﻿504 
  Mr. 
  W. 
  Sutherland 
  : 
  Another 
  Method 
  of 
  

  

  each 
  addition. 
  At 
  the 
  point 
  of 
  exact 
  neutralization 
  the 
  

   conductivity 
  will 
  be 
  a 
  minimum, 
  namely, 
  that 
  of 
  a 
  normal 
  

   solution 
  of 
  NaCl. 
  If 
  more 
  NaOH 
  solution 
  is 
  added, 
  the 
  

   conductivity 
  increases 
  till 
  with 
  an 
  infinite 
  amount 
  it 
  becomes 
  

   that 
  of 
  normal 
  solution 
  of 
  NaOH. 
  The 
  experimental 
  method 
  

   of 
  using 
  the 
  method 
  to 
  find 
  the 
  equivalent 
  weight 
  of 
  an 
  acid 
  

   is 
  to 
  start 
  with 
  a 
  solution 
  of 
  NaOH 
  0'05 
  normal, 
  as 
  in 
  

   Sjoqvist's 
  investigation 
  with 
  albumin, 
  and 
  then 
  to 
  add 
  the 
  

   acid 
  in 
  instalments 
  till 
  it 
  is 
  present 
  in 
  great 
  excess. 
  Then 
  

   if 
  the 
  results 
  are 
  graphed 
  with 
  amount 
  of 
  acid 
  as 
  abscissa 
  

   and 
  electric 
  conductivity 
  as 
  ordinate, 
  they 
  give 
  in 
  the 
  

   simplest 
  cases 
  two 
  straight 
  lines 
  meeting 
  at 
  the 
  point 
  of 
  

   minimum 
  conductivity, 
  whose 
  abscissa 
  gives 
  the 
  amount 
  of 
  

   acid 
  required 
  to 
  make 
  a 
  known 
  volume 
  of 
  0*05 
  normal 
  

   solution 
  of 
  the 
  acid. 
  In 
  the 
  more 
  complex 
  cases 
  the 
  graph 
  

   does 
  not 
  give 
  the 
  two 
  ideal 
  straight 
  lines 
  near 
  the 
  point 
  of 
  

   minimum 
  conductivity, 
  but 
  forms 
  a 
  curve 
  with 
  the 
  two 
  

   straight 
  lines 
  as 
  fairly 
  decided 
  asymptotes. 
  If 
  these 
  asym- 
  

   ptotes 
  are 
  produced 
  till 
  they 
  meet, 
  their 
  point 
  of 
  intersection 
  

   gives 
  the 
  required 
  datum. 
  Neumann 
  tested 
  the 
  method 
  on 
  

   glycocoll 
  NH 
  2 
  CH 
  2 
  COOH 
  and 
  asparagine 
  C 
  2 
  H 
  3 
  NH 
  2 
  CONH 
  2 
  

   COOH 
  both 
  as 
  acids 
  to 
  NaOH 
  and 
  bases 
  to 
  HC1, 
  and 
  

   obtained 
  by 
  electric 
  titration 
  results 
  agreeing 
  with 
  their 
  

   known 
  equivalents. 
  Applying 
  the 
  method 
  then 
  to 
  four 
  of 
  

   Siegfried's 
  peptones, 
  Neumann 
  obtained 
  the 
  results 
  given 
  

   above 
  under 
  the 
  headings 
  " 
  equivalent 
  as 
  acid, 
  as 
  base." 
  

   These 
  do 
  not 
  stand 
  in 
  any 
  simple 
  intelligible 
  relation 
  to 
  the 
  

   provisional 
  molecular 
  weights. 
  The 
  situation 
  is 
  a 
  suitable 
  

   one 
  for 
  applying 
  the 
  methods 
  of 
  the 
  present 
  paper. 
  Neumann 
  

   measured 
  the 
  equivalent 
  conductivities 
  of 
  the 
  four 
  Na 
  

   peptonates 
  at 
  strengths 
  1/32 
  and 
  1/1024 
  normal, 
  as 
  given 
  in 
  

   the 
  next 
  table 
  along 
  with 
  the 
  values 
  of 
  A 
  01 
  + 
  A 
  02 
  and 
  b 
  in 
  (5) 
  

   derived 
  from 
  them. 
  His 
  values 
  of 
  the 
  conductivity 
  of 
  HC1 
  

   correspond 
  to 
  the 
  temperature 
  21° 
  # 
  5, 
  according 
  to 
  Kohl- 
  

   rausch's 
  latest 
  data. 
  At 
  this 
  temperature 
  A 
  01 
  for 
  Na 
  is 
  47, 
  

   by 
  which 
  we 
  obtain 
  A 
  02 
  for 
  the 
  peptone 
  ions. 
  Then 
  by 
  

   means 
  of 
  (8) 
  with 
  (0-036 
  + 
  0-0425)/2=0'03925 
  as 
  the 
  ap- 
  

   propriate 
  constant 
  for 
  21°* 
  5, 
  and 
  with 
  tentative 
  values 
  of 
  

   fti/(«i+w 
  2 
  ), 
  we 
  calculate 
  A 
  02 
  /v 
  2 
  as 
  given 
  in 
  the 
  table, 
  and 
  so 
  

   we 
  obtain 
  v 
  9 
  . 
  

  

  Table 
  III. 
  

  

  Peptone. 
  

  

  X(32). 
  

  

  A(1024). 
  

  

  Aoi-f 
  A02. 
  

  

  A 
  02. 
  

  

  b. 
  

  

  Aos/fo. 
  

  

  *v 
  

  

  Trypsmfibrin 
  a 
  ... 
  

  

  72-98 
  

  

  90-76 
  

  

  102 
  

  

  55 
  

  

  •1246 
  

  

  29-2 
  

  

  1-88 
  

  

  /3- 
  

  

  82-2 
  

  

  104-7 
  

  

  120 
  

  

  73 
  

  

  •121 
  

  

  35-4 
  

  

  206 
  

  

  Pepsinfibrin 
  a 
  I. 
  . 
  

  

  72-3 
  

  

  101-9 
  

  

  126 
  

  

  79 
  

  

  •186 
  

  

  23-2 
  

  

  3-4 
  

  

  II. 
  

  

  77-5 
  

  

  106-6 
  

  

  129 
  

  

  82 
  

  

  •163 
  

  

  27-1 
  

  

  302 
  

  

  Pepsinglutin 
  

  

  75-8 
  

  

  105-5 
  

  

  128-5 
  

  

  81-5 
  

  

  172 
  

  

  25-6 
  

  

  3-18 
  

  

  