Am.  Jour.  Pharm. 
Feb.,  1878. 
Pills  and  Till  Coatings. 
77 
this  way  they  will  keep  good  for  years.  I  have  a  specimen  of  some 
pills  thus  coated  more  than  four  years  since  ;  on  cutting  them  open  they 
will  be  found  less  hard  then  they  would  have  become  in  as  many  weeks 
if  left  exposed  as  these  have  been  and  uncoated. 
There  is  a  drawback  to  this  covering  in  the  case  of  pills  containing 
essential  oils;  the  oil  dissolves  some  of  the  coloring  matter  of  the  pill, 
and  takes  it  through  the  coating  which  then  becomes  yellow  or  brown 
and  unsightly*  Manufacturers  of  these  pills  on  the  large  scale  usually 
get  over  this  difficulty  by  substituting  gingerine  for  any  essential  oil  in 
the  formula,  but  such  a  procedure  is  inadmissible  in  dispensing. 
Under  these  circumstances  the  covering  recommended  by  M.  Cal- 
loud  ("Journal  de  Pharmacie,"  xxiii,  310)  might  be  used  with  advan- 
tage; it  consists  of  a  powder  prepared  as  follows  : 
One  part  of  powdered  tragacanth  mixed  with  two  of  water  is  pressed 
through  muslin  ;  this  is  then  mixed  with  twenty  parts  powdered  sugar 
of  milk  and  spread  on  a  procelain  slab  in  a  thin  layer  to  dry  ;  lastly,  it 
is  reduced  to  a  fine  powder.  This  is  not  easily  accomplished,  but  I 
have  found  by  experience  that  the  excellence  of  this  coating  largely 
depends  on  the  fineness  of  the  powder.  The  pills  are  merely  moistened 
with  water  and  rolled  in  the  powder,  keeping  up  a  rotary  motion  till 
dry,  and  repeating  the  operation  if  necessary. 
Pills  of  this  kind  also  do  well  with  gelatin  coating,  one  of  the  oldest 
methods,  and  one  which  is  now  seldom  used  in  this  country,  but  the 
Americans  still  adopt  it  to  some  extent,  and  one  house  in  New  York 
advertises  somewhat  extensively  a  full  line  of  gelatin-coated  pills. 
The  process  is  exceedingly  simple,  but  like  all  others  requires  some 
amount  of  practice  and  dexterity  for  its  successful  accomplishment. 
The  only  necessary  apparatus  consists  of  a  pin  board,  /.  a  piece  of 
wood  into  which  pins  have  been  pressed,  so  as  to  allow  the  points 
to  project  a  good  distance  above  the  surface,  and  a  small  vessel  of 
melted  gelatin.  I  generally  use  the  French  sheet  gelatin — say  four 
parts,  water  sixteen,  glycerin  one.  The  points  of  the  pins 
should  be  slightly  greased  before  placing  the  pills  on  them,  and 
any  scum  or  skin  should  be  removed  from  the  solution  before  dipping 
them  ;  when  removed  a  rotary  motion  with  occasional  inversion  is  kept 
up  till  the  gelatin  has  set,  they  are  then  put  aside  to  dry.  In  the  "  Phar- 
macist "  (March,  1877)  Mr.  Charles  B.  Allaire  describes  an  ingenious 
little  apparatus,  which  can  be  readily  constructed  for  coating  pills  with 
