136 
13. General remarks. 
It will be clear from the contents of this paper, that the theore- 
tical formula 
ne | 
0,434 log es + ay = mt 
is borne out by experiment in different ways. 
The hydrogen-ions having been found to absorb the enzyme 
radiation, the question was considered, if the hydroxyl-ions possess 
this property also. If such were the case, the equation should be 
0,434 1— 
By repeating the experiments of Part 3, but now with solutions 
of different pz, in most cases py=7,21, it was tried several times 
1 
OY aif == ir. 
y 
‚found for two 
to decide this point. Combination of the factor 
different py, should give the necessary equations to calculate both 
n and 7. As will be clear, however, from the considerations in Part 3, 
the inevitable small experimental errors have an even larger influence 
at a py below or above the py=7,52 of maximum activity. It 
proved to be impossible to carry out experiments of sufficient accu- 
racy for this purpose. Still, the values, obtained for 7, though 
varying widely, were generally so small, sometimes even negative, 
that they allowed the conclusion, that the hydroxyl-ions (i.e. negative 
electricity) do not absorb the urease radiation. 
Since the writer’s first study on Enzyme-action *) in 1904, in which 
the probability was first pointed out, that also the catalytic action 
of hydrogen-ions and of many other catalysts might be due to radia- 
tion, the conception of catalysis as a radiation phenomenon has 
been taken up from different sides. 
In a series of papers Lewis *) has worked out the theory, that 
hydrogen-ions act catalytically through radiations, a molecnle of the 
catalysed compound becoming only reactive, if its energy has been 
increased by absorbed radiation (ultra red heat. radiation) to the 
“critical” condition. 
In extensive experimental researches NirRATAN DHAR*) pointed 
1) Proc. K. Akad. Wetensch. Amsterdam and Zeitsch. physikal Chem. 49,4. 
2) T. Chem. Soc. 1914, 2330, etc. 
3) Proc. K. Akad. Wetensch. Amsterdam 1916 and T. Chem. Soc. 1917, 690. 
