Am.  Jour.  Pharm.  1 
Aug.,  1881.  i 
Chemical  Notes. 
399 
rature  rises  decomposes  into  cerous  fluoride  and  free  fluorine,  just  as 
*  manganese  tetrachloride  at  ordinary  temperatures  separates  into  man- 
ganous  chloride  and  free  chlorine. — Ber.  der  Chem.  Ges.,  xiv,  p.  1144. 
On  Boron  Hydride. — While  the  existence  of  a  hydride  of  boron 
seemed  possible  because  of  the  relations  of  the  element  to  the  nitrogen 
group,  on  the  one  hand,  and  to  silica  on  the  other,  in  both  of  which 
cases  hydrides  were  known,  the  compound  had  not  been  ])repared. 
Jones  and  Taylor  already  in  1879  indicated  the  existence  of  such  a 
compound,  and  they  now  describe  it  more  in  detail.  They  found  that 
it  could  not  be  prepared  by  a  method  analogous  to  that  used  in  the 
preparation  of  silicon  hydride,  viz.,  the  formation  of  magnesium  sili- 
oide  by  the  action  of  magnesium  upon  potassium  silicofluoride.  The 
methods  which  allow  of  its  production  are  the  preparation  of  magne- 
sium boride  by  (1)  heating  magnesium  with  boric  anhydride,  (2)  by 
direct  union  of  boron  and  magnesium,  (3)  by  the  action  of  magne- 
asium  upon  boron  trichloride.  Magnesium  boride,  obtained  in  any  of 
these  ways  yields,  on  addition  of  an  acid,  boron  hydride  mixed'  with  a 
laiTge  excess  of  hydrogen.  The  gas  burns  with  a  green  flame,  is 
decomposed  by  heat,  with  separation  of  boron,  dissolves  slightly  in 
water,  and  gives  a  black  precipitate  with  silver  nitrate,  containing  sil- 
ver and  boron ;  it  combines  with  ammonia,  yielding  a  compound 
which  is  decomposed  by  acids.  The  composition  of  the  hydride,  so 
far  as  could  be  ascertained  by  combustion  of  the  gas  with  copper 
oxide,  is  represented  by  the  formula  HgB. — Jour.  Chem.  Soc,  May, 
1881,  p.  213. 
On  the  Artificial  Production  of  Nitric  Acid. — The  well-known  fact 
that  nitrogen  and  oxygen  in  the  presence  of  watery  vapor  are  con- 
verted by  the  passage  of  the  electric  spark  into  nitric  acid  was  estab- 
lished by  Fremy  and  Becquerel  with  the  aid  of  a  Ruhmkorf  coil. 
Since  that  time,  electro-magnetic  machines  have  been  so  greatly 
improved  that  the  problem  of  manufacturing  nitric  acid  artiflcially 
can  be  now  taken  up  seriously  and  with  promise  of  commercial  suc- 
cess. According  to  a  Belgian  journal,  this  has  been  accomplished  as 
follows :  The  electric  spark  is  made  to  discharge  through  a  series  of 
closed  vessels  through  which  a  current  of  air  is  passing,  Avhereby  red 
nitrous  fumes  are  produced,  which,  carried  by  the  current  of  air,  pass 
up  an  absorption-tower  in  which  caustic  potash  solution  is  descending. 
Absorption  takes  place  at  once,  and  a  tolerably  strong  solution  of 
potassium  nitrate  results. — Moniteur  Ind.,  vol.  7,  p.  526. 
