^msllZ'S££:Tm'}    Practical  Notes  from  Various  Sources.  425 
AMMONIUM  CITRATE. 
It  is  difficult  to  obtain  a  definite  normal  ammonium  citrate,  owing  to 
the  similar  condition  of  the  carbonates.  Bicarbonate  of  ammonium 
gives  the  best  result,  but  not  wholly  free  from  uncertainty.  The  re- 
sult with  salicylic  acid  is  possibly  analogous  to  that  with  the  other 
monad  citrates.  The  indications,  however,  point  to  the  following  re- 
action : 
(XH4)3Ci+HSl=NH4Sl+(NH4)2HCi. 
The  solution  readily  yields  most  splendid  crystals  of  ammonium 
salicylate,  i  hey  are  so  large  and  distinct  that  very  low  powers  serve 
best  to  exhibit  them.  Their  form  is  intermediate  between  that  of  the 
potassium  salt,  obtained  from  the  acetate,  and  the  sodium  salt  derived 
from  the  citrate.  The  solution  has  a  palatable,  sweetish  acidulous 
taste. 
All  of  these  mixed  salicylates  crystallizing  well  are  obtainable  from 
either  strong  or  weak  solutions  with  equal  ease.  Those,  however,  crys- 
tallizing with  difficulty,  appear  better  from  weak  solutions.  All  the 
solutions  are  more  or  less  tinted  of  a  brown-yellow  color.  Those  from 
the  potassium  tartrate  and  the  borax  have  the  deepest  shade,  whilst 
those  from  the  sodium  pyrophosphate  and  the  ammonium  citrate  have 
the  lightest. 
The  solutions  resulting  from  borax  and  sodium  phosphate  are  the 
most  unpalatable,  while  those  of  ammonium  citrate  and  Rochelle  salt 
are  the  least  so. 
PRACTICAL  NOTES  FROM  VARIOUS  SOURCES. 
By  the  Editor. 
Testing  of  Potassium  Iodide. — Dr.  J.  Miihe  (Phar.  Centralh.,  1885, 
p.  85)  stated  that  pure  potassium  iodide  is  decomposed  with  the  libe- 
ration of  iodine  by  water  containing  carbonic  acid  gas,  but  Weppen  and 
Liiders  (Ibid.,  p. 129)  obtained  different  results.  On  repeating  the  ex- 
periments, H.  Beckurts  and  W.  Freytag  (Ibid.,  p.  215-218)  ascertained 
that  a  5  per  cent,  solution  of  pure  potassium  iodide  in  previously 
boiled  water  is  not  decomposed  by  a  stream  of  pure  carbonic  acid 
gas ;  but  the  liberation  of  free  iodine  was  at  once  observed,  if  the  so- 
lution was  mixed  with  water,  impregnated  with  carbonic  acid  gas  and 
kept  on  hand  for  some  time.  The  same  carbonic  acid  water,  deprived 
of  most  of  the  gas  by  prolonged  exposure  in  a  beaker,  as  well  as  dis- 
tilled water  which  had  been  kept  on  hand  for  some  time,  at  once 
