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  DESCRIPTION 
  OF 
  AN 
  ELECTRICAL. 
  MACHINE, 
  

  

  than 
  it 
  is 
  positive, 
  nor 
  more 
  positive 
  than 
  it 
  is 
  negative. 
  Upon 
  this 
  

   ground, 
  a 
  suggestion 
  of 
  the 
  same 
  author, 
  that 
  the 
  diminution 
  of 
  light 
  

   near 
  the 
  middle 
  of 
  the 
  spark 
  results 
  from 
  the 
  combination 
  of 
  the 
  dif- 
  

   ferent 
  fluids 
  at 
  this 
  point, 
  appears 
  to 
  me 
  injudicious, 
  since 
  there 
  is 
  as 
  

   little 
  ground 
  for 
  supposing 
  the 
  union 
  of 
  the 
  fluids 
  to 
  take 
  place 
  there 
  

   as 
  elsewhere. 
  But 
  admitting 
  that 
  the 
  union 
  does 
  take 
  place 
  as 
  sup- 
  

   posed, 
  is 
  this 
  a 
  reason 
  for 
  the 
  observed 
  diminution 
  of 
  light? 
  If, 
  when 
  

   isolated, 
  either 
  fluid 
  is 
  capable 
  of 
  emitting 
  a 
  brilliant 
  light, 
  should 
  

   not 
  their 
  co-operation 
  increase 
  the 
  effect 
  ? 
  If, 
  after 
  their 
  union, 
  they 
  

   do 
  not 
  shine, 
  it 
  can 
  only 
  be 
  in 
  consequence 
  of 
  their 
  abandoning, 
  at 
  

   that 
  moment, 
  all 
  the 
  light 
  with 
  which 
  they 
  were 
  previously 
  associated. 
  

   It 
  cannot 
  be 
  imagined 
  that 
  the 
  light 
  accompanying 
  one 
  should 
  neutral- 
  

   ize 
  that 
  accompanying 
  the 
  other. 
  

  

  In 
  deflagrating, 
  by 
  voltaic 
  electricity, 
  a 
  wire 
  of 
  uniform 
  thickness, 
  

   equally 
  refrigerated, 
  the 
  most 
  intense 
  evolution 
  of 
  heat 
  and 
  light 
  is 
  

   always 
  midway. 
  

  

  In 
  truth, 
  the 
  theory 
  which 
  the 
  learned 
  author 
  sanctions, 
  requires 
  

   two 
  postulates 
  so 
  irreconcilable, 
  that 
  unless 
  one 
  be 
  kept 
  out 
  of 
  view, 
  

   the 
  other 
  cannot 
  be 
  sustained. 
  It 
  requires 
  that 
  the 
  fluids 
  should 
  exer- 
  

   cise 
  an 
  intense 
  reciprocal 
  attraction 
  adequate 
  to 
  produce 
  chemical 
  af- 
  

   finity, 
  and 
  of 
  course, 
  enter 
  into 
  combination 
  when 
  they 
  meet, 
  and 
  

   yet 
  rush 
  by 
  each 
  other 
  with 
  inconceivable 
  velocity, 
  not 
  only 
  through 
  

   the 
  air, 
  but 
  also 
  through 
  the 
  restricted 
  channel 
  afforded 
  by 
  a 
  small 
  

   wire. 
  If 
  the 
  fluids 
  combine 
  at 
  a 
  point 
  intervening 
  between 
  the 
  sur- 
  

   faces 
  from 
  which 
  they 
  proceed, 
  what 
  becomes 
  of 
  the 
  compound 
  which 
  

   they 
  form? 
  Is 
  it 
  credible 
  that 
  such 
  a 
  compound 
  would 
  afford 
  no 
  indi- 
  

   cation 
  of 
  its 
  existence 
  ? 
  But, 
  again, 
  how 
  are 
  two 
  surfaces, 
  the 
  one 
  

   previously 
  deprived 
  of 
  a 
  large 
  portion 
  of 
  the 
  negative 
  electricity 
  natu- 
  

   rally 
  due 
  to 
  it, 
  the 
  other 
  made 
  as 
  deficient 
  of 
  the 
  positive 
  fluid, 
  to 
  

   regain 
  their 
  natural 
  state 
  ? 
  By 
  a 
  combination 
  midway, 
  the 
  resinous 
  

   and 
  vitreous 
  surcharges 
  might 
  be 
  disposed 
  of, 
  but 
  whence 
  could 
  the 
  

   vitreous 
  and 
  resinous 
  deficiencies 
  be 
  supplied 
  ? 
  

  

  Dr 
  Thompson, 
  in 
  common 
  with 
  the 
  great 
  majority 
  of 
  modern 
  

   chemists, 
  ascribes 
  chemical 
  affinity 
  to 
  the 
  attraction 
  between 
  the 
  

   two 
  electricities 
  combined 
  with 
  ponderable 
  particles. 
  As 
  the 
  combi- 
  

   nations 
  between 
  such 
  particles 
  take 
  place 
  only 
  in 
  definite 
  proportions, 
  

  

  