1902.] on the Electronic Theory of Electricity, 178 



The way is cleared, however, for some consistent explanations if we 

 can assume that one or more free electrons can attach themselves to a 

 neutral atom and so give it a negative charge of electricity. We may 

 suppose as a first assumption that in a neutral atom which is otherwise 

 complete, there exist localities at which one or more electrons can find 

 a permanent attachment. The atom is then no longer neutral but 

 negatively electrified. If the atom can as it were accommodate one 

 electron it is a monovalent element, if two it is divalent, and so on. If 

 it cannot accommodate any at all it is an avalent or non-valent element. 

 Consider the case of gaseous molecules. Chemical facts teach us 

 that the molecules of free gaseous hydrogen, oxygen or other gases 

 contain two atoms, so that these free molecules are represented by the 

 symbols Hg, Oj, etc. In these cases hydrogen and oxygen are so to 

 speak combined with themselves. We can explain this by the supposi- 

 tion that most neutral atoms are unstable structures. In contact with 

 each other some lose one or more electrons and an equal number gain 

 one or more electrons. Hence in a mass say of hydrogen we have some 

 atoms which are positively electrified and some which are negatively 

 electrified then called atomic ions, and these ions united pair and pair 



form the molecules of hydrogen which may be represented by (H, H). 

 Similarly for other gases. Certain neutral atoms such as those of 

 argon are monatomic and non-valent and these appear to be unable 

 to enter into combination either with each other or with other atoms. 

 Accordingly, in a mass of free hydrogen there are no free electrons and 

 all the positively charged and negatively charged H atoms are in union. 

 Hence the gas is a non-conductor of electricity. But we can make it 

 a conductor by heating it to a high temperature. The explanation of 

 this is that a high temperature dissociates some of the molecules into 

 atoms and these under the action of electric force move in opposite 

 directions, thus creating an electric current. Thus air at ordinary 

 temperatures is an almost perfect non-conductor, but at a white heat 

 it conducts electricity freely. 



The monovalent elements like hydrogen are those neutral atomic 

 structures which can lose one electron or take up one electron, becoming 

 respectively positive atomic ions and negative atomic ions. In the 

 same way the divalent elements such as oxygen are those neutral 

 atomic structures which can part with two electrons and take up two, 

 and so on for trivalent, quadrivalent, etc., atoms. The work required 

 to remove the second electron probably is very much greater than that 

 required to remove the first. Hence in polyvalent atoms the valencies 

 have unequal energy values. 



Consider now a mass of intermingled oxygen and hydrogen con- 

 sisting of neutral molecules. The state is a stable one as long as all 

 the molecules are neutral. If, however, we dissociate a few of the 

 hydrogen and oxygen molecules by an electric spark or by heat then 

 there is a recombination. A positive oxygen ion unites with two 

 negative hydrogen ions and a negative oxygen ion with two positive 



