Am.  Jour.  Phartib.  \ 
March,  1893.  / 
Manufacture  of  Pepsin. 
H7 
by  these  patents  are  doubtful,  while  some  of  the  processes  were  in 
use  in  one  form  or  another  long  before  the  patents  were  filed. 
Characteristics  of  Good  Pepsins. — All  good  pepsins  should  be  of  a 
light  color;  the  scales  a  light  lemon,  slightly  greenish  and  nearly 
transparent ;  the  powder  white,  or  nearly  so.  They  should  be 
soluble  in  water,  with  a  characteristic,  but  not  offensive  or  putrescent 
smell,  nor  should  they  be  very  hygroscopic.  Deficiency  in  any  of 
these  respects  is  usually  due  to  faulty  manufacture,  or  to  the  presence 
of  mucus,  albumin,  peptone  or  inert  animal  tissue.  The  digestive 
power  of  good  pepsin  should  be  near  2,000  times  its  own  weight. 
Tests  for  Pepsins. — The  different  official  tests  for  ascertaining  the 
digestive  strength  of  pepsin  are  perhaps  sufficient  to  ascertain  if  a 
sample  is  above,  below,  or  of,  the  required  standard ;  but  they  do 
not  give  the  actual  strength.  There  is  no  recognized  test  which 
under  all  circumstances  will  give  uniform,  impartial  results,  and 
slight  variations  in  the  manipulation  will  frequently  occasion  widely 
different  results  with  the  same  pepsin.  It  must  also  be  borne  in 
mind  that  the  real  digestive  power  of  a  pepsin  is  measured  by  the 
amount  of  peptone  which  it  is  able  to  produce  in  a  given  time,  under 
certain  conditions;  while,  at  present,  it  is  usual  to  be  satisfied  with 
ascertaining  the  amount  of  albumin  dissolved.  The  first  step  in  the 
digestive  action  of  pepsin  on  coagulated  albumin,  is  the  conversion 
of  the  latter  into  soluble  acid  albumin,  or  syntonin ;  from  which 
state  it  is  subsequently  converted  into  parapeptone  and  then  into 
peptone  proper.  A  weak  pepsin  may  dissolve  all  the  albumin  and 
convert  it  simply  into  syntonin,  but  fail  to  carry  the  digestion 
further  and  may  not  produce  peptone,  whilst  a  much  stronger  pepsin 
may,  in  the  same  time,  convert  the  albumin  not  only  into  syntonin, 
but  also  into  peptone.  So  far  as  appearance  goes,  both  samples 
would  appear  to  have  done  equal  work,  the  albumin  being  dissolved 
in  both  instances ;  while,  in  reality,  the  one  is  double  the  strength 
of  the  other.  It  must  also  be  remembered  that  in  testing  a  sample 
of  pepsin,  the  results  are  materially  influenced  by  various  conditions. 
Pepsin,  if  allowed  to  act  on  more  albumin  than  it  can  digest,  will 
convert  the  albumin  principally  into  syntonin  and  produce  very 
little,  or  no  peptone  at  all.  Being  undialyzable  also,  it  cannot  pene- 
trate the  albumin,  and  exerts  its  dissolving  power  only  on  the  outer 
surface  of  it;  it  is  therefore  evident  that  the  more  finely  divided  the 
albumin  is,  the  greater  will  be  its  outer  surface  and  the  more  readily 
