Am.  Jour.  Pharrti. 
March.  1905. 
Life-History  of  a  Doctrine. 
117 
Let  us  take  another  doctrine — that  of  phlogiston.  The  embry- 
ology of  this  doctrine  has  not  been  clearly  worked  out,  but  its  life- 
history  has  been  traced  pretty  carefully.  We  know  how  it  died  and, 
in  the  events  that  followed,  it  is  not  difficult  to  find  evidence  of  its 
existence  after  death.  It  was  through  the  influence  of  this  doctrine 
that  chemists  came  to  recognize  the  common  features  of  those  phe- 
nomena that  we  now  group  together  under  the  general  name  of 
oxidation.  They  were  all  ascribed  to  one  cause,  a  subtle  substance, 
phlogiston.  The  search  of  this  substance  became  the  great  problem 
of  chemistry.  The  possibility  of  finding  it  was  a  great  incentive  to 
work.  What  matters  it  that  the  doctrine  of  phlogiston  became 
aged  and  died  and  was  buried  ?  It  did  good  service — inestimable 
service:  It  kept  its  disciples  at  work  and  led  them  through  this 
work  nearer  and  nearer  to  the  truth.  In  its  life  it  passed  through 
the  period  of  infancy  with  all  its  attendant  dangers,  through  the 
period  of  enthusiastic  youth,  through  sturdy  manhood,  and  it 
reached  old  age  with  its  attendant  signs  of  weakness  and  decay.  It 
died  at  last,  but  only  after  a  mighty  struggle.  The  act  of  dying 
was  prolonged.  Since  then  generations  of  astute  teachers  of  chem- 
istry have  pointed  out  to  their  perhaps  even  more  astute  scholars 
the  errors  of  phlogisticians,  and  they  have  all  smiled  and  wondered 
how  these  deluded  men  could  ever  have  been  deluded.  Possibly 
they  forget  that  those  at  whom  they  smile  were  the  leaders  of  their 
times,  and  that  these  leaders  were  trying  as  earnestly  as  the  chem- 
ists of  our  own  day  to  learn  the  truth. 
What  is  the  spiritual  part  of  the  doctrine  of  phlogiston  that  lives 
after  its  death  ?  Clearly  it  is  the  idea  that  all  the  phenomena  of 
combustion,  including  calcination,  have  a  common  cause.  That 
cause  has,  to  be  sure,  been  shown  to  be  oxygen.  The  phlogisticians 
thought  that  the  cause  was  phlogiston,  a  purely  imaginary  sub- 
stance. Priestley  and  Scheele  and  Lavoisier  showed  that  it  is  an 
invisible  gas  working  quite  differently  from  the  way  the  phlogisti- 
cians supposed.  The  life  of  the  doctrine  of  phlogiston  left  us  richer 
in  material  possessions  and  in  ideas.  The  discovery  of  oxygen, 
which  is,  no  doubt,  the  most  important  discovery  ever  made  in  the 
field  of  chemistry,  tended  to  give  a  materialistic  trend  to  the 
thoughts  of  chemists.  Both  the  philosopher's  stone  and  phlogiston 
were  imaginary  substances  that  were  sought  in  vain.  Although 
both  have  been  described  by  enthusiastic,  but  inaccurate,  and  per- 
