﻿Chemistry 
  and 
  Physics. 
  443 
  

  

  free 
  from 
  sodium, 
  and 
  generally 
  the 
  spectra 
  of 
  iron 
  salts 
  do 
  not 
  

   interfere. 
  — 
  Jour. 
  Ind. 
  Eng. 
  Chem., 
  12, 
  500. 
  * 
  h. 
  l. 
  w. 
  

  

  2. 
  The 
  Employment 
  of 
  Boric 
  Acid 
  in 
  the 
  Volumetric 
  Deter- 
  

   mination 
  of 
  Ammonia, 
  — 
  About 
  seven 
  years 
  ago 
  Winkler 
  in 
  Ger- 
  

   many 
  proposed 
  the 
  substitution 
  of 
  boric 
  acid 
  for 
  sulphuric 
  acid 
  

   in 
  the 
  fixation 
  of 
  ammonia 
  distilled 
  over 
  in 
  the 
  course 
  of 
  the 
  

   Kjeldahl 
  process 
  for 
  the 
  determination 
  of 
  nitrogen. 
  This 
  method 
  

   has 
  the 
  advantage 
  that 
  the 
  amount 
  of 
  boric 
  acid 
  in 
  excess 
  need 
  

   not 
  be 
  known, 
  since 
  this 
  acid 
  is 
  so 
  weak 
  that 
  the 
  ammonia 
  com- 
  

   bined 
  with 
  it 
  can 
  be 
  titrated 
  directly 
  with 
  sulphuric 
  acid 
  when 
  

   suitable 
  indicators 
  are 
  employed, 
  so 
  that 
  only 
  a 
  single 
  volumetric 
  

   solution 
  is 
  needed 
  for 
  the 
  titration. 
  Winkler 
  obtained 
  good 
  

   results 
  by 
  his 
  method, 
  using 
  methyl 
  orange 
  and 
  Congo 
  red 
  as 
  

   indicators, 
  and 
  the 
  process 
  was 
  used 
  later 
  by 
  Adler, 
  who 
  found 
  

   it 
  desirable 
  in 
  titrating 
  to 
  employ 
  a 
  color 
  standard 
  made 
  by 
  

   adding 
  0-15 
  cc. 
  of 
  0-1 
  normal 
  sulphuric 
  acid 
  and 
  a 
  few 
  drops 
  of 
  

   methyl 
  orange 
  to 
  250 
  cc. 
  of 
  distilled 
  water. 
  The 
  titration 
  then 
  

   of 
  the 
  ammonia 
  distillate, 
  fixed 
  by 
  50 
  cc. 
  of 
  4 
  per 
  cent, 
  boric 
  acid 
  

   solution 
  and 
  containing 
  the 
  same 
  amount 
  of 
  methyl 
  orange, 
  until 
  

   the 
  standard 
  color 
  was 
  reached, 
  gave 
  the 
  correct 
  result. 
  

  

  M. 
  F. 
  Scales 
  and 
  A. 
  P. 
  Harrison 
  of 
  the 
  U. 
  S. 
  Department 
  of 
  

   Agriculture 
  have 
  studied 
  this 
  method 
  rather 
  elaborately 
  and 
  

   recommend 
  it 
  as 
  being 
  convenient 
  and 
  accurate. 
  In 
  making 
  the 
  

   titrations 
  they 
  advise 
  the 
  subtraction 
  of 
  0-35 
  cc. 
  from 
  the 
  burette 
  

   reading 
  where 
  1 
  cc. 
  of 
  the 
  sulphuric 
  acid 
  solution 
  is 
  equal 
  to 
  1 
  mg. 
  

   of 
  nitrogen, 
  in 
  order 
  to 
  correct 
  for 
  the 
  effect 
  of 
  the 
  presence 
  of 
  

   50 
  cc. 
  of 
  4% 
  boric 
  acid. 
  They 
  obtained 
  excellent 
  results 
  both 
  

   with 
  Congo 
  red 
  and 
  methyl 
  orange 
  as 
  indicators, 
  but 
  prefer 
  

   bromophenol 
  blue 
  as 
  giving 
  a 
  sharper 
  end-reaction, 
  especially 
  

   when 
  the 
  light 
  from 
  an 
  electric 
  bulb 
  is 
  passed 
  through 
  the 
  liquid 
  

   against 
  a 
  white 
  reflecting 
  surface 
  until 
  the 
  disappearance 
  of 
  the 
  

   purple 
  color. 
  — 
  Jour. 
  Ind, 
  Eng. 
  Chem., 
  12, 
  350. 
  h. 
  l. 
  w. 
  

  

  3. 
  Historie 
  de 
  la 
  Chemie, 
  par 
  Maurice 
  Delacre. 
  8vo, 
  pp. 
  

   632. 
  Paris, 
  1920 
  ( 
  Gauthier-Villars 
  et 
  Cie).— 
  The 
  manuscript 
  

   of 
  this 
  interesting 
  historical 
  essay 
  was 
  finished 
  in 
  1916 
  at 
  Ghent 
  

   where 
  the 
  author 
  was 
  a 
  Professor 
  in 
  the 
  University, 
  but 
  on 
  

   account 
  of 
  the 
  German 
  occupation 
  it 
  was 
  not 
  until 
  1918 
  that 
  it 
  

   could 
  be 
  sent 
  to 
  France, 
  finally 
  through 
  the 
  assistance 
  of 
  Cardinal 
  

   Mercier. 
  In 
  Paris 
  the 
  work 
  was 
  crowned 
  by 
  the 
  Institute 
  of 
  

   France 
  with 
  the 
  award 
  of 
  the 
  Binoux 
  prize. 
  

  

  The 
  book 
  presents 
  the 
  subject 
  in 
  an 
  attractive 
  way, 
  showing 
  

   the 
  progressive 
  development 
  of 
  the 
  science 
  and 
  presenting 
  bio- 
  

   graphical 
  accounts 
  of 
  many 
  of 
  the 
  masters, 
  as 
  well 
  as 
  extracts 
  

   from 
  their 
  writings. 
  It 
  is 
  written 
  from 
  an 
  unusual 
  point 
  of 
  

   view, 
  as 
  the 
  author 
  admits 
  in 
  his 
  preface 
  that 
  he 
  considers 
  the 
  

   discovery 
  of 
  facts 
  more 
  important 
  than 
  the 
  development 
  of 
  

   hypotheses. 
  He 
  says 
  that 
  he 
  has 
  lived 
  too 
  much 
  in 
  the 
  midst 
  of 
  

   theories 
  and 
  has 
  been 
  obliged 
  to 
  teach 
  them 
  for 
  too 
  long 
  a 
  time 
  

   not 
  to 
  have 
  conceived 
  an 
  incurable 
  aversion 
  to 
  them. 
  In 
  spite 
  of 
  

  

  