 
Magnesium. — With  potassium  metaphosphate,  the  sole  product  is 
the  compound  3P205,2MgO,K20,  which  crystallizes  in  large,  mono- 
clinic  prisms,  very  soluble  in  dilute  acids ;  sp.  gr.  at  20°  =  2*4.  It 
is  analogous  to  the  double  magnesium  sodium  phosphate  obtained  by 
Fleitmann  and  Hennerberg  in  the  wet  way. 
Potassium  pyrophosphate  or  orthophosphate  yields  rhombic  prisms 
of  the  salt  P205,2MgO,K20,  previously  described  by  Grandeau.  Mag- 
nesium phosphate  yields  the  same  products  as  the  oxide,  but  the  chlo- 
ride yields  a  chlorophosphate  unless  the  alkaline  phosphate  is  present 
in  considerable  excess. 
With  sodium  metaphosphate  at  a  low  temperature,  the  magnesium 
oxide  not  being  in  excess,  the  salt  9P2O5,10MeO,8Na2O  is  obtained  in 
highly  macled,  monoclinic  prisms;  sp.  gr.  at  20°  =  2*7.  This  com- 
pound has  previously  been  described  by  Wallroth.    At  a  high  tem- 
