﻿126 
  

  

  Mr. 
  C. 
  A. 
  Sadler 
  on 
  the 
  

  

  where 
  fi 
  is 
  the 
  ratio 
  of 
  the 
  sensibility 
  of 
  the 
  electroscope 
  Eg 
  

   to 
  that 
  of 
  Eg; 
  S' 
  is 
  the 
  area 
  of 
  the 
  tertiary 
  radiator 
  and 
  ©^ 
  

   the 
  mean 
  solid 
  angle 
  subtended 
  by 
  the 
  radiator 
  Rg 
  at 
  the 
  

   window 
  of 
  the 
  ionization-chamber 
  I; 
  and 
  cc, 
  13, 
  Xi, 
  and 
  Xg 
  as 
  

   defined 
  above 
  and 
  corrected 
  for 
  the 
  obliquity 
  of 
  the 
  rays. 
  

   This 
  correction 
  was 
  determined 
  experimentally. 
  

   Equating 
  these 
  values 
  of 
  k, 
  we 
  find 
  

  

  ^, 
  = 
  •093, 
  

  

  and 
  we 
  may 
  therefore 
  write 
  

  

  ^ 
  = 
  -093xR'x^x(Xi-hX2). 
  

  

  The 
  value 
  of 
  k 
  calculated 
  from 
  the 
  data 
  given 
  in 
  Tables 
  Y. 
  

   and 
  VI. 
  are 
  given 
  below. 
  

  

  Table 
  VII. 
  

  

  Secondary 
  

   Kadiators. 
  

  

  Iron 
  

  

  Cobalt 
  

  

  Nickel 
  

  

  Copper 
  

  

  Zinc 
  

  

  Arsenic 
  

  

  Selenium 
  .. 
  

   Silver 
  

  

  Values 
  of 
  k. 
  

  

  Values 
  of 
  

  

  Tertiary 
  Radiators. 
  

  

  Cr. 
  

  

  c»VO 
  

  

  275 
  

  

  216 
  

  

  162 
  

  

  117-5 
  

   50-5 
  

   36-0 
  

  

  Fe. 
  

  

  Co. 
  

  

  Ni. 
  

  

  Cu. 
  

  

  Zn. 
  

  

  Cr. 
  

  

  Fe. 
  

  

  Co. 
  

  

  m. 
  

  

  Cu. 
  

  

  

  

  •176 
  

  

  

  

  

  

  31-5 
  

  

  

  

  

  

  •154 
  

  

  •309 
  

  

  

  

  

  526 
  

  

  38-4 
  

  

  

  

  

  •145 
  

  

  •252 
  

  

  •287 
  

  

  

  

  403 
  

  

  670 
  

  

  43-2 
  

  

  

  

  •127 
  

  

  •225 
  

  

  •305 
  

  

  •288 
  

  

  

  307 
  

  

  528 
  

  

  657 
  

  

  430 
  

  

  

  •109 
  

  

  •207 
  

  

  •282 
  

  

  •340 
  

  

  •358 
  

  

  137 
  

  

  227 
  

  

  288 
  

  

  390 
  

  

  412 
  

  

  •0757 
  

  

  •150 
  

  

  •195 
  

  

  •233 
  

  

  •288 
  

  

  96-0 
  

  

  151-0 
  

  

  197 
  

  

  267 
  

   5-35 
  

  

  300 
  

   5-30 
  

  

  •0624 
  

  

  •120 
  

  

  •149 
  

  

  •187 
  

  

  •231 
  

   •0282 
  

  

  Zn. 
  

  

  •327 
  

   •278 
  

   •0313 
  

  

  Note. 
  — 
  In 
  the 
  case 
  of 
  each 
  tertiary 
  radiator, 
  when 
  the 
  secondary 
  beam 
  is 
  

   only 
  just 
  more 
  penetrating 
  than 
  the 
  radiation 
  characteristic 
  of 
  the 
  tertiary 
  

   radiator, 
  the 
  value 
  of 
  k 
  is 
  small 
  and 
  cannot 
  be 
  determined 
  nearly 
  as 
  accurately 
  

   as 
  the 
  later 
  values 
  ; 
  nor 
  can 
  the 
  value 
  of 
  \' 
  corresponding 
  to 
  the 
  initial 
  small 
  

   value 
  of 
  k 
  be 
  determined 
  with 
  accuracy. 
  Consequently 
  the 
  initial 
  values 
  of 
  

  

  r-, 
  are 
  somewhat 
  uncertain, 
  and 
  it 
  is 
  impossible 
  to 
  determine 
  from 
  them 
  

  

  k 
  

   whether 
  —, 
  for 
  any 
  given 
  tertiary 
  radiator 
  rises 
  to 
  a 
  maximum, 
  and 
  then 
  

  

  A 
  

  

  decreases 
  in 
  value, 
  or 
  whether 
  it 
  continuously 
  decreases 
  from 
  the 
  initial 
  

   value. 
  

  

  