electricity is at first sight very surprising, but the deeper we pursue our inquiries the more this fundamental difference between the units of positive and negative electricity is emphasised. In fact, as we shall see later, the atoms are quite unsymmetrical structures with regard to the positive and negative units contained in them, and indeed it seems certain that if there were not this difference in mass between the two units, matter, as we know it, could not exist.

It is natural to inquire what explanation can be given of this striking difference in mass of the two units. I think all scientific men are convinced that the small mass of the negative electron is to be entirely associated with the energy of its electrical structure, so that the electron may be regarded as a disembodied atom of negative electricity. We know that an electron in motion, in addition to possessing an electric field, also generates a magnetic field around it, and energy in the electromagnetic form is stored in the medium and moves with it. This gives the electron an apparent or electrical mass, which, while nearly constant for slow speeds, increases rapidly as its velocity approaches that of light. This increase of mass is in good accord with calculation, whether based on the ordinary electrical theory or on the theory of relativity. Now we know that the hydrogen atom is the lightest of all atoms, and is presumably the simplest in structure, and that the charged hydrogen atom, which we shall see is to be regarded as the hydrogen nucleus, carries a unit positive charge. It is thus natural to suppose that the hydrogen nucleus is the atom of positive electricity, or positive electron, analogous to the negative electron, but differing from it in mass. Electrical theory shows that the mass of a given charge of electricity increases with the concentration, and the greater mass of the hydrogen nucleus would be accounted for if its size were much smaller than that of the electron. Such a conclusion is supported by evidence obtained from the study of the close collisions of a particles with hydrogen nuclei. It is found that the hydrogen nucleus must be of minute size. of radius less than the electron, which is usually supposed to be about 10-13 cms. ; also the experimental evidence is not inconsistent with the view that the hydrogen nucleus may actually be much smaller than the electron.

While the greater mass of the posi

tive atom of electricity may be explained in this way, we are still left with the enigma why the two units of electricity should differ so markedly in this respect. In the present state of our knowledge it does not seem possible to push this inquiry further, or to discuss the problem of the relation of these two units.

We shall see that there is the strongest evidence that the atoms of matter are built up to these two electrical units, viz., the electron and the hydrogen nucleus or proton, as it is usually called when it forms. part of the structure of any atom. It is probable that these two are the fundamental and indivisible units which build up our universe, but we may reserve in our mind the possibility that further inquiry may some day show that these units are ccmplex, and divisible into even more fundamental entities. On the views we have outlined the mass of the atom is the sum of the electrical masses of the individual charged units composing its structure, and there is no need to assume that any other kind of mass exists. At the same time, it is to be borne in mind that the actual mass of an atom may be somewhat less than the sum of the masses of component positive and negative electrons when in the free state. On account of the very close proximity of the charged units in the nucleus of an atom, and the consequent disturbance of the electric and magnetic field surrounding them, such a decrease of mass is to be anticipated on general theoretical grounds.

Unfortunately, Einstein's expression was shown to hold only in a quantitative manner, and further correction was necessary. This was undertaken by Debye.

The fallacy in Einstein's investigation lay in this way: Einstein assumed for the sake of simplicity that a vibrating particle only gives rise to monochromatic light and absorbs such; Debye, observing this, worked out an expression for atomic heat on the basis of absorption and emission of a number of vibration frequencies covering, as a matter of fact, the whole spectrum. He assumed firstly, that a vibrating atom in a solid cannot vibrate simply in S.H.M. with one frequency, but owing to the effect of other neighbouring atoms and the probability of collision, assumes a complex mode of vibration; the complex vibration being calculated by the method of Fourier. If the temperature, T, be a multiple of a for a substance,

characteristic constant

T

T

(4)

which is Debye's equation.

Debye's formula subjected to experimental tests proved to agree exceedingly well with experimental results.

Two theories which deserve mention before we pass on to the Rutherford Bohr theory, are the theories of Bjerrum and of Kruger.

The Bjerrum theory has been of considerable use in the question of the rotawater vapour tional spectrum of structed by Eucken.

con

Kruger's theory can be regarded as a modification of the Rutherford Bohr theory or, to be more accurate, an application of it.

Kruger accepts Rutherford's theory of atoms, and regards gaseous molecules as gyroscopic in nature, meaning that molecular rotation is regarded as impossible. and molecules are only capable of carrying out precessional vibrations. These vibrations are regarded as being fundamentally different from the ordinary vibrations of atoms along the line forming their centres.

Considering molecular collision, Kruger postulates that the ring of rotating electrons of a Bohr atom, which serve to hold two atoms in union, suffers displacement in a direction perpendicular to the direction of motion, with the ultimate result that the atoms themselves describe small circular or approximately circular orbit and thus the molecule as one whole exhibits a precessional kind of motion.

