506         Dr.  C.  R.  A.  Wright's  Reply  to  "An  Examination 
proposition  of  this  kind  relating  to  the  nature  of  matter ;  and 
when  it  is  stated  that  the  atomic  hypothesis  is  unnecessary, 
what  is  meant  is  that  in  chemical  investigation,  where  the  object 
is  to  discover  new  facts,  properties,  substances,  or  reactions,  to 
connect  such  discoveries  with  previous  ones,  to  furnish  the 
foundation  for  prediction  by  means  of  induction,  to  systematize 
and  correlate  the  results  obtained,  &c,  neither  of  these  two  ideas 
is  in  any  way  involved. 
It  does  not,  however,  follow  that  because  one  does  not  see  the 
necessity  of  admitting  Dalton's  hypothesis,  one  is  therefore  de- 
barred from  employing  the  generalization  and  convention  of 
which  he  was  the  distinguished  originator,  nor  that  one  is  guilty 
of  inconsistency  in  so  doing;  but  it  does  follow,  if  any  one 
makes  the  statement  that  the  atomic  theory  is  involved  in 
Dalton's  generalization  and  that  this  generalization  has  no  ex- 
istence apart-  from  the  atomic  theory,  that  he  is  employing  the 
term  atomic  theory  in  a  sense  different  from  that  in  which  I  have 
used  the  phrase  atomic  hypothesis. 
When  the  developments  that  have  been  made  on  Dalton's 
original  conceptions  are  closely  examined,  it  is  noticeable  that 
an  entire  change  of  idea  in  many  respects  has  taken  place,  so 
that  the  term  atom  is  now  employed  to  mean  something  very 
different  from  what  it  meant  when  Dalton  first  introduced  the 
word  into  chemistry.  One  of  the  objections  urged  in  my  paper 
against  the  use  of  the  language  of  the  atomic  hypothesis  is  that 
this  language  is  practically  ambiguous,  owing  to  the  gradual 
alteration  that  has  taken  place  in  the  meaning  of  the  terms,  an 
alteration  carried  so  far  by  Dr.  Williamson  as  to  lead  to  the 
distinct  denial  of  the  necessity  of  admitting  the  very  proposition 
expressing  Dalton's  acceptation  of  the  term  atom,  viz.  that 
matter  is  made  up  of  small  indivisible  portions.  For  the  sake 
of  clearness,  therefore,  it  does  not  seem  desirable  that  the  terms 
involved  in  this  admittedly  unnecessary  hypothesis  should  be 
retained  and  used  in  senses  often  opposed  to  those  in  which 
they  were  at  first  employed.  It  may  be  urged  that  no  other 
single  word  exists  capable  of  expressing  the  different  ideas  con- 
veyed by  the  term  atom  as  now  employed ;  and  grammatically 
speaking,  there  appears  to  be  no  reason  why  the  word  atom 
should  not  indicate  a  minimum  ratio  or  indivisible  proportion  as 
much  as  an  indivisible  fragment  of  matter ;  still  it  does  not  seem 
philosophical  to  use  terms  which  not  only  are  easily  susceptible 
of  double  meanings,  but  which  must  necessarily  entail  ambi- 
guity ;  and  in  point  of  fact  there  is  no  actual  necessity  to  use 
such  terms,  inasmuch  as  all  the  ideas  involved  can  be  conveyed 
in  other  and  more  definite  language. 
It  being  thus  shown  that  what  Mr.  Atkinson  actually  dis- 
