A meeting of the Doncaster Scientific Society was held at the Mansion House, on Wednesday, February 23rd, when a paper on “The Constitution of Matter,” was read by Mr. A, Abbott, B.A. The following is a digest of the essay.

The question of the constitution of matter has occupied the minds of men during all ages. The earliest theories of which we know anything are those put forward by the Greek philosophers. Empedocles, in the year 440 B. C. suggested that all things are made up of four elements – air, earth, fire and water. To these four, Aristotle added a fifth, which he called “being”. This was an immaterial substance, and was the basis of all substances, bodies differing from one another in possessing more or less of the original four elements combined with it.

It is easy to see how theories of this kind led, in later times, to the vain attempts of the alchemists to transform one substance into another. Owing to the great authority of the Greeks in mental science, their views passed unchallenged for centuries. It is probable that they themselves were not the originators of the opinions which they held, but that they owed them to the Hindus.

In the fifth century, Democritus supposed that all matter is made up of small parts, which he called atoms, and which differed from one another in number and size, but not in the nature of their substance. He maintained that they were infinite in number, and infinitely variable in form. He considered that they were in motion from their very nature, while Ananagoras believed that they were kept in motion by mental power.

The doctrine of atoms was further developed by Epicurus and Lucretius. There was then, at the very origin of atomic ideas, a distinction drawn between matter and space, “vacuum” and “plenum”.

The opposite hypothesis to this, viz., that of the continuity of matter, was held by Descartes, who said that matter fills all space, but that it possesses various degrees of density. Various theories were put forward at the beginning of this century by German philosophers, one of the most interesting, in the light of later ideas, being that all space is filled with a continuous mass, through which waves are transmitted in various directions. Wherever these waves meet, they form nodal points, and these nodal points are atoms.

Newton believed that “God in the beginning formed matter in solid massv, hard impenetrable, moveable particles.” None of the preceding theories was, however, based on experiment, and it was left to John Dalton, of Manchester, to bring forward, in 1904, a chemical atomic theory based on the laws of definite proportion and of multiple proportions. According to his theory, all chemical compounds are produced by the union of one or more atoms of one element with one or more atoms of other elements. In the compound these atoms still exist, but have their properties modified. This theory, it can be safely said, has been the most fruitful ever introduced into the branch of science.

From the earliest times, the idea that all matter is derived originally from one primary substance has haunted the minds of philosophers, and in 1815 Prout came to the conclusion, from a study of the relative weights of the elementary atoms, that all elements are formed by the condensation of Hydrogen, the lightest known element. Later researches on atomic weights shew that while those of many elements are certainly exact multiples of that of Hydrogen, many of them differ from it, and Prout’s hypothesis has therefore been abandoned, the result being due, to a great extent, to the work of Stas, who devoted his whole life to the exact determination of 19 atomic weights.

Between 1860 and 1870 a great impetus was given to the consideration of the nature of the elements by the discovery of the “Periodic Law” bt Newlands, Lothar Meyer, and Mendelejeff, who showed that if the elements be arranged in the order of their atomic weights, each element resembles in properties that separated from it by an interval of six other elements. By means of this law, Mendelejeff was enabled to predict the existence of three new elements which were afterwards discovered. The properties of each were identical with those predicted by Mendelejeff. In 1886, Sir William Crookes summed up the evidence for the theory that all elements are derived from one primary substance, which he called ”protyle.”
(1) The possibility that 70 elements, which have come into gortuitious existence, should reveal such remarkable relationships, as are made manifest by the Periodic Law, is very small.
(2) Elements which are very much alike in properties and between which there is no chemical affinity are often found near one another.
(3) The existence of groups of elements (radicals) which behave exactly like elements, seems to point to the possibility of the elementary atoms possessing a compound nature.
Crookes considered that before the earth began to cool down, everything was in an Nitra-gaseous state, and that there was only one king of matter. As this cooled down, the first step in granulation took place and the atoms were formed, those of smallest weight being formed first.

The theory of atoms is now universally held, and various theories have been brought forward as to their form, size, and mode of motion. Although very small, they are not infinitely small, but are indivisible. They attract each other with a force known as chemical affinity, which is possible related to gravity. This force gives rise to the formation of groups of atoms, known as molecules.

According to the Kinetic theory of gasses of which Democritus had some idea, but when was first definitely brought forward by Daniel Bernouilli, gasses are composed of small particles moving with a very high velocity in straight lines, colliding with and rebounding from other particles, and from the sides of the containing vessel. The theory has been developed by various physicists, and Clausius has calculated the velocity of the molecules of various gasses, (that of the molecules of Hydrogen being over a mile a second) as well as the length of the average free path of a molecule. Besides this molecular motion, it is believed that the atoms have a motion of their own within the molecules. Both motions are accelerated by heat. Lord Kelvin has endeavoured by several different methods to calculate the size of a molecule. He came to the conclusion that if a drop of water were magnified to the size of the earth, then a group of molecules would possess a size something between that od a heap of small shot and a heap of footballs. That atoms must be very small, is shewn by the fact that a single grain of musk will scent a large room, while Hofmann proved that rosaniline dye will impart a distinct tinge to 100 million times its own weight of alcohol.

Recently a theory known as that of “Vortex Atoms” has arisen; it is due to Lord Kelvin. Everyone is familiar with the rings made by some smokers. Each particle in one of these rings has a definite circular path, about a circular axis, while the axis itself moves in a straight line. Helmholz shewed that in a perfect fluid, free from friction, such a vortex ring would be indestructible. It might change its form, but the connection of its constituent parts would never be broken. Lord Kelvin considers that this perfect medium and these vortex rings represent the universe. A fluid fills all space, and what we call matter are simply portions of the fluid animated with vortex motion. These portions are atoms. Of all hypothesis this is the most probable. In it is revived the old hypothesis of the unity of matter, which has proved so fascinating to philosophers in all times. In spite of the fact that the hypothesis is still the same as was held hundreds of years ago, and in spite of the fact that our ideas on the construction of matter are still vague and uncertain, we can fairly claim that our knowledge is advancing, and can hope that at some future period this problem, apparently insoluble, may be made clear.