﻿Chemistry 
  and 
  Physics. 
  313 
  

  

  He 
  now 
  finds 
  that 
  a 
  small 
  error 
  was 
  introduced 
  in 
  the 
  case 
  of 
  

   cobalt, 
  due 
  to 
  the 
  fact 
  that 
  the 
  metal 
  deposited 
  on 
  the 
  platinum 
  

   electrode 
  contained 
  a 
  minute 
  quantity 
  of 
  the 
  hydrate 
  Co 
  2 
  3 
  . 
  (H 
  2 
  0) 
  2 
  . 
  

   No 
  such 
  result 
  however 
  occurs 
  with 
  nickel. 
  Moreover 
  he 
  finds 
  

   that 
  a 
  solution 
  of 
  iodine 
  in 
  potassium 
  iodide 
  of 
  decinormal 
  

   strength 
  is 
  capable 
  of 
  dissolving 
  the 
  deposited 
  metal 
  from 
  the 
  

   platinum 
  terminal 
  at 
  once, 
  without 
  attacking 
  the 
  latter. 
  In 
  the 
  

   case 
  of 
  nickel 
  the 
  platinum 
  is 
  left 
  perfectly 
  clean, 
  while 
  after 
  the 
  

   removal 
  of 
  the 
  cobalt 
  a 
  stain 
  remains 
  due 
  to 
  about 
  one 
  half 
  per 
  

   cent 
  of 
  oxide. 
  To 
  remove 
  this 
  oxide, 
  the 
  electrodeposited 
  cobalt 
  

   was 
  reduced 
  by 
  hydrogen 
  before 
  use 
  ; 
  and 
  then 
  it 
  proved 
  to 
  be 
  

   pure 
  on 
  solution 
  in 
  iodine. 
  The 
  determination 
  was 
  made 
  by 
  

   titrating 
  with 
  sodium 
  thiosulphate 
  the 
  excess 
  of 
  iodine 
  left 
  after 
  

   the 
  pure 
  metals 
  were 
  dissolved. 
  As 
  a 
  result 
  of 
  two 
  complete 
  and 
  

   concordant 
  series 
  of 
  analyses 
  the 
  fiual 
  values 
  obtained 
  are 
  58*72 
  

   for 
  nickel 
  and 
  59-37 
  for 
  cobalt, 
  H 
  being 
  1 
  and 
  I 
  126*53; 
  the 
  

   atomic 
  mass 
  of 
  cobalt 
  beinaj 
  apparently 
  about 
  one-half 
  a 
  unit 
  

   higher 
  than 
  that 
  of 
  nickel. 
  — 
  Zeit. 
  anorg. 
  Chem., 
  viii, 
  i, 
  December, 
  

   1894. 
  G. 
  F. 
  B. 
  

  

  4. 
  On 
  the 
  Atomic 
  Mass 
  of 
  Bismuth. 
  — 
  More 
  than 
  forty 
  years 
  

   ago 
  Schneider 
  fixed 
  the 
  mass 
  of 
  the 
  bismuth 
  atom 
  as 
  208, 
  rela- 
  

   tive 
  to 
  that 
  of 
  hydrogen. 
  A 
  few 
  years 
  subsequently, 
  i. 
  e. 
  in 
  1859, 
  

   Dumas 
  made 
  atomic 
  mass 
  determinations 
  of 
  a 
  number 
  of 
  ele- 
  

   ments, 
  among 
  which 
  was 
  bismuth 
  ; 
  giving 
  to 
  this 
  metal 
  the 
  value 
  

   210. 
  This 
  figure 
  continued 
  to 
  be 
  accepted 
  down 
  to 
  1883 
  when 
  

   Marignac 
  undertook 
  his 
  well 
  known 
  investigations 
  upon 
  atomic 
  

   mass 
  and 
  by 
  a 
  series 
  of 
  determinations 
  which 
  were 
  carried 
  out 
  

   with 
  great 
  thoroughness 
  concluded 
  upon 
  208*16 
  as 
  the 
  atomic 
  

   mass 
  of 
  bismuth 
  ; 
  thus 
  corroborating 
  the 
  work 
  of 
  Schneider. 
  In 
  

   consequence 
  of 
  the 
  slightly 
  higher 
  result 
  208*9, 
  obtained 
  by 
  

   Classen 
  by 
  an 
  electrolytic 
  method, 
  Schneider 
  has 
  now 
  repeated 
  

   and 
  extended 
  his 
  work 
  in 
  this 
  direction. 
  The 
  method 
  adopted 
  by 
  

   him 
  in 
  this 
  new 
  series 
  of 
  determinations 
  is 
  based 
  upon 
  a 
  compari- 
  

   son 
  of 
  the 
  equivalent 
  relation 
  of 
  metallic 
  bismuth 
  to 
  the 
  trioxide 
  

   of 
  bismuth 
  ; 
  with 
  a 
  view 
  of 
  testing 
  certain 
  suggestions 
  made 
  by 
  

   Classen 
  concerning 
  possible 
  errors 
  in 
  his 
  former 
  estimations. 
  The 
  

   result 
  finally 
  obtained, 
  for 
  O 
  = 
  16, 
  is 
  208*05 
  ; 
  the 
  greatest 
  diver- 
  

   gence 
  from 
  this 
  mean 
  among 
  the 
  values 
  obtained 
  in 
  all 
  the 
  experi- 
  

   ments 
  being 
  only 
  0*21. 
  This 
  result 
  not 
  only 
  coufirms 
  the 
  value 
  

   originally 
  obtained 
  by 
  Schneider 
  himself, 
  and 
  also 
  that 
  of 
  Marig- 
  

   nac, 
  but 
  it 
  is 
  specially 
  important 
  as 
  tending 
  to 
  show 
  that 
  bismuth 
  

   belongs 
  to 
  the 
  increasing 
  class 
  of 
  elements 
  whose 
  atomic 
  masses 
  

   are 
  represented 
  by 
  whole 
  numbers.— 
  ^ 
  prakt. 
  Ch., 
  II, 
  1, 
  461, 
  

   November, 
  1894. 
  g. 
  f. 
  b. 
  

  

  5. 
  On 
  the 
  Use 
  of 
  Dihydroxy 
  tartaric 
  acid 
  as 
  a 
  Reagent 
  for 
  

   Sodium. 
  — 
  By 
  oxidizing 
  tartaric 
  acid 
  in 
  presence 
  of 
  iron, 
  Fenton 
  

   observed 
  the 
  production 
  of 
  a 
  new 
  crystallized 
  acid, 
  which 
  by 
  oxi- 
  

   dation 
  is 
  converted 
  into 
  dihydroxytartaric 
  acid. 
  To 
  effect 
  this 
  

   oxidation, 
  the 
  crystallized 
  acid 
  is 
  covered 
  with 
  glacial 
  acetic 
  acid 
  

   and 
  a 
  solution 
  of 
  bromine 
  in 
  this 
  glacial 
  acid 
  is 
  added 
  drop 
  by 
  

  

  Am. 
  Jour. 
  Sci.— 
  Third 
  Series, 
  Yol. 
  XLIX, 
  No. 
  292.— 
  April, 
  1895. 
  

   21 
  

  

  