770 
Diphtheria  Antitoxin. 
Am.  Jour.  Pharm. 
Nov.,  1918. 
protein  content.47  Most  of  the  antitoxin  is  precipitated  by  alcohol 
35-45  per  cent.  The  action  is  reversible  only  to  a  slight  degree. 
Acetone  precipitates  antitoxin  and  long  contact  inactivates  it.48 
Oxalic  acid  slowly  injures  it.49 
Phenol  is  used  in  0.3-0.5  per  cent,  solution  to  preserve  antitoxic 
sera.  This  does  not  change  its  antitoxic  content.50  Tricresol  (0.4 
per  cent.)  is  used  to  preserve  antitoxic  serum.  Formaldehyde 
injures  it.   -Putrefaction  completely  destroys  antitoxin. 51 
Aluminium  sulphate  (5  per  cent.)  and  potassium  alum  precipitate 
albumin  from  the  serum,  and  the  filtrate  retains  its  antitoxic  value.52 
Dilute  NaOH,  when  added  to  this  filtrate,  causes  a  precipitate  which 
holds  the  antitoxin.  This  latter  precipitate  is  soluble  in  excess  of 
NaOPI  when  more  than  one  third  part  of  potassium  alum  has  been 
added  to  the  serum.53 
Antibodies  can  be  salted  out  or  floculated  by  high  electrolytic  con- 
centration.53a  There  are  some  data  that  even  pure  neutral  salts  011 
concentration  may  perhaps  injure,  or  hold  back,  certain  antigens,54 
and  this  perhaps  might  occur  in  the  case  of  antitoxin.  Salts  with 
univalent  cations,  i.  e.,  NaCl,  Na2S04,  (NH4)2S04,  NH4SCN, 
NH4Br  exercise  no  influence  on  the  diphtheria-toxin-antitoxin  com- 
bination in  serum.55 
Antitoxin  is  not  precipitated  by  NaCl,56  but  NaCl  and  KC1  as 
used  by  d'Astros  and  Rietsch,  precipitated  the  antitoxin  incom- 
pletely.57 Likewise,  a  solution  of  CaCl2  with  NaCl  precipitates 
antitoxin  quantitatively  from  serum.58    The  filtrate  after  one  half 
47  Mellanby. 
48  v.  Groer,  F.,  and  Kassowitz,  K.,  p.  448;  Brodie,  T.  G.,  Journ.  Path.,  Vol. 
4,  p.  461,  1897. 
49  Brodie,  p.  464. 
50  Freund  and  Sternberg. 
51  Brieger,  L.,  Festschrift  f.  R.  Koch.,  p.  445,  1903. 
52  Freund  and  Sternberg. 
53  See  also  Rakuzin,  M.  A.,  /.  Russ.  Phys.  Chem.  Soc,  1916,  Vol.  48,  p. 
465;  Rakuzin,  M.  A.,  and  Flier,  G.  D.,  ibid.,  p.  711. 
53a  See  London,  E.  S.,  and  Pakhotina,  E.  P.,  Comp.  rend.  Soc.  Biol,  1917, 
Vol.  80,  p.  756. 
54  See  Pick,  E.  P.,  "  Biochemie  der  Antigene." 
55  Pick,  E.  P.,  and  Schwarz,  O. 
56  Brieger  and  Krause. 
57  DAstros,  L.,  and  Rietsch,  M.,  Comp.  Rend.  Soc.  de  Biol,  Vol.  52,  p. 
337,  1900. 
58  Brieger,  L.,  and  Boer,  Zeits.  f.  Hyg.,  Vol.  21,  p.  259. 
