Black,  whose  mind  had  been  trained  in  the  strictest  habits  of
inductive  philosophy,  and  who,  in  his  celebrated  Essay  on  the  true
cause  of  the  causticity  of  the  alkalies,  had  given  so  remarkable  an
example  of  its  correct  and  rigorous  application,  was  never  entirely
convinced  of  the  accuracy  or  relevancy  of  Newton's  reasoning
on  this  subject,  and  did  not  consider  the  argument  derived  from
it  against  the  theory  of  phlogiston  as  altogether  irrefragable.*

It  is  less  our  object,  however,  to  state  objections  to  a  theory  which
we  know  to  be  false,  than  to  explain  the  reason  why  it  was  so  long
considered  to  be  true. Much  must  undoubtedly  be  attributed  to
the  influence  of  the  persuasion  which  had  completely  occupied  the
minds  of  the  chemists  of  all  nations  that  the  bases  of  this  theory
were  satisfactorily  established,  and  that  it  was  fully  competent  to
explain  the  results  of  chemical  action  which  had  been  hitherto  ob-
served. Even  the  great  theories  of  Newton  in  optics  and  physical
astronomy  were  not  accepted  by  men  of  science  with  a  more  entire
and  unhesitating  faith :  Black,  Priestley,  Watt,  and  Kirwan  in  Eng-
land, Bergman  and  Scheele  in  Sweden,  Macquer  and  Morveau  in
France,  not  merely  acquiesced  in  its  general  truth,  but  warmly  de-
fended it :  whilst  in  Germany,  the  country  of  its  birth,  it  continued
to  maintain  its  empire  undisturbed  long  after  it  had  been  elsewhere
abandoned  as  altogether  untenable. Cavendish,  whose  mind  had
received  the  most  enlarged  philosophical  training  of  all  the  great
chemists  of  his  age,  whilst  he  admitted  generally  its  conclusions,
cautiously  guarded  himself  against  any  undue  influence  which
they  might  exercise  upon  the  character  of  the  deductions  which
could  properly  be  drawn  from  his  own  experiments:  it  was
Lavoisier  alone  who,  from  the  first  opening  of  his  chemical  life,
struggled  with  remarkable  foresight  and  undaunted  resolution
against  the  principles  of  the  phlogistic  theory,  when  the  state  of
chemical  science  was  not  sufficiently  advanced  to  remove  very
serious  objections  to  his  own. It  was  the  great  discovery  of  the

*  Black's  Lectures,  by  Robiton,  rol. ii. p. 644. It  was  in  consequence  of
Dr. Black's  doubts  on  this  subject  that  Dr. 