356 
Pepsin. 
J  Am.  Joub.  Phaem. 
I     Aug.  1,  1873. 
2.  The  monobasic  rather  than  the  corresponding  bibasic  acid  (e. 
butyric  than  succinic  acid) ;  3.  Or  than  the  bibasic  acid  having  nearly 
the  same  percentage  composition  (acetic  acid  and  succinic  acid) ;  also 
-{4)  of  acids  containing  the  same  carbon  and  hydrogen,  that  which 
has  least  oxygen  (succinic  and  malic  acids). 
In  the  case  of  two  substances  in  presence  of  two  solvents,  they  are 
distributed  as  if  each  of  the  substances  acted  alone.  This  relation  is 
analogous  to  the  law  of  the  solubility  of  mixed  gases,  and  is  capable 
of  being  applied  to  the  separation  of  two  mixed  substances  (ib.  [4], 
xx,  425-431). — Amer.  Chemist,  May,  1873,  from  J.  Lond.  Chem. 
Soc. 
PEPSIN. 
By  Charles  Symes,  Ph.D. 
There  are  few  medicines,  perhaps,  which  have  received  so  extensive 
a  trial,  and  yet  respecting  which  such  differences  of  opinion  exist,  as 
pepsin.  It  cannot  be  doubted  that  this  arises  chiefly  from  the  fact 
that  it  has  not  been  recognized  by  the  Pharmacopoeia,  and  hence  no 
standard  tests  of  quality  exist  in  this  country.  Chemists  purchase 
the  kind  they  think  best,  influenced  perhaps  by  the  advertisements  of 
manufacturers  or  the  report  of  some  experimenter  who  may  have  used 
very  carefully  prepared  samples,  and  not  the  commercial  article  ;  or 
it  might  be  they  are  guided  by  price,  the  best  qualities  being  usually 
attributed  to  the  highest  priced  article  of  its  kind,  and  this,  indeed, 
should  be  a  correct  guide.  But  I  have  also  heard  of  orders  for  pepsin 
in  which  the  only  condition  stipulated  for  was  its  low  price.  It  occa- 
sionally occurs  that  extremes  meet,  and  my  experience  indicates  that 
they  are  not  so  wide  apart  as  would  be  supposed,  even  in  this  instance. 
It  will  not  be  surprising,  however,  under  such  circumstances,  that 
pepsin  might  mean  anything  possessing  more  or  less  digestive  power,* 
an  appearance  varying  from  that  of  decorticated  liquorice  to  pulv. 
doveri,  and  an  odor  from  almost  nil  to  the  strong  smell  of  bacon.  Va- 
riable as  it  might  be,  it  has  stood  the  test  of  time,  and  at  last  assert- 
ed its  right  to  recognition  and  admission  to  at  least  the  outer  circle, 
viz  :  to  the  Appendix,  of  the  British  Pharmacopoeia. 
For  some  time  past  I  have  been  conducting  a  series  of  experiments 
on  pepsin,  first  with  a  view  of  ascertaining  the  quality  of  commercial 
specimens  by  different  makers  ;  and  secondly,  of  testing  the  various 
processes  which  have  been  proposed  for  its  preparation  as  a  medicinal 
