﻿190 
  True 
  — 
  Toxic 
  Action 
  of 
  Acids 
  and 
  

  

  few 
  cases, 
  therefore, 
  can 
  the 
  line 
  of 
  argument 
  pursued 
  above 
  

   receive 
  thoroughly 
  satisfactory 
  application 
  to 
  these 
  acids. 
  The 
  

   toxic-values 
  of 
  the 
  acids 
  and 
  salts 
  have, 
  however, 
  been 
  tabu- 
  

   lated, 
  as 
  well 
  as 
  estimated 
  values 
  for 
  the 
  factors, 
  judged 
  from 
  

   the 
  physiological 
  evidence. 
  

  

  In 
  general, 
  the 
  acids 
  show 
  a 
  very 
  considerable 
  variation 
  

   in 
  their 
  toxic-values 
  due 
  to 
  their 
  chemical 
  structure. 
  The 
  

   boundary-concentrations 
  lie 
  between 
  3200 
  and 
  12,800. 
  Disso- 
  

   ciation 
  varies 
  between 
  rather 
  wide 
  limits, 
  from 
  24 
  per 
  cent 
  in 
  

   p. 
  oxybenzoic 
  acid 
  to 
  100 
  per 
  cent 
  in 
  o. 
  nitrobenzoic 
  acid. 
  The 
  

   toxic 
  activity 
  here 
  as 
  in 
  the 
  fatty 
  series 
  is 
  preponderant 
  in 
  the 
  

   cations 
  when 
  dissociation 
  is 
  far 
  advanced. 
  When 
  this 
  is 
  not 
  

   the 
  case, 
  the 
  influence 
  of 
  the 
  residual 
  molecules 
  exceeds 
  it 
  

   more 
  or 
  less 
  decidedly. 
  In 
  hippuric, 
  salicylic 
  and 
  o. 
  nitro- 
  

   benzoic 
  acids, 
  the 
  H 
  ions 
  are 
  especially 
  influential. 
  In 
  benzoic 
  

   and 
  cinnamic 
  acids, 
  the 
  action 
  of 
  the 
  residual 
  molecules 
  is 
  dis- 
  

   tinctly 
  predominant. 
  In 
  general, 
  the 
  sodium 
  salts 
  show 
  here 
  

   a 
  very 
  much 
  weaker 
  toxicity 
  than 
  the 
  acids, 
  the 
  death-limit 
  

   varying 
  between 
  25 
  and 
  100. 
  In 
  JN~a 
  cinnamate 
  the 
  limit 
  lies 
  

   at 
  800 
  and 
  gives 
  the 
  most 
  vicious 
  sodium 
  salt 
  in 
  the 
  entire 
  list. 
  

   As 
  far 
  as 
  the 
  available 
  data 
  go, 
  the 
  salts 
  of 
  these 
  acids 
  dissociate 
  

   freely, 
  from 
  85 
  per 
  cent 
  to 
  96 
  per 
  cent 
  at 
  the 
  death-limit. 
  

  

  "In 
  the 
  case 
  of 
  acids, 
  the 
  dissociation 
  of 
  whose 
  sodium 
  salts 
  

   has 
  been 
  determined, 
  relations 
  not 
  unlike 
  those 
  obtaining 
  in 
  

   the 
  fatty 
  series, 
  already 
  discussed, 
  are 
  found 
  to 
  exist. 
  

  

  In 
  the 
  case 
  of 
  benzoic 
  acid, 
  dissociating 
  about 
  38 
  per 
  cent 
  at 
  

   the 
  death-limit, 
  38 
  per 
  cent 
  of 
  the 
  toxic 
  effect 
  may 
  be 
  regarded 
  

  

  as 
  due 
  to 
  H 
  ions, 
  62 
  per 
  cent 
  to 
  residual 
  molecules 
  and 
  to 
  

   anions. 
  The 
  toxic-value 
  of 
  the 
  sodium 
  salt 
  is 
  200 
  ; 
  less 
  than 
  

  

  15 
  units 
  can 
  be 
  referred 
  to 
  Na 
  ions, 
  185 
  units 
  are 
  chargeable 
  to 
  

   92 
  per 
  cent 
  of 
  anions 
  and 
  8 
  per 
  cent 
  of 
  residual 
  molecules. 
  

   Since 
  we 
  may 
  safely 
  place 
  the 
  toxic-value 
  of 
  this 
  number 
  of 
  

   anions 
  at 
  less 
  than 
  185 
  units, 
  the 
  toxic-value 
  of 
  72 
  per 
  cent 
  of 
  

   undissociated 
  molecules 
  is 
  more 
  than 
  3783. 
  

  

  In 
  the 
  m. 
  and 
  p. 
  nitrobenzoic 
  acids 
  it 
  becomes 
  difficult 
  to 
  

   apply 
  the 
  line 
  of 
  reasoning 
  thus 
  far 
  used 
  to 
  the 
  explanation 
  of 
  

   the 
  results. 
  The 
  possibility 
  exists, 
  of 
  course, 
  that 
  the 
  death- 
  

   limits 
  are 
  not 
  correctly 
  located. 
  The 
  thought 
  also 
  suggests 
  

   itself 
  that 
  at 
  this 
  great 
  dilution 
  hydrolytic 
  changes 
  may 
  take 
  

   place 
  affecting 
  the 
  essential 
  structure 
  and 
  physiological 
  prop- 
  

   erties 
  of 
  the 
  molecule. 
  Owing 
  to 
  this 
  anomalous 
  behavior, 
  a 
  

   further 
  study 
  of 
  these 
  isomers 
  seems 
  especially 
  advisable. 
  

  

  Cinnamic 
  acid 
  deserves 
  a 
  passing 
  comment. 
  Although 
  a 
  

   mono-basic 
  acid, 
  it 
  has 
  an 
  extremely 
  toxic 
  effect, 
  equalling 
  that 
  

   of 
  H 
  2 
  S0 
  4 
  , 
  which 
  cuts 
  off 
  two 
  H 
  ions 
  per 
  molecule 
  at 
  the 
  death- 
  

  

  