The  quantitative  laws  of  chemical  composition,
to  the  discussion  of  which  so  much  time  is
applied  and  the  use  of  which,  as  they  express
themselves  in  formula  and  equation,  is  so  con-
stant, are  too  often  ignored.  Quantitative
experiments,  and  the  proper  utilization  of  the
data  which  they  give,  are  indispensable  parts
of  the  laboratory  work.
The  directions  for  laboratory  work  should
be  so  simple,  clear,  and  full  that  the  experi-
ments can  be  done  with  the  minimum  of  indi-
vidual supervision.     The  object  of  the  experi-

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ment,  the  apparatus,  the  kind  and  quantity  of
the  materials,  and  the  method  of  manipulation
should  be  clearly  explained.  This  part  of  the
directions  is  important  in  order  that  we  may
be  certain  that  each  separate  pupil  has  before
him  exactly  the  desired  phenomenon.  Ques-
tion marks  should  call  attention  to  the  matters
to  be  observed,  and  direct  questions,  calling
for  reflection,  should  be  asked.  The  questions
should  be  of  two  kinds,  which  should  be  care-
fully distinguished.  One  class  includes  ques-
tions, the  answers  to  which  are  obtainable  by
observation  and  reasoning  alone.  The  answers
to  the  other  class  of  questions  will  require
reference  to  the  book,  or  some  other  source  of
information,  as  well.  The  pupil  requires  to  be
notified  which  sort  of  question  he  is  handling,
in  order  that  he  may  not,  on  the  one  hand,
use  the  book  when  he  should  be  employing  his
own  eyes  or  head,  or,  on  the  other  hand,  en-
deavor to  answer  from  his  own  observations,
supplemented  by  a  little  speculation,  a  ques-
tion which  calls  for  actual  information  that  he
is  not  in  a  position  to  supply.
