A theory can rank as scientific only insofar as it offers a solution of the problems it professes to explain. Now the Mechanical Theory is unable to meet these problems.

Facts of Chemistry

Atomic Weights

Diversity and constancy of Atomic Weights; — Each of the simple bodies at present known has its own specific atomic weight. These atomic masses are ranged in ascending scale beginning with Hydrogen whose atomic weight is represented by unity, up to Uranium whose atomic weight is 238.5.

Now it is a remarkable thing that these elementary bodies which differ so much from each other in their relative masses all show an equal resistance to further division. They preserve their integrity through all chemical reactions.

Examination of the Mechanical Explanation;— In the Mechanical Theory the constant persistence of atomic weights is explained simply by two realities, mass and motion; for the whole universe is reducible to these two factors. But neither of these can explain the fact.

If mass is homogeneous why does the divisibility of matter stop short at atomic masses that are unequal in quantity? To say that the secret of the constant diversity of these weights lies in the homogeneity of matter is surely to attribute a diversity in effect to an absolute identity of cause?

On the other hand, equally incapable is local movement of accounting for the constant inequality of atomic weights. It is by a series of chemical reactions that all atoms undergo those manifold changes which transform their intrinsic energy, or reduce it to a minimum; but the forms of motion, to which mechanists attribute the permanence of the atomic nature, are essentially variable and reducible, and therefore we have no explanation how the elementary masses, once deprived of their protecting agents, always triumph over all physical and chemical causes that tend to disintegrate them.

Chemical Affinity

Meaning of Affinity, and Criticism of the Mechanical Conception of it; — Affinity is an elective tendency in virtue of which some bodies tend towards other bodies to make definite combinations. Each simple body has its own specific tendency, its own circle of sympathetic elements.

According to the Mechanical Hypothesis, two bodies have a mutual affinity if their motions are able to harmonise, to coalesce, to result in a state of stable equilibrium. The tendency of the elements is entirely extrinsic; it depends solely upon the impulse communicated to the atoms and on the direction that results from it.

Now it is an undeniable fact that the impulse and direction of motion can vary indefinitely in the molecules of bodies subjected to the influence of heat, of electricity, or of other physical forces. The affinity should therefore undergo the same variations and in this case we rightly ask how it is that any one body will not combine with any other.

Experience attests that nothing can overcome the perfect indifference of some bodies for one another, as also the specific and invariable character of the affinity existing between others.

Valence of Atomicity

Meaning of Valence and Criticism of the Mechanical Explanation: — Valence is the name given to the property possessed by each of the atoms of a given element, of uniting itself to 1, 2, 3, …..n atoms of hydrogen or chlorine.

Although valence is not absolutely constant, it would be false to conclude that it is subject to the caprices of chance. It depends on the nature of the elements, yet it is subject, within well defined limits, to the influence of certain extrinsic causes. This we express by saying it is relatively constant.

Now does the Mechanical Hypothesis supply any cause capable of guaranteeing this relative constancy? Evidently not. Local motion, we are told, is the only agent put forward to determine the number and the manner of the arrangement of the atomic masses that are contained in the molecule of the compound. But, on this hypothesis, the variations of the internal movements would always correspond to all the variations of external causes, and thus valence would lose its constancy.

Chemical combination

Between a chemical combination or compound and a simple mixture there is an essential difference of a threefold nature: —

• Every compound is characterised both by the entire disappearance of the greater number of the physical and chemical properties of the component elements, and by the appearance of new stable properties.
• A second sign showing that a combination has taken place is given by the considerable body of heat which is discharged in the process of the chemical reaction.
• Combinations are regulated by laws of weight which are not observable either in physical actions or in simple mixtures.

But this opinion cannot be reconciled with the principle of the conservation of energy. Many combinations are accompanied with an enormous discharge of heat, electricity, light and chemical energy. The immediate surroundings are affected b y it, becoming heated, illuminated and charged with electricity. Now every increase of energy gained by a body of any kind always implies, according to the above mentioned principle, a corresponding loss suffered by some other bodies. The enormous quantities of force set free by the reactions is accordingly the measure of the real loss sustained by the new compound; in other words, it measures the importance of the changes that have taken place in the elemental properties.

