SOLUTION  OF  PYROPHOSPHATE  OF  SODA  AND  IRON.  395^ 
duced  a  whitish  precipitate,  the  supernatant  liquid  retaining  a 
yellowish  brown  color. 
11.  Before  precipitation  commenced,  No.  6  was  mixed  with 
solution  of  citric  acid,  a  slight  turbidity  appeared  without  pro- 
ducing a  precipitate ;  in  the  course  of  a  week  syrup  and  little 
alcohol  was  added ;  the  liquid  remained  unchanged  in  appearance 
for  six  weeks. 
12.  No.  11  was  boiled,  when  the  cloudiness  increased ;  the 
alcohol  which  had  evaporated  was  added,  when  the  liquid  at  once 
became  turbid  and  precipitated. 
13.  Before  precipitation  commenced,  No.  6  was  mixed  with 
acetate  of  ammonia,  which  did  not  react  upon  the  iron,  and  the 
solution  remained  transparent  for  seven  weeks. 
14.  Alcohol,  added  to  No.  13,  produced  turbidity  and  gradu- 
ally a  white  precipitate. 
15.  On  boiling,  No.  13  assumed  a  slight  yellowish  color,  then 
became  milky  and  gradually  produced  a  white  precipitate. 
16.  No.  8,  which  had  been  rendered  turbid  by  the  addition  of 
sulphuric  acid,  became  clear  and  almost  colorless  again  on  the 
addition  of  carbonate  of  ammonia,  and  remained  in  this  condi- 
tion for  seven  weeks. 
17.  Little  alcohol  added  to  No.  16  gradually  produced  a  white 
/precipitate. 
18.  Boiling  scarcely  affects  No.  16,  except  in  the  presence  or 
subsequent  addition  of  alcohol. 
19.  1  part  pure  pyrophosphate  of  iron  with  5  parts  pyrophos- 
phate of  soda,  dissolved  in  120  parts  distilled  water,  yielded  a 
colorless  solution,  remaining  clear  for  seven  weeks,  with  the  ex- 
ception of  the  production  of  a  little  mould ;  boiling  did  not  sen- 
sibly affect  it,  but  disposed  it  to  the  slow  separation  of  a  white 
precipitate.  /  / 
20.  No.  19  gradually  yielded  a  white  precipitate  with  little 
alcohol. 
21.  Little  phosphoric  acid  added  to  No.  19  did  not  cause  any 
change  except,  on  heating,  a  white  precipitate. 
22.  No.  19  gradually  became  yellowish  on  standing,  with  little 
citric  acid  ;  boiling  rendered  it  turbid. 
