508  Aromatic  Sulphuric  Acid,  {^iTimT' 
pressure  in  packing  as  I  near  the  top,  as  it  is  the  lower  portions  of 
the  powder  that  are  likely  to  escape  thorough  exhaustion.  The  upper 
portions  have  always  the  advantage  of  contact  with  the  menstruum 
before  its  solvent  power  has  become  enfeebled  as  it  gradually  does  in 
its  descent,  so  that  when  it  reaches  the  extreme  lower  portions  of  the 
mass  this  power  is  almost  entirely  exhausted. 
In  cases  where  a  preliminary  maceration  is  considered  necessary, 
and  especially  when  the  substance  under  treatment  is  of  a  tough, 
compact  and  impenetrable  nature,  I  would  recommend  that  that  portion 
of  the  menstruum  with  which  the  powder  is  moistened  be  previously 
heated,  which  can  be  easily  done  in  a  few  minutes  in  a  stone  or  tin 
vessel,  or  in  a  bottle  tightly  corked  and  placed  in  a  water-bath.  The 
maceration  should  also  be  conducted  in  a  warm  place. 
The  power  of  heat  to  expand  vegetable  tissue  when  moist,  and  to 
augment  the  power  and  energy  of  solvents,  is  well  known  ;  by  its  aid, 
when  judiciously  managed,  the  pharmacist  may,  in  his  manipulations, 
often  greatly  shorten  tedious  and  lengthened  processes. 
It  will  generally  be  found  necessary  to  moisten  powders  more  that 
are  intended  for  preliminary  maceration  than  those  intended  for  imme- 
diate percolation,  otherwise  they  are  apt,  during  the  process,  to 
become  too  dry  for  packing  without  afterwards  being  remoistened. 
In  the  next  number  of  this  journal  I  shall  present  a  paper,  as  a 
supplement  or  continuation  of  this,  which  will  embrace  comments 
upon  the  new  processes  of  percolation  in  the  manufacture  of  fluid 
extracts,  especially  the  one  adopted  in  the  last  revised  edition  of  the 
U.  S.  Pharmacopoeia  ;  I  shall  add,  also,  suggestions  as  to  a  new  plan 
by  which  the  next  revision  of  the  Pharmacopoeia  may  be  rendered 
more  complete  and  thorough. 
Philadelphia,  October,  1874. 
AROMATIC  SULPHURIC  ACID. 
By  S.  Whittier. 
This  valued  medicine,  prepared  according  to  the  U.  S.  Pharma- 
copoeia, has  objections  apparent  to  every  physician  and  pharmaceutist. 
1st.  Its  instability  (requiring  frequent  Alteration). 
2d.  The  precipitate  it  gives  when  mixed  with  water. 
Thinking  it  justifiable  to  attempt  an  improvement,  avoiding  any 
alteration  that  would  impair  the  virtues  or  change  the  general  char- 
acter or  appearance  of  the  preparation  (except  its  objectionable  char- 
