Berzelius' Theory

Berzelius founded his theory,[27] which had been in one or two of its features anticipated by Davy,[28] on inferences drawn from Volta’s contact effects.

This seemed to him to indicate that chemical affinity arises from the play of electric forces, which in turn spring from electric charges within the atoms of matter. To be precise, he supposed each atom to possess two poles, which are the seat of opposite electrifications, and whose electrostatic field is the cause of chemical affinity.

By aid of this conception Berzelius drew a simple and vivid picture of chemical combination. Two atoms, which are about to unite, dispose themselves so that the positive pole of one touches the negative pole of the other; the electricities of these two poles then discharge each other, giving rise to the heat and light which are observed to accompany the act of combination.[29]

The disappearance of these leaves the compound molecule with the two remaining poles; and it cannot be dissociated into its constituent atoms again until some means is found of restoring to the vanished poles their charges.

Such a means is afforded by the action of the galvanic pile in electrolysis: the opposite electricities of the current invade the molecules of the electrolyte, and restore the atoms to their original state of polarization,

If, as Berzelius taught, all chemical compounds are formed by the mutual neutralization of pairs of atoms, it is evident that they must have a binary character.

Thus he conceived a salt to be compounded of an acid and an oxide, and each of these to be compounded of two other constituents. Moreover, in any compound the electropositive member would be replaceable only by another electropositive member, and the electronegative member only by another member also electronegative; so that the substitution of, e.g., chlorine for hydrogen in a compound would be impossible—an inference which was overthrown by subsequent discoveries in chemistry.

Berzelius succeeded in bringing the most curiously diverse facts within the scope of his theory. Thus “the combination of polarized atoms requires a motion to turn the opposite poles to each other.

To this circumstance is owing the facility with which combination takes place when one of the two bodies is in the liquid state, or when both are in that state; and the extreme difficulty, or nearly impossibility, of effecting an union between bodies, both of which are solid.

Each polarized particle must have an electric atmosphere.

This atmosphere is the predisposing cause of combination. It follows, that the particles cannot act but at certain distances, proportioned to the intensity of their polarity.

Hence, bodies which have affinity for each other always combine nearly on the instant when mixed in the liquid state, but less easily in the gaseous state. The union ceases to be possible under a certain degree of dilatation of the gases.

This we know by the experiments of Grothuss. A mixture of oxygen and hydrogen, when rarefied to a certain degree, cannot be set on fire.”

“Many bodies require an elevation of temperature to enable them to act upon each other. It appears, therefore, that heat possesses the property of augmenting the polarity of these bodies.”

Berzelius accounted for Volta’s electromotive series by assuming the electrification at one pole of an atom to be somewhat more or somewhat less than what would be required to neutralize the charge at the other pole.

Thus, each atom would possess a certain net or residual charge, which might be of either sign; and the order of the elements in Volta’s series could be interpreted simply as the order in which they would stand when ranged according to the magnitude of this residual charge.

This conception was afterwards overthrown by Faraday.

Berzelius permitted himself to publish some speculations on the nature of heat and electricity, which bring vividly before us the outlook of an able thinker in the first quarter of the nineteenth century.

He says that the great question is whether the electricities and caloric are matter or merely phenomena.

If ‘matter’ is to be granted only to such things as are ponderable, then these problematic entities are certainly not matter. But he believes that it is wrong to narrow the application of the word ‘matter’.

He thinks that:

• caloric is truly matter – it has chemical affinities without obeying gravity
• light and all radiations consist in modes of propagating such matter.

This conclusion makes it easier to decide regarding electricity.

He remarks: “From the relation which exists between caloric and the electricities, what may be true with regard to the materiality of one of them must also be true with regard to that of the other. There are, however, phenomena produced by electricity which necessarily means that electricity is matter.

Electricity, for instance, very often detaches everything which covers the surface of those bodies which conduct it.

It passes through conductors without leaving any trace of its passage. But it penetrates non-conductors which oppose its course, and makes a perforation precisely of the same description as would have been made by something which had need of place for its passage.

We often observe this when electric jars are broken by an overcharge, or when the electric shock is passed through a number of cards, etc.

We may therefore imagine caloric and the electricities to be matter. They are destitute of gravitation, but have affinity towards gravitating bodies.

When they are not confined by these affinities, they tend to place themselves in equilibrium in the universe.

The suns destroy at every moment this equilibrium. They send the re-united electricities in the form of luminous rays towards the planetary bodies, upon the surface of which the rays, being arrested, manifest themselves as caloric.

This last in its turn, during the time required to replace it in equilibrium in the universe, supports the chemical activity of organic and inorganic nature.”

It was scarcely to be expected that anything so speculative as Berzelius’ electric conception of chemical combination would be confirmed in all particulars by subsequent discovery.

It did not survive the lifetime of its author as a coherent theory. But some of its ideas have persisted. Among them, the core conviction that chemical affinities are of electrical origin.

While the attention of chemists was for long directed to the theory of Berzelius, the interest of electricians was diverted from it by a discovery of the first magnitude in a different region.

The philosophers of the 18th century suspected that a relation subsists between electricity and magnetism. This was based on some effects produced by lightning, of a kind which may be illustrated by a paper published in the Philosophical Transactions in 1735.[30]

A tradesman of Wakefield put up many knives and forks in a large box in a room. In July 1731, a sudden thunderstorm happened which damaged the room. The Box split. Many knives and forks melted, the sheaths remained untouched.

The owner emptied the box on a Counter where some Nails lay. The people who took the knives that lay on the Nails observed that the knives took up the Nails."

Lightning thus had the power of magnetizing steel. This led Franklin[31] in 1751 to attempt to magnetize a sewing-needle by means of the discharge of Leyden jars.

The attempt was successful. Van Marum afterwards showed that it was doubtful whether the magnetism was due directly to the current.

More experiments followed.[32]

In 1805, Jean Nicolas Pierre Hachette (b. 1769, d. 1834) and Charles Bernard Desormes (b. 1777, d. 1862) attempted to determine whether an insulated voltaic pile, freely suspended, is oriented by terrestrial magnetism; but without positive result.