1911.] The Properties of Colloidal Systems. 95 



Table IV. 





Time required for a change of 

 1200 recip. megohms in middle of curve. 



Time for change of 1800 recip. megohms 

 reckoned from beginning of action. 



A 



49 



33 



B 



123 



105 



C 



63 



42 



D 



97 



100 



It may be seen that the presence of calcium sulphate caused in certain 

 cases or stages of the reaction an increase in the rate of the reaction, some- 

 times a diminution. Tbe increase was more marked with the lower con- 

 centration of enzyme. From these figures the value of n comes out — 

 Water, from column 1, 1*2, from column 2, T03, 

 CaS0 4 „ 7, „ 1-3. 



The effect on n is therefore of the same nature as in the case of a simple 

 adsorption, viz., an increase. In otber words, there is less difference between 

 the activity of different concentrations of enzyme in the presence of calcium 

 sulphate than in the absence of neutral salt. An investigation of the 

 causes leading to the various numerical values at various stages of the reaction 

 or with various concentrations of enzyme would no doubt throw light on the 

 manner of its action. 



The greater effect on the rate of the reaction in the case where the 

 enzyme is present in lower concentration is, I think, what would be expected. 

 When the enzyme is in excess, the additional amount adsorbed under the 

 influence of calcium ions would probably have comparatively little effect, 

 since it is not unlikely that the amount adsorbed without this influence is 

 already capable of maximum hydrolytic action on the substrate. 



In another experiment, in which dialysed trypsin was used, the following 

 values of n were obtained : — 





Beginning of reaction. 



Middle of reaction. 



End of reaction. 



Water 



0-94 



1-7 



2-48 



CaS0 4 



5-7 



2-36 



1-81 



The action of electrolytes on trypsin is evidently a somewhat complex one, 

 and requires further research. 



It is held by some that the well-known fact that the presence of substrate 



