6 
Dialyzed  Iron. 
Am  Jour.  Pharira. 
Jan.,  1879 
ammonia  had  been  added  to  a  point  that  further  addition  would  have 
left  an  undissolved  precipitate.  To  3  fluidounces  of  solution  of  chlo- 
ride of  iron  6  fluidounces  of  water  of  ammonia  was  added  at  once. 
The  mixture  at  first  formed  a  thick  magma,  but  with  diligent  stirrings 
the  temperature  at  the  same  time  rising  to  11 6°  Fahr.,  turned  clear  in 
about  twenty  minutes.  It  was  dialyzed  in  11  days.  The  product 
measured  16J  fluidounces;  it  was  of  a  deeper  red  color  than  the 
former,  formed  no  scales  upon  evaporation,  and  contained  5  per  cent, 
of  solid  matter.  A  solution  of  iron  from  solution  of  chloride  of  iron 
and  water  of  ammonia,  prepared  in  the  same  manner  as  the  last,  was 
placed  aside  for  several  days.  It  remained  clear,  and  not  a  trace  of 
precipitate  could  be  discerned. 
After  using  the  iron  solution  prepared  as  above  stated  a  great  manv 
times,  and  always  with  the  same  satisfactory  result,  it  was  concluded 
that  for  this  reason,  and  because  it  is  made  in  a  shorter  time,  and  keeps 
better  than  the  second,  it  is  preferable  for  dialysis. 
As  already  stated,  the  different  solutions  of  dialyzed  iron  made  by 
the  improved  apparatus  contained  5  per  cent,  of  solid  matter.  Solu- 
tion of  nitrate  of  silver  produced  no  precipitate  with  the  diluted  solu- 
tions. But  when  they  were  first  precipitated  with  ammonia,  and  the 
filtrate  acidulated  with  nitric  acid,  and  nitrate  of  silver  was  now  added, 
turbidity  resulted,  showing  the  presence  of  hydrochloric  acid. 
What  kind  of  parchment  paper  ought  to  be  used  in  the  process  of 
dialysis  ?  Other  things  being  equal,  certainly  the  kind  with  which  the 
process  is  finished  in  the  shortest  time.  In  the  foregoing  processes  a 
paper  measuring  248  square  inches  to  1  ounce  avoirdupois  was  used. 
With  it,  as  will  be  remembered,  dialysis  was  always  finished  in  11 
days.  Latterly,  a  thinner  paper,  measuring  560  square  inches  to  1 
ounce  avoirdupois,  has  been  used,  with  the  result  of  shortening  the 
process  considerably.  With  it  dialysis  was  completed  in  5  days.  «  It 
may  here  be  stated  that  the  thick  parchment  paper  was  used  when 
the  temperature  of  the  atmosphere  ranged  between  700  and  950  Fahr. 
and  the  thin  paper  at  between  400  and  700. 
One  phenomenon  connected  with  dialysis  by  the  apparatus  deserves 
some  attention.  It  is,  the  vessel  holding  the  water  being  transparent  the 
process  can  be  conveniently  observed,  and  when  the  charged  apparatus 
is  placed  against  the  light,  if  the  heavy  parchment  paper  is  used  a  small 
band  of  saline  solution  (the  crystalloid  of  the  iron  solution)  will  be  seen 
