[CHAPTER IX]
PROTYLE: WHAT IS IT?
The notion of a primordial form of matter meets us at every stage of cosmogonical speculation. It is the outcome of an instinctive persuasion that, if we could only 'lift the painted veil' of phenomena, the real business of the universe would be found to be proceeding in the background, 'without haste or rest,' on a settled plan everywhere the same; that uniformity is fundamental, diversity only incidental; and that the transformations of the one simplified substance might be represented by a single formula, the discovery of which would place in our hands the master-key to the locked secrets of the universe. Among untutored thinkers some familiar kind of matter, idealized and generalized, commonly stood for the typical world-stuff. Water was the first favourite. Thales, the 'wise man' of Miletus, procured his cosmos by precipitation from an aqueous solution, and many savage tribes have devised analogous expedients. Anaximenes regarded air as the universal solvent; Heracleitus replaced it with fire, and set on foot a scheme of what is now often designated 'elemental evolution.' From the perpetual 'flux of things' he conceived that the four substances selected by Empedocles as the bases of nature were not exempt, and a fragment of his scheme survived in Francis Bacon's admission of the mutual convertibility of air and water. In the main, however, the author of the 'Novum Organum' adhered to the Paracelsian doctrine of an elemental triad,[52] although he regarded the association of salt as a fundamental 'principle' with sulphur and mercury as inept and unnecessary.[53]
These twilight fancies faded in the growing light of chemical science; yet the mental need that they had temporarily appeased survived, and had somehow to be satisfied. An 'Ur-Stoff' was still in demand, but the nineteenth century characteristically attempted to supply it by weight and measure. Dalton's combining equivalents afforded the warrant for Prout's hydrogen hypothesis. The problem to be faced was to find a unit-atom by the varied combinations of which all the rest of the chemical atoms might be formed. The condition indispensable to be fulfilled was that their weights should be exact multiples of that of the unit, and it came near to fulfilment by the hydrogen-atom or semi-atom. It was, nevertheless, a case in which approximate agreement was of no avail; the adverse decision of the balance finally became unmistakable; and Prout discreetly fell back, in 1831,[54] upon the expedient of deriving hydrogen itself from some body lower in the scale. His hypothesis, in short, dissolved into a conjecture. It had only emphasized the stipulation that the 'protyle' of the ancients must be such as would serve not only for the physical unification of the sum of things, but likewise as the substratum of all the chemical species.
Meanwhile, the theoretical search for it had been carried on in widely different fields of inquiry. Laplace's speculations, no less than Herschel's observations, had led to the conception of some kind of 'fire-mist' as the genuine star-plasm. But its nature and properties remained indefinite, or were assigned at the arbitrary choice of adventurous cosmogonists. So the 'shining fluid' of space was 'everything by turns and nothing long,' until Sir William Huggins, in 1864, gave it spectroscopic individuality. The 'recognition-mark' of nebulium is a vivid green ray, by the emission of which it is known to have a concrete existence. Yet the little that has besides been learned about it discountenances its identification with the materia informis of antique philosophy. This we should expect to be the subtlest of all substances. Professor Campbell, however, has gathered indications that nebulium is denser than hydrogen. Its luminosity, at least, which is invariably associated with that of hydrogen, spreads less widely in the same formations; it is confined to a lower level. The nebulium-atom is not, then, the chemical or the cosmical unit.
This evasive entity, or something that curiously simulates it, has proved to be of less recondite origin. Sir William Crookes is amply justified in claiming the venerable designation of protyle for the 'radiant matter' first produced in his vacuum-tubes nearly thirty years ago. The discovery was astonishing and unsought, and its significance has not yet been measured. Matter assumes the 'fourth state,' in which it is neither solid, liquid, nor gaseous,[55] under the compulsion of an electric discharge in high vacua. At an exhaustion of about one-millionth of an atmosphere the manner of its transit abruptly alters. Conduction gives way to convection. Luminous effects are abolished. The tubes cease to glow with brilliant, parti-coloured striæ; the poles are no longer marked by shimmering halos or brushes; only a green phosphorescence is seen where the glass walls of the receptacle are struck by the stream of projected particles. They come, with half the velocity of light, exclusively from the negative pole, the positive pole remaining inert. Hence the name 'cathode-rays,' bestowed by Goldstein on the carriers of electricity in highly-exhausted bulbs.