1045 



eons pliase is ooniiected with the progress of tlie reaction. It seems 

 probable, that in the examples of reactions cited in Table 2, the 

 changes concerned are real chemical reactions rather than diffusion 

 processes. For these reactions it would be interesting to find out a 

 relation between their orders and their temperature coefificients, but 

 unfortunately no experimental work in this direction is available. 



{b) Temperature coe/ficienU of catalysed reactions. 



We shall now consider the temperature coefficients of reactions 

 catalysed heterogeneously. The following is the summary of import- 

 ant reactions investigated up till now: 



TABLE 3. 



(1) Decomposition of \\X>2 ' Senter, Zeit. Phys. Chem. 1903, 44, 257 

 by catalase (blood) 



(2) Decomposition of H0O2 ^ Bredig and his pupils, ibid 1899, 31, 258, 

 by colloidal Au.Pt, Irêtc. ■ 320; 1901, 37, I, 323; 1901,38, 122; 1909, 



! 66, 175 



(3) Decomposition of H^O. ' Mc. Intosh, Jour. Phys. Chem. 1902,6,15 

 by colloidal Ag 



(4) Decomposition of HjOo Mark. Dissert. Heidelberg 1907 

 by colloidal MnO^ 



(5) Hydrogenation in presence Zalkind and Pitchtschikoff, J. Russ. Phys. 

 of colloidal Pd Chem. Soc. 1914, 46, 1527 



(6) Oxydation of NaH2P02 by Sieverts and Peters, Zeit. Phys. Chem. 

 colloidal Pd or Pd black 1916, 91, 199 



(7) Reduction of methylene Bredig and Summer, ibid 1910, 70, 34 

 blue by H.COOH in pres- 

 ence of colloidal metals , 



(8) Decomposition of {a) \ Blackadder, ibid 1913, 81^ 385 

 H.COOH and (6) H.COONa | 



in presence of colloidal Rh j 



(9) Oxydation of phenyl thio- Freundlich and Bjercke, ibid 1916, 91, 1 

 carbamide in presence of i 



blood charcoal I 



(10) Oxydation of oxalic acid Warburg, Pfiüg. Arch. 1914, 155, 547 

 in presence of blood char- 

 coal 1 



1.7 

 1.6 



5 

 2 



1.75 



2 



2 



(a) 2 

 (6) 2.5 



2.3 



2.1 



(11) Enzyme actions 



Generally higher than 



The following table shows the summary of results obtained with 

 catalysts in the solid state: 



