Am.  Jour.  Phann.  1 
November,  1913.  J 
The  Phenomena  of  Catalysis. 
507 
would  otherwise  be  an  exceedingly  slow  oxidation.  The  gunpowder 
might  take  a  century  to  oxidize  unless  it  were  set  off,  although  the 
products  of  the  reaction  would  be  the  same  regardless  of  the 
velocity. 
It  is  very  probable  that  for  years  catalysis  was  a  word  used,  as 
such  terms  are  often  used,  to  classify  or  group  together,  without 
further  commitment,  a  number  of  different  phenomena  which  were 
not  at  the  time  explicable.  It  was  known  that  hydrogen  and  oxygen 
could  be  mixed  and  would  remain  inert  indefinitely,  but  that  a  little 
platinum  or  an  electric  spark  in  the  presence  of  the  mixture  would 
cause  rapid  combination  to  form  water.  A  finite  quantity  of 
platinum  was  able  to  produce  the  reaction  between  an  unlimited 
quantity  of  these  gases.  Other  finely  divided  metals  acted  similarly. 
The  platinum  was  called  the  catalyzer.  The  spark  in  such  a  case 
was  not  usually  considered  as  a  catalyzer  in  the  narrower  sense. 
This  is  probably  because  the  case  is  an  application  of  intense  heat 
which  in  any  other  manifestation  is  equally  efficacious.  It  has  been 
the  custom  to  consider  as  cases  of  catalysis  only  those  reactions 
in  which  the  phenomenon  can  be  ascribed  to  some  material,  thus 
excluding  greatly  increased  reaction  velocity  due  to  light,  high 
temperature,  etc.  It  was  known,  on  the  other  hand,  that  the  de- 
composition of  hydrogen-peroxide  solution  was  greatly  hastened 
or  made  almost  instantaneous  by  colloidal  platinum  and  other  col- 
loidal metals.  Here  again  the  metal  was  not  consumed  and  had  not 
lost  any  of  its  power  after  it  had  apparently  accomplished  so  much. 
It  was  known  that  sugar  in  aqueous  solution  is  ordinarily  decom- 
posed by  the  water  into  dextrose  and  laevulose  with  exceedingly 
low  velocity,  but  the  same  reaction  takes  place  very  rapidly  in  pres- 
ence of  acids  or  certain  organic  ferments.  Thus  the  acid  and  the 
ferment  were  called  the  catalyzer. 
It  is  known  that  many  of  our  most  common  chemical  reactions 
owe  their  velocity  to  the  presence  of  water.  In  fact,  water  is  the 
most  common  and  most  important  catalyzer  of  all.  It  is  much 
easier  to  find  cases  of  chemical  reactions  which  need  water  for  any 
appreciable  velocity,  than  it  is  to  find  reactions  which  can  proceed 
in  its  absence.  Yet  in  most  of  them  the  water  apparently  does 
not  take  part -in  the  reaction  nor  is  lost  through  it,  and  the  same 
water  could  be  used  to  an  unlimited  extent.  Practically  all  of  the 
common  chemical  reactions  are  of  this  type.  Silver  nitrate  and 
sodium  chloride  do  not  react  in  the  dry  state,  and  the  mere  condition 