Further, Kruger points out that such motion is wholly kinetic in nature, and involves two degrees of freedom. Now in the range of temperature in which the principle of equipartition is known to hold good, the energy term will be one corresponding to two degrees of freedom, and one degree

1

2

=

RT; therefore the energy is R.T. which

is identical with the energy which Bjerrum postulated for diatomic molecules on the basis of molecular rotation as a whole over the same temperature region.

Kruger's theory possesses the advantage that it furnishes an explanation of the behaviour of monoatomic gases, viz., the behaviour of inert gases such as argon.

We now come to one of the most important pieces of work on the quantum theory, namely, Bohr's application of the quantum theory to the Rutherford Atom Model: and it seems necessary to give first a vague outline of the Rutherford Bohr theory of the atom.

as

Briefly the theory can be described follows: We consider the atom as consisting of a nuclear charge surrounded by a series of electrons rotating in definite orbits, nearly the whole mass being ascribed to the nucleus. The nucleus is very small in itself as compared with the whole volume of the atom. The outer row of electrons are those which gave the atom its characteristic chemical properties, such as valency, etc. The electrons on Rutherford's atom are regarded as "atmosphere" electrons. The above is a rough postulation of the Rutherford atom as conceived by its inventor in 1911.

Bohr pointed out that the above atom suffered from the drawback of a system of "atmosphere" electrons, a system unstable from the point of view of classical electrodynamics, but if Planck's conception was introduced the trouble vanished, instability no longer would exist from the theoretical point of view.

Rutherford considered the hydrogen atom as follows: as consisting of a nucleus with a single electron describing a closed orbit around it. Bohr considers while the electron is in a steady state of rotating motion in the aforesaid orbit, it is neither radiating nor absorbing energy. Radiation he con

siders to be the result of electron transference from one orbit to another. The quantum theory assumes that during the passage of the electron from one stable orbit to another homogeneous radiation is given out or absorbed at a definite frequency, and the amount given out or absorbed is hv. where h is Planck's constant.

The equations deduced from this are familiar ones, viz.:

which gives the frequency of the homogeneous radiation emitted by a gas when the atomic system changes from a stationary state defined by 7, to one 72.

By taking the expression and putting 72 = 2 and allowing 7, to vary, we get the Balmar series of lines of hydrogen spectrum. This is the most definite proof of the Bohr theory, and has therefore an effect on the corresponding quantum theory.

We have two more matters to consider briefly with regard to the quantum hypothesis, and they are: the photo electric effect and the Nernst heat theorem, in their relation to the quantum hypothesis: these we shall deal briefly with in the respective order: Photo-electric effect and Quantum Theory; Nernst Heat Theorem and Quantum Theory.

Some forty years ago what we call the "photo electric effect" was obtained by Hallwachs, who showed a charged body exposed to ultra violet light loses its charge. In the photo-electric effect we apparently deal with two phenomena: firstly, the normal photo-electric effect, and secondly the selective photo-electric effect. The effect produced moving electrons set free at surface depends on, firstly, the number of electrons emitted in unit time, and secondly on the speed of these electrons.

One of the most striking parts of the photo-electric effect is that the speed of electrons is the same for a given frequency of light independent of the intensity of the light, and more than this, on keeping the intensity constant and varying the quality of the light the speed of the electrons increases as the frequency increases. These facts have found an explanation on the quantum theory, in which, as we have seen, we regard light as heterogeneous. Sir J. J. Thomson enunciated the view we hold of the problem roughly as follows: Radiant energy which travels out from a source with a wave is not spread uniformly over the wave front, but is concentrated on those parts of the front where the pulses travel

we

along the lines of force. The energy of the wave, therefore, tends to become collected into regions, these regions being portions of lines of force occupied by pulses. The distribution of energy appears to be analogous almost to the old emission theory, the energy being located on moving particles sparsely distributed throughout space. The energy appearing in bundles and the energy content of such bundles being constant during travelling along lines of force. Thus when light falls on a metal plate, if the distance of the source is increased, diminish the number of bundles falling on given area, but the energy in individual units will not be diminished, but any effect which is produced will be less frequent but of the same character as before. Ladenburg recently found that the velocities of corpuscles emitted under the action of ultra violet light of varied wave lengths, varies continuously with the frequency, hence the velocity is proportional to the frequency, hence although the velocity of corpuscles is independent of the intensity of the lights, it varies apparently in a continuous manner with the quality of the light; this clearly renders it impossible to consider the corpuscles as being expelled by the explosion of the molecule

Einstein gave the expression:

Ve = mv2 = hv hv。 to the quantitative relation between the theory of quantum and the photo-electric effect where mv2 is the K.E. of an electron emitted by light of frequency, v, v, is the threshold frequency.

