﻿Resistance 
  of 
  Mixtures 
  of 
  Xylol 
  and 
  Alcohol. 
  1051 
  

  

  and 
  negative. 
  The 
  " 
  temperature 
  coefficients 
  " 
  given 
  below 
  

  

  .are 
  in 
  all 
  cases 
  those 
  corresponding 
  to 
  £ 
  = 
  15 
  c 
  , 
  i. 
  e. 
  ( 
  - 
  -~) 
  

  

  \y 
  clt 
  Jib' 
  

  

  The 
  temperature 
  coefficient 
  of 
  the 
  various 
  specimens 
  of 
  

   alcohol 
  was 
  as 
  variable 
  as 
  their 
  conductivity. 
  The 
  largest 
  

   coefficient 
  observed 
  with 
  "dry" 
  alcohol 
  was 
  + 
  0*010; 
  the 
  

   smallest 
  (obtained 
  with 
  the 
  specimen 
  from 
  which 
  the 
  mixtures 
  

   of 
  Table 
  I. 
  were 
  prepared) 
  was 
  -t- 
  0*0027. 
  The 
  addition 
  or* 
  

   water 
  to 
  the 
  alcohol 
  increases 
  the 
  temperature 
  coefficient, 
  as 
  

   might 
  be 
  expected 
  from 
  the 
  fact 
  that 
  the 
  temperature 
  co- 
  

   efficient 
  of 
  water 
  is 
  greater 
  than 
  that 
  of 
  alcohol. 
  

  

  The 
  following 
  determinations 
  were 
  made 
  of 
  the 
  tempe- 
  

   rature 
  coefficients 
  of 
  the 
  mixtures 
  mentioned 
  in 
  Table 
  I. 
  

  

  Table 
  II. 
  

  

  y- 
  

  

  7 
  - 
  

  

  (1 
  dy\ 
  

  

  \y 
  dtJib 
  

  

  025 
  

  

  0-102 
  

  

  0-055 
  

  

  4-47 
  X 
  10 
  " 
  7 
  

   1-95 
  X 
  10- 
  9 
  

  

  4-09x10-11 
  

  

  -0-0117 
  

   -0 
  0168 
  

   -0-0124 
  

  

  The 
  probable 
  error 
  of 
  these 
  determinations 
  of 
  the 
  tempe- 
  

   Tature 
  coefficient 
  is 
  about 
  0*001. 
  It 
  may 
  be 
  concluded 
  

   therefore 
  that 
  the 
  temperature 
  coefficient 
  is 
  a 
  maximum 
  for 
  

   a 
  mixture 
  for 
  which// 
  is 
  about 
  0*12. 
  If 
  the 
  mixtures 
  are 
  

   prepared 
  with 
  wet 
  alcohol 
  instead 
  of 
  dry 
  the 
  temperature 
  

   coefficients 
  appear 
  to 
  be 
  slightly 
  greater, 
  but 
  the 
  difference 
  

   did 
  not 
  exceed 
  the 
  probable 
  error. 
  The 
  temperature 
  co- 
  

   efficient 
  for 
  a 
  mixture 
  appears 
  to 
  be 
  quite 
  constant 
  while 
  its 
  

   ■conductivity 
  changes. 
  

  

  It 
  will 
  be 
  observed 
  that, 
  since 
  the 
  coefficient 
  of 
  alcohol 
  is 
  

   positive 
  and 
  that 
  of 
  the 
  mixtures 
  negative, 
  there 
  should 
  be 
  

   some 
  mixture 
  for 
  which 
  the 
  coefficient 
  is 
  zero. 
  Attempts 
  

   were 
  made 
  to 
  discover 
  the 
  composition 
  of 
  such 
  a 
  mixture, 
  

   but 
  it 
  was 
  found 
  that 
  its 
  composition 
  varied 
  so 
  much 
  with 
  the 
  

   specimen 
  of 
  alcohol 
  used 
  that 
  it 
  was 
  difficult 
  to 
  define 
  the 
  

   composition 
  accurately. 
  A 
  mixture 
  for 
  which 
  2/ 
  = 
  0'<d 
  has 
  

   approximately 
  a 
  zero 
  temperature 
  coefficient 
  ; 
  the 
  specific 
  

   conductivity 
  of 
  such 
  a 
  mixture 
  is 
  so 
  great 
  that 
  it 
  is 
  not 
  con- 
  

   venient 
  to 
  use 
  in 
  the 
  preparation 
  of 
  resistances 
  of 
  more 
  than 
  

   10 
  9 
  ohms. 
  

  

  The 
  conductivity 
  of: 
  the 
  xylol 
  was 
  too 
  small 
  to 
  be 
  measured 
  

  

  IB 
  2 
  

  

  