Chemical  Properties. — Bromine  closely  resembles  chlorine  chemi-
cally, although  it  usually  reacts  with  less  energy.  Thus,  while  chlorine
combines  with  hydrogen  under  influence  of  light,  bromine  does  not.
Bromine  combines  readily  with  the  metalloids  and  metals,   in  some


BROMINE  AND  HYDROGEN.  171

instances  (As,  Sb,  K)  with  considerable  violence,  yet  its  affinity  for
these  elements  is  not  as  great  as  is  the  case  with  chlorine.  For  example,
chlorine  will  displace  bromine  from  its  salts:

2AgBr    -f-     Cla    ^    2AgCI     -f     Bra.
Through  its  affinity  for  hydrogen,  bromine  reacts  substituting,  upon
many  organic  compounds.    Thus  —

CioHieO         -h         Bra        =        CioHiaBrO         -h         HBr

Cam|4ior.  Mono-brom-camphor.         Hydrobromic  Acid.
In  presence  of  water,  bromine  is  an  active  oxidizing  agent.
HiS         -f         Bra         =         2HBr         +         S.
Hydrogen  Sulphide.  Hydrobromic  Acid.
HaS         4-         4Bra         +         4H8O        -=-       HaSOi         -h      8HBr.
Hydrogen  Sulphide.  Sulphuric  Acid.
II  III

FeBra         -h         Br        =         FeBrs.
Ferrous  Bromide.  Ferric  Bromide.
Bromine  bleaches,  but  in  a  less  degree  than  chlorine.     It  bleaches
Jitmus  and  iri3ig'd"sorutions  and  colors  starch  jelly  yellow,
f  X    Bromine,  TTSVP.—^^^is  shiyuTdToiilaih  not  less  than  97  per  cent,  of
""  pure  bromine,  the  balance  consisting  of  chloride  and  water.     The  Ameri-
can bromine  usually  contains  from  1.5  (Michigan)  to  about  6  (Ohio)  per
cent,  of  chlorine.     The  German  bromine  essays  about  99  per  cent.     For
tests  see  U.  S.  Pharmacopoeia.
Uses. — In  the  free  state  bromine  is  used  in  the  manufacture  of  bro-
mides and  of  many  bromine  derivatives  of  the  coal-tar  compounds.
It  is  also  used  in^ medicine  internally  when  highly  diluted,  and  exter-
nally as  a  caustic.  It  is  also  extensively  used  as  a  disinfectant,  either  in
solution  or  mixed  with  some  porous  silicate  as  infusorial  earth.
BROMINE    AND    HYDROGEN.
HYDROGEN  BROMIDE.
Formula,  HBr.  Molecular  Weight,  80.36.
