White  to  brown

Comp

Carbon

Carbon

PbS

ZnS

Pyr.  etc

Infusible

Infusible

Easily  fusible

Infusible

parallel  vertical  columns,  and  the  trouble  of  writing  the
list  of  characters  over  each  time  may  be  avoided  if  they
are  written  on  the  edge  of  the  first  left  page  and  the
corresponding  strip  from  a  sufficient  number  of  the  sheets
following  neatly  cut  off.  A  little  contraction  of  some
common  words  will  save  space:  hardness  is  often  indicated
by  the  letter  H.;  specific  gravity  by  G. ;  yellow  may  be
written  yw,  and  so  on.  When  a  character  is  particularly
important  it  may  be  underscored  or  followed  by  an  exclama-
tion point.  It  is  not  worth  while  to  repeat  in  tabular  form
the  entire  description  in  the  text;  a  little  experience  will
soon  show  how  much  may  be  advantageously  written  down.
It  will  also  be  a  useful  exercise  to  fill  out  a  similar
column,  so  far  as  the  individual  case  allows,  for  any  specie*
from  the  specimen  itself,  and  then  it  may  be  compared
with  the  description  in  the  book,  or  the  list  in  the  stu-
dent's note-book  made  out  from  the  book.  If  the  species
was  not  known  at  first,  this  list  of  characters  will  often
suffice  to  enable  the  student  to  determine  it.
DESCRIPTION   OF   41/iiERAL   SPECIES.  161

It  is  not  necessary  to  learn  by  sheer  effort  of  memory  all
the  characters  from  the  book  at  once;  this  would  be  diffi-
cult and  tiresome;  the  most  important  can  be  learned  (and
first  the  chemical  composition),  while  the  knowledge  of
most  of  the  physical  characters  is  rather  to  be  acquired
gradually  by  the  repeated  handling  of  the  specimens
themselves.
