248 
SOLUBLE  PYROPHOSPHATE  OF  IRON. 
is  connected  with  the  decomposition  afterwards  affected.  I  have 
also  convinced  myself  that  the  formation  of  the  abundant  inter- 
cellular substance  of  the  albumen  of  several  leguminous  plants, 
as  Gleditschia  and  Sophora,  indicates  in  a  manner  perfectly  an- 
alogous the  transformation  of  outer  cellular  strata  into  a  homo- 
geneous jelly,  in  which,  often  for  a  long  time  afterwards,  traces 
of  the  primary  membrane  of  the  cells  can  be  recognized,  until 
even  these  entirely  disappear.  Nor  do  I  doubt  that  the  forma- 
tion of  the  intercellular  substance  of  Fucoidece,  of  Chondrus 
crispus,  &c,  is  indicative  of  an  analogous  event.  We  have 
consequently,  in  the  formation  of  gum  tragacanth,  a  special  in- 
stance of  a  widely  diffused  process  of  disorganization  of  cellulary 
membrane,  proceeding  from  exterior  to  interior,  at  one  time 
affecting  the  whole  wall  of  the  cells  [die  ganze  Zellwand];  at 
another,  attacking  only  the  outer  layers,  and  ending  with  their 
transformation  into  a  more  or  less  soluble  jelly.  On  the  other 
hand,  I  consider  it  less  appropriate  to  range,  as  Unger  does,  the 
formation  of  gum  tragacanth,  in  the  same  parallel  with  the  for- 
mation of  secondary  and  tertiary  gelatinous  cell-membrane,  such 
as  occur  in  the  testa  of  Cydonia,  Linum,  Collomia,  Ruellia,  &c; 
at  least  I  am  not  aware  that  these,  before  they  possess  the  con- 
dition of  gelatinous  membranes,  were  previously  in  the  condition 
of  membranes  of  cellulose. — London  Pharmaceutical  Journal^ 
Jan.  1859. 
ON  SOLUBLE  PYROPHOSPHATE  OF  IRON. 
By  M.  Robiquet, 
To  obtain  the  soluble,  or  citro-ammoniacal  pyrophosphate  of 
iron,  M.  Robiquet  dissolves  the  pyrophosphate  of  iron  in  a 
gelatinous  condition,  (as  obtained  by  precipitating  the  pyro- 
phosphate of  soda  with  persulphate  of  iron,)  in  a  solution  of 
citrate  of  ammonia.  When  the  liquor  is  clarified,  it  is  kept 
during  some  minutes  at  ebullition,  filtered  and  evaporated  at  a 
gentle  heat  to  the  syrupy  consistence,  spread  on  plates  with  a 
brush  and  the  desiccation  finished  in  a  stove. 
The  product  obtained  is  presented  under  the  form  of  light 
yellowish  transparent  vitreous  scales.    If  instead  of  drying  it 
