﻿Manganin 
  Resistances 
  with 
  Atmospheric 
  Humidity. 
  155 
  

  

  The 
  range 
  of 
  the 
  box 
  is 
  from 
  4000 
  ohms 
  to 
  1 
  ohm. 
  

   Measurements 
  were 
  made 
  of 
  some 
  individual 
  coils 
  and 
  of 
  

   some 
  in 
  series, 
  as 
  indicated 
  in 
  col. 
  1, 
  Table 
  II. 
  The 
  change 
  

   in 
  resistance 
  is 
  given 
  in 
  parts 
  in 
  100,000, 
  the 
  values 
  in 
  an 
  

   atmosphere 
  of 
  about 
  60 
  per 
  cent, 
  relative 
  humidity 
  at 
  17° 
  C. 
  

   being 
  taken 
  as 
  unit 
  values. 
  

  

  Table 
  III. 
  gives 
  the 
  variations 
  in 
  resistance 
  of 
  some 
  coils 
  

   in 
  box 
  No. 
  2385 
  by 
  O. 
  Wolff, 
  the 
  results 
  of 
  the 
  observations 
  

   being 
  in 
  chronological 
  order. 
  It 
  is 
  noteworthy 
  that 
  when 
  

   the 
  box-coils 
  were 
  measured 
  in 
  an 
  atmosphere 
  dried 
  by 
  P 
  2 
  5 
  , 
  

   the 
  resistance 
  of 
  the 
  three 
  higher 
  coils 
  diminished 
  by 
  appre- 
  

   ciable 
  amounts, 
  but 
  the 
  1000 
  and 
  100 
  ohm 
  coils 
  remained 
  

   practically 
  constant. 
  When, 
  however, 
  the 
  atmosphere 
  was 
  

   converted 
  into 
  one 
  saturated 
  with 
  moisture, 
  the 
  100 
  ohm 
  

   coils 
  alone 
  remained 
  approximately 
  constant 
  in 
  resistance 
  ; 
  

   the 
  value 
  of 
  the 
  other 
  coils 
  fell 
  by 
  very 
  considerable 
  amounts. 
  

   Although 
  this 
  fall 
  was 
  probably 
  entirely 
  due 
  to 
  leakage, 
  it 
  

   persisted, 
  in 
  a 
  diminished 
  degree, 
  after 
  exposure 
  of 
  the 
  coils 
  

   to 
  a 
  normal 
  atmosphere 
  for 
  thirty 
  days. 
  

  

  Table 
  III. 
  

   Observations 
  on 
  Coils 
  in 
  Wolff 
  Box 
  No. 
  2385. 
  Unit 
  Values 
  

   in 
  an 
  atmosphere 
  of 
  about 
  60 
  per 
  cent, 
  relative 
  humidity 
  

   at 
  17° 
  C. 
  

  

  Coils. 
  

  

  Nomiral 
  

  

  Value. 
  

  

  Atmosphere 
  

   P 
  2 
  3 
  

  

  dried 
  with 
  

   for 
  

  

  Water.' 
  Normal 
  Atmosphere. 
  

  

  

  2 
  

   days 
  

  

  3 
  

   days 
  

  

  7 
  

   days 
  

  

  10 
  

   days 
  

  

  4 
  1 
  10 
  

   days 
  day 
  days 
  

  

  30 
  

   days 
  

  

  ! 
  50000 
  &c. 
  

  

  ohms. 
  

   100000 
  

  

  -25 
  

  

  -31 
  

  

  = 
  36 
  

  

  -38 
  

  

  -2100 
  -220 
  -33 
  

  

  -15 
  

  

  10000/3 
  

  

  10000 
  

  

  -27 
  

  

  -40 
  

  

  -56 
  

  

  -59 
  

  

  - 
  630 
  -310 
  -71 
  

  

  -25 
  

  

  10000 
  a 
  

  

  10000 
  

  

  -20 
  

  

  -25 
  

  

  -33 
  

  

  -35 
  

  

  - 
  520 
  —265 
  1 
  -77 
  

  

  -18 
  

  

  1000/3 
  

  

  1000 
  

  

  

  

  

  

  - 
  1 
  

  

  _ 
  2 
  

  

  - 
  58 
  - 
  31 
  ! 
  — 
  6 
  

  

  1 
  

  

  _ 
  2 
  

  

  1000 
  a 
  

  

  1000 
  

  

  

  

  

  

  

  

  - 
  2 
  

  

  _ 
  61-22 
  -10 
  

  

  - 
  4 
  

  

  100/3 
  

  

  100 
  

  

  -2 
  

  

  

  

  

  

  - 
  1 
  

  

  

  

  + 
  20 
  

  

  

  

  100 
  a 
  

  

  100 
  

  

  

  

  

  

  - 
  2 
  

  

  _ 
  o 
  

  

  4- 
  1 
  

  

  + 
  2+1 
  

  

  

  

  In 
  the 
  case 
  of 
  this 
  box 
  the 
  humidity 
  effect 
  is 
  seen 
  only 
  in 
  

   the 
  change 
  of 
  resistance 
  resulting 
  when 
  the 
  coils 
  were 
  trans- 
  

   ferred 
  from 
  a 
  normal 
  atmosphere 
  into 
  a 
  dry 
  one, 
  When 
  the 
  

   saturated 
  atmosphere 
  was 
  substituted, 
  the 
  leakage 
  effect 
  

  

  