AmDe0cU'if9iarm'}      Ether  for  Medication  by  the  Skin.  625 
remedies  and  many  different  preparations  to  the  skin,  with  the  view 
of  producing  remote  or  local  effects,  or  both,  in  the  form  of  com- 
pounds very  ill  designed  for  their  special  purpose.  The  officinal 
formulae  of  outward  applications  include  emplastra,  various  liniments, 
of  alcoholic,  saponaceous,  or  oleaginous  composition,  and  certain  fatty 
unguents.  Of  these  medicaments  for  enepidermic  use  the  oily 
liniments  and  the  ointments,  because  of  their  easy  admixture  with 
the  sebaceous  secretion  of  the  human  skin,  are  probably  the  most 
active.  I  am  afraid  the  structure  of  none  of  the  fourteen  plasters  of 
the  British  Pharmacopoeia  is  such  as  to  permit  the  absorption  of  its 
active  ingredients  by  the  skin.  The  body  of  an  officinal  plaster  is 
made  of  litharge  in  union  with  oleic,  margaric  and  stearic  acids,  or 
of  wax,  of  lard,  of  frankincense,  of  resin,  of  soap,  of  suet,  and  of  some 
fixed  oils,  in  various  combinations.  "  Neither  a  plaster  so  formed," 
as  I  wrote  in  one  of  my  former  papers  upon  this  subject,  "  nor  a 
solution  in  alcohol  of  the  active  principles  of  drugs  is  a  scientific 
medicament  for  enepidermic  employment  and  percutaneous  action, 
if  we  have  regard  to  the  structure  and  physiology  of  the  human 
skin."  In  practice  it  is  found  that  there  are  at  least  three 
separate  obstacles  to  the  absorption  of  a  medicine  through  the  skin, 
namely,  the  fatty  sebaceous  secretion  of  the  skin,  the  epidermis, 
and  insolubility  of  the  drug.  So  far  as  I  know,  ether  is  the 
best  menstruum  for  the  solution  of  many  remedies  for  local  use 
through  the  skin.  It  is  a  good  solvent  of  the  active  principles  of 
many  drugs,  and  it  is  a  ready  solvent  of  the  fatty  constituents  of 
the  sebaceous  secretion  of  the  skin.  An  ethereal  liniment  supplies 
the  most  intimate  application  of  a  remedy  to  the  bare  dermal  surface. 
Dr.  Lauder  Brunton  has  written  :  "  It  would  appear  that  the  fat  of 
the  skin,  as  well  as  the  epidermis,  presents  an  obstacle  to  the 
absorption  of  substances  in  solution;  but  when  they  are  applied  in 
such  a  form  that  they  can  readily  mix  with  the  sebaceous  matter  of 
the  skin,  they  are  tolerably  readily  absorbed  ;  as,  for  example,  when 
they  are  used  in  the  form  of  ointment.  *  *  *  They  are  absorbed 
also  when  dissolved  in  ether,  and  especially  in  chloroform,  even 
when  simply  painted  over  the  surface.  Alcoholic  solutions  are  not 
absorbed  when  painted  in  this  way."  Chloroform  has  many  disad- 
vantages, but  ether  is  an  excellent  agent,  for  use  either  as  a 
menstruum,  in  tinctures  for  external  employment,  or  as  a  simple 
solvent,  for  the  preparation  of  a  liniment. 
