﻿Chemistry 
  and 
  Physics. 
  81 
  

  

  uranio-lead 
  than 
  for 
  common 
  lead. 
  This 
  important 
  result 
  has 
  

   been 
  recently 
  confirmed 
  both 
  qualitatively 
  and 
  quantitatively 
  by 
  

   the 
  second 
  investigation 
  of 
  the 
  problem 
  by 
  T. 
  R. 
  Merton. 
  The 
  

   author 
  says 
  : 
  " 
  . 
  . 
  . 
  the 
  results 
  show 
  that 
  there 
  is 
  a 
  small 
  but 
  

   real 
  difference 
  in 
  the 
  spectra, 
  which 
  agrees 
  closely 
  with 
  the 
  

   value 
  found 
  by 
  Aronberg. 
  A 
  difference 
  has 
  also 
  been 
  found 
  

   between 
  the 
  wave-length 
  of 
  the 
  principal 
  line 
  in 
  ordinary 
  lead 
  

   and 
  lead 
  from 
  Ceylon 
  thorite." 
  Merton 
  has 
  also 
  found 
  evidence 
  

   in 
  favor 
  of 
  the 
  belief 
  that 
  the 
  thallium 
  in 
  pitchblende 
  is 
  an 
  

   isotope 
  of 
  ordinary 
  thallium, 
  the 
  former 
  probably 
  having 
  the 
  

   greater 
  atomic 
  weight. 
  — 
  Nature, 
  104, 
  93, 
  1919. 
  h. 
  s. 
  u. 
  

  

  9. 
  Helium 
  Series 
  in 
  the 
  Extreme 
  Ultra-Violet. 
  — 
  The 
  formula 
  

   for 
  the 
  helium 
  series 
  first 
  discovered 
  in 
  a 
  terrestrial 
  source 
  by 
  

   Fowler 
  indicates 
  that 
  lines 
  may 
  be 
  expected 
  at 
  the 
  approximate 
  

   wave-lengths 
  1640-1, 
  1214-9, 
  and 
  1084-7 
  Angstrom 
  units. 
  With 
  

   the 
  aid 
  of 
  his 
  vacuum 
  spectrograph, 
  Th. 
  Lyman 
  has 
  finally 
  suc- 
  

   ceeded 
  in 
  establishing 
  the 
  existence 
  of 
  the 
  first 
  two 
  of 
  these 
  pre- 
  

   dicted 
  lines. 
  The 
  experimental 
  evidence 
  relating 
  to 
  the 
  line 
  of 
  

   highest 
  frequency 
  is 
  not 
  conclusive. 
  

  

  The 
  author 
  says: 
  "With 
  a 
  powerful 
  disruptive 
  discharge 
  in 
  

   helium, 
  a 
  sharp, 
  fairly 
  strong 
  line 
  appears 
  at 
  1640-2; 
  no 
  trace 
  

   of 
  it 
  is 
  found 
  in 
  hydrogen 
  under 
  the 
  same 
  electrical 
  conditions, 
  

   and 
  it 
  does 
  not 
  occur 
  in 
  helium 
  when 
  the 
  discharge 
  circuit 
  is 
  

   free 
  from 
  capacity. 
  Under 
  the 
  same 
  violently 
  disruptive 
  condi- 
  

   tion 
  the 
  line 
  at 
  1216, 
  always 
  present 
  in 
  helium 
  and 
  hydrogen, 
  

   develops 
  a 
  satellite 
  on 
  its 
  more 
  refrangible 
  side; 
  this 
  satellite 
  is 
  

   not 
  well 
  resolved, 
  but 
  its 
  wave-length 
  appears 
  to 
  be 
  about 
  

   1215- 
  1."— 
  Nature, 
  104, 
  314, 
  1919. 
  h. 
  s. 
  u. 
  

  

  10. 
  The 
  Realities 
  of 
  Modern 
  Science; 
  by 
  John 
  Mills. 
  Pp. 
  

   xi, 
  327. 
  New 
  York, 
  1919 
  (The 
  Macmillan 
  Co,).— 
  "The 
  present 
  

   volume 
  is 
  intended 
  for 
  the 
  general 
  reader, 
  interested 
  in 
  modern 
  

   science, 
  who 
  finds 
  few 
  clews 
  to 
  recent 
  advances 
  in 
  his 
  memories 
  

   of 
  the 
  formal 
  instruction 
  of 
  school 
  or 
  college 
  days." 
  "The 
  

   general 
  reader 
  is 
  under 
  no 
  compulsion 
  from 
  a 
  traditional 
  curric- 
  

   ulum 
  and 
  may 
  pick 
  and 
  choose 
  his 
  sources 
  of 
  information. 
  To 
  

   the 
  study 
  of 
  science 
  he 
  may, 
  however, 
  need 
  an 
  introduction 
  and 
  

   this 
  need 
  the 
  present 
  volume 
  attempts 
  to 
  satisfy. 
  ' 
  ' 
  

  

  The 
  ground 
  covered 
  in 
  the 
  text 
  is 
  so 
  extensive 
  as 
  to 
  preclude 
  

   the 
  possibility 
  of 
  doing 
  justice 
  to 
  it 
  in 
  a 
  short 
  notice. 
  The 
  most 
  

   concise 
  idea 
  of 
  the 
  contents 
  of 
  the 
  volume 
  may 
  be 
  obtained 
  from 
  

   the 
  following 
  titles 
  of 
  the 
  twenty-two 
  chapters, 
  which 
  are 
  : 
  The 
  

   Beginnings 
  of 
  Knowledge; 
  The 
  Machines 
  of 
  the 
  Ancients; 
  

   Weights 
  and 
  Measures 
  ; 
  The 
  Beginnings 
  of 
  Science 
  ; 
  The 
  Begin- 
  

   nings 
  of 
  Experimentation 
  ; 
  The 
  Realities 
  of 
  Science 
  ; 
  The 
  Molec- 
  

   ular 
  Composition 
  of 
  Matter; 
  The 
  Electron; 
  Energy; 
  Some 
  

   Uses 
  of 
  Mathematics; 
  Rates; 
  Force, 
  a 
  Space 
  Rate 
  of 
  Energy; 
  

   Molecular 
  Motions 
  and 
  Temperature 
  ; 
  Motion 
  of 
  Electrons 
  ; 
  The 
  

   Interactions 
  of 
  Moving 
  Electrons; 
  The 
  Continuity 
  and 
  Corre- 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  XLIX, 
  No. 
  289.— 
  January, 
  1920. 
  

  

  