482  Romance  of  Chemical  Elements.  {Am'jJ°y%^I8arm" 
ments  of  the  manganese  group  with  atomic  weights  of  about  98  and 
187,  and  properties  which  are  between  those  of  the  chromium  and 
platinum  group.  The  last  two  elements,  Nos.  85  and  87,  belong  to 
the  radioactive  substances,  and  there  is  the  theoretical  possibility 
that,  owing  to  their  great  electropotential,  they  are  not  able  to  exist. 
That  is  to  say,  the  periodic  system  requires,  e.  g.,  the  element  No. 
87  to  be  the  most  electro-positive  element,  more  electro-positive  than 
caesium,  and  at  the  same  time  unstable,  that  is,  radioactive.  It  is 
very  possible  that  such  an  element  has  so  short  a  life,  like  brevium, 
that  it  can  practically  not  exist. 
Names  of  the  Elements. 
Let  us  return  to  the  known  elements.  When  one  looks  over  the 
list  of  pretty  names,  one  naturally  wonders  how  they  came  about. 
And  indeed  some  of  them  have  a  very  interesting  story.  States 
and  planets,  colors  and  mineral  names  are  represented.  We  have, 
e.  g.,  Europe  in  europium,  France  in  gallium,  Norway  in  thulium, 
America  in  columbium,  Russia  in  ruthenium,  Germany  in  germa- 
nium, Scandinavia  in  scandium,  Poland  in  polonium,  Cyprus  in  cop- 
per. From  our  solar  system  we  have  represented  the  sun  in  helium, 
earth  in  tellurium,  moon  in  selenium,  mercury  in  mercury,  uranus 
in  uranium,  and  the  little  planets  or  asteroids  are  also  represented : 
Ceres  in  cerium,  Pallas  in  palladium.  The  mythologies  of  various 
nations  have  been  ransacked  and  furnish  us  iridium  from  Iris,  nio- 
bium from  Niobe,  tantalum  from  Tantalus  of  the  Greek  mythology, 
while  thorium  from  Thor,  vanadium  from  Vanades  are  taken  from 
the  Scandinavian  mythology. 
The  city  of  Paris  is  represented  in  lutecium,  while  the  Scottish 
village  Strontian  is  honored  in  strontium  and  the  town  of  Ytterby 
in  Sweden  has  the  unique  distinction  of  having  four  elements  named 
after  it,  namely  ytterbium,  yttrium,  terbium,  erbium. 
According  to  their  color  several  elements  have  been  named  from 
the  Greek  or  Latin  terms  :  color — chromium ;  white — silver ;  yellow 
— chlorine ;  green — thallium  and  praseodymium ;  blue — caesium  and 
indium ;  purple — iodine  ;  red — rhodium  and  rubidium.  Many  other 
properties  have  played  a  role  in  giving  a  name  to  an  element,  as 
shown  in  Table  III.  There  is  a  certain  regularity  in  this  apparent 
disorder  of  naming.  For  instance  in  the  time  of  Lavoisier  the  ele- 
ments hydrogen,  nitrogen,  oxygen  were  discovered  and  named  by 