Einstein's law, which can be stated as follows, "When a photochemical reaction. takes place owing to the absorption of radiation in terms of quanta, each single molecule of a photosensitive substance requiring just one quantum hv.. in order that it may be decomposed," has been investigated by Bodenstein, who found the law to break down badly, because one quantum is apparently capable of decomposing several molecules. Baley has dealt with this problem, and his argument is essentially follows: that in the case of a dissolved substance which reacts photochemically. less energy is required per molecule than is required for the same substance in a gaseous state, and hence Einstein's law will only hold for the gaseous state.

as

We now consider our last problem, namely the relation between the Nernst Heat Theorem and the Quantum Hypothesis. The application of the quantum hypo

In composing this article, I have followed more or less the treatment of the subject by Lewis in Vol. III. of his System of Physical Chemistry." Space unfortunately has prevented the production of anything but the mistiest of misty outlines of the subject. Many things of importance have been no more than mentioned; many more have not even been mentioned. The mathematics I have openly shirked. The only hope which I express for the article is that it may have dispelled amongst some chemists the fear and awe which the title. "Quantum Theory," appears to have for many of us who are research organic chemists, and not mathematical physicists.

AMERICAN DYE PRODUCTION. THE DEMAND FOR STANDARDISATION. Prior to the war Germany dominated the world's dye markets, producing about three-fourths of all synthetic dyes. Of the remaining fourth about one-half were made of German intermediates, and consequently the production of these dyes was dependent upon Germany. Soon after the declaration of war the supply of German dyes was cut off from the world's markets. An acute dye famine developed, threatening the activities of the vast textile and other industries dependent upon dyes for their operation. Prices increased to previously unheard of levels, and certain dyes were not to be had at any price. During and since the war the United States, the United Kingdom and France have made extensive developments in the manufacture of dyes, and have exported dyes in significant quantities since the signing of the Armistice. The complete German monopoly of the world's dye production has been broken at least temporarily, if not permanently. Extensive developments in dye manufacture in the various countries have resulted in an approximate doubling of the world's capacity to produce synthetic dyes, and sharp competition may be expected in the world's dye markets. It is already in evidence in the Far East.

The German dye industry. for instance, offers a united front to the world in a combination known as the I.G. (Interessen Gemeinschaft). It possesses the advantage of cumulated experience, lower manufacturing costs, and a unified organisation for buying and selling. The three Swiss dye manufacturers have also formed an ainalgamation. China leads the world as a consumer of dyes with a consumption estimated at about 70 million lbs. per annum; the United States ranks second with an average consumption of about 55 million lbs., followed by the United Kingdom with a consumption of nearly 50 million lbs. per year. It is expected that Germany will make every endeavour to recover a part of her former trade with these three dye consuming nations. In case protective measures are retained by the new dye producing countries Germany may resort to the establishment of factories or seek affiliations, as has already been done by the Swiss manufacturers in establishing plants in poth the United States and the United Kingdom.

The foregoing has been taken from an advance summary* of the Report on the annual Census of Dyes and other Synthetic Organic Chemicals recently completed by the United States Tariff Commission. The following statement of the dye industry of the United States has been extracted from the same source:

GROWTH OF DYE PRODUCTION.

The Report shows that during the year 1922 the domestic dye and organic chemical industry made notable progress. Many products were manufactured for the first time in the United States, and there were large increases in the quantity of production, with conspicuous reductions in prices.

The domestic production of dyes during the year by 87 firms was 64,632,187 lb., an increase of 66 per cent. over that of 1921. The sales for 1922 totalled 69,107,105 lb., valued at 41,463,790 dols. The size of the industry in 1922 was in sharp contrast with that of 1914, when only seven firms manufactured a total of 6,619,2 lb., valued at 2,470,096 dols. The dye industry in that period was in no sense a self-contained one, as the dyes produced were made almost entirely of intermediates imported chiefly from Germany. The increase in production during 1922 was largely due to an expansion in general business. Beginning about June the textile and other dye-consuming industries became more active after the depression, and during the remainder of the year the demand for dyes steadily increased.

LARGE PRICE REDUCTIONS.

The average selling price of all domestic dyes for 1922 was 60 cents. per lb., compared with 83 cents in 1921 and 1 dol. 26 cents per lb. in 1917. The 1922 figures represent a 28 per cent. decline from that of 1921. There were price reductions for both the bulk colours and dyes consumed in smaller quantities. The average price of indigo in 1921 was 45 cents per lb., compared with 24 cents in 1922, a 47 per cent. decrease.

INCREASED OUTPUT OF VAT AND ALIZARIN DYES.

One of the conspicuous developments of the year was the increased production of vat and alizarin dyes. The vat colours are of great complexity and have presented serious difficulties in their commercial production. Their use is on the increase, as the public is beginning to recognise that