Am.  Jour.  Pharm. 
Nov.,  1886. 
Germanium  and  its  Compounds. 
545 
more  acid  to  precipitate  the  sulphide  of  germanium.  The  precipi- 
tated sulphide  of  germanium  is  washed  with  dilute  sulphydric  acid, 
heated  with  concentrated  nitric  acid  to  form  oxide,  and  reduced  at  a 
red-heat  in  a  current  of  hydrogen.  To  reduce  larger  quantities,  it  is 
best  to  knead  the  oxide  with  from  10  to  15  per  cent,  of  starch  and 
boiling  water  to  a  paste,  and  moderately  heating  in  a  closed  crucible. 
By  this  process  germanium  is  obtained  as  a  dark-gray  powder.  With 
borax  it  fuses  into  a  regulus,  fusing  point  ==  600°  C.  It  crystallizes 
readily,  is  very  brittle,  readily  pulverized  and  breaks  with  a  scaly 
fracture.  Germanium  has  a  bright  metallic  lustre,  a  greyish-white 
color,  sp.  gr.  5*469,  is  not  affected  by  hydrochloric  acid,  but  dissolves 
readily  in  nitro-hydrochloric  acid.  Nitric  acid  converts  it  into  a 
white  oxide,  and  by  heating  with  concentrated  sulphuric  acid,  sulph- 
uretted hydrogen  is  evolved,  a  white  sulphate,  soluble  in  water,  remain- 
ing. Concentrated  solution  of  caustic  potash  does  not  affect  it ;  with 
nitrates  and  chlorates  deflagrating  mixtures  are  formed.  The  atomic 
weight  was  obtained  according  to  J.  Volhard's  method  from  the  tetra- 
chloride and  found  to  be  72*32,  corresponding  with  the  results  oi 
Lecoq  de  Boisbaudran,  who  used  another  method,  and  states  it  to  be 
72*28.  The  vapor  density  of  the  chloride  (GeClJ,  according  to  L.  F. 
Nilson  and  O.  Pettersson,  in  Stockholm,  at  301*5°=7*43,  and  at  739° 
=7*44.  Gustav  Kobb  found  the  spectrum  to  be  very  distinct  and 
measureable;  1  line  in  orange,  1  in  yellow,  4  in  violet,  and  12  in 
green  and  blue. 
Combinations  of  Germanium. — Two  oxides,  2  sulphides,  2  chlor- 
ides and  1  iodide  are  known.  They  do  not  color  the  flame  of  a  Bunsen 
burner,  nor  do  they  yield  a  spectral  reaction.  Solutions  of  germanium 
salts  are  decomposed  by  many  water-reducing  metals,  especially  zinc, 
germanium  being  precipitated.  Most  compounds  of  germanium  arc 
easily  reduced  by  means  of  reducing  agents  at  a  high  temperature. 
Oxides  of  Germanmm. — Compact  germanium  retains  its  lustre 
when  exposed  to  the  air ;  at  a  red-heat  it  becomes  coated  with  a  thin 
layer  of  oxide,  whilst  powdered  germanium  when  slightly  heated 
begins  to  form  oxide.  Germanium  protoxide  is  formed  by  decompos- 
ing the  chloride  (GeCI2)  with  alkalies;  the  resulting  hydrated  oxide 
heated  moderately  in  a  current  of  carbonic  acid,  yields  the  gray-black 
monoxide.  This  is  insoluble  in  dilute  sulphuric  acid,  but  dissolves 
readily  in  hydrochloric  acid  to  form  germanous  chloride.  This  solu- 
tion shows  a  characteristic  reaction,  and  is  an  energetic  reducing 
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