﻿Posnjdk 
  and 
  Merwin 
  — 
  Hydrated 
  Fe 
  ; 
  rides. 
  313 
  

  

  In 
  another 
  paper 
  6 
  van 
  Bemmelen 
  trie 
  3 
  t 
  ~erify 
  state- 
  

   ments 
  f 
  onnd 
  in 
  the 
  literature 
  dealing 
  with 
  the 
  preparation 
  

   of 
  crystallized 
  ferric 
  hydrates. 
  Er 
  .1 
  of 
  them 
  

  

  to 
  be 
  erroneous, 
  though 
  he 
  claimed 
  to 
  ha~r 
  pre| 
  ared 
  a 
  

   crystallized 
  ferric 
  oxide 
  monohydrate. 
  I: 
  was 
  form 
  

   when 
  hexagonal 
  plates 
  of 
  sodinm 
  ferrite 
  were 
  Lea 
  died 
  

   with 
  water 
  at 
  15". 
  His 
  belief 
  that 
  a 
  true 
  hydrate 
  

   formed 
  is 
  based 
  on 
  the 
  fact 
  that 
  this 
  substitution 
  did 
  

   neither 
  destroy 
  the 
  form 
  nor 
  the 
  transparency 
  of 
  these 
  

   crystals 
  and 
  that 
  they 
  were 
  not 
  hygros 
  : 
  : 
  ; 
  i 
  : 
  Howe" 
  

   he 
  found 
  that 
  they. 
  begin 
  to 
  decompose 
  and 
  Lose 
  their 
  

   water 
  below 
  100°, 
  while 
  the 
  known 
  natural 
  hydrated 
  

   ferric 
  oxides 
  are 
  apparently 
  perfectly 
  stable 
  at 
  that 
  tem- 
  

   perature. 
  Retention 
  of 
  transparency 
  in 
  cases 
  of 
  pseu- 
  

   domorphism 
  are 
  well 
  known 
  and 
  it 
  seems 
  quitr 
  evident, 
  

   therefore, 
  that 
  his 
  crystals 
  were 
  not 
  crystals 
  :: 
  ? 
  definite 
  

   hydrate 
  but 
  were 
  pseudomorphs. 
  

  

  In 
  view 
  of 
  the 
  insufficiency 
  of 
  previously 
  used 
  methods 
  

   tc 
  produce 
  the 
  hydrates 
  of 
  ferric 
  oxide. 
  0. 
  En' 
  :er- 
  

   mined 
  to 
  employ 
  high 
  pressure 
  for 
  that 
  purpose. 
  This, 
  

   according 
  to 
  b 
  irn 
  . 
  gave 
  the 
  desired 
  results 
  for 
  "the 
  red 
  

   colloid 
  immersed 
  in 
  water 
  changed 
  in 
  the 
  course 
  : 
  : 
  ; 
  z-~ 
  

   days 
  under 
  pressxu 
  -. 
  and 
  a 
  temperature 
  of 
  30-41 
  5 
  , 
  into 
  

   the 
  yellow 
  hydrate 
  2Fe 
  2 
  3 
  -3H2<J 
  rresp 
  o 
  ling 
  t 
  limon- 
  

   ite: 
  above 
  42-5° 
  and 
  up 
  to 
  62-5° 
  into 
  the 
  yellowish-red 
  

   hydrate 
  Fe 
  2 
  3 
  \ELO 
  corresponding 
  to 
  gc 
  ethite, 
  and 
  •?": 
  :ve 
  

  

  into 
  the 
  brick-red 
  hydrate 
  Ft 
  - 
  _ 
  H 
  . 
  rres 
  

   ing 
  to 
  turgite. 
  The 
  upper 
  tempr 
  ? 
  tui 
  e 
  limit 
  of 
  stabili":~ 
  

   for 
  the 
  latter 
  was 
  not 
  discovers 
  These 
  products 
  

  

  according 
  to 
  Buff 
  were 
  s 
  fine-grained 
  that 
  even 
  under 
  a 
  

   magnification 
  of 
  600 
  times, 
  crystal! 
  im'ty 
  could 
  not 
  be 
  reo- 
  

  

  snbstanee. 
  Tan 
  Bemmden 
  apparently 
  ehanged 
  Ms 
  opinion, 
  as 
  he 
  describes 
  

   the 
  yellow 
  colloid 
  belonging 
  to 
  the 
  same 
  class 
  as 
  the 
  reddish-brown 
  : 
  "das 
  

  

  r^l:-r. 
  — 
  r= 
  = 
  -rrJLS.lTi4'r 
  Z: 
  = 
  tz: 
  — 
  i 
  . 
  . 
  ":iz.irT 
  i== 
  ~;.E 
  = 
  cr 
  -. 
  — 
  =.= 
  i:-/:!^ 
  

  

  als 
  das 
  braanrote 
  gel 
  moss 
  jedoeh 
  diesen 
  zugezaehlt 
  werden." 
  

  

  r 
  .zl~ 
  il 
  :i:e 
  ±r5T-~Tr.Ti:r.ri 
  3""^- 
  iii 
  _ 
  :-- 
  2-~h-'t- 
  :jl-t5~;;.-t 
  "It 
  ~t11:~ 
  

   5nr.5~=.r. 
  j-r 
  ii: 
  r 
  _ 
  r~ 
  ::-: 
  ~:n 
  :f 
  jii? 
  ir-rir.;! 
  i; 
  r~-:~- 
  ". 
  ~ir 
  r-:: 
  .:-i-:r:"^i 
  

   substance. 
  This 
  statement 
  is, 
  theref 
  ore, 
  based 
  not 
  on 
  new 
  facts 
  bat 
  rather, 
  

   we 
  think, 
  on 
  his 
  conception 
  of 
  colloids 
  denned 
  by 
  him 
  as 
  follows: 
  "Ich 
  

   betraehte 
  die 
  kolloiden 
  Verbindnngen 
  der 
  Elements 
  >xyde 
  Sulfide 
  z 
  *lze 
  

  

  1. 
  5. 
  ~. 
  "~" 
  " 
  ~ 
  •'• 
  1 
  ;: 
  t7 
  111*. 
  .1" 
  ~.5 
  - 
  - 
  - 
  - 
  ; 
  - 
  - 
  .- 
  -^ 
  - 
  — 
  — 
  - 
  — 
  - 
  - 
  _-_ 
  "^~ 
  - 
  •J.i~ 
  , 
  f 
  ~ 
  ~ 
  -Tl 
  1.; 
  

  

  nnbestimmte 
  Verbandungen 
  in 
  einem 
  besonderen 
  Aggregatzastand. 
  " 
  _ 
  ie 
  

   Absorption, 
  p. 
  38.) 
  This 
  definition 
  of 
  colloids 
  - 
  does 
  not 
  agree 
  with 
  our 
  

   present 
  knowledge; 
  however, 
  the 
  fact 
  stands, 
  and 
  is 
  of 
  interest, 
  that 
  van 
  

  

  and 
  yellow 
  hydrated 
  ferric 
  oxides, 
  although 
  he 
  was 
  unwilling 
  to 
  give 
  them 
  

  

  r^-ir-: 
  : 
  ri:r. 
  

  

  f 
  lie 
  A^:~~i:r. 
  i. 
  14": 
  ,"::-. 
  f 
  ~r 
  ?:-::. 
  TV. 
  I" 
  7 
  4: 
  ,"" 
  1 
  : 
  - 
  

   ' 
  Ber. 
  dentseh. 
  ehem. 
  Ges.. 
  34, 
  3417, 
  1901. 
  

  

  