170         ST.  REGIS  SULPHUR  WATER  OP  MASSENA,  N.  Y. 
bonate  and  oxalate  of  ammonia,  then  evaporating  the  filtrate  with 
a  small  excess  of  hydrochloric  acid,  igniting  the  residue  to  drive 
off  ammoniacal  salts,  redissolving  in  water,  precipitating  remain- 
ing traces  of  earths  with  carbonate  of  ammonia,  filtering,  evapo- 
rating to  dryness,  and  igniting.  The  residue  were  the  chlorides 
of  the  alkalies.  The  potassa  was  only  separated  by  a  large  ex- 
cess of  chloride  of  platinum.  In  the  mixed  chlorides  the  amount 
of  each  was  determined  by  the  indirect  method,  with  a  volumetric 
solution  of  silver. 
500  cubic  centimetres  of  the  water  were  drawn  off  by  a  syphon, 
and  precipitated  by  an  excess  of  Tenth  normal  solution  of  silver, 
which  carried  down  chlorine,  bromine,  carbonic  acid,  sulphur  from 
sulphurets,  and  on  heating  also  that  of  hyposulphurous  acid,  half 
of  the  sulphur  from  the  latter  forming  sulphuric  acid.  The  ex- 
cess of  silver  was  removed  by  Tenth  normal  solution  of  chloride 
of  sodium,  and  the  excess  of  the  latter  determined  by  the  corres- 
ponding solution  of  silver  with  the  aid  of  chromate  of  potassa. 
The  silver  precipitate  treated  with  ammonia  was  separated  into 
soluble  chloride  and  carbonate,  and  insoluble  sulphuret  of  silver. 
To  determine  the  combined  amounts  of  sulphurets  and  hypo- 
sulphite, several  quantities  of  500  cc.  were  measured  with  a  di- 
lute solution  of  iodide  of  starch.  Neither  the  silver  nor  this  test 
can  be  used  to  determine  them  separately.  For,  one  equivalent 
of  iodine,  while  it  substitutes  one  eq.  of  sulphur  in  a  sulphide  or 
sulphuretted  hydrogen,  oxydises  four  eq.  of  sulphur  in  hyposul- 
phurous acid  to  one  eq.  of  pentathionic  acid.  On  heating  a  so- 
lution of  a  hyposulphite  with  nitrate  of  silver,  half  of  the  sulphur 
only  is  carried  down  as  sulphuret  of  silver,  the  other  half  being 
oxydised  to  sulphuric  acid. 
Another  portion  of  the  water  was  precipitated  with  a  neutral 
solution  of  chloride  of  cadmium,  and  the  filtrate  measured  with 
the  solution  of  iodide  of  starch.  This  last  amount,  corresponding 
to  hyposulphurous  acid,  deducted  from  that  found  for  the  water 
previous  to  the  treatment  with  cadmium,  leaves  the  amount  of 
iodine  corresponding  to  sulphurets. 
A  portion  of  the  hot  solution  from  which  silver  had  precipitated 
chlorine  and  sulphur,  was  acidulated  with  hydrochloric  acid,  and 
precipitated  with  chloride  of  barium.    The  sulphate  of  baryta 
