i86 
Albuminate  of  Iron, 
{Am.  Jour.  Pharn  .. 
April,  1880. 
5  drops  more  a  decided  turbidity  was  produced,  and  after  adding  5; 
drops  more,  a  further  addition  failed  to  produce  a  precipitate  in  the 
clear, filtrate.  The  precipitated  albumen  was  not  subjected  to  nearer 
experiment,  but  it  deserves  a  thorough  examination  since  there  were 
decided  evidences  of  change,  //  being  no  longer  coagulahle  by  heat.  Its 
quantity,  also,  was  not  determined,  but  it  appeared  to  be  less,  both  in  vol- 
ume and  weight,  than  that  obtained  from  the  same  albumen  by  precipita- 
tion with  ferric  chloride. 
The  first  two  experiments  (7  and  8)  have  shown,  beyond  a  doubt^ 
that  concentrated  solutions  of  albumen  (in  the  form  of  the  natural! 
egg-white)  are  readily  precipitated  by  ferric  chloride,  either  in  the  pres- 
ence or  absence  of  hydrochloric  acid,  but  that  the  precipitates  obtained 
under  either  condition  again  become  soluble  when  the  excess  of  ferric 
chloride  has  been  removed  by  washing.  They  likewise  show  that 
while  Bernbeck's  view,  that  the  solubility  of  the  albuminate  is  due  to 
excess  of  hydrochloric  acid  in  the  liq.  ferri  chlor.  is  probably  incorrect, 
the  condition  in  which  the  albuminate  of  iron  is  precipitated  when 
lerric  chloride,  free  from  hydrochloric  acid  is  employed,  is  of  such  a 
character  that  it  can  be  readily  washed  so  as  to  free  it  from  excess  of 
ferric  chloride  ;  while  that  obtained  by  Friese's  method,  being  in  a 
very  finely  divided  condition,  cannot  be  washed  with  the  same  readi- 
ness, and  that,  therefore,  a  portion  of  the  precipitate,  being  completely 
freed  from  excess  of  ferric  chloride,  may  again  enter  solution  before 
the  remainder  is  sufficiently  washed. 
Experiment  9  has  shown  that  the  process  of  precipitation,  by  the 
intervention  of  common  salt,  can  be  inverted  so  that  the  ferric  chloride 
will  act  as  the  final  precipitant.^  The  method,  however,  has  the  dis- 
advantage in  that  the  solution  of  albumen  and  salt  filters  very  slowly,, 
while  that  of  albumen  and  ferric  chloride  filters  with  comparative 
rapidity.  It  is  not  clear,  on  the  one  hand,  why  common  salt  should  effect 
the  precipitation  in  dilute  solutions  of  albuminate  of  iron,  and  why,  on 
the  other  hand,  ferric  chloride  should  only  precipitate  albumen  when  it 
is  in  its  natural  solution.  Both  propositions  must  for  the  present  be 
accepted  as  facts,  which  may  find  explanation  by  further  experiments. 
It  may  be,  furthermore,  inferred  that  the  small  quantity  of  chloride  of 
sodium  and  other  salts,  naturally  present  in  egg-white  in  its  concentrated 
natural  solution,  is  sufficient  to  effect  precipitation  upon  the  addition! 
1  This  is  already  shown  by  Hager's  method,  but  his  method  was  not  known  io 
me  at  the  time  the  experiment  was  made. 
