MODERN ALCHEMISTS.

New Zealand Herald, Volume LVIII, Issue 17932, 7 November 1921, Page 9

MODERN ALCHEMISTS.

-*■ • CONSTITUTION OF MATTER. NEW LIGHT ON THE ATOM. Tho scientific conception of the universe now perceives all matter as consisting of tho samo units. These units are electrons, particles of very small mass with a negative charge of electricity, and protons, particles with a positive charge and with mass roughly equivalent to that of a hydrogen atom. The properties and qualities of tho elements depend on tho numbor and arrangement of tho units contained in their atoms. Tho differences, therefore, are physical, depending on mass, electric charge, and arrangement. Scienco, it would seem, is. on tho ovo of another great simplification in its conception of the fabric of the universe, by the explanation of chemical " laws" in terras of physical laws. In one sense it is a justification by experimental scienco of the theory which underlay alchemy, says a correspondent of the London Times. The old alchemists believed in tho possibility of transmuting (ho "baser" metals into gold. By incantations and crucibles, with magic rites and strong acids thoy explored the properties of matter, hoping to discover the secret which would make them masters of tho world. Doubtless thero is a lone flop between knowing the ingredients of tho elenionts and ability to change 0110 into another; a very long step, as it involves "monkeying" with tho prodigious subatomic forces. But the progress achieved has led to a conception of matter very different from that which people now middle-aged learnt at school. Twenty-fivo years ago wc believed that the stuff of the universe was composed of ultimate, indivisible particles called atoms, each stamped with its own properties and impossible to break up into anything else. Each of the elements— oxygen, gold, sulphur, carbon, and so forth—had its own kind of atom, so that all matter consisted of combinations of a limited number of different kinds of atoms. Thoso already known and those whoso discovery might bo anticipated amounted to undor 100 in all. But already thero was a suspicion that tho elements wero not altogether unrelated. They could bo arranged according to their atomic weights in a certain order, an ascending spiral in which tho chemical properties corresponded with tho position of the elements on tho curvo. Clearly tho order was more than accidental, for the properties and position of unknown elements were predicted and tho prediction confirmed by later actual discoveries. Clearly also it was tho kind of ordor to bo expected if thero had been an evolution of the olcmcnts from somo primitive substance, or if thoso of lesser weight had conio into existence by the disintegration of thoso that wero heavier. Moreover, the periodic law was not absolute. Irregularities existed as if another factor were at work, something capricious such as exists in tho evolution of living forms, or something to suggest that somo of tho elements might not bo clcmenlary. Lastly, analysis by tho spectroscope indicated in thu most direct fashion that tho elements wcro uot tho ultima to constituents of mutter. Tho discovery of radium with its startling property of instability, tho discovery that it could give off helium, and that radioactivity could induce tho disintegration of other elements, turned speculations into certainties. Physicists can now understand how tho elements can bo built up out of the samo materials and yrt havo different chemical qualities. Their present task is simply lo tit physical explanations to chemical observations. Each atom is an ordered planetary system. The central " sun " is a proton .surrounded by tho orbit of 0110 or more electrons, and each system is kopt stable by the balancing of tho positive charge of electricity on the proton with the sum of tho negative charges on tho electrons. The masses of tho proton and of the, electrons and tho charges they carry can be measured. Sir J. J. Thomson has calculated tho conditions of stability for such systems with varying numbers of revolving electrons. Ho finds that systems with from ono up to eight electrons can have stable orbits of tho same diameter, but that further electron* can bo added only in an outer layer up to eight, and so on until atoms with an indefinite number of :hdli con be pictured. 1 1