Am.  Jour.  Pharm. 
April,  1909. 
Enzymes  of  Cow's  Milk. 
179 
(2)  It  is  active  in  neutral,  faintly  alkaline  and  faintly  acid 
solution ;  a  very  slight  excess  of  acid  rapidly  inhibits  its  action. 
(3)  Its  optimum  point  is  3/°-42°  C,  its  activity  at  52 0  C.  is  about 
equal  to  that  it  exhibits  at  28 0  C. ;  its  proteolytic  power  is  destroyed 
at  76 0  C,  and  its  action  on  gelatin — which  it  liquefies — takes  place 
at  650  C. 
(4)  It  decomposes  hydrogen  dioxide  with  the  liberation  of 
oxygen,  being  probably  one  of  the  ferments  which  react  with  the 
Wilkinson-Peters  test  or  the  Dupouy  test,  observed  by  Charles  H. 
LaWall,  and  reported  to  the  pharmaceutical  meeting  of  the  Phila- 
delphia College  of  Pharmacy  in  January,  1909  ("The  Differentiation 
of  the  Enzymes  of  Milk  by  Hydrogen  Dioxide  and  its  Tests,"  by 
Charles  H.  LaWall,  American  Journal  of  Pharmacy,  February, 
1909,  5). 
(5)  It  is  inhibited  in  action  by  mercuric  chloride,  formaldehyde, 
carbon  disulphide  and  phenol,  but  not  by  chloroform,  ether,  benzol, 
or  toluol. 
Later,  without  knowledge  of  the  work  of  Babcock  and  Russell, 
Bertrand  and  Bourquelot  demonstrated,  by  other  methods,  the 
presence  of  an  oxidizing  ferment  in  milk.  "  As  long  ago  as  188 1," 
states  the  Dietetic  and  Hygienic  Gazette  (1904,  523),  "Arnold  had 
found  that  fresh  cow's  milk  became  blue  on  contact  with  tincture 
of  guaiac,  and  that  this  reaction  is  no  longer  produced  if  the  milk  be 
heated  to  a  temperature  of  8o°  C.  In  1890  Kowalesky  established 
undeniably  that  the  same  reaction  takes  place  in  milk  when  mixed 
with  old  oil  of  turpentine.  But  at  that  time  this  reaction  was  at- 
tributed to  the  presence  of  ozone.  Later  it  was  recognized  that  free 
ozone  cannot  exist  in  the  system,  and  Bertrand  and  Bourquelot 
demonstrated  that  the  reaction  of  milk  toward  oxidizing  agents  is 
due  to  the  presence  of  a  ferment  (an  oxydase).  Of  itself  it  is 
powerless  to  oxidize  oxidizable  substances  without  the  assistance  of 
an  intermediary  agent  highly  oxygenated,  such  as  the  tincture  of 
guaiacum,  old  turpentine  or  oxygenated  water.  But,  when  these 
agents  yield  their  oxygen  to  this  ferment,  the  latter  is  able  to  hold 
it,  and  in  consequence  to  oxidize  any  oxidizable  substance  with  which 
it  comes  in  contact.  For  example,  if  some  drops  of  tincture  of 
guaiac  are  added  to  fresh  milk,  this  does  not  change  color.  But  if 
at  the  same  time  some  drops  of  oxygenated  water  are  poured  into 
the  milk,  a  blue  color  begins  to  show  itself  at  once.  The  ferment 
has  absorbed  a  portion  of  the  oxygen,  and  coming  into  contact  with 
the  guaiac  has  oxidized  the  latter.    Thus  this  ferment  belongs  to 
