Amjine^902arm'}       Preparing  a  Hematin  Product \  277 
sary  to  carry  the  digestion  so  far  as  to  convert  all  the  acid-hematin 
into  albumose,  to  obtain  a  precipitate  of  pure  hematin  on  neutraliza- 
tion. This  method,  which  I  first  tried  myself,  and  then  had  con- 
trolled by  one  of  my  students,  Mr.  S.  A.  Young,  gave  eminently 
satisfactory  results.  I  shall  give  the  process  in  detail.  We  operated 
on  quantities  of  100  c.c.  to  1,000  c.c.  of  blood  at  a  time. 
III.  PROCESS  FOR  THE  ISOLATION  OF  THE  HEMATIN. 
Material  required: 
Defibrinated  Beef's  Blood1  1,000  c.c. 
Pepsin,  U.S.P  i'5  gm. 
Dilute  Hydrochloric  Acid,  U.S.P  ~)      Of  each  a  sufficient 
T.  S.  Sodium  Carbonate,  U.S.P  r        quantity  to  make 
Thymol   J  18  to  30  gms.  of  hematin. 
(1)  To  the  blood  add  2,000  c.c.  of  dilute  hydrochloric  acid  and 
0*5  gm.  of  pepsin.  Pour  into  large  bottles,  which  should  be  a  fourth 
filled.  Add  to  each  bottle  a  small  crystal  of  thymol  (the  size  of  a 
split  pea)  and  set  the  bottles  in  a  large  water-bath  (a  wash-boiler 
will  answer  the  purpose),  which  is  kept  at  a  temperature  of  400  C, 
for  twenty-four  to  thirty-six  hours. 
(2)  Render  the  contents  of  the  bottles  just  neutral  to  litmus  by 
the  sodium  carbonate  solution.  Fill  the  bottles  with  cold  water 
and  let  them  stand  in  a  cool  place  until  the  precipitate  has  settled. 
(3)  Carefully  decant  the  supernatant  liquid,  leaving  the  precipi- 
tate and  adhering  liquid  in  the  bottles.  Again  fill  the  bottles  with 
water,  let  settle,  and  decant.  To  the  washed  and  moist  precipitate 
in  the  bottles  add  now  enough  of  a  mixture  of 
40"   c.c.  of  diluted  hydrochloric  acid, 
o*5  gm.  of  pepsin, 
960*  c.c.  of  water, 
to  a  third  fill  the  bottles ;  add  to  each  a  small  crystal  of  thymol,  and 
digest  at  400  C.  for  twenty-four  hours.  Then  proceed  by  (2)  (above). 
Decant  a  little  of  the  clear  liquid  into  a  test-tube,  and  add  an 
equal  volume  of  soda  solution  and  a  drop  of  T.  S.  cupric  sulphate. 
If  this  produces  a  pink  color,  repeat  (3)  (above).  If  the  color  is 
blue,  proceed  by  the  next  paragraph. 
1  Blood  which  has  been  rendered  non-coagulable  by  removing  the  fibrin. 
This  is  done  by  stirring  the  blood  vigorously  with  a  rough  wooden  stick  for 
some  ten  minutes,  beginning  immediately  after  it  has  been  drawn  from  the 
animal. 
