1 143 
eous  pliase  is  coniiected  witli  ilie  progress  ol'  the  reaction.  It  seeiiis 
probable,  that  in  tlie  examples  of  reactions  cited  in  Tal)le  2,  the 
changes  concenied  are  rea!  Chemical  reactions  rather  than  ditl'nsion 
processes.  For  these  reactions  it  wonld  be  interesting  to  (ind  out  a 
relation  between  tlieir  orders  and  their  temperatnre  coeflicients,  bnt 
unfortunately  no  experimental  work  in  this  direction  is  available. 
{b)  Teiiipemhire  coefficients  of  catalysed  reactions. 
We  shall  now  consider  the  temperatnre  coefticients  of  reactions 
cataljsed  lieterogeneonsly.  The  following  is  the  sumraary  of  import- 
ant reactions  investigated  up  till  now : 
TABLE  3 
Reaction. 
Reference. 
10 
(!)  Decomposition  of 
by  catalase  (blood) 
Senter,  Zeit.  Phys.  Chem.  1903,  44,  257 
1.7 
(2)  Decomposition  of  H3O2 
by  colloidal  Au,  Pt,  Ir  etc. 
Bredig  and  his  pupils,  ibid  1899,  31,  258, 
320;  1901,  37,  1,  323;  1901,  38,  122;  1909, 
66,  175 
1 .6 
(3)  Decomposition  of  HoO-, 
by  colloidal  Ag 
Mc.  Intosh,  Jour.  Phys.  Chem.  1902,6,  15 
5 
(4)  Decomposition  of  HjOo 
by  colloidal  MnO, 
Mark.  Dissert.  Heidelberg  1907 
2 
(5)  Hydrogenationin  presence 
of  colloidal  Pd 
Zalkind  andPiTCHTscHiKOFF,  J.  Russ.  Phys. 
Chem.  Soc.  1914,  46,  1527 
1.75 
(6)  Oxydation  of  NaH2P02  by 
colloidal  Pd  or  Pd  black 
SiEVERTs  and  Peters,  Zeit.  Phys.  Chem. 
1916,  91,  199 
2 
(7)  Reduction  of  methylene 
blue  by  H COOH  in  pres- 
ence of  colloidal  metals 
Bredig  and  Sommer,  ibid  1910,  70,  34 
2 
(8)  Decomposition  of  (a) 
H.COOH  and  (6)  H.COONa 
in  presenceof  colloidal  Rh 
Blackadder,  ibid  1913,  81,  385 
(a)2 
ib)  2.5 
(9)  Oxydation  of  phenyl  thio- 
carbamide  in  presence  of 
blood  charcoal 
Freundlich  and  Bjercke,  ibid  1916,  91,  1 
2.3 
(10)  Oxydation  of  oxalic  acid 
in  presence  of  blood  char- 
coal 
Warburg,  Pflüg.  Arch.  1914,  155,  547 
2.1 
(11)  Enzyme  actions 
Generally  higher  than 
2 
The  following  table  shows  the  snmmary  of  resnlts  obtained  with 
catalysts  in  the  solid  state : 
