426  Practical  Notes  from  Various  Sources.  {Am'/uJ.?i§6arm' 
liberated  iodine.  The  absence  of  nitrites  and  hydrogen  peroxide  had 
been  previously  ascertained.  The  authors  explain  this  behavior  by 
the  gradual  change  of  the  C02  at  first  dissolved  in  the  water,  into 
H2C03,  and  that  the  decomposition  of  the  iodide  is  effected  by  hydro- 
gen carbonate,  but  not  by  carbon  dioxide.  The  importance  of  these 
observations  in  connection  with  the  testing  for  nitrous  acid  by  means 
of  potassium  iodide  is  obvious. 
Chloride  of  iodine  and  bromide  of  iodine  produce  with  starch  paste  a 
violet  color,  according  to  the  observations  of  H.  Beckurts  and  W.  Freytag 
(Phar.  Centralh.,  1886,  p.  231);  for  if  to  the  blue  aqueous  solution  of  io- 
dine and  starch,  chlorine  water  or  bromine  water  be  carefully  added,  the 
blue  color  is  changed  to  violet,  and  this  is  destroyed  by  an  excess  of 
the  reagents  named,  the  liquid  becoming  colorless  or  yellowish-red.  If 
to  a  mixture  of  chlorine  water  or  bromine  water  with  starch  solution, 
a  solution  of  iodine  be  carefully  added,  a  violet  colored  precipitate  of 
iodine-chloride  starch  or  iodine-bromide  starch  is  produced,  the  color 
disappearing  on  the  application  of  heat  and  reappearing  again  on  cool- 
ing. The  same  violet  color  is  produced  on  adding  to  potassium  iodide 
a  small  quantity  of  chlorate  or  bromate,  also  starch  solution  and  di- 
luted sulphuric  acid  ;  the  violet  color  often  changes  to  blue,  most 
likely  through  the  decomposition  of  the  iodine  chloride  with  the  libe- 
rated hydriodic  acid,  whereby  hydrochloric  acid  and  free  iodine  are 
produced. 
Nitrates  contaminated  with  Chlorate. — O.  Schlickum  observed  that 
samples  of  saltpetre  free  from  chloride,  on  being  heated  to  fusion, 
.  would  yield  a  solution  causing  a  precipitate  with  silver  nitrate.  H. 
Beckurts  (Archiv  d.  Phar.,  April,  1886,  p.  333)  has  made  similar  ob- 
servations with  both  sodium  and  potassium  nitrate,  and  attributes  this 
reaction  to  the  presence  of  minute  quantities  of  chlorate  or  perchlorate. 
He  found  also  that  at  least  0*25  per  cent,  of  potassium  chlorate  must 
he  added  to  pure  potassium  nitrate  before  the  former  can  be  detected 
by  the  decoloration  of  indigo  solution  in  the  presence  of  diluted  sul- 
phuric acid  and  a  minute  quantity  of  sulphurous  acid ;  but  after  treat- 
ing such  mixtures  with  nascent  hydrogen,  the  presence  of  chloride 
•could  be  established. 
Sal  pepticus  or  Peptochloride  of  Sodium  or  Digestive  Salt  are  names 
suggested  by  Dr.  Prosser  James  {Brit.  Med.  Jour.,  May  16)  for  a  mix- 
ture of  sodium  chloride  and  pepsin,  which  has  been  found  useful  in 
cases  of  dyspepsia. 
