involved in the Formation of Complex Atoms. 731 



a serious error. He considered the deviations from whole 

 numbers on the oxygen basis, all except two of which were 

 positive, and attempted to explain them. It is very evident 

 that if the elements are built up from hydrogen, the deviations 

 which have to be explained are the differences between the 

 atomic weights on the oxygen basis and the particular 

 multiples of 1'0078 which are supposed to make up the 

 elements in question. That is, for carbon the deviation to be 

 explained is the difference between 12 times 1*0078 and the 

 atomic weight of carbon on the oxygen basis. It is found 

 that all except three of these deviations are negative. 



Two systems which are at a distance apart may be con- 

 sidered as being made to approach each other by some 

 outside force. Let them approach until a new system 

 is formed. If the total energy of this new system is less 

 than the sums of the energies of the separate systems, it 

 will be stable. In other words, the stability of a system 

 depends upon whether or not its energy is less than for any 

 neighbouring configuration. This evidently means that in 

 the formation of the system energy was radiated, and there- 

 fore, according to the definition of mass given above, there 

 was a loss of mass. This energy which is radiated might be 

 called the " free energy of formation " of the element in 

 question. If the two systems described above were two 

 hydrogen atoms, the system formed would be a hydrogen 

 molecule. If, however, four hydrogen atoms should come 

 together in such a way that the resulting system should be 

 made up of four nuclei and two negative electrons, a helium 

 nucleus would result. Just what conditions the configuration 

 of the system which is formed is a question, at the present 

 time. It seems very likely, however, that a process like the 

 one described must take place. 



It might seem at first thought that if the free energy of 

 formation of these elements is negative, they should be 

 formed in hydrogen under ordinary conditions, but there 

 are several things to consider in this connexion. "Whether 

 or not a reaction will proceed of its own accord depends on 

 two things : first, the sign of the free energy of tho 

 reaction, and second, the rate of the reaction. That it is 

 impossible to predict whether or not a reaction will proceed 

 is illustrated by considering the two reactions N 2 + 2 = 2NO 

 and N 2 +3H 2 = 2NH 3 , the first of which is exothermic and 

 the second endothermic. In neither case does the reaction 

 proceed if the substances are brought together under 

 ordinary conditions. Just what the conditions are which are 



3 B 2 



