W. J. V. OSTERHOUT 421 



Putting K = 4(10-17) and Cxz^ = 0.1 we get^ 



.Q_17 ^ (CNa4XCa)^ 



~ (80)* (20) (0.1) 



whence CNa4XCa = 0.000936. 



Proceeding in the same manner with the other mixtures we get the 

 values given in Table III. Starting with the lowest value (that in 62.0 

 per cent CaCl2) we observe that there is an increase as the per cent of 

 CaCl2 decreases until 2.44 per cent is reached (the amount of this 

 increase is shown in Column 6 of the table). Conversely we find 

 (Table II) that the velocity constants are higher in 62.0 per cent 

 CaCls than in any other mixture and that they decrease as the per 

 cent of CaCl2 decreases to 2.44 per cent. Thus in the case of Km 

 the value in 62.0 per cent CaCla is 0.009, in 2.44 per cent CaCla it 

 is less by 0.00354, while in 15.0 per cent it is less by 0.0017, and in 

 35.0 per cent by 0.00041; if we multiply these numbers by the con- 

 stant factor 0.251 they agree very closely with the figures for the 

 increase in Na4XCa. These values are plotted in Fig. 2, which 

 shows that the decrease in Km is directly proportional to the increase 

 in the amount of Na4XCa. Hence we assume that Na4XCa acts as 

 a negative catalyzer or inhibitor of the reaction M -^ B. 



An inspection of Table II shows that the value of Ka fluctuates 

 with that of Km except that as CaCl2 increases the value of Ka rises 

 more rapidly than that of Km. This is also obvious from Fig. 1, 

 which shows that the greater the per cent of CaCl2 in the mixture 

 the greater the maximum attained. Since this maximum increases 

 as the value of Ka -^ Km increases, it is evident that the value of Ka 

 -^ Km must rise as the per cent of CaCl2 becomes greater. The 

 value of Ka -t- Km in the solution containing 1.41 per cent of CaCla 

 is 0.03333 while in the solution containing 62.0 per cent CaCl2 it is 

 0.05889, an increase of 0.02556. If we calculate this increase for the 

 other mixtures and plot the values so obtained against the per cent 

 of CaCl2 in the surface, we obtain a straight line as shown in Fig. 3. 

 This indicates that CaCl2 catalyzes the reaction A ^> M\ for if this 

 were not the case the value of Ka and Km would rise and fall in such 

 a way that the value of Ka -^ Km would remain constant. 



It is evident from Figs. 2 and 3 that the values of Ka and Km are 

 determined by the amount of Na^XCa and by the per cent of CaCl2 



