﻿Expenditure 
  and 
  Food 
  Requirements 
  of 
  Women 
  Workers. 
  47 
  

  

  2. 
  Technique. 
  

  

  The 
  general 
  method 
  of 
  estimating 
  energy 
  expenditure 
  by 
  indirect 
  

   calorimetry 
  with 
  the 
  help 
  of 
  the 
  Douglas 
  bag 
  is 
  now 
  too 
  well 
  known 
  

   to 
  require 
  further 
  description.* 
  A 
  bag 
  of 
  about 
  50 
  litres 
  content 
  was 
  used. 
  

   Although 
  a 
  careful 
  test 
  showed 
  that 
  no 
  appreciable 
  loss 
  of 
  C0 
  2 
  occurred 
  

   until 
  after 
  two 
  hours 
  from 
  filling 
  the 
  bag 
  (see 
  Table 
  II. 
  Appendix), 
  the 
  

   expired 
  air 
  was 
  measured 
  and 
  analysed 
  immediately 
  after 
  each 
  experiment. 
  

   A 
  Wright's 
  wet 
  meter 
  reading 
  to 
  1 
  c.c. 
  was 
  used 
  for 
  the 
  measurement, 
  and 
  

   the 
  analyses 
  were 
  carried 
  out 
  in 
  Haldane's 
  apparatus. 
  Potassium 
  pyro- 
  

   gallate, 
  as 
  absorbent 
  for 
  oxygen, 
  was 
  found 
  by 
  far 
  preferable 
  in 
  this 
  form 
  of 
  

   apparatus 
  to 
  sodium 
  hydrosulphite, 
  which 
  is 
  recommended 
  by 
  Durig-f- 
  for 
  use 
  

   in 
  the 
  Zuntz-Geppert 
  apparatus. 
  All 
  analyses 
  were 
  made 
  in 
  duplicates, 
  and 
  

   results 
  showing 
  a 
  difference 
  greater 
  than 
  5/100 
  per 
  cent, 
  were 
  discarded 
  and 
  

   repeated. 
  

  

  In 
  a 
  few 
  preliminary 
  experiments 
  the 
  valve, 
  head 
  and 
  mouthpiece 
  was 
  used 
  

   as 
  supplied 
  by 
  the 
  makers, 
  Messrs. 
  Siebe, 
  Gorman 
  & 
  Co., 
  Ltd. 
  It 
  became 
  

   soon 
  evident 
  that 
  this 
  arrangement, 
  excellent 
  as 
  it 
  is 
  for 
  investigation 
  by 
  

   trained 
  observers 
  on 
  themselves, 
  had 
  serious 
  drawbacks 
  when 
  applied 
  to 
  girl 
  

   munition 
  workers 
  under 
  factory 
  conditions. 
  The 
  main 
  objections 
  were 
  raised 
  

   (1) 
  against 
  the 
  nose-clip 
  and 
  mouthpiece, 
  which 
  latter 
  besides 
  being 
  painful 
  

   to 
  the 
  giims 
  in 
  some 
  cases, 
  gives 
  rise 
  to 
  excessive 
  salivation 
  in 
  all 
  ; 
  (2) 
  against 
  

   the 
  position 
  of 
  the 
  corrugated 
  rubber 
  tubing 
  which 
  coming 
  from 
  the 
  valve 
  

   passes 
  over 
  the 
  head 
  to 
  connect 
  with 
  the 
  bag. 
  This 
  wide 
  tubing, 
  intersecting 
  

   the 
  field 
  of 
  vision, 
  interferes 
  seriously 
  with 
  the 
  power 
  of 
  the 
  subject 
  to 
  make 
  

   the 
  fine 
  adjustments 
  necessary 
  in 
  lathe 
  work.J 
  The 
  second 
  objection 
  was 
  

   successfully 
  overcome 
  by 
  the 
  construction 
  of 
  a 
  new 
  double-acting 
  valve 
  in 
  

   which 
  the 
  expired 
  air 
  passes 
  downwards. 
  A 
  detailed 
  description 
  of 
  this 
  

   valve 
  is, 
  however, 
  unnecessary 
  as 
  it 
  still 
  necessitated 
  the 
  objectionable 
  use 
  

   of 
  the 
  mouthpiece. 
  

  

  It 
  -seemed 
  possible 
  to 
  avoid 
  all 
  the 
  above 
  raised 
  objections 
  by 
  employing 
  a 
  

   suitable 
  face 
  mask, 
  and 
  thus 
  reverting 
  to 
  the 
  principle 
  which 
  was 
  first 
  

   introduced 
  into 
  the 
  technique 
  of 
  respiration 
  experiments 
  by 
  Edward 
  

  

  * 
  For 
  full 
  working 
  details 
  see 
  E. 
  P. 
  Oathcart, 
  'Journ. 
  Roy. 
  Array 
  Med. 
  Corps,' 
  

   November, 
  1918. 
  

  

  t 
  ' 
  Biochem. 
  Zeitschr.,' 
  vol. 
  4, 
  p. 
  65 
  (1907). 
  

  

  \ 
  A 
  further 
  objection, 
  from 
  the 
  investigator's 
  point 
  of 
  view, 
  is 
  against 
  the 
  clicking 
  

   noise 
  made 
  by 
  the 
  mica 
  discs 
  of 
  the 
  valves 
  which, 
  by 
  attracting 
  the 
  attention 
  of 
  the 
  

   subject, 
  gives 
  rise 
  to 
  wilful 
  and 
  intentional 
  breathing 
  irregularities. 
  This 
  was 
  easily 
  

   overcome 
  by 
  using 
  the 
  excellent 
  rubber 
  valves 
  recommended 
  by 
  Y. 
  Henderson, 
  'Journ. 
  

   Biol. 
  Chern., 
  : 
  vol. 
  33, 
  p. 
  47 
  (1918). 
  

  

  