﻿488 
  Transactions. 
  — 
  Chemistry. 
  

  

  It 
  is 
  therefore 
  quite 
  certain 
  that 
  any 
  substance 
  capable 
  of 
  dialyzing 
  will, 
  

   when 
  swung 
  clear 
  of 
  all 
  attachments 
  in 
  pure 
  water, 
  describe 
  movements 
  

   of 
  great 
  persistency 
  which 
  are 
  due 
  to 
  osomose, 
  and 
  in 
  order 
  to 
  complete 
  

   the 
  evidence 
  which 
  is 
  yet 
  required 
  to 
  show 
  that 
  osomose 
  is 
  the 
  cause 
  of 
  

   the 
  persistent 
  suspension 
  of 
  clay 
  in 
  water, 
  it 
  only 
  remains 
  to 
  be 
  shown 
  

   that 
  this 
  substance 
  (clay) 
  is 
  capable 
  of 
  dialyzing. 
  

  

  For 
  this 
  purpose 
  I 
  adduce 
  Prof. 
  Graham's 
  opinion 
  of 
  the 
  mode 
  in 
  which 
  

   osomose 
  is 
  effected 
  (an 
  opinion 
  in 
  which 
  I 
  fully 
  concur). 
  This 
  able 
  chemist 
  

   (the 
  discoverer, 
  by 
  the 
  way, 
  of 
  osomose) 
  attributes 
  it 
  entirely 
  to 
  the 
  exertion 
  

   of 
  chemical 
  affinity. 
  Any 
  dialyzing 
  diaphragm 
  having 
  water 
  on 
  the 
  one 
  

   side 
  and 
  saline 
  water 
  on 
  the 
  other, 
  is, 
  he 
  holds, 
  constantly 
  absorbing, 
  that 
  

   is 
  combining 
  with 
  water 
  towards 
  the 
  side 
  which 
  is 
  in 
  contact 
  with 
  water 
  

   alone, 
  and 
  giving 
  it 
  up 
  to 
  the 
  other 
  side, 
  that 
  is, 
  to 
  the 
  saline 
  solution 
  there. 
  

  

  Thus 
  it 
  appears 
  that 
  any 
  substance 
  which, 
  while 
  insoluble, 
  or 
  nearly 
  so, 
  

   in 
  water, 
  can 
  still 
  weakly 
  combine 
  with 
  it, 
  and 
  in 
  various 
  proportions, 
  is 
  

   competent 
  to 
  dialyze. 
  

  

  Now, 
  clay 
  is 
  most 
  certainly 
  such 
  a 
  substance 
  ; 
  it 
  hydrates 
  readily, 
  and 
  

   is 
  as 
  readily 
  de-hydratad, 
  that 
  is 
  in 
  part, 
  and 
  the 
  proportion 
  in 
  which 
  it 
  

   hydrates 
  manifestly 
  varies, 
  and 
  under 
  the 
  very 
  conditions 
  it 
  is 
  necessary 
  

   that 
  it 
  should 
  do 
  so 
  for 
  my 
  argument, 
  that 
  is, 
  as 
  placed 
  in 
  pure 
  water 
  and 
  

   saline 
  water, 
  as 
  is 
  manifest 
  to 
  the 
  eye 
  even 
  when 
  clay 
  in 
  water 
  is 
  coagulated 
  

   by 
  salt. 
  

  

  Indeed, 
  Prof. 
  Grraham 
  has 
  shown 
  that 
  porous 
  earthenware 
  dialyzes 
  ; 
  he, 
  

   however, 
  attributed 
  this 
  property 
  to 
  the 
  alumina 
  present 
  therein 
  ; 
  but 
  I 
  fail 
  

   to 
  see 
  how 
  alumina 
  could 
  be 
  liberated 
  from 
  the 
  earthenware 
  in 
  his 
  experi- 
  

   ment. 
  I 
  should 
  rather 
  attribute 
  the 
  effect 
  he 
  observed 
  to 
  that 
  portion 
  of 
  

   the 
  ware 
  which 
  had 
  been 
  hydrated 
  to 
  clay. 
  

  

  It 
  is 
  therefore, 
  I 
  think, 
  now 
  clearly 
  shown 
  that 
  clay 
  is 
  capable 
  of 
  

   dialyzing, 
  and 
  so 
  is 
  competent, 
  under 
  conditions 
  already 
  named, 
  to 
  describe 
  

   movements 
  due 
  to 
  osomose. 
  

  

  The 
  principal 
  cause, 
  then, 
  if 
  not 
  indeed 
  the 
  sole 
  cause, 
  of 
  the 
  persistent 
  

   suspension 
  of 
  clay 
  in 
  water, 
  is 
  undoubtedly 
  motion 
  communicated 
  to 
  it 
  by 
  

   osomose 
  ; 
  and 
  as 
  osomose 
  is 
  the 
  more 
  rapidly 
  produced 
  in 
  saline 
  solutions 
  

   the 
  weaker 
  they 
  are, 
  and 
  further, 
  as 
  the 
  motion 
  thereby 
  derivable 
  should 
  be 
  

   applied 
  with 
  greater 
  effect 
  to 
  clay 
  particles 
  the 
  more 
  hydrated 
  and, 
  con- 
  

   sequently, 
  the 
  lighter 
  they 
  are, 
  it 
  follows 
  that 
  suspension 
  of 
  clay 
  in 
  water 
  

   will 
  be 
  the 
  more 
  persistent 
  the 
  less 
  saline 
  the 
  water 
  is 
  — 
  a 
  fact 
  which, 
  as 
  

   you 
  may 
  remember, 
  I 
  have 
  long 
  since 
  demonstrated. 
  

  

  In 
  water 
  saline 
  to 
  a 
  certain 
  extent, 
  clay 
  particles 
  by 
  de-hydration 
  acquire 
  

   a 
  density 
  too 
  great 
  to 
  allow 
  of 
  their 
  remaining 
  sensitive 
  to 
  the 
  motion 
  proper 
  

   to 
  osomose 
  ; 
  they 
  therefore 
  coalesce, 
  and 
  gravity 
  soon 
  asserts 
  itself* 
  

  

  