GLEANINGS  PROM  THE  GERMAN  JOURNALS.  405 
ammonia,  and  afterwards  acidulated  with  acetic  acid;  the  test 
liquid  is  now  added  and  well  stirred  in,  until  a  drop  just  pro- 
duces a  brown  color,  with  a  drop  of  ferrocjanide  of  potassium. 
The  excess  which  is  necessary  to  produce  this  brown  color,  is 
determined  from  acetate  of  ammonia  acidulated  with  acetic  acid, 
to  which  the  uranic  nitrate  is  added  until  the  same  color  is  pro- 
duced with  ferrocyanide  of  potassium  ;  for  50  c,  c.  m.  of  liquid 
it  will  be  about  -8  c.  c.  m.  This  method  is  very  convenient  in 
the  analysis  of  urine. 
1  c.  c.  m.  solution  of  uranium  is  equivalent  to  5.281  m.  grm. 
As.  In  the  presence  of  arsenic  and  phosphoric  acids,  both  may 
be  estimated  together,  and  after  precipitating  the  arsenic  by 
HS,  the  phosphoric  acid  alone.  The  difference  will  indicate  the 
quantity  of  uranium  necessary  for  the  arsenic. —  (Ann.  d.  Chem. 
and  Ph.  xli.  195-200.) 
Arendt  and  Knop  recommended  uranic  oxide  for  the  same 
purpose  in  1856  (Centralbl.)  and  Pisani  lately  in  Comptes  Rend, 
lii.  72,  106. 
Estimation  of  Acids  in  Salts. — E.  Langer  and  R.  Wawnikie- 
wicz,  have  been  induced  by  Professor  Bunsen^  to  experiment 
with  acidimetric  liquids  for  the  estimation  of  acids  combined 
with  bases  that  are  precipitated  by  potassa  or  carbonate  of  soda  ; 
the  excess  of  alkali  is  corrected  by  normal  hydrochloric  acid. 
Experimenting  with  pure  nitrates  and  sulphates,  they  have 
found  that  carbonate  of  soda  will  answer  for  salts  of  baryta, 
strontia,  zinc,  lead,  bismuth,  nickel,  alumina  ;  potassa  was  used 
for  salts  of  copper,  silver,  ammonia  and  iron. — (Ann.  d.  Chem. 
und  Ph.  xli.  230-288.) 
The  titration  of  tiyi  is  effected  by  Stromeyer,  by  dissolving  it 
in  hydrochloric  acid  and  immediately  mixing  it  with  sesquichlo- 
ride  of  iron  ;  SnCl+Fe^Clg^SnCl^-f  2FeCl.  The  protochloride 
of  iron  is  oxidized  by  permanganate  of  potassa,  1  equiv.  oxygen 
represents  1  equiv.  tin. 
Tin  dissolved  more  readily  in  a  somewhat  concentrated  solu- 
tion of  ferric  chloride,  containing  some  free  acid  without  evolving 
hydrogen.  Sn-|-2Fe2Cl3==  SnClg-f  4FeCl  ;  in  this  case  2  oxy- 
gen represent  1  tin.  The  tin  must  be  free  from  other  metals. 
—(Ann,  d.  Ch.  und  Pharm.  xli.  261-264.) 
