﻿244 
  Scientific 
  Intelligence. 
  

  

  favorable 
  to 
  the 
  production 
  of 
  spherical 
  masses 
  of 
  iron. 
  When 
  

   the 
  falling 
  globules 
  touched 
  the 
  tub 
  containing 
  the 
  mercury, 
  or 
  

   the 
  earth 
  outside, 
  they 
  broke 
  up 
  with 
  a 
  flame 
  into 
  scintillating 
  

   globules 
  giving 
  a 
  report 
  like 
  a 
  rifle. 
  When 
  the 
  fused 
  carburetted 
  

   iron 
  was 
  run 
  into 
  a 
  small 
  cylindrical 
  cavity 
  in 
  a 
  large 
  mass 
  of 
  

   iron 
  or 
  copper, 
  the 
  fused 
  metal 
  was 
  very 
  rapidly 
  cooled 
  and 
  dia- 
  

   monds 
  were 
  obtained 
  mixed 
  with 
  graphite, 
  the 
  yield 
  however 
  

   being 
  small. 
  Moissan 
  has 
  also 
  observed 
  that 
  the 
  so-called 
  black 
  

   diamond, 
  included 
  in 
  transparent 
  diamonds 
  from 
  Brazil, 
  is 
  a 
  

   variety 
  of 
  carbon 
  differing 
  from 
  the 
  diamond. 
  When 
  such 
  dia- 
  

   monds 
  are 
  pulverized 
  and 
  heated 
  in 
  oxygen 
  at 
  200° 
  below 
  the 
  

   ignition-point 
  of 
  the 
  diamond, 
  the 
  black 
  matter 
  burns 
  away, 
  leav- 
  

   ing 
  the 
  residual 
  diamond 
  white. 
  — 
  G. 
  JR., 
  cxxiii, 
  206, 
  210, 
  July, 
  1896. 
  

  

  G. 
  F. 
  B. 
  

  

  7. 
  Gn 
  the 
  preparation 
  of 
  Metallic 
  Hydroxides 
  by 
  Electrolysis. 
  

   — 
  Experiments 
  by 
  Lorenz 
  have 
  shown 
  that 
  metallic 
  hydroxides 
  

   can 
  be 
  easily 
  prepared 
  by 
  electrolysis. 
  The 
  bath 
  used 
  is 
  an 
  

   aqueous 
  solution 
  of 
  potassium 
  or 
  sodium 
  chloride, 
  sulphate 
  or 
  

   nitrate, 
  according 
  to 
  the 
  ease 
  with 
  which 
  the 
  desired 
  hydroxide 
  is 
  

   formed 
  in 
  these 
  solutions. 
  A 
  platinum 
  plate 
  constitutes 
  the 
  

   cathode, 
  and 
  a 
  plate 
  of 
  the 
  metal 
  whose 
  hydroxide 
  is 
  to 
  be 
  

   obtained, 
  the 
  anode. 
  By 
  stirring 
  constantly 
  the 
  solution, 
  the 
  

   hydroxide 
  comes 
  down 
  as 
  an 
  insoluble 
  precipitate. 
  Thus 
  an 
  

   anode 
  of 
  copper 
  in 
  potassium 
  chloride 
  solution 
  gives 
  a 
  yellowish- 
  

   red 
  precipitate 
  of 
  cuprous 
  hydroxide, 
  while 
  in 
  a 
  solution 
  of 
  potas- 
  

   sium 
  nitrate 
  it 
  yields 
  a 
  blue 
  precipitate 
  of 
  cupric 
  hydroxide. 
  In 
  

   this 
  way 
  the 
  hydroxides 
  of 
  silver, 
  magnesium, 
  zinc, 
  cadmium, 
  

   aluminium, 
  lead, 
  manganese 
  and 
  iron 
  are 
  readily 
  obtained. 
  

   Mercury 
  in 
  a 
  bath 
  ol 
  potassium 
  chloride 
  gives 
  no 
  precipitate, 
  

   calomel 
  being 
  formed 
  ; 
  but 
  in 
  a 
  bath 
  of 
  the 
  nitrate, 
  a 
  black 
  pre- 
  

   cipitate 
  is 
  produced. 
  Thallium 
  in 
  baths 
  of 
  potassium 
  salts 
  is 
  

   covered 
  with 
  suboxide, 
  a 
  brown 
  precipitate 
  of 
  hydroxide 
  being 
  

   gradually 
  formed. 
  Tin 
  in 
  a 
  bath 
  of 
  chloride, 
  sulphate 
  or 
  nitrate 
  

   yields 
  orthostannic 
  acid, 
  which 
  is 
  thus 
  easily 
  obtained 
  pure. 
  

   Antimony 
  and 
  bismuth 
  thus 
  treated 
  become 
  covered 
  with 
  a 
  grey 
  

   coating, 
  no 
  hydroxides 
  resulting. 
  Nickel 
  in 
  a 
  nitrate 
  bath, 
  is 
  

   quickly 
  covered 
  with 
  a 
  black 
  coating; 
  but 
  in 
  a 
  chloride 
  bath 
  the 
  

   green 
  hydroxide 
  is 
  easily 
  obtained. 
  Since 
  the 
  method 
  is 
  applica- 
  

   ble 
  to 
  the 
  preparation 
  of 
  hydroxides 
  insoluble 
  in 
  water, 
  the 
  

   hydroxyl 
  ions 
  and 
  the 
  metal 
  ions 
  being 
  formed 
  in 
  equivalent 
  pro- 
  

   portions, 
  the 
  hydroxide 
  is 
  obtained 
  in 
  neutral 
  solutions 
  ; 
  a 
  great 
  

   advantage 
  over 
  the 
  chemical 
  method, 
  in 
  which 
  it 
  is 
  necessary 
  to 
  

   wash 
  the 
  hydroxide 
  free 
  from 
  alkali. 
  Moreover 
  as 
  the 
  precipi- 
  

   tated 
  hydroxides 
  are 
  formed 
  in 
  the 
  solution 
  and 
  not 
  at 
  the 
  elec- 
  

   trodes, 
  the 
  latter 
  do 
  not 
  become 
  foul 
  and 
  a 
  large 
  quantity 
  of 
  the 
  

   product 
  can 
  be 
  prepared 
  with 
  the 
  same 
  strength 
  of 
  current 
  and 
  

   solution. 
  Evidently 
  the 
  anode 
  should 
  be 
  made 
  of 
  pure 
  metal 
  in 
  

   all 
  cases. 
  — 
  Zeitschr. 
  Anorg. 
  Ghem., 
  xii, 
  436, 
  July, 
  1896. 
  g. 
  f. 
  b. 
  

  

  8. 
  Gn 
  " 
  Excited 
  " 
  Metals, 
  and 
  on 
  Excited 
  Aluminum 
  as 
  a 
  

   Reducing 
  agent. 
  — 
  A 
  metal 
  the 
  activity 
  of 
  which 
  is 
  increased 
  by 
  

  

  