375.)  Here  they  are  biscuited  (or  cruced),  that  is,  raised  to  a  red  heat
sufficient  to  give  some  hardness,  but  not  to  vitrify  or  even  to  cause
incipient  fusion.  They  are  then  slowly  cooled,  and  holes  drilled  for  the
pins,  or  else  holes  drilled  into  the  base  of  the  blocks,  as  may  be  pre-
ferred :  the  pins  are  fastened  in  place  by  a  little  "body-slip,"  carefully
worked  in  with  the  knife-point.  Slight  defects  of  carving  may  now  be
corrected :  the  enamels  are  then  applied  with  a  camel's-hair  brush.
They  must  be  reduced  to  the  consistence  of  cream,  and  require  much
skill  and  judgment  in  their  application,  so  that  the  point-enamel  shall
blend  properly  with  the  body-enamel ;  also  the  gum-enamel  must  pre-
serve its  distinctness  of  outline,  and,  by  its  varying  thickness,  give  those
alternations  of  shade  observable  in  the  natural  gum.  It  should  hei'e
be  remarked,  that  some  carvers  make  no  allowance  in  the  body  for
shrinkage  in  length  of  the  tooth,  but  compensate  by  the  addition  of
point-enamel.     The  crowns  of  bicuspids  and  molars  are  usually  enam-


740


PORCELAIN    TEETH.
Fig.   376.
elled ;  also  part  of  the  inner  surface  of  the  blocks,  and  in  some  blocks
the  gum-enamel  extends  to  the  base.  When  platina  pins  are  inserted,
the  part  of  the  block  to  be  covered  by  the  backing  is  not  enamelled.
It  is  scarcely  necessary  to  remark  that  a  large  assortment  of  body-,
point-,  and  gum-enamels  is  required ;  also,  that  these  must,  with  great
care,  be  kept  separate,  with  their  respective  test-pieces  attached  ;  for,
except  by  the  pinkish  color  of  gum-enamel,  they  cannot  be  distin-
guished when  in  form  of  powder,  paste,  or  cream.
The  blocks  are  now  well  dried,  and  are  ready  for  the  furnace.  Fig.
