Am  ApSi' igiT™'  ^  Chemical  Reactions  of  Diphtheria  Antitoxin. 
NaCl  (0.85  per  cent.),  was  precipitated  with  a  saturated  aqueous 
solution  of  uranium  acetate  c.p.,  then  centrifugalized.  The  precipi- 
tate was  dissolved  in  normal  salt  solution  by  the  addition  of  a  few 
drops  of  n/10  NaOH.  The  uranium  was  precipitated  by  Na2HP04 
and  centrifugalized.  This  solution  was  diluted  to  250  Cc,  an  arbi- 
trary amount.  It  was  found  that  one  Cc.  protected  from  one  L  -f- 
dose.  Less  was  not  tried.  This  solution  gave  a  precipitate  with 
picrolonic  acid,  gold  chloride,  platinum  chloride,  copper  acetate  and 
alcohol.  The  filtrate  after  precipitation  with  Na2HP04  and  centri- 
fugalizing  was  diluted  to  250  Cc.  Even  3  Cc.  of  this  solution  did 
not  protect  from  one  L  +  dose.  Uranium  acetate  precipitates  an- 
titoxin. 
Globulin  preparation  I,  diluted  with  an  equal  volume  of  normal 
NaCl,  was  cautiously  precipitated  with  uranium  acetate  solution, 
then  centrifugalized.  The  precipitate  was  treated  with  15  Cc. 
NaCl  (0.85  per  cent.)  and  15.6  Cc.  n/10  NaOH.  This  formed 
an  emulsion.  The  emulsion  was  precipitated  with  Na2HP04,  then 
precipitated  with  picrolonic  acid.  The  precipitate  was  suspended 
in  NaCl  (0.85  per  cent.)  and  shaken  with  isobutyl  alcohol  (Merck) 
to  remove  the  picrolonic  acid.  The  solution  was  diluted  to  250  Cc. 
Even  3  Cc.  did  not  protect  from  one  L  +  dose. 
The  iso-butyl  alcohol  gave  a  white  precipitate  which  was  made 
into  a  colloidal  solution  with  250  Cc.  NaCl  (0.85  per  cent.).  2  Cc. 
of  this  solution  protected  against  one  L  +  dose  of  the  toxin. 
Five  Cc.  of  preparation  II  (2,250  units)  were  precipitated  with 
platinum  chloride  (10  per  cent.)  aqueous  solution.  The  precipitate 
was  shaken  with  n/100  NaOH  as  well  as  with  NaCl  (0.85  per 
cent.)  centrifugalized,  neutralized  and  diluted  to  350  Cc.  Even  3 
Cc.  of  this  solution  did  not  protect  against  one  L  -f-  dose  of  the 
toxin.  A  second  sample  was  likewise  precipitated  with  the  same 
platinum  chloride  solution  and  the  precipitate  stirred  with  distilled 
water,  then  with  NaCl  (0.85  per  cent.)  and  then  centrifugalized. 
The  washings  from  the  precipitate  and  the  centrifugalized  solution 
from  the  platinum  were  added  together  and  warmed  on  a  bath  to 
65 0  C. ;  then,  while  warm,  were  saturated  with  H2S  and  the  gas 
boiled  off  in  vacuo.  In  this  case  the  platinum  sulphide  separated 
nicely  giving  practically  a  colorless  solution.  There  is  some  diffi- 
culty in  obtaining  a  colorless  solution  in  every  test.  The  solution 
was  filtered  through  filter  paper  and  diluted  to  100  Cc.  One  Cc. 
protected  against  one  L  -f-  dose.  After  standing  two  days,  one  Cc.  of 
