76 
Papaine. 
j  Am.  Jour.  Pharm. 
I      Feb.,  1881. 
times  its  weight  of  moist  fibrin,  of  which  the  largest  portion  had  been 
transformed  into  peptone  not  precipitable  by  nitric  acid,  and  that,  in 
consequence  of  the  complete  hydration  of  the  fibrin,  it  had  even  formed 
a  small  quantity  of  a  crystallizable  amide  body,  it  being  known  that 
the  same  occurs  in  the  process  of  good  peptic  digestion. 
In  another  experiment  0'05  gram  of  the  same  papaine  liquefied  100 
grams,  that  is  to  say  2,000  times  its  weight,  of  moist  fibrin,  with  the 
exception  of  a  residue  of  dyspeptone,  weighing  after  drying  4*2  grams ; 
and  regarding  the  latter  it  may  be  stated  that  it  is  always  mixed  with 
some  impurities,  such  as  hair,  straw,  etc. 
The  energy  of  this  digestive  action  has  inclined  me  to  think  that  in 
time  the  ferment,  being  of  an  albuminoid  nature,  would  be  able  to  act 
upon  itself  in  such  a  way  as  to  cause  its  hydration,  and  experience  has 
verified  this  prevision.  When  an  aqueous  solution  of  papaine,  con- 
tained in  a  sealed  tube,  is  allowed  to  remain  at  50  °C.  for  several  weeks, 
it  becomes  slightly  turbid,  and  contains  then  in  solution  a  product 
m(jre  hydrated  than  the  original,  as  shown  by  the  following  experiments. 
Three  grams  of  purified  papaine,  containing,  a  deduction  being  made 
for  the  ash,  G  52*19,  H  7-12,  N  16*4,  were  dissolved  in  20  cubic  cen- 
timeters of  water  and  heated  for  15  days  to  50°C. ;  the  solution 
became  turbid  and  deposited  0*064  gram  of  a  substance  containing  0*007 
gram  of  ash.  The  filtered  solution  evaporated  in  vacuo,  and  precipi- 
tated by  alcohol,  furnished  1*8  gram  of  colorless  papaine,  which  gave 
on  analysis,  deduction  being  made  for  the  ash,  C  51*29,  H  7*02.  The 
alcoholic  mother  liquid  furnished  0*65  gram  of  a  residue  in  which 
CTystals  were  slowly  formed,  apparently  identical  with  the  crystallized 
nitrogenous  matter  separated  from  the  juice  of  the  papaya,  and  which 
will  be  referred  to  later.  1*5  gram  of  papaine,  already  modified  by 
the  action  of  water,  was  redissolved  in  20  cubic  centimeters  of  water 
and  the  solution  again  heated  for  15  days  to  50  °C.  The  solution  pre- 
cipitated by  alcohol  then  gave  a  product  containing,  deduction  being 
made  for  the  ash,  C  50*46,  50*42,  H  7*38,  and  the  alcoholic  mother 
liquid  on  evaporation  left  an  uncrystallizable  residue  weighing  0*16 
gram.  It  is  thus  seen  that  by  simple  digestion  with  water  at  50  °C. 
the  composition  of  the  papaine  becomes  so  modified  as  to  cause  a 
decrease  of  2  per  cent,  of  carbon. 
This  conclusion  has  been  strengthened  by  a  new  experiment,  in 
which  5  grams  of  papaine,  containing  C  51*8,  H  7*2,  having  been 
heated  for  two  months  with  20  cubic  centimeters  of  water  at  50 °C., 
