172 
Moss  Mucilages  as  Emulsifiers. 
( Am.  Jour.  Pharm. 
\       April,  1888. 
and  lastly,  enough  water  to  make  four  fluid-ounces  shaking  the  whole 
thoroughly  together. 
The  emulsions  thus  formed  seem  to  be  practically  inseparable,  they 
having  stood  for  over  three  months  showing  no  apparent  separation. 
Examined  under  the  microscope  the  particles  of  oil  are  not  so  mi- 
nutely or  uniformly  divided  as  in  emulsions  made  by  some  other 
agents,  or  made  in  a  mortar  in  the  usual  way. 
An  emulsion  was  also  prepared  according  to  the  same  formula,  by 
mixing  the  mucilage  of  Irish  moss  with  the  oil  and  other  ingredients 
in  a  mortar  in  the  usual  way  for  preparing  emulsions  with  acacia,  in- 
stead of  in  a  bottle  as  before.  Examined  under  the  microscope  it  was 
found  to  be  almost  perfect,  the  particles  of  oil  being  very  uniformly 
and  minutely  divided.  But  as  to  its  standing  qualities  it  appears  to 
be  not  better  than  those  made  by  simply  shaking  in  a  bottle.  It  is 
not  always  the  most  perfect  emulsion  as  seen  under  the  microscope, 
that  stands  the  best  and  is  the  best,  but  those  in  which  the  oil  is  not 
so  finely  divided  often  stand  without  separation  longer  than  the  others. 
Iceland  moss  is  officinal  in  the  Pharmacopoeia  as  Cetraria,  species 
Cetraria  islandica. 
Its  princi]3al  constituent  is  lichenin,  which  may  be  obtained  as  a 
starchy,  mucilaginous  substance  by  boiling  the  drug  in  water.  The 
bitter  taste  is  due  to  cetraric  acid,  or  cetrarin,  which  may  be  removed 
by  treating  with  a  weak  alkaline  solution.  In  preparing  the  Iceland 
moss  gelatin  for  trial  as  an  emulsifier,  the  operation  was  conducted  in 
the  manner  given  above  for  making  the  Irish  moss  gelatin,  excepting 
that  the  Iceland  moss  was  first  garbled  and  then  macerated  for  two 
hours  in  tepid  water  containing  a  little  carbonate  of  sodium  in 
solution  and  afterwards  washed  well  in  cold  water.  The  four  ounces 
of  cetraria  used  yielded  one  ounce  of  gelatin,  or  twenty-five  per  cent, 
less  than  the  amount  obtained  from  the  same  quantity  of  Irish  moss. 
It  has  a  slightly  brownish  color,  is  semi-transparent  and  somewhat 
hygroscopic,  as  when  freshly  made  it  had  a  decidedly  short  fracture, 
while  in  a  few  days  it  was  found  to  be  very  pliable  and  even  tough. 
On  attempting  to  make  an  emulsion  according  to  the  formula  given 
above,  using  Iceland  moss  gelatin  in  place  of  the  Irish  moss  gelatin, 
it  was  a  complete  failure,  the  mucilage  apparently  not  having  the  ad- 
hesive qualities  necessary;  but  upon  the  addition  of  a  small  quantity  of 
gum  acacia  to  it  an  emulsion  was  easily  formed,  which,  although  it 
separates  in  a  short  time,  readily  shakes  up  to  a  fairly  good  emulsion. 
