﻿Chemistry 
  and 
  Physics. 
  441 
  

  

  4. 
  Catalytic 
  Hydrogenation 
  and 
  Reduction; 
  by 
  Edward 
  B. 
  

   Maxted. 
  12mo, 
  pp. 
  104. 
  Philadelphia, 
  1919 
  (P. 
  Blakiston's 
  

   Son 
  & 
  Co. 
  Price 
  $1.25 
  net). 
  — 
  This 
  is 
  the 
  American 
  issne 
  of 
  a 
  

   book 
  originating 
  in 
  Great 
  Britain, 
  one 
  of 
  the 
  series 
  of 
  "Text- 
  

   books 
  of 
  Chemical 
  Research 
  and 
  Engineering, 
  ' 
  ' 
  edited 
  by 
  W. 
  P. 
  

   Dreaper. 
  It 
  presents 
  from 
  a 
  chemical 
  point 
  of 
  view 
  the 
  numer- 
  

   ous 
  examples 
  of 
  catalytic 
  hydrogenation 
  which 
  have 
  been 
  

   published 
  from 
  time 
  to 
  time. 
  Special 
  attention 
  is 
  given 
  to 
  

   experimental 
  methods, 
  and, 
  in 
  addition 
  to 
  simple 
  hydrogenation 
  

   of 
  unsaturated 
  linkages, 
  various 
  reductions 
  of 
  a 
  less 
  simple 
  

   nature 
  are 
  included. 
  A 
  chapter 
  is 
  devoted 
  also 
  to 
  dehydro- 
  

   genation. 
  The 
  exceedingly 
  important 
  topic, 
  the 
  technical 
  hydro- 
  

   genation 
  of 
  unsaturated 
  oils 
  for 
  the 
  purpose 
  of 
  converting 
  them 
  

   into 
  hardened 
  fats, 
  is 
  well 
  discussed 
  from 
  a 
  theoretical 
  stand- 
  

   point. 
  

  

  As 
  the 
  book 
  brings 
  together 
  much 
  information 
  and 
  gives 
  many 
  

   references 
  to 
  the 
  literature, 
  it 
  will 
  be 
  useful 
  and 
  interesting 
  to 
  

   many 
  organic 
  chemists 
  and 
  chemical 
  engineers. 
  h. 
  l. 
  w. 
  

  

  5. 
  The 
  Dispersion 
  of 
  Diamond. 
  — 
  In 
  an 
  earlier 
  paper, 
  entitled 
  

   " 
  Ref 
  ractivity 
  and 
  Atomic 
  Interaction," 
  L. 
  Silberstein 
  

   developed 
  a 
  number 
  of 
  general 
  formulae 
  which 
  may 
  be 
  applied, 
  

   of 
  course, 
  to 
  many 
  special 
  problems. 
  A 
  typical 
  example 
  of 
  a 
  

   special 
  case 
  is 
  presented 
  in 
  a 
  more 
  recent 
  mathematical 
  article, 
  

   by 
  the 
  same 
  author, 
  the 
  introductory 
  sentence 
  of 
  which 
  reads 
  : 
  

   "The 
  object 
  of 
  the 
  present 
  paper 
  is 
  to 
  apply 
  the 
  concept 
  of 
  

   electrical 
  interaction 
  of 
  atoms, 
  . 
  . 
  . 
  , 
  to 
  the 
  refractive 
  properties 
  

   of 
  diamond 
  considered 
  as 
  a 
  known 
  assemblage 
  of 
  fixed 
  'atomic 
  

   centres,' 
  each 
  containing 
  a 
  single 
  dispersive 
  electron 
  and 
  becom- 
  

   ing 
  a 
  doublet 
  in 
  presence 
  of 
  an 
  external 
  electric 
  field. 
  ' 
  ' 
  

  

  The 
  final 
  formula 
  obtained 
  is 
  theoretically 
  restricted 
  to 
  wave- 
  

   lengths 
  which 
  do 
  not 
  greatly 
  exceed 
  the 
  limits 
  of 
  the 
  visible 
  

   spectrum. 
  Long 
  infra-red 
  radiations 
  are 
  excluded 
  by 
  the 
  

   assumption 
  of 
  the 
  mutual 
  immobility 
  of 
  the 
  "centres" 
  them- 
  

   selves; 
  that 
  is, 
  of 
  the 
  whole 
  atoms. 
  Wave-lengths 
  as 
  short 
  as 
  

   those 
  of 
  X-rays, 
  say, 
  are 
  barred 
  by 
  the 
  hypothesis 
  that 
  the 
  elec- 
  

   tric 
  field 
  is 
  homogeneous. 
  The 
  formula 
  does 
  apply 
  to 
  visible 
  

   and 
  to 
  not 
  too 
  remote 
  ultra-violet 
  light 
  since, 
  for 
  these 
  radiations, 
  

   a 
  wave-length 
  cube 
  would 
  contain 
  10 
  11 
  or 
  10 
  10 
  atomic 
  doublets. 
  

   Surface 
  phenomena 
  are 
  not 
  taken 
  into 
  account 
  in 
  the 
  analysis, 
  

   for 
  the 
  crystal 
  is 
  treated 
  as 
  a 
  space 
  lattice 
  of 
  points, 
  indefinitely 
  

   extended 
  in 
  all 
  directions. 
  The 
  structural 
  form 
  of 
  diamond, 
  

   involved 
  in 
  the 
  geometry, 
  is 
  that 
  given 
  by 
  Bragg. 
  More 
  specifi- 
  

   cally, 
  the 
  atomic 
  configuration 
  of 
  this 
  crystal 
  is 
  supposed 
  to 
  

   consist 
  of 
  the 
  superposition 
  of 
  two 
  face-centered 
  lattices, 
  one 
  of 
  

   which 
  is 
  obtained 
  from 
  the 
  other 
  by 
  translating 
  it 
  rigidly 
  along 
  

   a 
  cube 
  diagonal 
  one-quarter 
  of 
  the 
  length 
  of 
  the 
  diagonal. 
  Each 
  

   point 
  of 
  both 
  lattices 
  is 
  occupied 
  by 
  a 
  carbon 
  atom. 
  The 
  result 
  

   of 
  this 
  superposition 
  is 
  that 
  each 
  carbon 
  atom 
  occupies 
  the 
  center 
  

   of 
  a 
  regular 
  tetrahedron 
  four 
  corners 
  of 
  which 
  are 
  occupied 
  by 
  

   the 
  four 
  nearest 
  neighbors 
  of 
  that 
  atom. 
  

  

  