Amjiiy,ri887harm"}    Irish  Moss  a  Substitute  for  Acacia.  359 
any  evidence  of  its  superiority  to  other  substances  used  for  the  same 
purpose,  such  as  acacia  and  tragacanth.  In  consequence  I  abandoned 
further  consideration  of  it,  especially  as  the  cost  was  not  then  an  ele- 
ment of  so  urgent  importance  as  it  is  now. 
A  few  months  since,  however,  in  conversation  with  a  pharmaceuti- 
cal friend,  the  subject  of  a  substitute  for  acacia  came  up.  Remember- 
ing my  previous  experiments  with  Irish  moss  I  thought  this  sub- 
stance might  possess  some  qualities  which  would  make  it  worth  con- 
sidering with  this  object  in  view.  Since  then  I  have  from  time  to 
time  as  leisure  permitted  gone  into  the  subject,  and  the  results  of  my 
experiments,  so  far  as  they  appear  to  me  to  be  worth  recording,  I  pro- 
pose to  lay  before  you. 
The  only  two  British  species  of  alga?  which  yield  a  mucilaginous 
jelly  with  water  are  Gelidium  corneum  and  Chondrus  crispus,  or  Irish 
moss.  The  latter  is  the  more  plentiful,  and  being  a  well-known  arti- 
cle of  commerce  is  easily  obtainable.  The  composition  of  commercial 
Irish  moss  is  given  by  Church  as — 
Water   188 
Albuminoids   9'4 
Mucilage   55*4 
Cellulose   2  2 
Mineral  matter   14*2 
ioo-o 
Stanford  says  it  yielded  him  63' 7  per  cent,  of  carragheenin,  or  veg- 
etable jelly ;  this  probably  includes  the  albuminoids  and  mucilage 
given  in  Church's  analysis. 
The  mucilage  may  be  obtained  by  boiling,  by  heating  on  a  water- 
bath,  and  by  cold  maceration.  The  usual  method  is  boiling.  How- 
ever, having  put  a  quantity  of  the  moss  into  water  to  soak  one  after- 
noon, and  being  unable  to  attend  to  it  till  the  next  day,  I  found  when 
I  examined  it  that  the  water  was  distinctly  viscous.  By  putting  a 
larger  quantity  of  moss  into  a  smaller  quantity  of  water,  and  macerat- 
ing with  occasional  gentle  stirring  for  twenty-four  hours,  I  obtained  a 
mucilage  of  about  three-fourths  the  viscosity  of  acacia  mucilage. 
At  the  commencement  I  encountered  a  difficulty  which  threatened 
to  be  a  serious  objection.  I  found  it  exceedingly  troublesome  to  get 
the  mucilage  clear,  the  insoluble  particles  suspended  in  it  being  so  mi- 
nute that  the  straining  medium  necessary  to  exclude  them  required  to 
be  so  fine  that  the  mucilage  would  scarcely  pass  through  it.  Mr. 
