148 
Manufacture  of  Pepsin. 
Am  Jour.  Pharru. 
March,  1893. 
will  it  be  acted  on  and  dissolved.  Syntonin  and  peptone  are  also 
more  soluble  in  weak  solutions;  100  grains  of  albumin  require  about 
1  ounce  of  acidulated  water  for  solution  ;  if  less  water  is  used,  the 
solution  is  retarded. 
The  activity  of  different  pepsins  varies,  and  as  it  is  difficult  to  esti- 
mate the  undissolved  portion  of  albumin,  which  after  four  hours  of 
digestion  is  always  in  a  more  or  less  advanced  state  of  digestion,  it 
is  best  to  regulate  the  amount  of  albumin  in  such  a  manner  that 
after  the  termination  of  the  experiment  it  is,  as  nearly  as  possible, 
completely  dissolved.  To  effect  this,  one  or  two  preliminary  tests 
will  be  required  before  beginning  the  ultimate  experiment.  In  fact, 
those  who  have  from  time  to  time  to  examine  samples  of  pepsin 
and  desire  to  get  uniform  results,  will  find  it  requisite  to  see  that 
their  experiments  are  each  time  carried  on  under  precisely  the  same 
conditions,  and  to  pay  attention  to  the  following  points :  The  eggs 
used  must  be  fresh  ;  the  time  during  which  the  eggs  are  boiled  must 
be  uniform,  as  must  also  the  degree  of  fineness  to  which  the  coagulated 
albumin  is  reduced,  the  proportion  of  albumin  and  acidulated  water 
used,  the  degree  of  acidity  of  the  acidulated  water,  the  temperature 
at  which  digestion  is  carried  on,  the  time  required  to  effect  solution 
of  the  albumin,  and  the  agitation  of  the  mixture  during  digestion. 
It  will  be  serviceable  to  take  a  sample  of  the  best  pepsin  obtainable 
as  a  standard,  and  compare  any  pepsin  under  examination  with  it, 
so  as  to  ascertain  how  much  of  any  pepsin  is  required  to  produce 
the  same  results  with  the  same  amount  of  albumin,  fluid  and  acid, 
with  the  same  degree  of  heat,  during  the  same  period  of  digestion, 
and  with  the  same  amount  of  agitation.  Fresh  eggs  are  placed  in 
cold  water,  heat  applied  until  the  water  boils  and  the  eggs  kept  in 
the  boiling  water  for  fifteen  minutes.  They  are  then  taken  out, 
plunged  in  cold  water  to  cool,  the  coagulated  white  of  egg  then 
separated  from  the  yolk,  and  rubbed  and  squeezed  through  a  sieve 
of  thirty  meshes  to  the  square  inch.  Two  hundred  grains  of  this 
finely  divided  albumin  are  triturated  in  a  mortar  with  distilled  water, 
containing  5  minims  of  strong  hydrochloric  acid  to  the  ounce. 
When  well  triturated  the  mixture  is  put  in  a  widemouth  bottle 
and  sufficient  acidulated  water  added  to  make  the  whole  measure 
2  fluidounces.  One-tenth  of  a  grain  of  the  pepsin  under  examina- 
tion is  then  added,  and  the  whole  digested  for  four  hours  at  a 
temperature  of  1040  F.,  shaking  the  bottle  every  ten  minutes.  The 
