Pepsin  Assay.  5°7 
men  present  within  the  prescribed  time,  and  under  the  conditions 
i  given.  This,  of  course,  requires  a  series  of  trials.  From  this 
ascertained  proportion  is  figured  the  power,  thus :  if  twice  as  much 
of  one  pepsin  as  of  another  is  required  to  do  the  same  work  under 
like  conditions,  with  no  excess  of  albumen  present,  then  the  former 
pepsin  has  one-half  the  power  of  the  latter  ;  or  if  one- half  as  much 
is  needed  then  it  tests  double  that  of  the  other — the  dissolving 
power  of  a  pepsin  is  inversely  proportional  to  the  quantity  of  pepsin 
required. 
A  ioo  Minute  Assay. — The  writer  has  found  that  any  pepsin 
tested  under  the  following  conditions,  will  dissolve  exactly  one-half 
as  many  times  its  weight  of  coagulated  albumen  as  by  the  6-hour 
test,  in  ioo  to  105  minutes.  We  can  thus  obtain  reliable  results 
without  so  much  sacrifice  of  time — a  pepsin  dissolving  I, OOO  times 
its  weights  of  albumen  at  1250  F.  in  100  minutes,  will  dissolve 
2,000  at  105 0  F.  in  6  hours.  The  conditions  are:  The  same  rela- 
tive proportions  of  the  acidulated  water  and  albumen  as  by  the  long 
time  test ;  but  one-half  of  each  as  compared  with  the  weight  of  pepsin 
used;  temperature  1250  F.  ;  agitation  every  5-10  minutes;  time 
100-105  minutes;  practically  complete  solution  of  all  the  albumen 
present.  Hence  the  following  formula — for  the  sake  of  even  num- 
bers and  a  unit,  a  1  :  2,000  test  pepsin  is  designated. 
Take  pepsin  (1  :  2,000  by  the -6-hour  test),  .     o*oi  parts,  or  gm.  or  }(  gr. 
Coagulated  egg-albumen  (fresh  egg,  "} 
boiled   15   minutes,  white  pressed  j-  10'     parts,  or  gm.   or  250  gr. 
through  30  mesh  hair  sieve,  ...  J 
Distilled  water  containing  0*2  per  cent.  \  ioo*     parts,  or  gm.  or  cc.  or  5^ 
HC1,   f  fl.  oz. 
Using  the  above  designated  number  of  grams,  a  flask  is  required 
of  at  least  100  cc.  capacity  when  about  two-thirds  full;  or  5^  fl. 
oz.  for  the  grain  weights  given.  For  every  100  gm.  of  albumen 
required  provide  3-33  fresh  eggs.  Measure  the  prescribed  quantity 
of  acidulated  water  at  ordinary  laboratory  temperature.  Put  the 
pepsin  in  the  flask  with  a  little  of  the  acidulated  water  ;  follow  with 
the  albumen  previously  triturated  with  some  of  the  acidulated 
water  ;  rinse  mortar  and  neck  of  flask  with  remaining  acidulated 
water,  and  immediately  set  flask  in  a  water-bath,  which  is  already 
at  1250  F.  Maintain  this  temperature  within  a  degree  above  or 
below  for  100-105  minutes,  rotating  flask  every  5-10  minutes.  If 
Am.  Jour.  Pharm. 
Oct.,  1892. 
