In  modem  medicine  mustard  is  most
frequently  employed  in  the  well-known
form  of  poultice.  If  its  effects  be  properly
watched,  this  application  is  safe  and  most
valuable  where  a  speedy  result  is  desired ;
but  If  allowed  to  remain  on  too  lousr,
especially  in  persons  who  from  disease  or
other  causes  ai-e  not  sensitive  to  pain,  it
may  produce  ulceration  and  gangrene.
Internally  mustard  is  employed  as  an
emetic  in  narcotic  poisoning,  &c.  As  a
condiment  mustard  is  valuable  for  its
stimulant  effects,  which  render  it  useful
in  cases  of  weak  digestion,  or  as  an  ad-
junct to  fatty  and  other  indigestible  arti-
cles of  feod.
The  White  Mustard,  S.  alba,  is  also  In-
digenous in  this  country.  Its  seeds  are
larger  than  those  of  the  Black  Mustard,
and  of  a  yellow  colour  externally.  Chemi-
cally they  differ  in  containing  a  crystal-
line substance  known  as  sulpho-sinaplsln.
Moreover,  its  myrosine  yields  with  water
a  pungent  oil  of  a  different  character  from
the  Volatile  Oil  of  Mustard  previously
mentioned.  The  seeds  have  similar  pro-
perties to  those  of  8.  nigra.  They  have
been  recommended  to  be  swallowed  whole
as  stomachics  and  laxatives,  a  process  by
no  means  free  from  danger.  The  seed-
leaves  or  cotyledons  of  this  plant,  together
with  those  of  Lepidium  sativum,  form  the
well-known  agreeable  salad  known  as
mustard  and  cress.*  The  facility  and  speed
with  which  this  salad  may  be  grown  at  all
seasons  and  in  all  places,  together  with  its
wholesome  properties,  are  great  advan-
tages. It  is,  moreover,  both  interestingand
instructive  to  watch  the  germination  of
these  seeds,  and  the  peculiar  shape  of  their
seed-leaves.
The  seeds  of  8.  arvensis,  the  Common
Charlock,  yield  an  oil  that  is  good  for


Digitized  by  (^OOgle


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