﻿Measuring 
  large 
  Molecular 
  Masses. 
  507 
  

  

  the 
  formula 
  

  

  Xasa+G/n*, 
  (12) 
  

  

  where 
  a 
  and 
  c 
  are 
  parameters 
  characteristic 
  of 
  each 
  peptone,, 
  

   and 
  have 
  the 
  following 
  values 
  : 
  — 
  

  

  Pepton 
  e. 
  

  

  Trjpsiufibrin 
  a. 
  Trypsinfibrin 
  (3. 
  Pepsinfibrin 
  a. 
  Pepsinfibriu 
  a. 
  

  

  commercial. 
  Borkel. 
  

  

  a 
  102 
  10-56 
  12-7 
  878 
  

  

  c 
  0-0549 
  00275 
  0-0187 
  0-016 
  

  

  The 
  following 
  comparison 
  is 
  given 
  to 
  show 
  how 
  the 
  formula 
  

   expresses 
  the 
  experimental 
  facts 
  : 
  — 
  

  

  Trypsinfibrinpeptone 
  a, 
  

  

  1/1000». 
  8 
  16 
  32 
  " 
  64- 
  128 
  256 
  512 
  1024 
  

  

  A 
  exp. 
  ... 
  15-88 
  18-01 
  20-44 
  23"70 
  2882 
  36*99 
  49-23 
  66-51 
  

  

  Xcalc. 
  ... 
  15-11 
  17-14 
  20-02 
  24"09 
  29-84 
  37'98 
  49"48 
  65-76 
  

  

  To 
  explain 
  the 
  formula 
  we 
  may 
  assume 
  that 
  the 
  parameter 
  

   a 
  represents 
  the 
  molecular 
  conductivity 
  of 
  a 
  salt 
  whose 
  

   variation 
  with 
  concentration 
  is 
  not 
  detectable 
  at 
  these 
  dilu- 
  

   tions 
  in 
  the 
  presence 
  of 
  the 
  rest 
  of 
  the 
  peptone. 
  The 
  difference 
  

   between 
  12*7 
  for 
  the 
  commercial 
  sample 
  of 
  pepsinfibrinpep- 
  

   tone 
  and 
  8*78 
  for 
  Borkel's 
  preparation 
  may 
  be 
  ascribed 
  to 
  

   soluble 
  impurity 
  in 
  the 
  commercial 
  sample. 
  But 
  in 
  the 
  other 
  

   ea<es 
  a 
  may 
  originate 
  in 
  some 
  organic 
  salt 
  of 
  an 
  amine 
  base 
  

   which 
  is 
  split 
  off 
  from 
  the 
  peptone 
  upon 
  solution 
  in 
  water. 
  

   Then 
  the 
  term 
  c/w* 
  arises 
  from 
  the 
  conductivity 
  of 
  the 
  acids 
  

   separated 
  from 
  the 
  peptone 
  by 
  water. 
  Ostwald's 
  dilution 
  

   law 
  for 
  organic 
  acids 
  at 
  high 
  dilution 
  makes 
  their 
  con- 
  

   ductivity 
  proportional 
  to 
  l/n*. 
  I 
  have 
  suggested 
  that 
  

   this 
  law 
  of 
  Ostwald's 
  originates 
  in 
  the 
  organic 
  acids 
  

   consisting 
  of 
  double 
  molecules 
  which 
  are 
  partly 
  dissociated 
  

   by 
  water 
  according 
  to 
  the 
  law, 
  the 
  dissociated 
  molecules 
  

   being 
  completely 
  ionized 
  and 
  the 
  undissociated 
  not 
  at 
  all. 
  

   Thus, 
  then, 
  the 
  formula 
  (12) 
  shows 
  that 
  either 
  peptone 
  is 
  an 
  

   organic 
  acid 
  or 
  has 
  organic 
  acids 
  split 
  off 
  from 
  it, 
  and 
  that 
  

   the 
  single 
  acid 
  or 
  mixture 
  of 
  acids 
  forms 
  so 
  dilute 
  a 
  solution 
  

   that 
  its 
  molecular 
  conductivity 
  can 
  be 
  accurately 
  represented 
  

   by 
  c/rfi. 
  With 
  an 
  amount 
  of 
  ionized 
  dissociated 
  di-acid 
  

   proportional 
  to 
  Ijifi 
  the 
  molecular 
  conductivity 
  ought 
  to 
  be 
  

   proportional 
  to 
  AJn%(l 
  + 
  bm¥), 
  where 
  m 
  is 
  the 
  actual 
  con- 
  

   centration 
  of 
  the 
  organic 
  ions. 
  The 
  fact 
  that 
  this 
  term 
  

   lorn 
  does 
  not 
  appear 
  in 
  (12) 
  proves 
  that 
  the 
  actual 
  concen- 
  

   tration 
  of 
  the 
  organic 
  ions 
  is 
  too 
  small 
  to 
  make 
  it 
  appreciable. 
  

   This 
  is 
  exactly 
  what 
  we 
  should 
  expect 
  of 
  such 
  acids 
  as 
  

   we 
  have 
  found 
  to 
  form 
  Xa 
  salts 
  when 
  peptone 
  is 
  neutralized 
  

  

  