102  Syrups  of  Squills,  Seneka  and  Ipecac.  {"^Mk^ch^i,!™' 
the  liquid  to  the  boiling  point.  Here  arises  the  chief  difficulty,  in  my 
opinion  ;  at  any  rate  I  have  found  it  to  be  a  great  one,  for,  in  at- 
tempting to  remove  this  deposit  by  filtration,  especially  if  a  consider- 
able quantity  of  liquid  is  prepared,  the  filter  is  soon  clogged  by  the 
gummy  matter,  and  the  liquid  filters  very  slowly.  I  have  known 
filtration  to  cease  towards  the  close  of  the  operation.  In  such  a  case 
the  best  that  can  be  done  is  to  provide  a  new  filter  and  empty  the 
old  one  into  it,  expressing  it  to  avoid  loss  as  much  as  possible.  This 
is  tedious  and  wasteful  of  the  virtues  of  the  drug.  On  one  occasion 
I  prepared  a  quantity  of  the  tincture,  and  such  was  the  tardiness  of 
filtration  that  several  days  were  occupied  in  completing  it.  Towards 
the  end  I  noticed  a  few  patches  of  a  mouldy  growth  that  had  formed 
on  the  surface  of  the  albuminous  matter  in  the  filter,  and  by  smelling 
it  perceived  that  the  liquid  was  spoiled  before  the  syrup  tvas  made. 
The  failure  was  suggestive,  and  I  concluded  that  if  a  few  days  were 
enough  to  spoil  the  liquid  a  few  hours  time  might  injure  it,  and,  in 
fact,  the  germs  of  fermentation  might  begin  to  work  as  soon  as  the 
liquid  was  cold,  since  the  protective  agency  of  alcohol  was  gone. 
Reasoning  as  above,  I  resorted  to  a  method  of  filtration  often  used 
when  a  difficult  precipitate  is  to  be  removed,  namely,  rubbing  the 
muddy  liquid  with  magnesia.  In  this  case  it  acted  with  the  double 
advantage  of  mingling  its  particles  with  the  albuminous  matter,  thus 
facilitating  filtration  and  neutralizing  any  free  acid  that  might  be 
present  from  incipient  fermentation.  The  result  was  very  satisfactory. 
Filtration  was  greatly  hastened,  and  the  syrup  produced  was  not 
muddy  looking  or  translucent,  as  is  generally  the  case,  but  was  beauti- 
fully transparent.  It  was  kept  a  year  without  fermenting,  though 
almost  daily  in  use. 
I  have  since  tried  the  same  method  of  filtration  with  syrup  of 
ipecacuanha  and  syrup  of  seneka,  with  like  results. 
There  is  a  point  that  may  seem  objectionable  in  using  magnesia  or 
its  carbonate  as  above,  and  it  has  been  duly  considered  before  offering 
these  suggestions.  It  is  this :  Magnesia  is  alkaline  in  its  reactions, 
and  as  the  active  principle  of  seneka  is  considered  to  be  acid  (poly- 
galic),  it  would  seem  that  they  are  incompatible,  but  as  they  are  both 
feeble  in  their  affinities  and  as  filtration  proceeds  rapidly  there  is 
practically  no  objection  to  mixing  them.  There  is,  it  is  true,  a  very 
slight  escape  of  carbonic  acid  when  the  carbonate  of  magnesia  is 
rubbed  with  the  concentrated  liquid,  but  it  may  be  due  to  a  small 
