6 1 8  A ction  o f  Nitric  A cid  on  Metals.       { Am  Decern rm* 
provided  that  the  temperature  is  below  that  at  which  oxygen  is  dis- 
engaged. Fused  potassium  nitrite,  however,  is  decomposed  by  it 
with  great  violence.  Sodium  carbonate  is  reduced  at  a  dull  red  heat, 
potassium  carbonate  at  a  somewhat  higher  temperature,  and  calcium 
and  barium  carbonates  not  at  all. 
The  arsenites,  arsenates  and  chromates  are  all  reduced  at  a  dull 
red  heat. 
Boron  behaves  also  as  a  reducing  agent  in  the  wet  way.  It  reduces 
potassium  permanganate  solution,  partially  in  the  cold,  entirely  on 
heating.  It  reduces  ferric  chloride  to  ferrous  chloride.  It  precipi- 
tates silver  from  silver  nitrate  solution  in  fine  crystals,  and  reduces 
palladium,  platinum  and  gold  from  solutions  of  the  chlorides  of 
these  metals. 
Boron  thus  combines  with  the  non-metals  much  more  readily  than 
with  the  metals.  It  is  a  more  powerful  reducing  agent  than  either 
silicon  or  carbon,  and,  on  the  whole,  is  most  nearly  allied  to  the 
latter  element. 
ACTION  OF  NITRIC  ACID  ON  METALS.1 
By  C.  Montemartini. 
In  the  experiments  described  in  this  paper,  the  metals  cadmium, 
iron,  nickel  and  cobalt  were  respectively  dissolved  in  nitric  acid  of 
various  degrees  of  concentration,  at  least  20  times  the  amount  of 
acid  required  for  solution  being  used  so  as  to  exclude  secondary 
reactions  as  far  as  possible. 
The  experiments  were  principally  carried  out  at  a  temperature  of 
8°,  and  the  results  are  given  in  a  series  of  tables.  From  these  it 
appears  that  the  evolution  of  ammonia  is  not  limited  to  dilute  solu- 
tions of  nitric  acid  ;  thus,  for  instance,  0  00139  gram  of  ammonia 
was  formed  per  gram  of  cadmium  dissolved  in  47  per  cent,  nitric 
acid  ;  0  005  1  gram  of  ammonia  per  gram  of  iron  dissolved  in  52  per 
cent,  nitric  acid;  and  0-01839  gram  of  ammonia  per  gram  of 
cobalt  dissolved  in  42-8  per  cent,  nitric  acid. 
The  gases  evolved  by  the  dissolution  of  1  gram  of  the  following, 
metals  in  excess  of  27-5  per  cent,  nitric  acid  were  as  follows: 
1  Gazzetta,  22,  i,  250-265,  and  277-343;  Jour.  Chem.  Soc,  1892,  p.  1278. 
