104  Pill  Coating.  {Am,Feb.!"'i8^farm' 
Dissolve  at  a  gentle  heat,  then  add  the  white  of  an  egg,  and  heat 
until  the  albumen  coagulates,  strain  through  flannel  into  a  water 
bath  kept  at  a  low  temperature,  add  <5ij.  glycerin,  gij.  S.V.R.,  and 
acid,  boric,  gr.  vi. 
A  beautifully  clear  solution  is  thus  obtained  ;  the  clearer  the  solu- 
tion the  better  the  polish.  When  gelatin  coating  is  carried  out  on 
a  small  scale,  it  is  the  usual  custom  to  coat  the  pills  singly,  but  I 
have  adopted  another  plan  and  find  it  answer  equally  well  and 
occupy  considerably  less  time. 
I  have  a  rounded  piece  of  thin  wood  with  a  thick  layer  of  cork 
stuck  round  the  edge,  and  in  the  centre  a  small  hole,  through  which 
I  have  a  little  ferrule,  which  enables  me  to  place  the  concern  on  a 
small  iron  peg  fastened  in  a  wooden  stand. 
The  cost  of  making  the  whole  turn  out  would  amount  to  about 
ninepence.  It  is  convenient*  to  have  three  or  four  boards  at  hand; 
the  stand,  of  course,  would  be  adaptable  to  any  of  them.  I  have 
the  boards  with  good  needles  firmly  fastened  in  the  cork  to  the 
number  of  six,  twelve,  twenty-four  and  forty-eight.  Now  attach 
the  pills  to  be  coated  to  the  points  of  the  needles  and  dip  in  the 
solution,  taking  care  not  to  keep  them  in  too  long,  as  a  thick  coat- 
ing is  undesirable.  Place  the  board  with  the  pills  on  back  on  the 
peg,  revolve  in  a  gentle  manner  to  render  the  coating  even,  and 
give  it  an  occasional  turn  round.  By  doing  the  coating  in  the 
evening  the  pills  are  ready  to  be  taken  off  the  needles  and  stored 
away  in  bottles  the  next  morning. 
(2)  Pearl  Coating. — To  do  this  successfully  several  conditions  are 
of  great  importance,  without  attention  to  which  the  French  chalk 
will  fail  to  shine.  Care  must  be  taken  in  the  selection  of  a  proper 
excipient  for  working  the  mass,  for  although  pills  when  pearl  coated 
are  not  within  view  of  the  naked  eye,  they  nevertheless  must  be 
properly  made  to  be  properly  coated. 
Glycerin  being  hygroscopic  is  not  an  excipient  that  should  be 
used. 
The  pills  ought  to  be  as  nearly  round  as  possible  and  moderately 
hard  and  dry ;  it  is  best  to  keep  them  exposed  on  trays  for  at  least 
a  day  before  the  coating  is  proceeded  with.  Should  the  mass  be 
crumbly  the  condition  may  be  considered  to  be  one  of  the  most 
bitter  enemies  of  successful  coating ;  the  operation  will  necessarily 
be  a  failure,  as  the  pills  will  most  likely  crack,  and  when  that  takes 
