Am.  Jour.  Pharru.  \ 
March,  1903.  J 
Life-History  of  a  Doctrine. 
125 
Association  for  the  Advancement  of  Science  last  summer,  Professor 
Edward  Divers  took  as  his  theme  "  The  Atomic  Theory  without 
Hypothesis."  Let  me  quote  a  few  passages  from  his  address.  He 
says  :  "  The  atomic  theory  of  chemistry  stands  unsurpassed  for  the 
way  in  which  it  has  fulfilled  the  purpose  of  every  great  theory — that 
of  giving  intellectual  mastery  of  the  phenomena  of  which  it  treats. 
But  in  the  form  in  which  it  was  enunciated,  and  still  is  universally 
expressed  and  accepted,  it  has  the  defect  of  resting  upon  a  meta- 
physical basis,  namely,  upon  the  ancient  hypothesis  that  bodies  are 
not  continuous  in  texture,  but  consist  of  discrete,  ultra-minute  parti- 
cles whose  properties,  if  known,  would  account  for  those  of  the 
bodies  themselves.  Hence  it  has  happened  that,  despite  the  light 
it  throws  upon  the  relations  of  chemical  phenomena  and  the  simple 
means  it  affords  of  expressing  those  relations,  this  theory  has  always 
been  regarded  with  misgiving,  and  failed  to  achieve  that  explicit 
recognition  which  its  abounding  merit  calls  for.  Indeed,  the  desire 
has  been  expressed  to  see  the  time  when  something  on  a  more  solid 
foundation  shall  have  taken  its  place."  Professor  Divers  thinks  that 
in  dealing  with  chemical  phenomena  we  can  avoid  thinking  of  dis- 
crete particles  of  matter.  The  law  of  constant  proportions  is,  to  be 
sure,  entirely  comprehensive  as  a  law  without  the  aid  of  the  atomic 
theory,  and  so  is  the  law  of  multiple  proportions,  but  can  we  possi- 
bly, as  yet,  co-ordinate  them  without  this  aid  ?  I  do  not  think  I  can, 
and  this  doesn't  worry  me.  The  kind  of  atom  that  my  mind's  eye 
sees  seems  to  help  me,  but  that  eye  has  not  troubled  itself  with  other 
attributes  of  the  atom  than  that  one  which  is  needed.  It  will  be 
remembered  that  in  Dalton's  time  it  was  proposed  to  substitute  for 
the  atom  the  equivalent,  and  some  even  wanted  to  use  the  concep- 
tion of  combining  numbers.  This  last  conception  appeals  to  the 
systematic  mind  at  first,  but  one  cannot  go  very  far  with  it  without 
tacitly  accepting  the  atomic  theory.  On  this  point  Professor  Divers 
says :  "  Refusing  to  commit  themselves  to  belief  in  the  hypothesis, 
chemists  have  thought  from  the  first  to  escape  the  adoption  of  the 
atomic  theory  by  putting  Dalton's  discovery  into  something  like 
these  words  :  Numbers  called  proportional  or  combining  numbers 
can  be  assigned  to  the  chemical  elements — one  to  each — which  will 
express  all  the  ratios  of  the  weights  or  masses  in  which  substances 
interact  and  combine  together.  "  Perhaps,"  says  Professor  Divers, 
"  the  atomic  theory  is  successfully  set  aside  by  expressing  what  is  an 
