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  ANNUAL 
  BEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  it 
  has 
  no 
  material 
  mass 
  as 
  distinguished 
  from 
  electromagnetic 
  mass. 
  

   Therefore 
  we 
  consider 
  a 
  negative 
  electron 
  to 
  be 
  not 
  a 
  particle 
  of 
  

   matter 
  bearing 
  an 
  electric 
  charge, 
  but 
  simply 
  a 
  particle 
  or 
  unit 
  of 
  

   negative 
  electricity. 
  

  

  It 
  has 
  not 
  been 
  possible 
  to 
  make 
  similar 
  experiments 
  with 
  positive 
  

   electrons, 
  but 
  all 
  we 
  know 
  about 
  them 
  points 
  toward 
  the 
  conclusion 
  

   that 
  they 
  also 
  are 
  simply 
  units 
  of 
  positive 
  electricity. 
  It 
  is 
  believed, 
  

   therefore, 
  that 
  matter, 
  in 
  its 
  ordinary 
  sense, 
  is 
  simply 
  an 
  aggregate 
  

   of 
  positive 
  and 
  negative 
  electric 
  charges. 
  

  

  Furthermore, 
  the 
  electromagnetic 
  mass 
  of 
  any 
  electric 
  charge 
  can 
  

   be 
  shown 
  to 
  be 
  always 
  proportional 
  to 
  the 
  energy 
  of 
  the 
  electric 
  

   field 
  to 
  which 
  it 
  gives 
  rise. 
  It 
  is 
  unnecessary, 
  therefore, 
  to 
  distin- 
  

   guish 
  between 
  mass 
  and 
  energy. 
  Whenever 
  the 
  total 
  electrical 
  

   energy 
  of 
  a 
  group 
  of 
  electrons 
  changes 
  by 
  a 
  change 
  of 
  their 
  relative 
  

   positions 
  the 
  mass 
  of 
  the 
  group 
  also 
  changes 
  in 
  a 
  definite 
  proportion. 
  

   Theoretically, 
  therefore, 
  all 
  chemical 
  combinations 
  should 
  result 
  in 
  

   a 
  change 
  of 
  total 
  mass. 
  But 
  the 
  energy 
  changes 
  in 
  chemical 
  reac- 
  

   tions 
  correspond 
  to 
  mass 
  changes 
  which 
  are 
  too 
  small 
  for 
  detection 
  

   by 
  the 
  most 
  sensitive 
  instruments. 
  In 
  cases 
  of 
  atomic 
  disintegra- 
  

   tion, 
  such 
  as 
  in 
  radioactivity, 
  however, 
  the 
  energy 
  changes 
  are 
  very 
  

   large 
  in 
  comparison 
  with 
  the 
  energy 
  changes 
  in 
  chemical 
  reaction, 
  

   and 
  suggest 
  the 
  possibility 
  of 
  detecting 
  the 
  corresponding 
  mass 
  

   changes. 
  Sir 
  Oliver 
  Lodge 
  has 
  stated, 
  as 
  an 
  example 
  of 
  radioactive 
  

   energ} 
  r 
  , 
  that 
  if 
  the 
  total 
  energy 
  liberated 
  during 
  the 
  disintegration 
  

   of 
  1 
  gram 
  of 
  radium 
  could 
  be 
  utilized 
  for 
  the 
  purpose, 
  it 
  would 
  suf- 
  

   fice 
  to 
  lift 
  the 
  entire 
  British 
  Navy 
  several 
  thousand 
  feet. 
  These 
  

   energy 
  changes 
  are 
  large 
  enough 
  to 
  suggest 
  the 
  possibility 
  of 
  show- 
  

   ing 
  that 
  the 
  mass 
  of 
  radium 
  is 
  greater 
  than 
  the 
  total 
  mass 
  of 
  the 
  

   elements 
  into 
  which 
  it 
  splits 
  up. 
  Such 
  measurements 
  have 
  not 
  as 
  yet 
  

   been 
  made, 
  since 
  radium 
  splits 
  up 
  so 
  slowly. 
  We 
  therefore 
  combine 
  

   two 
  fundamental 
  laws 
  — 
  the 
  principle 
  of 
  the 
  conservation 
  of 
  mass 
  and 
  

   the 
  principle 
  of 
  the 
  conservation 
  of 
  energy 
  — 
  into 
  a 
  single 
  principle, 
  

   that 
  of 
  the 
  conservation 
  of 
  energy. 
  

  

  In 
  this 
  connection 
  attention 
  should 
  be 
  called 
  to 
  the 
  probable 
  reason 
  

   for 
  the 
  slight 
  excess 
  in 
  the 
  atomic 
  weight 
  of 
  hydrogen 
  over 
  that 
  of 
  

   the 
  least 
  common 
  multiple 
  of 
  the 
  other 
  atoms. 
  In 
  the 
  heavier 
  atoms 
  

   positive 
  and 
  negative 
  electrons 
  are 
  packed 
  together 
  in 
  the 
  nucleus, 
  

   so 
  that 
  their 
  electric 
  fields 
  partially 
  neutralize 
  each 
  other, 
  thus 
  dimin- 
  

   ishing 
  the 
  total 
  energy 
  and 
  hence 
  the 
  total 
  mass. 
  If 
  we 
  suppose 
  the 
  

   universe 
  to 
  have 
  been 
  originally 
  formed 
  by 
  the 
  grouping 
  together 
  of 
  

   positive 
  and 
  negative 
  electrons, 
  the 
  energy 
  liberated 
  as 
  they 
  com- 
  

   bine 
  to 
  diminish 
  the 
  total 
  mass 
  in 
  the 
  observed 
  ratio 
  0.77% 
  is 
  suffi- 
  

   cient 
  to 
  have 
  accounted 
  for 
  the 
  heat 
  of 
  the 
  sun 
  and 
  stars 
  for 
  about 
  

   a 
  million 
  million 
  million 
  years 
  — 
  an 
  ample 
  period 
  to 
  satisfy 
  the 
  most 
  

   exacting 
  geological 
  and 
  evolutionary 
  theories. 
  

  

  