﻿Chemistry 
  and 
  Physics. 
  467 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistry 
  and 
  Physics. 
  

  

  1. 
  On 
  Solution 
  and 
  Pseudo-solution. 
  — 
  Some 
  years 
  ago 
  Linder 
  

   and 
  Pictox 
  concluded 
  from 
  their 
  examination 
  of 
  various 
  grades 
  

   of 
  arsenous 
  sulphide 
  solution, 
  that 
  there 
  is 
  no 
  defined 
  boundary 
  

   line 
  between 
  suspension 
  on 
  the 
  one 
  hand 
  and 
  perfect 
  solution 
  on 
  

   the 
  other 
  ; 
  the 
  difference 
  being 
  one 
  of 
  degree 
  of 
  aggregation 
  

   only. 
  They 
  have 
  now 
  added 
  another 
  grade 
  of 
  this 
  solution, 
  

   having 
  found 
  that 
  on 
  pouring 
  a 
  two 
  per 
  cent 
  arsenous 
  oxide 
  solu- 
  

   tion 
  into 
  hydrogen 
  sulphide 
  water, 
  the 
  mixture 
  is 
  not 
  only 
  dif- 
  

   fusible 
  but 
  can 
  be 
  filtered 
  through 
  a 
  porous 
  pot. 
  Of 
  the 
  As 
  2 
  S 
  8 
  

   solutions 
  already 
  prepared 
  therefore, 
  grade 
  (a) 
  is 
  made 
  up 
  of 
  

   aggregates 
  visible 
  under 
  the 
  microscope, 
  (f3) 
  is 
  invisible 
  but 
  not 
  

   diffusible, 
  (;') 
  is 
  diffusible 
  but 
  not 
  filterable 
  and 
  (6) 
  is 
  both 
  dif- 
  

   fusible 
  and 
  filterable, 
  although 
  it 
  scatters 
  and 
  polarizes 
  a 
  beam 
  

   of 
  light. 
  Experiments 
  with 
  the 
  higher 
  grade 
  solutions 
  chiefly 
  (;/) 
  

   show 
  that 
  as 
  regards 
  their 
  power 
  of 
  coagulating 
  these 
  solutions, 
  

   metallic 
  salts 
  can 
  be 
  divided 
  into 
  well 
  defined 
  groups 
  depending 
  

   upon 
  the 
  valency 
  of 
  the 
  metal 
  ; 
  trivalent 
  metals 
  having 
  the 
  high- 
  

   est 
  coagulative 
  power, 
  bivalent 
  metals 
  only 
  one 
  tenth 
  of 
  this 
  

   power 
  and 
  univalent 
  metals, 
  including 
  hydrogen 
  and 
  ammonium, 
  

   less 
  than 
  one 
  five-hundredth. 
  Moreover 
  these 
  differences 
  are 
  

   shown 
  by 
  the 
  same 
  metal 
  when 
  its 
  valence 
  varies. 
  And 
  the 
  

   authors 
  have 
  observed 
  that 
  silver 
  and 
  thallium 
  (in 
  its 
  thallous 
  

   salts) 
  fall 
  in 
  the 
  same 
  group 
  as 
  copper 
  and 
  the 
  bivalent 
  metals, 
  

   while 
  mercury 
  and 
  lead 
  belong 
  in 
  the 
  trivalent 
  group 
  with 
  alu- 
  

   minum 
  and 
  iron. 
  From 
  a 
  table 
  giving 
  the 
  relative 
  quantities 
  

   needed 
  for 
  coagulation 
  it 
  appears 
  that 
  one 
  molecule 
  of 
  aluminum 
  

   chloride 
  A1C1 
  3 
  possesses 
  the 
  same 
  coagulative 
  power 
  as 
  16'4 
  

   molecules 
  of 
  cadmium 
  chloride 
  or 
  YoO 
  molecules 
  of 
  sulphuric 
  

   acid. 
  As 
  to 
  the 
  nature 
  of 
  coagulation 
  it 
  was 
  observed 
  that 
  when 
  

   effected 
  by 
  barium 
  chloride 
  the 
  arsenous 
  sulphide 
  contained 
  

   barium 
  not 
  removable 
  by 
  water, 
  though 
  exchangeable 
  for 
  another 
  

   metal 
  when 
  digested 
  with 
  a 
  cold 
  solution 
  of 
  it, 
  such 
  as 
  calcium 
  

   nitrate. 
  Since 
  coagulation 
  is 
  due 
  to 
  the 
  positive 
  constituent 
  of 
  a 
  

   salt, 
  the 
  authors 
  were 
  led 
  to 
  inquire 
  whether 
  the 
  coagulative 
  

   power 
  of 
  salts 
  of 
  the 
  same 
  metal 
  is 
  proportional 
  to 
  the 
  number 
  of 
  

   free 
  positive 
  ions 
  in 
  the 
  solution. 
  And 
  a 
  comparison 
  of 
  the 
  molec- 
  

   ular 
  conductivities 
  of 
  the 
  chlorides, 
  bromides, 
  iodides, 
  nitrates 
  

   and 
  sulphates 
  of 
  potassium, 
  hydrogen, 
  sodium 
  and 
  ammonium, 
  

   which 
  are 
  due 
  to 
  the 
  free 
  ions 
  present, 
  with 
  the 
  coagulative 
  power, 
  

   appears 
  to 
  indicate 
  that 
  this 
  power 
  is 
  entirely 
  controlled 
  by 
  the 
  

   number 
  of 
  free 
  positive 
  ions 
  present. 
  — 
  J. 
  Chem. 
  Soc., 
  lxvii, 
  63, 
  

   February 
  1895. 
  g. 
  f. 
  b. 
  

  

  2. 
  On 
  the 
  Fluidity 
  of 
  Metals 
  below 
  their 
  Melting 
  Points. 
  — 
  It 
  

   has 
  been 
  pointed 
  out 
  by 
  Sprixg 
  that 
  many 
  metals 
  exhibit 
  prop- 
  

   erties 
  characteristic 
  of 
  the 
  liquid 
  state, 
  even 
  when 
  at 
  temperatures 
  

  

  