570  Romance  of  Chemical  Elements.    {A  ^uSist'  igS™' 
Manganese. 
The  manufacture  of  glass  has  been  known  for  a  long  time; 
the  Egyptians  already  understood  the  making  of  it.  Later  Byzan- 
tium (Constantinople)  became  the  center,  and  in  1289  the  famous 
glass  works  of  Murano  in  Venecia  were  founded.  But  the  raw 
materials  of  glass  (flint,  potash  and  lime)  contained  always  some 
traces  of  iron,  which  imparted  the  familiar  green  color  (in  bottles) 
to  glass.  This  green  color  was  destroyed  by  adding  some  pyrolu- 
site,  a  mineral  which  had  already  been  examined  by  J.  H.  Pott,  in 
1740,  who  showed  that  it  contained  no  iron,  as  was  supposed. 
Scheele  in  1775  recognized  it  as  the  oxide  of  a  distinct  metal  which 
was  isolated  by  J.  G.  Gahn  in  1780  and  called  manganese,  from  the 
Greek  fxavydv^w,  manganidso,  I  purify,  in  allusion  to  the  use  of  its 
dioxide  in  the  manufacturing  of  glass. 
Tellurium. 
Another  mineral  which  puzzled  the  alchemists  was  called  "  aurum 
paradoxum,"  or  "  metallum  problematum,"  for  it  looked  like  a  metal, 
and  did  not  behave  like  one.  In  1782  Miiller  von  Reichenstein  and 
in  1798  M.  H.  Klaproth  studied  this  supposed  metal,  and  the  latter 
recognized  it  as  a  non-metal  and  gave  it  the  name  tellurium,  from 
the  Lat.  tellus  =  earth,  as  it  occurs  as  a  mineral. 
Tungsten. 
Wolfram  has  been  an  old  German  miner's  term  for  a  mineral 
that  was  "wolf rig" — wolfish,  gluttonous  in  its  behavior,  for  when- 
ever it  was  melted  with  tin  ores,  it  looked  as  if  the  tin  percentage 
was  decreasing.  The  alchemists  gave  it  the  name,  for  we  find  in 
Agricola's  writings  "  spuma  lupi"  =  wolf's  stone.  In  Sweden  the 
mineral  was  known  as  tungsten,  from  the  Swedish  tung  =  heavy 
and  sten  =  stone,  from  which  Scheele  in  1781  prepared  tungstic 
acid,  and  in  1783  the  brothers  d'Elhuyar  isolated  the  metal. 
Uranium. 
Sir  W.  Herschel  in  1781  discovered  a  new  planet,  which  was 
later  called  uranus  from  the  Greek  ovpavos,  uranos,  =  heaven.  This 
discovery  naturally  attracted  great  attention  and  as  M.  H.  Klaproth 
in  1789  recognized  a  new  metallic  oxide,  in  pitchblende,  he  gave  it 
