Am'  i)°eucr;  i892arm' }  A  morphous  Boron.  6 1 7 
a  mixture  of  the  dry  acid  with  boron  becomes  incandescent,  and 
iodine  is  evolved ;  chloric  acid  is  reduced  to  chlorous  acid, 
The  hydracids  react  with  greater  difficulty.  Hydrogen  fluoride  is 
not  attacked  until  a  dull  red  heat  is  reached,  when  boron  fluoride  is 
formed  and  hydrogen  liberated.  Hydrogen  chloride  is  attacked 
only  at  a  bright  red  heat,  whilst  its  aqueous  solution  has  no  action 
whatever  on  boron. 
Sulphurous  anhydride  is  reduced  to  sulphur  at  an  incipient  red 
heat.  Steam  is  not  attacked  until  a  full  red  heat  is  attained,  but  the 
action,  once  started,  proceeds  with  great  energy,  boric  acid  being 
formed  and  hydrogen  set  free.  Carbonic  oxide  is  reduced  to  carbon, 
at  1,200°.  Silica  is  reduced  to  silicon  when  heated  in  a  forge. 
Nitrous  oxide  is  decomposed  by  boron  at  a  dull  red  heat,  boron 
nitride  and  boric  acid  being  formed ;  nitric  oxide  is  not  affected  by  it. 
Metallic  oxides  are  more  readily  reduced  by  boron  than  by  carbon. 
When,  for  instance,  a  mixture  of  boron  and  cupric  oxide  is  heated 
in  a  glass  tube,  the  reaction  which  ensues  is  so  violent  as  to  melt  the 
glass.  Stannous  oxide,  litharge,  antimonious  and  bismuth  oxides 
are  all  readily  reduced.  A  mixture  of  boron  and  lead  peroxide 
detonates  violently  when  triturated  in  a  mortar.  Ferric  and  cobalt- 
ous  oxides  are  reduced  at  a  red  heat,  but  the  oxides  of  the  alkaline 
earths  are  not  affected.  Hydrogen  is  liberated  by  boron  from  fused 
potassium  hydroxide.  A  mixture  of  boron,  sulphur,  and  nitre 
deflagrates  at  a  dull  read  heat,  whilst  small  quantities  of  boron  pro- 
jected into  fused  potassium  chlorate  burn  with  a  most  dazzling 
flame. 
Boron  acts  very  energetically  on  the  metallic  fluorides ;  it  decom- 
poses the  fluorides  of  the  alkalis  and  alkaline  earths  at  a  bright  red 
heat ;  zinc  fluoride  at  a  dull  red  heat,  boron  fluoride  being  formed ; 
and  it  acts  with  even  explosive  violence  on  lead  and  silver  fluorides. 
Its  action  on  the  metallic  chlorides  is  not  so  energetic.  The  chlorides 
of  the  alkalis,  the  alkaline  earths,  zinc  and  lead  are  not  attacked  at 
a  red  heat,  but  mercurous  chloride  is  reduced  to  mercury  at  7000. 
Lead,  zinc,  cadmium  and  copper  iodides  are  not  reduced  by  boron, 
but  tin  and  bismuth  iodides  are  reduced  with  facility.  Potassium, 
sodium,  calcium  and  barium  sulphates  are  reduced  by  boron  at  a 
red  heat  to  the  corresponding  sulphides. 
Notwithstanding  its  great  affinity  for  oxygen,  boron  may  be 
immersed  in  fused  potassium  nitrate  without  any  reaction  occurring. 
