THE 
LONDON,  EDINBURGH,   and   DUBLIN 
PHILOSOPHICAL     MAGAZINE 
AND 
JOURNAL    OF   SCIENCE. 
[FOURTH    SERIES.] 
APRIL   1872. 
XXX.  On  the  Relations  between  the  Atomic  Hypothesis  and  the 
Condensed  Symbolic  Expressions  of  Chemical  Facts  and  Changes 
known  as  Dissected  [Structural)  Formula.  By  C.  R.  A. 
Wright,  D.Sc,  Lecturer  on  Chemistry  in  St.  Mary's  Hospital 
Medical  School*. 
ON  comparing  the  published  views  and  statements  of  different 
chemists  on  the  subject  of  the  Atomic  Hypothesis,  it  is 
evident  that  in  some  instances  the  same  meanings  are  not  always 
given  to  the  words  employed  in  stating  the  fundamental  posi- 
tions of  the  various  lines  of  argument,  and  that  the  meaning 
and  scope  of  the  phrase  "  Atomic  Hypothesis  "  are  very  differ- 
ently understood  by  different  thinkers.  Thus  highly  contra- 
dictory statements  are  to  be  met  with— one  chemist  considering 
that  the  "law  of  multiple  proportions  has  no  existence  apart 
from  the  atomic  theory,"  and  that  the  atomic  theory  is  "  the 
very  life  of  chemistry,"  while  others  deny  in  toto  the  truth  of 
the  first  proposition,  and  say  that  "  the  science  of  chemistry  does 
not  require  or  prove  the  atomic  theory ." 
The  object  aimed  at  in  the  following  pages  is  to  show : — first, 
that  the  main  salient  facts  and  generalizations  on  which  chemical 
philosophy  is  founded  are  capable  of  expression  in  words,  and 
of  representation  by  the  symbols  in  ordinary  use,  without  in  any 
way  involving  the  ideas  bound  up  in  the  hypothesis  of  the  ex- 
istence of  material  atoms  as  devised  by  Dalton  (in  its  chemical 
relations)  and  subsequently  extended ;  and  secondly,  that  this 
hypothesis,  though  affording  a  clear  raison  d'etre  for  many  of 
these  facts,  is  yet  incapable  of  accounting  readily  fpr  all  of  them, 
*  Communicated  by  the  Author. 
Phil  Mag.  S.  4.  Vol.  43.  No.  286.  April  1872.  R 
