﻿W. 
  Foshag 
  — 
  Sulphohalite. 
  77 
  

  

  above 
  measured 
  crystals. 
  It 
  measured 
  17mm. 
  and 
  

   weighed 
  2-2gm. 
  It 
  is 
  a 
  well-defined 
  octahedron 
  with 
  one 
  

   cubic 
  face 
  present. 
  

  

  It 
  is 
  quite 
  possible 
  that 
  many 
  of 
  the 
  so-called 
  octa- 
  

   hedral 
  halites 
  if 
  examined 
  closely, 
  especially 
  if 
  they 
  have 
  

   only 
  a 
  slight 
  saline 
  taste, 
  will 
  prove 
  to 
  be 
  sulphohalite. 
  

   Its 
  low 
  index, 
  1455, 
  is 
  much 
  lower 
  than 
  any 
  of 
  the 
  asso- 
  

   ciated 
  isotropic 
  minerals 
  and 
  is 
  the 
  most 
  convenient 
  

   means 
  of 
  identifying 
  this 
  mineral. 
  

  

  U. 
  S. 
  National 
  Museum, 
  Washington, 
  D. 
  C. 
  

   October 
  7, 
  1919. 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistry 
  and 
  Physics. 
  

  

  1. 
  The 
  Application 
  of 
  Rotating 
  Redactors 
  in 
  the 
  Determina- 
  

   tion 
  of 
  Iron. 
  — 
  Walter 
  Scott 
  has 
  described 
  the 
  use 
  of 
  rapidly 
  

   rotating 
  cylinders 
  of 
  zinc 
  or 
  aluminium 
  for 
  the 
  reduction 
  of 
  

   ferric 
  sulphate 
  solutions 
  in 
  order 
  to 
  determine 
  the 
  iron 
  by 
  titra- 
  

   tion 
  with 
  permanganate. 
  The 
  rapidity 
  and 
  efficiency 
  of 
  this 
  

   method 
  of 
  reduction 
  in 
  the 
  case 
  of 
  vanadic 
  acid 
  has 
  been 
  pre- 
  

   viously 
  demonstrated 
  by 
  Professor 
  Gooch 
  and 
  the 
  present 
  author 
  

   and 
  was 
  described 
  in 
  this 
  Journal 
  in 
  1918 
  (46, 
  427), 
  and 
  the 
  

   investigation 
  under 
  consideration 
  was 
  also 
  carried 
  out 
  in 
  the 
  

   Kent 
  Chemical 
  Laboratory 
  at 
  the 
  suggestion 
  of 
  Professor 
  Gooch. 
  

  

  It 
  was 
  found 
  that 
  zinc 
  cylinders 
  rotating 
  at 
  700 
  or 
  800 
  revo- 
  

   lutions 
  per 
  minute 
  and 
  exposing 
  a 
  surface 
  of 
  about 
  75 
  sq. 
  cm. 
  

   to 
  the 
  liquid 
  the 
  volume 
  of 
  which 
  was 
  about 
  50 
  cc, 
  the 
  reduction 
  

   was 
  complete 
  in 
  2 
  or 
  3 
  minutes 
  with 
  small 
  quantities 
  of 
  iron, 
  

   and 
  in 
  only 
  a 
  slightly 
  longer 
  time 
  with 
  larger 
  quantities, 
  such 
  

   as 
  0-7 
  g. 
  The 
  reduction 
  was 
  somewhat 
  more 
  rapid 
  when 
  the 
  

   operation 
  was 
  started 
  at 
  the 
  boiling 
  point 
  of 
  the 
  liquid 
  than 
  

   when 
  the 
  liquid 
  was 
  cold. 
  It 
  appears 
  that 
  aluminium 
  gives 
  a 
  

   somewhat 
  more 
  rapid 
  reduction 
  than 
  does 
  zinc. 
  It 
  is 
  evident, 
  

   since 
  excellent 
  results 
  were 
  obtained, 
  that 
  the 
  method 
  furnishes 
  

   a 
  satisfactory 
  substitute 
  for 
  the 
  well-known 
  "Jones 
  reductor" 
  

   process 
  where 
  the 
  solution 
  is 
  passed 
  through 
  a 
  column 
  of 
  amal- 
  

   gamated 
  zinc 
  fragments. 
  In 
  some 
  of 
  the 
  experiments 
  the 
  rotat- 
  

   ing 
  cylinders 
  were 
  made 
  anodes 
  by 
  passing 
  an 
  electric 
  current 
  

   to 
  an 
  immersed 
  platinum 
  cathode 
  but 
  this 
  device 
  appeared 
  to 
  

   give 
  no 
  particular 
  advantage. 
  — 
  Jour. 
  Indust. 
  and 
  Eng. 
  Chem., 
  

  

  11, 
  1135. 
  H. 
  L. 
  w. 
  

  

  