﻿462 
  JOURNAL 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  20 
  

  

  the 
  inked 
  areas 
  showing 
  black 
  on 
  the 
  films, 
  whereas 
  on 
  the 
  plates 
  they 
  showed 
  

   clear. 
  That 
  is, 
  with 
  the 
  films 
  the 
  ink 
  is 
  the 
  active 
  portion, 
  the 
  charred 
  

   paper 
  producing 
  no 
  fogging. 
  It 
  is 
  also 
  noted 
  that 
  the 
  chemical 
  fog 
  of 
  de- 
  

   velopment 
  is 
  much 
  lighter 
  over 
  the 
  portions 
  of 
  the 
  film 
  covered 
  by 
  the 
  charred 
  

   paper 
  as 
  compared 
  with 
  the 
  uncovered 
  areas. 
  

  

  The 
  results 
  suggest 
  that 
  there 
  are 
  perhaps 
  two 
  difi"erent 
  kinds 
  of 
  gases 
  

   given 
  off, 
  one 
  kind 
  by 
  the 
  charred 
  paper 
  and 
  another 
  by 
  the 
  ink, 
  both 
  of 
  which 
  

   fog 
  the 
  photographic 
  emulsion, 
  but 
  the 
  one 
  from 
  the 
  charred 
  paper 
  more 
  

  

  rapidly. 
  

  

  It 
  was 
  found 
  that 
  a 
  short 
  washing 
  of 
  these 
  films 
  in 
  distilled 
  water, 
  about 
  

   five 
  minutes, 
  followed 
  by 
  thorough 
  drying, 
  gave 
  results 
  similar 
  to 
  those 
  ob- 
  

   tained 
  with 
  plates. 
  Very 
  good 
  copies 
  were 
  obtained 
  from 
  washed 
  film 
  

   after 
  8 
  days 
  contact 
  with 
  the 
  charred 
  paper. 
  

  

  Mr. 
  R. 
  W. 
  G. 
  Wyckoff 
  presented 
  a 
  paper 
  entitled 
  "Crystal 
  structure 
  of 
  

   ammonium 
  chloride 
  and 
  hydrazine 
  hydrochloride," 
  which 
  was 
  illustrated 
  

   by 
  diagrams. 
  It 
  was 
  discussed 
  by 
  Messrs. 
  Hawksworth, 
  Tuckerman, 
  

   Crittenden, 
  and 
  Brown. 
  

  

  Author's 
  Abstract: 
  The 
  crystal 
  structure 
  of 
  hydrazine 
  dihydrochloride. 
  

   Using 
  Laue 
  photographic 
  and 
  spectrographic 
  data 
  and 
  making 
  use 
  of 
  the 
  re- 
  

   sults 
  of 
  theory 
  of 
  space 
  groups, 
  the 
  manner 
  of 
  arrangement 
  of 
  the 
  atoms 
  

   within 
  the 
  unit 
  cube 
  of 
  a 
  crystal 
  of 
  hydrazine 
  hydrochloride, 
  which 
  contains 
  

   four 
  chemical 
  molecules 
  and 
  is 
  7.89 
  A.tl. 
  on 
  a 
  side, 
  has 
  been 
  determined. 
  The 
  

   corresponding 
  space-group 
  is 
  Th^. 
  The 
  parameter 
  v 
  defining 
  the 
  positions 
  of 
  

   the 
  chlorine 
  atoms 
  is 
  found 
  as 
  0.27+ 
  and 
  the 
  most 
  probable 
  value 
  of 
  the 
  

   nitrogen 
  parameter 
  is 
  estimated 
  as 
  about 
  0.04. 
  The 
  distance 
  between 
  ad- 
  

   jacent 
  chlorine 
  atoms 
  thus 
  is 
  approximately 
  3.69 
  A.U.; 
  between 
  chlorine 
  and 
  

   nitrogen 
  atoms 
  about 
  3.14A.U. 
  It 
  is 
  pointed 
  out 
  that 
  these 
  results 
  are 
  

   markedly 
  at 
  variance 
  with 
  the 
  hypothesis 
  of 
  constant 
  atomic 
  radii. 
  

  

  On 
  the 
  crystal 
  structure 
  of 
  ammonium 
  chloride. 
  — 
  It 
  is 
  shown 
  that 
  the 
  Laue 
  

   photographic 
  data 
  obtained 
  from 
  crystals 
  of 
  the 
  low 
  temperature 
  form 
  of 
  

   ammonium 
  chloride 
  are 
  in 
  agreement 
  with 
  the 
  powder 
  data 
  in 
  assigning 
  to 
  it 
  

   a 
  structure 
  containing 
  one 
  chemical 
  molecule 
  within 
  the 
  unit 
  cube. 
  The 
  

   disagreement 
  between 
  the 
  symmetry 
  of 
  the 
  arrangement 
  of 
  the 
  atoms 
  of 
  

   ammonium 
  chloride 
  and 
  its 
  described 
  crystallographic 
  symmetry 
  is 
  thus 
  com- 
  

   pletely 
  established. 
  As 
  a 
  result 
  it 
  is 
  pointed 
  out 
  that 
  unless 
  these 
  crystallo- 
  

   graphic 
  data 
  are 
  shown 
  to 
  be 
  erroneous 
  it 
  will 
  not 
  be 
  permissible 
  to 
  accept 
  

   etch 
  figure 
  data 
  and 
  face 
  development 
  as 
  definite 
  indications 
  of 
  the 
  sym- 
  

   metry 
  of 
  the 
  arrangement 
  of 
  the 
  atoms 
  within 
  a 
  crystal. 
  

  

  Mr. 
  W. 
  W. 
  CoBLENTz 
  read 
  a 
  paper 
  on 
  ''Further 
  measurements 
  of 
  stellar 
  

   temperatures 
  and 
  planetary 
  radiation,'' 
  which 
  was 
  illustrated 
  by 
  lantern 
  slides. 
  

   It 
  was 
  discussed 
  by 
  Messrs. 
  White, 
  Pawling, 
  and 
  Abbot. 
  

  

  Author's 
  Abstract: 
  During 
  the 
  past 
  summer, 
  through 
  the 
  generosity 
  of 
  

   the 
  Lowell 
  Observatory, 
  Flagstaff, 
  Arizona, 
  who 
  financed 
  this 
  research, 
  a 
  

   further 
  opportunity 
  was 
  presented 
  to 
  continue 
  the 
  measurements 
  of 
  1921 
  re- 
  

   lating 
  stellar 
  temperatures 
  and 
  planetary 
  radiation. 
  Especial 
  acknowledge- 
  

   ment 
  is 
  due 
  Dr. 
  C. 
  O. 
  Lampland 
  for 
  kindly 
  operating 
  the 
  telescope. 
  

  

  The 
  speaker 
  reported 
  a 
  verification 
  of 
  the 
  estimate 
  presented 
  before 
  this 
  

   Society 
  (The 
  meeting 
  of 
  December 
  17, 
  1921) 
  of 
  the 
  temperatures 
  of 
  16 
  stars 
  

   as 
  determined 
  from 
  their 
  spectral 
  energy 
  distribution 
  which 
  was 
  obtained 
  by 
  

   means 
  of 
  a 
  new 
  spectral 
  radiometer, 
  consisting 
  of 
  a 
  series 
  of 
  transmission 
  

   screens 
  and 
  a 
  vacuum 
  thermocouple. 
  

  

  