$66  Varieties.  {Am^I?^rm' 
lizes  very  slowly  at  86*09°.  The  density  of  the  specimen  is  5*935.  Gallium  crys- 
tallized under  water  crepitates  sometimes  on  heating. — Scient.  Amer.,  November 
ii,  1876. 
Chemical  Reactions  of  Gallium.— By  M.  Lecoq  de  Boisbaudran. — 'Solutions- 
of  pure  gallium,  mixed  with  acid  acetate  of  ammonia,  are  not  rendered  turbid  by 
sulphuretted  hydrogen,  but  if  zinc  is  present  the  sulphide  of  this  metal  is  charged 
with  gallium,  but  the  liquid  is  not  entirely  freed  from  it.  If  the  salts  of  zinc  are- 
not  plentiful  enough  to  draw  down  at  once  all  the  gallium  precipitable  by  sulphu- 
retted hydrogen,  it  must  be  added  in  small  portions  until  these  products  no  longer 
give  the  ray  Ga  a  417*0  in  the  spectroscope.  Only  slight  traces  of  gallium  remain 
then  in  the  liquid.  On  proceeding  thus,  the  amount  in  the  precipitates  appears  to 
remain  at  first  almost  constant,  or  at  least  to  decrease  slowly,  and  then  more  an$ 
more  rapidly  :  it  does  not,  therefore,  seem  to  be  a  function  of  the  amount  of  gallium 
in  the  liquid.  Is  there  not  here  an  indication  of  a  combination  between  the  two- 
substances,  or  perhaps  more  probably  a  surface-attraction  analogous  to  the  fixation 
of  a  coloring  matter  upon  a  mordant.  It  is  known  that  salts  of  zinc  slightly  acid 
are  precipitated  by  sulphuretted  hydrogen,  the  action  being  limited  by  the  quantity 
of  strong  acid  set  at  liberty.  If  the  experiment  is  made  with  a  chloride  of  zinc 
containing  gallium,  a  notable  quantity  of  this  metal  falls  along  with  the  sulphide  of 
zinc.  An  ammoniacal  solution  of  the  salts  of  gallium  and  zinc  is  precipitated  by 
hydrosulphate  of  ammonia.  An  excess  of  the  reagent  does  not  remove  the  gallium,, 
unless,  indeed,  the  sulphide  of  zinc  is  in  such  small  quantity  as  to  dissolve  also. 
The  case  is  different  when  the  salt  of  gallium  is  pure.  The  ammoniacal  solution 
is  not  rendered  turbid  by  the  sulphide  of  ammonium.  If  a  neutral  or  slightly  acid 
solution  of  the  chlorides  of  zinc  and  gallium  is  submitted  to  fractionated  precipita- 
tion with  sulphide  of  ammonium  containing  free  ammonia,  the  gallium  is  concen- 
trated in  the  first  products.  If  an  ammoniacal  solution  of  zinc  and  gallium  is 
submitted  to  the  same  treatment,  the  gallium,  on  the  contrary,  accumulates  in  the 
last  precipitates. — CJiem.  Ne-zvs,  October  27,  1876. 
Contributions  to  the  Theory  of  Luminous  Flames. — By  Dr.  Karl  Heu- 
mann. — In  this  part  of  his  treatise  the  author  arrives  at  important  results,  both  theor- 
etical and  practical.  He  shows  that  the  carbon  in  the  flame  exists  as  a  solid  body,, 
and  not,  as  Frankland  assumes,  in  the  state  of  vapor.  He  finds  that  gas-jets  of  steatite 
are  decidedly  preferable  to  those  of  iron,  since  they  consume  less  gas  for  an  eqnal 
strength  of  light.  Metallic  jets,  in  general,  notably  enfeeble  the  light.  He  refers 
to  the  result  obtained  by  the  Commission  of  the  English  Board  of  Trade  who 
reported,  in  opposition  to  the  view  of  Vogel,  that  a  refrigeration  of  the  gas  does  not 
decrease  the  amount  of  light,  and  considers  that  they  must  have  experimented  with 
a  kind  of  gas  poor  in  hydrocarbons  capable  of  condensation.  On  the  contrary,  he 
finds  that  if  the  jet  and  the  outflowing  current  of  gas  are  both  strongly  heated  the 
luminous  effect  is  increased  to  an  extraordinary  degree.— -Chem.  Ne=wst  Nov.  10, 1876. 
