ANTAGONISM 153 



We have seen that the value of KA -4- KM increases as 

 the per cent, of CaCl 2 increases and we interpreted this 

 to mean that the reaction A > M is catalyzed by CaCl 2 . 

 In the same manner we infer that the reaction R > 8 is 

 catalyzed by CaCL, since we find that the value of KR 

 Ks increases with increasing percentage of CaCl 2 , as 

 shown in Fig. 65. It is not certain that the curve does 

 not reach a minimum in the mixture of 97.56 NaCl + 

 2.44 CaCL, but for practical purposes we may, for the 

 present, regard it as a straight line. 15 



The relation between KN and Ko is taken as constant 

 in the proportion of 100 to 99. 



It is evident that when the constants have been empir- 

 ically determined for two mixtures the constants for 

 any other mixture can be calculated at once, since all of 

 them depend in a definite manner on Na 4 XCa (KA and KR 

 also depend on the per cent.of CaCl 2 ). The agreement 

 between the constants thus obtained by calculation 

 and those found by trial is fairly close, as is evident from 

 Figs. 64 and 65. 16 



It has already been shown that the height to 



16 



Since in pure NaCl or CaCl 2 the salt compound Na 4 XCa is not formed, 

 we should expect that in these solutions all the reactions would be more 

 rapid than in the mixtures. That this expectation is fully realized is 

 evident from Table X. 



The velocity constants are somewhat higher in NaCl than in GaCL,; 

 this is not explained by the assumptions already made, but it does not 

 seem desirable at present to make additional assumptions for this 

 purpose. We might expect the values of K A -4- K M and R R +- J s to 

 reach a maximum in CaClj. This is actually the case. It might perhaps 

 be expected that these values would fall to a minimum in NaCl. This 

 is the case with -BT A -f- & M , but not for K R -f- K s 



16 The constants obtained by calculation would fall exactly on the 

 graphs in these figures while those found by trial are indicated by 

 the points given. 



