A  M.  Joor.  Phaem.  ") 
July  1,1874.  J 
Formula  for  Gharta  Sinapis. 
339 
IMPROVED  FORMULA  FOR  CHART  A  SINAPIS. 
By  A.  W.  Gerrard. 
Dispenser  and  Teacher  of  Pharmacy  to  University  College  Hospital. 
The  formula,  given  in  the  "Additions  to  the  Pharmacopcecia,"  for 
the  preparation  of  mustard  paper  is  unsatisfactory  and  expensive. 
The  proportion  of  solution  of  gutta-percha  necessary  to  render  the 
ounce  of  mustard  ordered  sufficiently  fluid  for  coating  is  ten  drachms. 
This  would  contain  more  than  a  drachm  of  gutta-percha,  which,  when 
it  is  applied  to  the  paper  and  the  chloroform  has  evaporated,  gives 
the  surface  of  the  mustard  a  glossy,  varnished  app  earance.  In  fact, 
the  gutta-percha  acts  as  a  varnish,  much  retarding  the  absorption  of 
moisture  and  the  development  of  the  essential  oil  upon  which  the 
activity  of  the  paper  depends.  Another  objection  to  gutta-percha  is 
its  insufficient  adhesive  power,  for  the  coating  cracks  and  peels  from 
the  paper  after  but  slight  handling. 
With  the  object  of  remedying  these  objections,  I  made  a  trial  of  a 
solution  of  india-rubber  in  benzol  as  a  menstruum  ;  for  I  judged 
from  its  physical  properties  much  less  of  this  than  of  gutta-percha 
would  be  required  to  keep  the  particles  of  mustard  cohesive,  and  at 
the  same  time  the  action  would  be  retarded  only  to  a  minimum 
degree.  I  found  it  well  answered  my  intention.  After  several  ex- 
periments to  determine  the  most  suitable  proportions,  I  have  adopted 
the  following  : 
Take  of 
Caoutchouc,  1  part. 
Benzol,  ......        49  parts. 
Black  mustard,  in  powder,  a  sufficiency. 
Dissolve  the  caoutchouc  in  the  benzol  ;  then  stir  in  the  mustard 
till  of  a  proper  consistence  for  spreading  on  paper. 
In  this,  as  also  in  the  B.  P.  form,  the  presence  of  the  fixed  oil  in 
the  mustard  gives  the  back  of  the  paper  a  greasy  appearance.  More- 
over, its  removal,  which  might  be  effected  either  by  pressure  or  by 
percolation  with  benzol,  would  be  an  advantage,  not  only  as  removing 
the  cause  of  this  greasiness,  but  it  would  render  the  mustard  more 
active. 
Papers  spread  with  a  mixture  made  according  to  the  form  I  have 
here  given,  have  a  dull,  smooth  surface,  and  the  mustard  adheres  well 
together,  although  it  contains  only  one-fourth  as  much  india-rubber 
