506  The  Phenomena  of  Catalysis.  {^oVeXr^iJiT" 
fectly  incorporated  before  the  Glycerin  had  been  added;  also, 
previous  experience  had  taught  that  alcohol  and  some  other 
liquids  would  not  mix  with  Lanolin  until  diluted  with  sufficient 
Water.  Hence,  a  fl.  ounce  of  Water  was  added  and  well  stirred 
in,  when  the  mass  became  a  perfectly  smooth  cataplasm. 
THE  PHENOMENA  OF  CATALYSIS.1 
Remarkable  Results  Produced  in  Chemical  Reactions  by  the 
Mere  Presence  of  Certain  Substances  Which  Undergo 
No  Permanent  Change. 
By  W.  R.  Whitney. 
This  is  a  purely  chemical  term  and  stands  for  the  process  of 
greatly  increasing  the  velocity  of  chemical  reactions  by  employment 
of  materials  which  are  not  consumed  in  the  process.  Any  analogy  is 
apt  to  be  misleading,  but  Ostwald  suggests  the  parallelism  between 
catalysis  in  chemistry  and  the  effect  in  mechanics  of  the  change  from 
a  too  thick  to  a  good  lubricating  oil  on  a  shaft  rotating  under  con- 
stant force.  The  speed  will  increase  without  application  of  addi- 
tional energy.  In  a  sense,  this  definition  is  too  academic.  In  most 
of  the  processes  called  catalytic,  the  velocity-increase  is  so  enor- 
mous that,  without  the  catalyzing  agent,  the  process  would  hardly 
take  place  at  all.  For  this  reason  a  catalyst  is  sometimes  defined 
as  any  substance  which  produces  a  chemical  action  without  being 
consumed  in  the  process. 
Catalysis  is  usually  limited  to  describe  cases  where  a  definite 
material,  or  even  a  definite  form  of  material,  seems  to  bring  about 
a  reaction  or  produces  a  great  increase  in  the  velocity  of  the  reaction. 
Heating  the  reagents  produces  great  increase  in  velocity  of  most 
chemical  reactions,  and  some  are  made  to  speed  up  by  the  effect 
of  light,  and  so  heat  and  light  are  sometimes  called  catalyzers. 
But  it  is  customary  to  consider  this  type  as  at  least  partially  under- 
stood and  to  class  under  catalysis  the  less  easily  explained  cases, 
where  the  mere  presence  of  some  material  apparently  does  the 
work  and  is  yet  not  consumed.  It  acts  more  like  the  trigger  of  a 
gun.    This  sets  off  the  reaction,  which  in  our  gunpowder  analogy 
1  Reprinted  from  Sciences  Conspectus,  3,  1913,  pp.  84-88. 
