ANoVemberPi9iT* }  Experiences  with  Salol-coating  of  Pills.  517 
temperature  is  now  allowed  to  fall  until  the  salol  is  nearly  ready 
to  solidify;  at  this  point  the  pills  are  placed  in  the  vessel,  which 
is  immediately  rotated  to  prevent  the  pills  from  sticking  together 
either  from  capillarity  through  melted  salol  or  neighboring  pills,  or 
from  sudden  reduction  of  temperature  congealing  the  salol  in  the 
pills.  A  thump  against  a  block  or  the  hand  will  separate  pills  which 
rotation  alone  does  not.  Rocking  the  vessel  on  the  angle  will  also 
keep  the  pills  separated  and  in  a  motion  well  suited  to  proper  coat- 
ing. The  pills  must  not  be  rotated  too  rapidly  even  in  the  flat- 
bottomed  dish  with,  perpendicular  sides,  as  the  centrifugal  force 
may  throw  the  pills  against  the  wall  of  the  dish  and  out  of  contact 
with  the  salol. 
Resting  the  vessel  upon  the  counter  or  the  hand  during  rota- 
tion, and  using  just  enough  motion  to  keep  the  pills  separated  gives 
the  best  result.  The  vessel  should  be  rotated  or  rocked  until  free 
from  sensible  heat.  The  pills  are  then  turned  out  into  a  box.  The 
coat  of  salol  taken  on  in  this  first  treatment  will  not  usually  mask 
the  color  of  a  black  pill.  For  the  second  treatment,  the  dish  is 
again  heated  just  sufficiently  to  melt  the  salol  remaining  in  it,  when 
it  has  cooled  to  some  extent,  the  salol  still  liquid,  the  pills  are  put 
back  into  it  and  rotated  as  before,  until  cold. 
The  second  treatment  will  show  a  decided  change  in  appear- 
ance. A  third  application  of  salol  is  made  in  the  same  manner. 
This  treatment  appreciably  increases  the  shell  of  salol.  For  the 
fourth  coating  it  is  necessary  to  supply  more  salol,  usually  about 
one-third  of  the  original  amount  taken,  it  being  added  to  whatever 
remains  in  the  vessel.  For  the  fourth  and  final  coating,  the  vessel 
does  not  need  to  be  made  any  warmer  than  for  the  first  three  coat- 
ings, nor  is  it  necessary  to  transfer  the  pills  to  another  dish,  as 
suggested  by  the  National  Formulary. 
The  rough  or  uneven  appearance  of  the  coating  that  may  be 
met  with  in  one's  first  efforts  can  be  repaired  by  heating  sufficiently 
to  melt  off  all  the  salol,  and  then  resorting  to  proper  conditions. 
This  rough  appearance  is  usually  due  either  to  insufficient  salol  or 
to  a  sudden  drop  in  the  temperature  of  the  melted  salol. 
Should  the  pills  partly  coated  be  thrown  into  a  vessel  which 
is,  too  hot,  the  salol  will  be  melted  at  the  point  of  contact  and  the 
pills  show  unevenness  where  salol  has  been  lost,  or  even  bare  spots. 
To  remedy  this  appearance,  melt  off  all  the  salol,  and  return  to  the 
conditions  outlined. 
