﻿Rhythmic 
  Precipitation 
  . 
  

  

  15 
  

  

  which 
  there 
  may 
  be 
  a 
  bending 
  of 
  the 
  bands. 
  (See 
  tig. 
  3.) 
  

   These 
  are 
  doubtless 
  due 
  to 
  irregularities 
  of 
  the 
  diffusion, 
  and 
  

   perhaps, 
  in 
  part, 
  to 
  irregular 
  distribution 
  of 
  certain 
  impurities 
  

   or 
  disturbing 
  factors. 
  The 
  quite 
  leisurely 
  deposition 
  of 
  the 
  

   very 
  fine 
  silver 
  chromate 
  granules 
  suggests 
  that 
  each 
  one 
  is 
  

   formed 
  almost 
  independently 
  and 
  kept 
  independent, 
  at 
  least 
  

   for 
  some 
  time, 
  by 
  the 
  gelatine. 
  The 
  experiments 
  of 
  Hatschek 
  

   and 
  Liesegang 
  investigating 
  the 
  possible 
  sowing 
  action 
  of 
  pre- 
  

   cipitate 
  already 
  in 
  the 
  gelatine 
  have 
  shown 
  how 
  little 
  this 
  action 
  

   needs 
  to 
  be 
  taken 
  into 
  account 
  in 
  the 
  formation 
  of 
  the 
  Liese- 
  

   gang 
  rings. 
  The 
  question 
  as 
  to 
  whether 
  this 
  isolation 
  of 
  pre- 
  

   cipitated 
  granules 
  is 
  entirely 
  due 
  to 
  the 
  action 
  of 
  the 
  gelatine 
  

  

  Fig. 
  5. 
  

  

  o 
  

  

  

  "p 
  

  

  — 
  > 
  

  

  

  next 
  arises. 
  An 
  experiment 
  was 
  made 
  with 
  diffusion 
  of 
  silver 
  

   into 
  a 
  chromate-bearing 
  gelatine 
  to 
  which 
  a 
  small 
  amount 
  of 
  

   citric 
  acid 
  had 
  been 
  added. 
  No 
  banded 
  precipitate 
  was 
  formed 
  

   but 
  a 
  continuous 
  precipitate 
  in 
  the 
  colloidal 
  state. 
  That 
  is 
  to 
  

   say, 
  by 
  increasing 
  the 
  concentration 
  of 
  hydrions 
  the 
  number 
  of 
  

   points 
  at 
  which 
  precipitation 
  takes 
  place 
  had 
  been 
  increased 
  

   and 
  the 
  size 
  of 
  the 
  particles 
  resulting 
  from 
  precipitation 
  had 
  

   been 
  decreased. 
  (The 
  definition 
  of 
  a 
  colloid 
  suspension 
  being 
  

   that 
  the 
  particles 
  range 
  in 
  size 
  somewhere 
  between 
  the 
  limits 
  

   of 
  'Iju 
  and 
  lfA/j, 
  in 
  diameter.) 
  

  

  In 
  the 
  case 
  where 
  the 
  chromate 
  solution 
  is 
  diffusing 
  outwards 
  

   this 
  action 
  of 
  the 
  hydrions 
  appears 
  to 
  be 
  prevented 
  or 
  very 
  

   much 
  curtailed, 
  possibly 
  owing 
  to 
  the 
  potassions 
  present. 
  Also 
  

   in 
  the 
  "secondary" 
  bands 
  of 
  the 
  silver 
  diffusion 
  this 
  action 
  

   appears 
  to 
  have 
  been 
  prevented. 
  This 
  is 
  also 
  probably 
  due 
  to 
  

   the 
  "dominance" 
  of 
  potassions 
  relatively 
  to 
  the 
  hydrions 
  in 
  

  

  