184 



PHENOMENA, ATOMS, AND MOLECULES 



The fact that they are actually so very nearly straight and parallel is 

 excellent evidence of the correctness of the theory, especially so, since the 

 curves obtained by plotting Wd in a similar way (see Fig. 2) are by no 

 means straight. 



Fig. 3. 



Before proceeding further we will now examine the data and choose the 

 most probable values of q to be used in subsequent calculations. 



The slope of the lines in Fig. 3 enables us to calculate q by Equation 50. 

 The results thus obtained are given in Table XIII. 



TABLE XIII 



q = Heat of Formation of Hydrogen at Constant Pressure. 



Pressure . 

 ff 



0,015 

 108,000 



0.039 

 96,000 



0.207 

 91.500 



I . I 



100,000 



4-4 

 97,000 



We may also determine q from the experiments at higher pressures. 

 For this purpose we may combine Equations 50 and 43. The difficulty 

 arises that F is not strictly independent of the temperature, but varies 

 with it slightly and to an extent that depends on the relative magnitude 

 of BP and E (see Equation 42). Since the variation of F with the tem- 

 perature is small compared with that of Wd, we may proceed as follows 

 in calculating q: 



