5 16  Experiences  with  Salol-coating  of  ^^.{^vJS/iq™' 
dish  being  now  kept. quite  warm  (almost  hot),  the  pills  rotated 
quite  rapidly  until  they  are  quite  shiny,  then  turned  into  a  cool 
dish,  and  the  rotation  continued  until  the  pills  are  quite  cool." 
This  plan  was  followed  to  the  letter,  in  the  first  several  attempts 
which  were  made.  The  results,  however,  were  not  satisfactory, 
mainly  because  insufficient  salol  is  ordered  for  the  first  three 
treatments.  Further,  the  use  of  more  heat  in  the  fourth  treatment 
is  very  likely,  in  fact  almost  certain,  to  melt  off  some  of  the  salol, 
and  again,  transferring  to  a  cool  dish  produces  uneven  coating  due 
to  a  too  sudden  or  irregular  reduction  of  temperature.  It  was,  there- 
fore, found  better  to  take  more  salol  with  which  to  start  the  treat- 
ment, and  also  as  nearly  as  possible  use  the  same  temperature  in  all 
of  the  treatments.  After  a  number  of  experiments  the  following 
plan  was  marked  out  and  has  been  used  with  constant  success"  by 
a  number  of  operators. 
One  of  the  most  important  details  from  the  standpoint  of  prac- 
tice is  the  selection  of  the  vessel  in  which  to  do  the  coating.  Con- 
cave capsules  and  similar  shaped  vessels  are  not  well  suited  because 
the  pills  tend  to  roll  out  during  the  rotation  of  the  vessel,  or  at 
least  get  to  some  extent  out  of  contact  with  the  melted  salol.  Flat 
bottom  vessels  with  flaring  sides  are  better  suited  because  the  pills 
are  not  so  likely  to  be  thrown  away  from  the  salol  during  rotation. 
But  there  is  still  some  chance  of  the  pills  flying  over  the  flaring 
sides.  The  vessel  which  appears  to  be  best  suited  is  a  flat  bottomed, 
white  enamel  pan,  with  perpendicular  sides ;  a  handle  gives  addi- 
tional convenience  to  this  vessel ;  a  size' convenient  for  coating  24  to 
30  pills  is  about  four  inches  in  diameter  by  about  1^/4.  inches  deep. 
The  inner  surface  should  be  smooth.  The  material  of  this  vessel 
seems  well  adapted  to  the  gradual  cooling  of  the  salol,  a  feature  which 
is  essential  to  success.  The  perpendicular  sides  of  this  vessel  prevent 
the  pills  from  flying  out  and  the  flat  bottom  keeps  the  pills  in  constant 
contact  with  the  salol. 
For  twenty-four  pills  of  one  grain  each,  twenty  grains  of  salol 
were  usually  found  to  be  sufficient  for  the  first  three  applications, 
and  for  the  fourth  and  final  treatment  about  seven  grains  additional 
were  required. 
The  vessel  having  been  decided  upon,  the  proportionate  amount 
of  salol  is  placed  in  it,  then  warmed  over  a  direct  flame  just  suffi- 
ciently to  melt  the  salol  (a  water  bath  is  unnecessary),  and  the 
salol  flowed  over  the  bottom  and  into  the  angle  of  the  vessel.  The 
