m.  Jour.,Pharru.\ 
March,  1893.  J 
Manufacture  of  Pepsin. 
143 
sulphurous  acid  may  be  added,  with  a  little  talc,  and  after  being; 
allowed  to  deposit  and  clarify,  they  may  be  strained  again.  The 
liquors  from  the  fleshy  portions,  when  saturated  with  salt,  give  a. 
dense  flocculent  precipitate,  which  rises  readily,  leaving  the  fluid 
below  perfectly  clear ;  such  a  precipitate  drains,  presses  and  dries 
well,  but  its  digestive  power  is  weak.  When  the  liquors  from  the 
inner  coatings  are  similarly  saturated  with  salt,  the  precipitate  appears 
watery,  remains  floating  about  in  the  fluid,  and  will  either  pass 
through  the  straining  cloth,  or  block  the  pores,  and  not  strain  or 
drain  at  all.  Separation  of  the  precipitate  by  pressing  offers  great 
difficulties,  but  the  small  quantity  so  obtained,  when  dried  and 
powdered,  will  possess  great  digestive  power.  By  mixing  the  two 
liquors,  or  by  adding  just  enough  liquor  from  the  fleshy  portions  to 
the  liquor  from  the  inner  portions,  it  is  possible  to  obtain  a  mixture 
from  which,  on  addition  of  salt,  pepsin  may  be  precipitated  in  a  con- 
dition in  which  it  rises  to  the  surface,  drains,  presses,  and  dries  well 
when  powdered,  whilst  it  will  prove  of  very  good  quality  and 
digestive  strength. 
When  it  has  been  ascertained  how  much  of  the  one  liquor  is  to 
be  added  to  the  other,  the  mixture  is  made  in  a  clean  70-gallon 
cask,  filled  to  about  five-sixths,  and  then  the  salt  is  added.  It  is 
best  to  add  more  salt  than  the  liquor  will  dissolve,  usually  enough 
to  nearly  fill  the  cask  to  the  top.  The  salt  has  to  be  added  quickly 
and  at  once,  and  the  stirring  has  to  be  kept  up  just  long  enough  to 
dissolve  the  salt ;  as  soon  as  the  pepsin  begins  to  rise  in  thick  flakes, 
the  stirring  is  to  be  discontinued,  and  the  precipitate  allowed  to  col- 
lect at  the  surface.  The  larger  the  flakes  the  better,  and  the  more 
convenient  for  straining,  pressing,  etc.  Unnecessary  stirring  will 
only  break  them  into  fine  particles,  and  make  the  subsequent  treat- 
ment of  the  precipitate  difficult.  When  the  pepsin  begins  to  rise  in 
the  desired  manner,  the  mixture  is  allowed  to  stand  undisturbed  till 
next  morning,  when  the  pepsin  is  removed,  and  transferred  to  a 
strong  straining  cloth,  2y2  feet  square.  Here  it  is  allowed  to  drain 
for  one  day,  and  the  draining  assisted  by  occasionally  passing  a 
large  spatula  between  the  moist  precipitate  and  the  cloth.  The  fol- 
lowing morning  the  drained  mass  is  folded  in  a  double  cloth  and 
well  pressed.  The  pressure  has  to  be  increased  gradually,  the 
pressed  mass  being  taken  out  of  the  press  once  or  twice  and  crum- 
bled up  by  hand,  then  pressed  again ;  the  drier  it  gets  the  more 
