MANUFACTURING  PILLS  ON  A  LARGE  SCALE.  13 
mixed  ;  now,  by  a  rapid  and  dexterous  rotary  and  shaking  motion 
of  the  pan  and  its  contents,  diffuse  the  powder  equally  over  the 
moistened  granules  till  they  are  completely  and  uniformly 
covered,  they  will  soon  require  additional  moistening  and  another 
supply  of  the  dry  powder,  which  on  further  rotation  will  be  pretty 
evenly  distributed.  By  repeating  the  process  of  moistening  and 
dusting  with  the  constant  and  skilful  application  of  the  com- 
bined rotary  and  shaking  motion,  pills  will  be  formed  which  will 
be  perfectly  round  and  nearly  uniform  in  size.  When  nearly  of 
the  required  size  a  sieve  is  used  of  the  previously  ascertained 
proper  number  of  meshes  to  the  inch,  by  which  those  yet  too  small 
are  returned  to  the  pan  for  further  treatment,  while  those  which 
have  attained  sufficient  size  are  separated.  If  any  are  too  large 
they  should  be  reserved  for  drying  and  powdering,  and  may  then 
be  mixed  with  more  of  the  powders  and  made  overjagain.  The 
chief  art  in  making  pills  by  this  process  lies  in  the  regulation  of 
the  temperature  and  in  a  dexterous  manipulation,  by  which  the 
moistened  granules  and  pills  are  prevented  from  adhering  together 
and  rendered  perfectly  round. 
The  pan  should  never  be  allowed  to  get  hot — never  more  than 
moderately  warm,  it  should  be  grasped  by  the  left  hand,  with 
which  the  motion  is  imparted  to  it,  while  the  right  hand  is  used 
to  prevent  the  pills  adhering  and  to  aid  their  rotary  motion  upon 
the  bottom  of  the  pan  and  upon  each  other. 
A  remarkable  feature  of  this  process  is  its  adaptation  to  large 
quantities.  I  have  never  known  it  tried  with  less  than  several 
pounds  of  the  ingredients,  and  though  some  trials  have  proved 
rather  abortive  it  has  generally  produced  very  uniform  and  round 
pills.  Compound  cathartic  and  rhubarb  pills  in  charges  of  ten 
pounds  succeed  particularly  well.  A  lot  of  pills  of  reduced  iron 
was  quite  spoiled ;  they  were  flat  and  ill-shaped,  probably  too 
heavy  to  remain  round  when  softened  by  the  heat.  Experience 
will,  of  course,  indicate  variations  from  the  process,  but  the  prin- 
ciple is  generally  applicable  to  substances  obtainable  in  dry 
powders.  Of  course  much  care  is  required  in  adjusting  the  size 
of  the  pills ;  the  granules  add  slightly  to  this,  although  the 
absence  of  the  pressure  applied  in  the  process  of  trituration  and 
in  rolling  and  cutting,  may  render  the  pills  by  this  process 
