Am-/uTy?iFoiarm-}  Story  of  the  Papaw.  347 
The  following  are  the  most  important  of  the  practical  methods 
of  separation.    The  first  three  are  the  methods  of  Peckholt : 
(1)  Exhaust  the  juice  with  ether  ;  then  exhaust  the  residue,  first 
with  absolute  alcohol  and  next  with  80  per  cent,  alcohol ;  the  dried 
residue  is  then  treated  with  water  which  dissolves  it  almost  entirely, 
forming  a  turbid  solution.  The  watery  solution  is  finally  precipi- 
tated with  alcohol ;  the  precipitate  washed  with  alcohol,  and  dried 
over  calcium  chloride.  Peckholt  obtained  by  this  process  7-848 
per  cent,  of  a  white,  light  amorphous  powder  which  he  called 
"  papayotin." 
(2)  Mix  the  juice  with  four  times  its  weight  of  water;  filter,  and 
precipitate  with  alcohol  (95  per  cent.);  wash  and  dry  the  precipi- 
tate. This  gives  3-762  per  cent,  of  a  product  practically  the  same 
as  (1)  but  not  quite  so  light. 
(3)  Evaporate  the  latex  to  dryness  and  then  completely  exhaust 
with  ether  and  alcohol  (absolute),  as  in  the  first  method.  Dissolve 
the  residue  in  water  and  precipitate  with  alcohol.  The  result 
being  a  light  brown  powder  of  which  Peckholt  obtained  5-338  per 
cent.    (He  called  this  "  parapayotin.") 
(4)  Wurtz  prepared  the  ferment  as  follows  :  The  milky  juice 
was  thrown  on  a  filter  and  the  coagulum  washed  with  water.  The 
aqueous  solution  then  obtained  was  reduced  to  a  small  volume  in  a 
vacuum,  and  was  precipitated  by  ten  times  its  volume  of  alcohol. 
This  precipitate  was  dried,  dissolved  in  water  and  precipitated  a 
second  time  with  alcohol,  washed  with  absolute  alcohol  and  dried 
in  a  vacuum.    The  product  of  this  process  he  called  "  papain." 
(5)  A  method  now  in  actual  use  in  one  of  the  West  India  Islands 
is  as  follows  :  Pour  into  the  strained  latex  five  times  its  volume  of 
full  strength  alcohol,  collect  the  precipitate  and  wash  with  absolute 
alcohol  ;  dry  over  calcium  chloride  or  sulphuric  acid.  (There  is  a 
considerable  loss  of  alcohol ;  the  product  is  small,  fairly  active,  but 
high  priced.) 
(6)  Method  devised  by  the  author :  Dry  the  latex  without 
heat ;  exhaust  the  dry  residue  first  with  ether,  then  with  chloro- 
form, followed  by  benzine ;  finally  extract  with  alcohol.  Under 
this  process,  if  the  extraction  is  thoroughly  carried  out,  everything  is 
removed  except  the  proteids  and  ash.  The  product  is  a  fine  grey- 
white  amorphous  powder  almost  completely  soluble  in  water,  more 
active  and  more  nearly  representative  of  the  peculiar  properties  of 
