572 
Papaine. 
Am,  Jour.  Pharm. 
Nov ,  1880. 
It  may  be  added  that  o*i  gram  of  specimen  III.  digested  ener- 
getically 5  grams  of  moist  fibrin,  even  after  having  been  heated  to 
'i05°C. 
M.  Wurtz  considers  that  the  preceding  analyses  demonstrate  that 
the  digestive  ferment  of  Carica  papaya^  named  "papaine"  by  himself 
and  M.  Bouchut,  possesses  the  composition  of  an  albuminoid  sub- 
stance. To  the  characters  previously  attributed  to  this  substance  he 
adds  the  following,  which  relate  to  papaine  purified  by  subacetate  of 
lead. 
It  is  very  soluble  in  water,  in  which  it  is  capable  of  dissolving  in 
less  than  its  own  weight,  after  the  manner  of  a  gum.  The  solution, 
even  when  dilute,  forms  upon  agitation  an  abundant  froth.  The 
crude  papaine  redissolved  leaves  sometimes  an  insoluble  while  residue. 
Solution  of  papaine  becomes  turbid  upon  boiling,  without  coagulat- 
ing like  albumen.  When  left  to  itself  during  several  days  it  also 
becomes  turbid,  and  if  then  examined  under  a  microscope  is  found  to 
be  full  of  vibriones  and  bacilla. 
It  gives  an  abundant  precipitate  with  hydrochloric  acid,  and  the  pre- 
cipitate dissolves  readily  in  excess  of  the  acid. 
Nitric  acid,  added  in  small  quantity,  precipitates  thick  yellowish 
flocks  that  dissolve  in  excess  of  the  acid. 
Neither  ordinary  phosphoric  acid  nor  acetic  acid  precipitate  it,  but 
metaphosphoric  acid  gives  a  plentiful  precipitate. 
Prussiate  of  potash  added  to  acetic  acid  gives  a  precipitate. 
Corrosive  sublimate  does  not  precipitate  immediately  the  solution  of 
pure  papaine,  or  only  gives  a  slight  turbidity  ;  after  a  time  the  turbidity 
becomes  more  apparent.  Upon  boiling  an  abundant  flocculent  pre- 
cipitate is  formed. 
Plumbic  subacetate  does  not  give  a  precipitate,  or  only  causes  a  slight 
turbidity,  soluble  in  an  excess  of  the  reagent.  If  excess  of  potash  be 
added  to  the  liquor  and  it  be  heated  it  becomes  blackened  in  consequence 
of  the  formation  of  sulphide  of  lead. 
Sulphate  of  copper  gives  a  violet  precipitate,  which  becomes  blue 
upon  boiling  and  dissolves  in  potash  with  a  beautiful  blue  color. 
Chloride  of  platinum  gives  an  abundant  precipitate  as  also  does 
tannic  acid. 
Picric  acid  gives  an  abundant  precipitate  insoluble  in  excess  of  the 
reagent. 
Millon's  reagent  gives  a  plentiful  yellowish-white  precipitate  that 
becomes  brick-red  when  slightly  heated. 
