The loss of the dissipation body due to the natural ionization of the air is first allowed for.
Volta then proved that all metals could be arranged in an electromotive 1 Modern researches have shown that the loss of charge is in fact dependent upon the ionization of the air, and that, provided the atmospheric moisture is prevented from condensing on the insulating supports, water vapour in the air does not per se bestow on it conductance for electricity.
The ionization of a solution, then, is usually diminished by raising the temperature, the rise in conductivity being due to the greater increase in fluidity.
Mache (62) thinks that the ionization observed in the atmosphere may be wholly accounted for by the radioactive emanation.
At extreme dilution, when the ionization is complete, a variation in temperature cannot change its amount.
The salts tabulated are those of which the equivalent conductivity reaches a limiting value indicating that complete ionization is reached as dilution is increased.
We may take it, then, that only that portion of these bodies is chemically active which is electrolytically active - that ionization is necessary for such chemical activity as we are dealing with here, just as it is necessary for electrolytic conductivity.
But the temperature coefficient of conductivity is now generally less than before; thus the effect of temperature on ionization must be of opposite sign to its effect on fluidity.
As the concentration is increased and un-ionized molecules are formed, a change in temperature begins to affect the ionization as well as the fluidity.
Solid copper chloride is brown or yellow, so that its concentrated solution, which contains both ions and undissociated molecules, is green, but changes to blue as water is added and the ionization becomes complete.