Second opinion: By paying greater attention to the facts of experience, many Mechanists recognise that chemical combinations involve some profound modifications in the characters of the atomic masses. This concession is important. But as every mistake carries with it serious consequences, the result of this acknowledgement is that the mechanical theory, as we shall see later, cannot reconcile with its own principles either the regular decomposition of bodies or the return of the elements back to their natural state.

Second Sign:

Thermal Phenomena; — According to the Mechanists, the generating cause of the heat discharged by chemical combinations is two-fold; it is due partly to the intensity of the molecular collisions, partly to the breaking up of the equilibrium existing between the atoms.

This explanation of the Mechanical Theory appears certainly insufficient when we take into consideration the two distinctive characteristics of the thermal phenomena, namely, intensity and invariability.

Thermo-Chemistry teaches that 16 grammes of oxygen combining with 2 grammes of hydrogen sets free 59 calories or units of heat, that is, a force capable of lifting (59x 425) 24.745 kilogrammes one metre high in a second. But is it not incredible that 18 grammes of matter, whose atoms moreover are in close proximity to each other, could by a simple modification of their spatial relations suddenly generate such an enormous display of energy ?

Yet be this as it may, the invariability of this phenomenon in a given combination is in manifest opposition to the mechanical theory. As soon as we were to identify all chemical energies with local motion pure and simple, the constancy of the phenomenon and its absolute independence in the presence of alien energies which provoke it, would disappear entirely.

An effect that is always constant demands a cause that is stable, permanent and invariable. And, it is needless to say, local motion in no way possess these qualities.

Third sign:

Laws of weight:— Most chemists regard the physical indivisibility of atoms as the real foundation of the laws of weight. Such was notably the opinion of Dalton who revived Greek Atomism. However well-founded this may have seemed, it is astonishing that mechanists look to the indivisibility of atoms* as a self-evident postulate, when, of all chemical facts, perhaps none is more manifestly opposed to their principles.

*It would be extraneous to point to Nuclear fission and Atom Bombs in this respect, where the enormity of an atom’s natural proclivity for unity is mirrored by the effects associated with its alteration (together with cataclysmic destruction over vast areas of its geographic environment, i.e. Nagasaki).
 
 
 
 
 
 

The Recurrence of Chemical Species

Statement of the Fact. — An element under stress of chemical agencies can pass through a countless number of compounds in each of which it assumes new properties. Molecular structures are scarcely formed before nature, with higher designs, either releases their elements again, or uses them for the formation of more complex compounds. Nevertheless, in spite of these great transformations in which the distinctive characteristics of the bodies appear to be the sport of material forces, t here are invariably presented to us the same species, simple or compound, endowed with the same chemical and physical properties.

Reasons for this fact; — Among the immediate and manifest conditions to which this fact is subject, there are at least three which chemists unanimously agree in asserting to be absolutely necessary:—

• The constancy of elective affinities — Most strange and disordered aggregations would be brought into existence at every moment if the affinities of bodies were open to the whims of chance or the contingent circumstances of reactions.
• The fixity of the laws of weight, since every change in the relations of weight on the part of bodies subject to reaction has an infallible influence upon the specific characteristics of the compound.
• Since the elements are deprived in the compound of their distinctive characteristics in order to assume in common a number of new properties , it is necessary that there be in the compound itself a cause that can control the exterior action and can differentiate its effect; otherwise, the simultaneous re-appearance of the elements with their natural properties would remain inexplicable.

Mechanism, should it chose the first, can explain the re-appearance of the elements and their properties under the influence of a similar extrinsic cause; but it would contradict the principle of the conservation of energy and refuse all credence to the universal testimony of the senses which assure us of the existence of momentous changes in the elements gathered in the compound.

Should it prefer the second, it assumes a hypothesis quite incapable of explaining the fact in question. For on the one hand, the atoms when combined are deprived of their natural properties; on the other hand, because of their essential identity, they cannot have any special aptitude to receive these or those determinate properties — any specific aptitude being incompatible with homogeneity of the atomic masses.

There is then no reason why the extrinsic agent, which releases from a compound one or more of its component atoms, should invariably restore to each its original motion.

 Testing Mechanism